Masters Degrees (Animal Sciences)

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Allometric description of ostrich (Struthio camelus var. domesticus) growth and development
(Stellenbosch : University of Stellenbosch, 2011-03) Kritzinger, Werne Jacobus; Brand, T. S.; Hoffman, Louwrens C.; Mellett, F. D.; University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The ostrich industry has overcome many challenges since it originated. However, it is still vulnerable to sudden changes in customer preferences and economic cycles. As feed costs are the greatest expense in ostrich production, optimising feed formulations is vital. This will be possible if the growth and development of the ostrich can be simulated by modelling software. Various studies were conducted to describe ostrich growth in the form of equations that can be used in modelling software to increase the accuracy of predictions. In the first study, birds were given the choice of four diets with varying energy (8.5 or 13.5 MJ ME/kg feed) and protein (180 or 120 g/kg feed) levels. The birds preferred the high density diet (high energy and protein) in each growth phase. A growth curve of assumed optimal growth was constructed. The chemical fractions of the body were shown to increase non-linearly with advancing age and equations were established to predict the change of the body composition over time. In the second trial, birds received a formulated growth diet and were fed according to their nutrient requirements. Growth data was collected on the separate body components of maturing birds. Feather and skin nodule growth was defined for birds hatched in the summer. Allometric equations were set up to determine, predict and model the ostrich skin size and skin weight, some bones, some organs and the commercially valuable muscles through the growth cycle. The final trial was conducted to determine the effect of diet density (energy and amino acid level) on the growth of ostrich body components. A four-stage, 3 x 5 (energy x protein) factorial design was developed with varying energy and protein feeding regimes. Protein (amino acid) level had no influence on body component growth. Energy level had no effect on feather growth, skin nodule growth, bone and organ growth and muscle growth. Increased levels of dietary energy increased the skin size and skin weight. Increasing the dietary energy level also had a significant effect on the total body fat of the birds. Allometric equations were set up for each variable to predict the effect of diet on ostrich growth. Results in this study provide a framework for simulation modelling. Predicting ostrich growth and development is paramount to accurate diet formulations and lower feeding costs.
Determination of the nutrient requirements of breeding ostriches
(Stellenbosch : University of Stellenbosch, 2010-03) Olivier, Theodore Riel; Brand, T. S.; Gous, R. M.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The nutrient requirements for breeding ostriches are currently not well-defined. Quantification of the nutrient requirements will improve the financial wellbeing of the industry. A study of the growth of the reproductive organs and liver, together with various production studies, were therefore undertaken in order to gain knowledge about the nutrition of breeding ostriches, thereby quantifying the nutrient requirements of breeding ostriches. Various studies were conducted to determine the influence of dietary protein, amino acids and energy on production levels of breeding ostriches. In a first study, five diets, varying in crude protein (CP) but with a constant energy content of 9.2 MJ ME/kg feed, were provided at a feed intake level of 2.5 kg/bird/day. The dietary CP levels were 7.5%, 9.1%, 10.8%, 12.3% and 14.0%. No differences (P>0.05) between treatments (total eggs per female per season) were found for number of unfertilized eggs (eggs per female per season; 8.9±0.8), dead-in-shell chicks (8.0±0.5), number of chicks hatched (19.1±1.1) and change in mass of females (-16.2±1.6kg). A tendency was observed for a difference in total egg production (mean and standard error; 39.1±3.6; P=0.08). The 12.3% CP diet caused the lowest (P<0.05) change in live mass (-3.8±2kg) for male birds. No interaction (P>0.05) occurred between the genotype of the bird and the dietary protein concentration for both egg and chick production. In a second study, six diets varying in ME (MJ ME/kg feed), were provided at an average feed intake level of 3.4 kg/bird/day. The levels were 7.5, 8.0, 8.5, 9.0, 9.5 and 10.0 MJ ME/kg feed respectively. No differences (P>0.05) were observed for total eggs produced per female per season (44.8±7.8), number of chicks hatched (15.4±4.1), number of infertile eggs (11.5±3.8), number of dead-in-shell eggs (12.1±3.2) and change in mass of females (10.7±3.6kg). Males increased linearly (y=2.4x + 2.45; R2=0.09; P<0.05) in live mass as the dietary energy content increased. Two eggs per diet per month were analyzed for crude protein, crude fat and trace elements, and one egg per diet per month was analyzed for fatty acid composition. Eggs from the first and last month of the season were subjected to amino acid analysis. Analysis of variance showed no difference in crude protein and fat (P>0.05) content of eggs between the experimental diets, as well as for the calcium content of eggshells. The proline content differed (P<0.05) between the diets. The C18:3n-3 (linoleic acid) content of the eggs increased (P<0.05) amongst the dietary treatments. Crude protein, fat and C18:3n-3 content in eggs increased (P<0.05) for the number of the egg in the laying cycle. In a third study, the feed intake of breeding ostriches, as affected by dietary energy content was investigated. Average feed intake (kg feed/bird/day) was not affected (P>0.05) at any dietary energy level when levels of 8.0, 8.7, 9.4, 10.1, 10.8 and 11.5 MJ ME/kg feed were provided. The mean and standard error was 3.7±0.2kg. The production of breeding female ostriches was not influenced by dietary ME and protein at these feed intake levels. Ostrich birds do not have the ability to regulate their feed intake at any dietary energy level as used in this study. The amount of nutrients deposited in the eggs had no influence on the reproductive efficiency of the breeding female ostrich. The experiments also revealed that female breeding ostriches were independent of dietary energy and protein as used in this study for the mean frequency of egg laying at various dietary protein and energy levels (P>0.05). In a fourth study, the growth and development of the reproductive organs of female birds at the onset of the breeding season were investigated. The amount of nutrients needs to be determined in order to support the growth of the reproductive organs during the breeding season, due to the fact that these organs are linked to egg production. It was thus necessary to investigate whether the reproductive organs grew and developed during a season. The first slaughter interval was conducted at the start of the breeding season. The ovary, oviduct and liver were collected, weighed after each slaughter and analyzed. Ovary and oviduct were analyzed for crude protein and fat. No differences (P>0.05) were observed between the different slaughter intervals for the mass, crude protein and fat content of both organs. No trend (P>0.05) in the weight of the oviduct could be observed over the 49-day period, this weight being highly correlated with body weight; whereas the ovary weight tended to be correlated with the time after the onset of the breeding period, although the variation in weights, both within and between weighings, was very high. The variation in the weight of the ovary probably reflects differences in the laying pattern of individuals. The number of follicles were not affected (P>0.05) by the number of days after mating. Livers were assessed for crude protein and fat, but no difference (P>0.05) was detected between the intervals, but the weight difference amongst the slaughter intervals was significant (P<0.05), suggesting that the ostriches used liver reserves to supplement nutrients that obtained from the diet for the development of the reproductive organs. This data will be used in an optimising model (Brand & Gous, 2006) to predict the nutrient requirements of female breeding ostriches. This study suggests that the female breeding ostrich might need additional protein during the first 7 weeks of the breeding season. Results from Chapter 4 and previous studies were used to calculate the energy, protein and amino acid requirements for the egg production and maintenance of the breeding female ostrich. Two methods were used to determine the energy requirement for egg production. The Metabolisable Energy requirement for egg production (MEe) and efficiency of ME utilization for energy deposition in the egg (ko) was calculated as 12.2 MJ (for an average size egg of 1.4kg) and 0.8 respectively. The Effective Energy requirement for egg production (EEe) and maintenance (EEm) was calculated as 15.9 MJ/day and 17.1 MJ/day respectively. Average total daily protein requirement (TPt) was calculated as 175g day. The amino acid requirements for maintenance and egg production is also provided, which is lower than previous studies. This study also provides evidence that the nutrient requirements are different for every month of the breeding season.
Developing a model for feedlot production of Boer goat slaughter kids
(Stellenbosch : Stellenbosch University, 2015-12) Van der Merwe, Daniel Andre; Brand, T. S.; Hoffman, Louwrens C.; Raffrenato, Emiliano; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: In this study, the effects of energy content of the feedlot diet as well as the length of the production period were investigated for Boer goat slaughter kids. The kids were housed in individual pens on the Elsenburg experimental farm, Western Cape, South Africa. Boer goat castrate kids were weaned at approximately 18 weeks of age (weighing 22.2 ± 3.5 kg) and were randomly allocated to one of three trial diets that varied in energy content; namely a low, medium and high energy diet (11.3, 12.0 and 12.7 MJ ME/ kg feed respectively) which were supplied ad libitum. The goats were further randomly allocated to one of five slaughter groups that were slaughtered at five week intervals at a commercial abattoir. The first group of goats was slaughtered at the start of the trial in order to serve as a baseline reference. During the study the effects of dietary energy content, and time spent in the feedlot were investigated for the feedlot production and slaughter characteristics of Boer goat kids. Additionally the effect of the energy content of the feedlot diets on the sensory and chemical properties of goat meat were evaluated. During the production period individual feed intake and live weight gain were monitored on a weekly basis. It was observed that live weight of the goats increased throughout the production period. Quadratic functions were used to describe the change in average daily gain and dry matter intake of the goats during the feeding period. Goats that were fed the low and medium energy diets exhibited higher daily gains (P= 0.02) and dry matter intakes (P< 0.01) than goats on the high energy diets. Dietary energy content and age of the animal in the feedlot did not influence the feed conversion ratio to produce a unit of live weight. A linear function was used to model the growth of the goats during this production period. The goats were not able to reach the point of inflection on the growth curve. Therefore the sigmoidal growth curve could not be plotted which could have been modelled by a function similar to the Gompertz model. Dressing percentages of the carcasses varied throughout the production period for all the diets, with goats on the low energy diet having the lowest dressing percentage (45.8%; P= 0.04). The energy content of the trial diets had no effect on the yield of the offal components and retail cuts of the carcass. Generally it was observed that the yields of the hindquarter and neck cuts decreased whilst that of the forequarter increased with the age of the goats at slaughter. The degree of carcass fatness increased with time spent in the feedlot, with the majority of fat being deposited in the abdominal cavity, rather than in the subcutaneous fat depot. Dietary energy content was expected to influence the levels of intramuscular fat, which in turn would affect the eating quality of the meat. However, the levels of energy in the diets fed to goats did not influence the tenderness, juiciness or the aroma and flavour profiles of the goat meat as observed during descriptive sensory analysis of the meat by a trained panel. Chemical analysis of the cooked meat samples also showed that the levels of intramuscular fat did not vary between the samples, resulting in the lack of differences detected between treatments in the sensory evaluation.
Development of a model for crossbred lamb production
(Stellenbosch : Stellenbosch University, 2021-12) Theron, Pietert Gert; Brand, T. S.; Cloete, Schalk W. P.; Van Zyl, Johan Hendrik Combrink ; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Historically the sheep industry has played an important role in the South African agricultural landscape, but due to changing circumstances and growing challenges it may find its continued survival under threat. Producers will therefore need to find ways of improving production output and efficiency to meet these challenges. This study therefore aimed to collect production data of crossbred sheep in order to construct predictive models that could be used as part of a precision livestock farming (PLF) system by producers. Two common wool producing breeds, the Dohne Merino and Merino, were selected as dam lines for this experiment. A mixed flock of these ewes were divided into breed specific groups of 20 and each group then mated to rams of their own breeds or with Dorper, Dormer or Ile de France rams as the most important meat and terminal sire breeds. This resulted in two purebred control lines (Dohne Merino and Merino) and six crossbred trial lines (Dohne x Dorper, Dohne x Dormer, Dohne x Ile de France, Merino x Dorper, Merino x Dormer and Merino x Ile de France) being produced. Four rams and four ewes of each genotype were reared under optimal growth conditions until one year of age. During this time growth, fat deposition and intake data were collected. The data thus generated were assessed with various regression models to predict growth and fat deposition as well as feed intake. The Gompertz growth model provided the best fit for the growth data while a linear regression of age on fat depth was the most accurate in predicting fat deposition rate. An accurate model for cumulative feed intake over the growth period was also constructed. At the end of this period the lambs were shorn and wool traits of economic importance assessed. The remaining lambs were weaned at ~31 kg and reared on pastures with no supplementary feed being provided until they were deemed slaughter ready at 4 mm of backfat depth (A2 carcass classification). The growth of these lambs was also monitored and subsequently modelled, where the Logistic model provided the best fit. Upon achieving slaughter readiness, the lambs were slaughtered and selected slaughter and carcass traits recorded. Overall it was found that rams outperformed ewes for the production traits studied. This is due to sexual dimorphism benefiting rams for these traits. Crossbred lambs also had a significant advantage over their purebred contemporaries for all the traits except feed efficiency and wool quality. This was attributable to a combination of heterosis for these traits as well as breed dimorphism between the smaller dam and larger sire lines. The increased degree of breed dimorphism between Merinos and the sire breeds meant that the improvement in the performance of crossbred Merino lambs relative to the dam line was greater than the corresponding performance improvement in Dohne Merinos. It is concluded that crossbreeding offers a viable method of improving commercial production efficiency in South African Dohne Merino and Merino flocks. Producers who wish to implement a PLF system for a terminal crossbreeding enterprise can now do so using guidelines from this study. It is advised that further work be done on various crossbreeding options to expand the current local knowledge. More crosses could be included in future research while more complete models for pasture-rearing systems would also be of benefit to the industry.
Effect of cottonseed oilcake meal on ostrich growth performance, meat chemical composition and sensory attributes
(Stellenbosch : Stellenbosch University, 2012-12) Schoon, Katryn; Hoffman, Louwrens C.; Brand, T. S.; Dalle Zotte, A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: This research study consists of three investigations with regard to ostrich (Struthio camelus var. domesticus) production, meat quality and the processing of ostrich meat into a value added meat product. The first study was conducted in order to establish whether the gradual replacement of soybean oilcake meal with cottonseed oilcake meal (CSOCM) as a protein source in the diet of slaughter ostriches would affect ostrich growth performance and meat quality. A total of 105 ostriches were divided into five feeding groups according to the CSOCM inclusion level: Control (0% CSOCM), 3%, 6%, 9% and 12% CSOCM, and fed with experimental diets from 6 to 13 months of age. As a result of feeding CSOCM, the final live weight and the average daily gain significantly increased in the 12% CSOCM group compared to the other treatment diets. The proximate composition, cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Considering all the results, CSOCM may be used as an alternative protein source to soybean oilcake meal in ostrich nutrition, resulting in decreased feed costs. Secondly, a descriptive sensory analysis, together with chemical and physical measurements, was performed to determine whether the manipulation of the fatty acid composition in the fan fillet (Iliofibularis muscle) as a result of feeding CSOCM would be detected on a sensory level. Two levels of CSOCM were investigated; 0% as a control and 9% CSOCM. No significant differences were found for the physical measurements (cooking loss (%) and shear force) as well as for the pH and proximate composition of the raw fan fillet. The Control group presented a higher (P<0.05) mono-unsaturated fatty acid (MUFA) content in the cooked fan fillet whereas the 9% CSOCM group showed a favourable increased (P<0.05) poly-unsaturated fatty acid (PUFA) content when compared to the cooked Control samples. As a result, the poly-unsaturated:saturated fatty acid (PUFA:SFA) ratio in the 9% CSOCM group was also higher (P<0.05). No differences (P>0.05) were found between the treatments for the n-6:n-3 (omega 6 to omega 3) ratio. The 9% CSOCM group had a more intense beef aroma, had a higher level of initial and sustained juiciness as well as increased tenderness (P<0.05). Inclusion of 9% CSOCM resulted in a favourable cooked ostrich fan fillet. Finally, the effect of feeding CSOCM on a processed ostrich meat product was investigated. Fan fillet (Iliofibularis muscle) from 13 month old birds receiving no cottonseed oilcake meal (Control) or 9% cottonseed oilcake meal (9% CSOCM) was used. Olive oil was used as a replacement for pork fat, and warthog (Phacochoerus africanus) meat was used to replace commercial pork meat in the production of a semi dry sausage, cabanossi. Olive oil was included at three levels (0%, 1% and 2%). Six treatments were investigated: Control 0% olive oil, Control 1% olive oil, Control 2% olive oil, 9% CSOCM 1% olive oil, 9% CSOCM 2% olive oil en 9% CSOCM 2% olive oil. The Control and 9% CSOCM ostrich meat did not differ significantly in chemical composition nor fatty acid profile. After smoking and drying the fat content in the cabanossi containing 0%, 1% and 2% olive oil averaged 7.2%, 7.45% and 8.65% respectively. Processed meat products containing less than 10% fat are classified as a low-fat meat product. Olive oil is a mono-unsaturated vegetable oil containing mainly Oleic acid (C18:1n9c), and low quantities of saturated fatty acids and polyunsaturated fatty acids. Total mono unsaturated fatty acids in the cabanossi increased from 47.0% to 73.0% of total fat, whilst total saturated fatty acids and total polyunsaturated fatty acids decreased from 40.6% to 19.9% and 11.6% to 6.6% respectively as olive oil increased from 0% to 2%. The inclusion of olive oil at 2% resulted in cabanossi with increased (P<0.05) tenderness, juiciness and cured red meat colour, all factors that appeal greatly to the consumer. Overall flavour was not adversely affected by the inclusion of olive oil. This investigation indicated that the use of CSOCM had no negative effect on the production performance of ostriches whilst a 9% CSOCM inclusion level resulted in meat that was found to be favourable by a trained sensory panel. Furthermore, the use of CSOCM as a feed component also had no negative effect on a processed product (cabanossi) derived from the meat obtained from the birds fed this feed component. The CSOCM used in this investigation had low levels of gossypol (10 to 20ppm) and more research is required on the effect of the use of CSOCM with higher levels of gossypol on the production performance of ostriches.
Effect of dietary energy and protein on the production parameters of slaughter ostriches (Struthio camelus var. domesticus)
(Stellenbosch : Stellenbosch University, 2015-12) Viviers, Swys Francois; Brand, T. S.; Hoffman, Louwrens C.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: When modern man assumed the responsibility of domesticating animals for his own purposes, he directly accepted the responsibility associated with feeding and caring for them. Considering intensive production systems, nutrition is one of the most important aspects in maintaining healthy livestock as well as ensuring profitability is achieved. This is due to the fact that the feeding of the livestock is often the most expensive overhead cost encountered. In ostrich production systems, nutrition costs total an estimated 70 – 80% of the costs associated with rearing the birds from chick to slaughter. When dissecting the typical composition of these ostrich diets, it becomes evident energy and protein are two of the most important, and abundant, nutrients found. Therefore, this study was conducted to investigate the effects of different concentrations of protein and energy in the diets of slaughter ostriches, on their production parameters. In the first study (Chapter 3), five diets with different protein concentrations were formulated across the four feeding phases of slaughter ostriches (pre-starter, starter, grower and finisher). Three replications per treatment were conducted resulting in 15 camps of ostriches. Significant differences (P < 0.05) were found in the live weights of the birds at the end of each feeding phase except the finisher phase. In terms of the production parameters, differences (P < 0.05) were found for the dry matter intake (DMI), average daily gain (ADG) and the feed conversion ratio (FCR). Results indicated that the birds on the middle diet (control) and on the diets containing proportionally higher protein concentrations, although not different from each other, consistently outperformed those on diets containing lower concentrations of protein. These trends were also evident when comparing the cold carcass and thigh weights of the treatment birds post-slaughter. Therefore, from a financial standpoint, it could be concluded that increasing the protein content of the diets beyond that level currently used in industry (control) is not sensible. The second study (Chapter 4) was an evaluation on the primary products harvested from the birds utilized in the first study, namely the feathers, skin and meat. The aim of the investigation was to determine if the dietary protein concentrations had any effect on these products. No differences (P > 0.05) were observed across the feather yields or classes measured, except for the ‘tail feathers’, where the birds fed the lowest protein levels in their diets yielded the fewest. Differences (P < 0.05) were however found in selected skin parameters measured. Decreased dietary protein resulted in smaller wet skin size, smaller sizes of the feather nodules, as well as smaller crust size after the tanning process was completed. However, this had no impact (P > 0.05) on the skin grades achieved. Hence it became clear that dietary protein has an impact on the skin size achieved, which did not translate into differences in skin quality. Similarly, it did not affect the feather yields or quality. Energy is the most important nutrient in livestock diets as it is the first limiting nutrient influencing intake. Therefore, in the third study (Chapter 5), treatments in the form of five different levels of energy in the diets of ostriches, were investigated. Structurally, the layout was similar to the first study with three replications per treatment yielding 15 camps of ostriches. Significant differences (P < 0.05) were found between the live weights of the birds after the pre-starter phase, but not overall after the completion of the trial. The middle diet (diet 3) containing 14.5 MJ ME/kg displayed the highest gains per day of 216.0 ± 8.08 g per chick. The results of the growth were mirrored in the production parameters (DMI, ADG, FCR), where no differences (P > 0.05) were found for the rest of the feeding phases. In a follow up investigation of the effects of dietary, this chapter focused on the impact these different energy levels (Chapter 5) had on the primary products harvested after slaughter (Chapter 6). In particular, the feather yield and quality, skin yield and selected quality parameters, as well as the chemical composition of the meat was studied. No differences were found (P > 0.05) across any of the feather yields or classes measured. Concerning the skin yields and quality, similar results were found with no differences (P > 0.05) between the crust sizes or grades. With regards to the proximate composition of the meat, no major effect (P > 0.05) was found as a result of the treatment diets. Therefore, dietary energy content exhibited little influence over the feather, skin and meat parameters measured in this study.
The effect of dietary energy content and the provision of a β-adrenergic agonist in the diet, on the production and meat quality of South African Mutton Merino feedlot lambs
(Stellenbosch : Stellenbosch University, 2014-12) Genis, Maria Petronella; Hoffman, Louwrens C.; Brand, T. S.; Stellenbosch University. Faculty of AgricSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Two studies were conducted on Elsenburg Experimental Farm, Western Cape, South Africa. The aim of these trials was to determine the following: 1) the effect of dietary energy as well as the inclusion of a β-adrenergic agonist (β- AA) on the production of South African Mutton Merino (SAMM) feedlot lambs 2) the effect of the trial diets on the rumen pH 3) the effect of varying dietary energy levels and the inclusion of a β-AA in the diet on the relationship between slaughter weight, commercial cut yield and bone:fat:muscle ratio of SAMM feedlot lambs 4) the effect of dietary energy as well as the inclusion/absence of a β-AA on the meat quality of SAMM feedlot lambs 5) the effect of dietary energy as well as the inclusion/absence of a β-AA on the sensory, physical and chemical characteristics of SAMM feedlot lambs. To quantify the effects of these parameters the study was conducted in two separate experiments. In the first experiment one hundred and eight (108) SAMM lambs, weaned at ca 120 days of age of different gender (rams and ewes) were housed in individual pens for approximately 6 weeks. The treatments consisted of three different dietary energy level diets (high – 12.7 ME MJ/kg, medium – 12.0 ME MJ/kg and low 11.3 ME ME/kg) with either the inclusion or absence of a β-AA (Zilpaterol hydrochloride, at 8.6 g/ton) in the diet. The experiment was arranged as a 2 x 2 x 3 factorial design with gender (rams or ewes), β-AA (provided or not) and dietary energy level (low, medium or high) as main factors. In the second experiment one hundred and twenty (120) SAMM lambs, weaned at ca 120 days of age of different gender (wethers or ewes) were housed in individual pens for approximately 6 weeks. The treatments consisted of three different dietary energy level diets (low – 11.3 ME MJ/kg, medium – 12.0 ME MJ/kg and high – 12.7 ME MJ/kg). The experiment was arranged as a 2 x 3 factorial design with gender (wethers or ewes) and dietary energy level (high, medium or low) as main factors. Where no interaction occurred the data is presented as the effect of dietary energy level, β-AA and gender on parameters. Three ruminally cannulated sheep were used for measuring the rumen pH. No differences were found between the three experimental diets on the rumen pH. Overall a gradual decline in pH from the time the animals were fed was observed. Dietary energy level only affected the dressing percentage in the first experiment, while it affected several parameters in the second experiment. The β-AA had no significant (P>0.05) effect on any parameters. While gender significantly (P<0.05) effect several of the production and carcass yield parameters. Main effects dietary energy and gender affected the leg yield and fat percentage in the bone:muscle:fat relationship respectively. While positive correlations between slaughter weight and the following parameters were observed: carcass weight, leg yield, shoulder yield, neck yield, flank yield and cranial fat thickness. Beta-adrenergic agonists are commonly used in livestock production to enhance meat production and decrease the fat content of the body. Beta-adrenergic agonists normally improve growth performance and enhance a leaner carcass. The factors β-AA and dietary energy level had no effect on the proximate composition of the loin, fat thickness or the tenderness of the meat. The ewes had a significant higher fat content than the ram lambs. The meat of the ram lambs was less tender than the meat from the ewe lambs. The acceptability of meat is dependent on the toughness (chewiness and resistance), flavour (aroma and taste) and succulence (juiciness) of the meat. It is known that dietary energy as well as the inclusion of a β-adrenergic agonist may influence the sensory, physical and chemical characteristics of the meat. No significant differences (P>0.05) due to dietary energy level or the inclusion of the β-AA were found for the physical characteristics of the meat. There were, however significant (P<0.05) differences found during the sensory testing for tenderness between gender (76.2% for ewes vs 72.9% for rams) and between the β- agonist groups (75.4% vs 72.9% for the inclusion of the β-AA). Sustained juiciness was also affected (P<0.05) by gender (68.0% for ewes vs 65.7% for rams) and the inclusion of a β- agonist groups (67.9% absent vs 65.8% included). Overall it was concluded that, of all three main effects, gender had affected the meat attributes the most.
The effect of different levels of supplementary feed on the production of finisher ostriches (Struthio camelus) grazing irrigated lucerne (Medicago sativa) pastures
(Stellenbosch : University of Stellenbosch, 2010-12) Strydom, Marline; Brand, T. S.; Van Heerden, J. M.; Jordaan, J. W.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The purpose of this study was to evaluate the production of slaughter ostriches in a grazing environment at different levels of supplementary feed. Two grazing trials were conducted. In the first trial, one group of finisher ostriches (six months old) was put into a feedlot and received a complete finisher diet. The other four groups were allowed to graze lucerne pasture (stocking rate of 15 birds/ha) with 1500, 1000, 500, and 0g supplementary feed/bird/day. Pasture production and intake were measured. There was no difference (P >0.05) between the end mean live weights of the feedlot ostriches and those two grazing groups receiving 1500 or 1000g supplementation. The average daily gain (ADG) of the group receiving 1000g supplementation was lower (P <0.05) than the ADG of the group receiving 1500g supplementation, but all three groups reached a mean target slaughter weight of 95kg within the 154 days of the study. Therefore, pastures together with the correct supplementation (at least 1000g/bird/day) can replace complete feeds in the finishing phase of slaughter ostriches and can play an important role in the production of these birds. For lucerne intake, a quadratic relationship (P <0.01) was found between pasture dry matter (DM) intake (g/bird/day) and supplementary feed intake (g/bird/day). The maximum lucerne intake level (1692.8g/bird/day) was achieved at 619.6g supplementary feed/bird/day. In the second grazing trial, finisher ostriches were allowed to graze lucerne pastures at two different stocking rates (10 and 15 birds/ha) while receiving either 0 or 800g supplementary feed/bird/day. Ostriches receiving supplementation had higher (P <0.05) mean end live weights than ostriches receiving no supplementation. Ostriches receiving supplementation reached a mean target slaughter weight of 95kg within the timespan of the trial, but ostriches receiving no supplementation did not. Stocking rate had no influence on mean end live weight of the birds. An interaction (P <0.05) was found between the level of supplementation and stocking rate for ADG of the birds. Stocking rate influenced ADG only for birds receiving no supplementation. As stocking rate increased, ADG of birds receiving no supplementation declined. Results of the pasture data indicated an increasing level of replacement of grazed lucerne DM by supplementary feed as the trial progressed and this was more pronounced at the higher stocking rate of 15 birds per hectare. A high stocking rate seems to have had a gradual depressing effect on lucerne DM production, while the less severe levels of defoliation at a lower stocking rate promoted lucerne DM production. A digestibility trial was conducted with mature ostriches (12 months old) to investigate the effect of supplementation on intake and digestibility of nutrients, as well as to investigate the substitution effect that ostriches may display when they receive supplementary feed in addition to grazing. The same dietary treatments as in the first grazing study were given to ostriches while they were kept in metabolism crates. These diets were also fed to 20-week old roosters to obtain energy values for these diets for roosters. These energy values would be used to predict ostrich energy values for the same diets by means of a regression equation. For the roosters, each diet treatment was mixed with 50% maize to prevent digestive disorders and ensure maximum feed intake. Ostriches started to substitute supplementary feed for pasture when supplementation was supplied at levels higher than 62% (i.e. 1000g supplementary feed/bird/day) of total feed intake. For each increase of 100g in supplementary feed intake, pasture was replaced at a rate of 4.9%. Higher (P <0.05) total feed intakes were reached by ostriches if they grazed lucerne pastures and received supplementation than if they grazed pasture alone. Pasture grazing alone had lower (P <0.05) dry matter digestibility (DMD) and apparent metabolizable energy (AME) values for both ostriches and roosters than if pastures were supplied with a supplement. A significant stepwise regression could not be computed for the prediction of ostrich AME values from rooster AME values. The economics of different feeding systems (extensive versus intensive) were evaluated with an economic analysis, which was based on the same materials and methods and results of the first grazing trial. A margin above feed cost (MAFC) analysis was performed to evaluate the economic viability of the different feeding systems. The present value (PV) of the MAFC for the pasture-based system with 1000g/bird/day supplementation was only 8.3% lower than that of the feedlot system over a period of six years, while the PV of the cost of the same pasture-based system was 78.4% lower than that of the feedlot system. Birds finished on lucerne pasture with 1000g supplementation led to a saving of 57% in feeding costs if compared to a feedlot system. A sensitivity analysis of the MAFC revealed that the pasture-based system was less sensitive to changes in feeding costs than the feedlot system. Therefore, the unique circumstances of each ostrich producer will play a role in the decision whether to raise ostriches in a feedlot or on pastures.
The effect of extrusion with molasses and addition of chitosan or tannins on the rumen undegradable protein fraction of plant protein sources
(Stellenbosch : Stellenbosch University, 2020-12) Jordaan, Leanne; Brand, T. S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Protein is one of the most expensive nutrients in livestock diets. Therefore, it is essential to pursue the efficiency of protein utilisation in ruminant diets. The inclusion of plant protein sources such as lupins and oilcakes in ruminant diets is limited due to high rumen degradable protein (RDP) content as it does not supply enough rumen undegradable protein (RUP) and amino acids for high producing ruminants. One way of improving nitrogen and thus protein efficiency may be to reduce the dietary protein degradation in the rumen, thereby increasing the proportion of RUP. Therefore, by protecting the protein from degradation in the rumen, it would increase the supply of amino acids to the small intestine. This could also reduce nitrogen wastage through excretion in urine, which renders more protein, especially essential amino acids, available for absorption to increase animal production parameters including growth, milk and wool production. The process of extrusion and the addition of a polymer (such as chitosan) or a polyphenol (such as tannins) have shown potential to reduce the rumen degradability of plant protein sources to increase the nutritional value thereof for ruminants. The aim of the current study was, therefore, to increase the RUP fraction of plant protein sources (lupins, canola oilcake meal and soybean oilcake meal) through extrusion (hot and cold) with molasses and the addition of a polymer (chitosan) and polyphenols (hydrolysable tannins). The effect of extrusion and addition of chitosan and tannins on the dry matter (DM) and crude protein (CP) rumen degradability were determined with the in situ technique, using Dohne Merino wethers weighing ±80 kg, fitted with rumen cannula. The sheep had ad libitum access to clean drinking water and a basal diet of wheat straw and lucerne hay (50:50) during the experimental period. Samples were incubated in the rumen of the sheep in polyester bags at different intervals over several periods during the four different trials. For the first study, lupin samples of L. albus and L. angustifolius were extruded at maximum temperature reaching 116 °C. Extrusion lowered the soluble fraction while increasing the potential degradable fraction without affecting the rate of degradation of the potential degradable fraction of CP. Extrusion significantly lowered the effective degradability of CP of both lupins by 28% at an outflow rate of 0.08% per hour. No differences were observed between lupin types. Extrusion was found to modify ruminal degradation parameters of L. albus and L. angustifolius, while also decreasing the effective rumen degradation, especially at faster outflow rates. For the second study, the effect of extrusion with 6% molasses at 116 °C was determined with locally produced canola oilcake meal (CM) and crushed sweet lupins (CL). Extrusion significantly lowered the CP soluble fraction of CM by 62.2%. The soluble fraction of CM did not differ from CL (46.0%) and CL did not differ significantly from crushed sweet lupins extruded (CLE, 38.2%). Extrusion increased the CP potential degradable fraction by 43.5%. At each outflow rate, namely 0.02, 0.04, 0.05, 0.06 and 0.08/h, the CP effective degradability was lower for CM than for CL. The average effective degradability for CM and CL was 68.2% and 78.0%, respectively. Extrusion significantly lowered the CP effective degradability for both protein sources at every outflow rate tested. The biggest effect was seen at 0.08/h where effective degradation was lowered by 25.6%. Extrusion with molasses was found to modify ruminal degradation parameters of both canola oilcake meal and crushed sweet lupins, while also decreasing the effective rumen degradation, especially at faster outflow rates. Thereby, the combined rumen undegradable protein fraction of canola oilcake meal and crushed sweet lupins was increased by 85.4% through extrusion. The third study evaluated the effect of cold extrusion with 6% molasses and the addition of 1% chitosan on the protein degradability of soybean oilcake meal. This research showed no differences with cold extrusion or the addition of chitosan and molasses on the rumen undegradable protein fraction of soybean oilcake meal. The benefits of extrusion could not be reached with soybean oilcake meal and cold extrusion as applied in this study. The fourth study evaluated the effect of cold extrusion with 6% molasses and the addition of 1% hydrolysable tannins on the protein degradability of soybean oilcake meal. This research showed no differences with cold extrusion with molasses and the addition of 1% hydrolysable tannins on the rumen undegradable protein fraction of soybean oilcake meal. The benefits of extrusion could not be reached with soybean oilcake meal and cold extrusion as applied in this study. The RUP fraction of lupins and canola oilcake meal was increased by extrusion with molasses in this study, and therefore it could be included more efficiently in ruminant diets. This study showed that the benefits of extrusion could be reached at a relatively lower temperature of 116 °C to reduce the chance of heat damage and possible production cost. The temperatures during cold extrusion might have been too low to elicit the desired effects. Furthermore, the addition of 1% chitosan or tannins might have been too low to elicit the desired protein binding effect. Even though no significant differences were seen in this study by cold extrusion or addition of chitosan and tannins, the literature shows that chitosan and tannins have great potential as a feed additive by binding protein. However, more research is needed to fully understand the mode of action of chitosan and tannins in the rumen and the bioavailability of bound protein in the small intestine. The possibility for further improvement still exists by adjusting the processing conditions of extrusion and method of including different additives. Achieved results in the first two studies should also be tested in a biological study to determine the availability of amino acids in the RUP fractions.
The effect of lairage time and transport density on live weight losses and meat quality in slaughter ostriches
(Stellenbosch : Stellenbosch University, 2012-12) Lorenzen, Jan Frederik George; Hoffman, Louwrens C.; Brand, T. S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Although transport and lairage of ostriches are accepted causes of production losses, these losses have not yet been quantified. Transport and lairage regulations focus on the wellbeing of the birds and, by default reduce some losses. This thesis investigated weight losses and meat quality of ostriches as a result of transport density, lairage duration and lairage feed availability (ad libitum). All birds were reared on the same farm and loaded and transported together. They were randomly divided into their respective groups on loading for the transport trial, and on offloading for the lairage trial. Bird grouping was according to density for the transport trial (4 groups, H1, H2: 0.56m2/bird and L1, L2: 0.96m2/bird) and according to time spent in lairage and feed availability for the lairage trial (n=30 birds/group; L0hr and L24hr; n=15 birds/group L48hr and L48hr ad libitum feed). Behavioural observations of the ostriches showed a tendency of the ostriches to lean against objects and to orientate towards forces exerted on it to help keep its balance. Reactions to sound fluctuations were noted, with birds reacting towards changes in sound volume during transport and lairage. Timepoint numbers were allocated for each time the birds were weighed during the trial. Time points 1, 2, 3, 4 and 5 were allocated to loading, arrival, 19 hr in lairage, 31 hr in lairage and 39 hr in lairage respectively for Trial 2. Results showed no differences (P > 0.05) in live weights or meat quality parameters between Groups H1, H2, L1 and L2 during transport. Differences (P < 0.05) were found in cumulative weight losses between L0hr and the rest of the groups for time point 1. Differences between L48hr and L48hr ad libitum were found for time point 4 for cumulative weight loss. L48hr also differed significantly between the other lairage duration groups for dressing percentages as a function of loading weight. Ad libitum feed availability had a significant effect on live body weight changes but not the meat quality parameters for the groups held for 48hr in lairage. The number of birds having bruises (≈50% per group) was similar between groups and lairage had no influence on bruising. Results seem to indicate that the evaluated transport densities had no effect on the weight loss or meat quality of ostriches. However, the results indicate that the lairage period should be studied further with specific reference to weight losses during lairage. Meat quality was unaffected by the lairage parameters reported in this thesis.
The effect of slaughter age on the lamb characteristics of Merino, South African Mutton Merino and Dorper lambs
(Stellenbosch : University of Stellenbosch, 2010-03) Van der Westhuizen, E. J.; Brand, T. S.; Hoffman, Louwrens C.; Cloete, J. J. E.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this study was to investigate the effect of feedlot production on the growth and carcass characteristics, as well as the distribution of the main tissues (muscle, fat and bone) and meat quality of Merino, South African Mutton Merino (SAMM) and Dorper lambs. The Merino and SAMM 2008 outperformed (P<0.05) the 2007 SAMM and both Dorper production groups in terms of average daily gain, while the Merino and both SAMM production groups achieved the best feed conversion ratio (P<0.05). The highest percentage A2 graded carcasses was achieved after 42 days under feedlot conditions by the Merino and both Dorper production groups, but it took only 21 days in the feedlot for the SAMM lambs to achieve the same result. Slaughter weight, carcass weight and dressing percentage all increased significantly with an increase in the number of days under feedlot conditions for all three breeds, while a decrease in the percentage head, trotters and red offal was also documented. The fatter retail cuts (thick rib, flank, prime rib and loin) increased (P<0.05) in percentage with an increase in the number of days under feedlot conditions. A significant decrease in the percentage leaner retail cuts (raised shoulder and hind-quarters) was found when the amount of days under feedlot conditions increased. The highest profit is obtained by the prime rib, loin and hind-quarters in a lamb carcass. For the Merino and Dorper lambs these three cuts, or a combination of the three showed the highest combined percentages after 42 and 63 days under feedlot conditions, respectively. The late maturing SAMM lambs achieved the highest percentages for these three cuts after 63 and 84 days under feedlot conditions in 2007 and 2008 respectively. Visceral and renal fat deposition increased throughout the production period for all breeds. The Dorper lambs attained the highest subcutaneous fat depth, and also produced the heaviest, but fattest carcasses. For A2-graded carcasses, Dorper lambs had the highest dressing percentage and lowest subcutaneous fat depth, followed by the SAMM and then Merino breed. A decrease in the percentage muscle and bone was found with an increase in the number of days under feedlot conditions, whilst an increase in the percentage fat was found under the same conditions. Meat quality was mostly affected by the 48h post mortem pH. This pH value is affected by the cooling rate of the carcasses, which in turn is affected by the level of carcass fatness. Carcass fatness increased with an increase in the number of days under feedlot conditions, resulting in a low 48h post mortem pH. A low 48h post mortem pH is accompanied by higher percentages of cooking and drip loss, as well as a high a*-colour reading for all three breeds.
The effect of the dietary inclusion of canola oilcake, full-fat canola and sweet lupins on the production performance and fat composition of broilers and pigs
(Stellenbosch : University of Stellenbosch, 2005-03) Smith, Natasha; Brand, T. S.; Hoffman, Louwrens C.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences.
The demand for protein for human and animal nutrition in South Africa is increasing and it will continuously increase. The effect of replacing soybean oilcake meal as protein source for broilers and full-fat soybean meal for weaner pigs, with different levels of sweet lupins (Lupinus angustifolius), canola oilcake and full-fat canola was examined. A basal diet with soybean oilcake as protein source was mixed with a diet using either sweet lupins or canola oilcake or full-fat canola in ratios of 100%, 67% and 33% respectively. In the broiler trial the test diets were fed for a period of six weeks with or without the enzyme Vegpro (Alltech). Pigs were fed the test diets, with and without Roxazyme® enzyme, ad libitum from 8.5 to 25 kg live weight. The fatty acid content of the fat pads of the broilers raised on the different diets was determined. The pigs were kept in the trial up to the grower- finisher phase. The fatty acid content of the carcass fat and muscle of pigs raised on the different diets was determined. The inclusion of enzymes had no effect on the growth, feed intake or feed conversion ratio of broilers fed the test diets. The provision of external dietary enzymes to the weaner pig diets failed to improve either dry matter intake or growth rate, but improved the feed conversion ratio. Broiler weights at six weeks of age were significantly higher for the control diet compared to the 20% lupin diet. There was no significant difference in the feed intake as the lupin content of the diets increased. The feed conversion ratio did not differ significantly between the control diet and the 6.6% lupin diet but became significantly poorer as the lupin content increased to 13.2% and 20% of the test diet. There were no significant differences in production performance of the control diet and the canola oilcake containing diet. The broiler weights at six weeks decreased significantly with each increase in the canola oilcake content of the diets. The feed intake of the 20% canola oilcake diet at week six was significantly less than the intake of the control diet, but not significantly less than the 6.6% and 13.2% canola oilcake diets. The feed conversion ratio of the control diet was significantly better than the 13.2% and 20% canola oilcake diets. No significant differences were found in week six between the 6.6% full-fat canola diet and the control diet for broiler weights and feed intake. The feed conversion ratio of the broilers fed the 13.2% and 20% full-fat canola diets was significantly poorer than the control diet. The final body weights of the weaner piglets fed the control diet were significantly higher than the final body weights of weaner piglets fed the lupin containing diets. The average daily gain of the weaner piglets fed the control diet was significantly higher than the gain of the weaner piglets fed the lupin containing diets. No significant differences in the feed intake and feed conversion ratio between the different lupin inclusion levels were detected. There were no significant differences in body weight, feed intake, average daily gain and the feed conversion ratio, between the various full-fat canola containing diets and the control diet. A significant difference in body weight was found between the weaner piglets fed the 20% canola oilcake diet and the weaner piglets fed the control diet. There were no significant differences in feed intake between the various inclusion levels of canola oilcake. The control and 6.6% canola oilcake containing diets had significantly higher average daily gains than the 20% canola oilcake containing diet. In the final trial the finisher pigs fed the test diet containing 25.00% lupins, had a final body weight significantly lighter than the final body weight of the finisher pigs fed the other test diets. The finisher pigs fed the test diet containing 25.00% lupins, also had a significantly reduced average daily gain and feed intake. The feed intake of the 25.00% canola oilcake diet was significantly lees than the feed intake of the 16.75% full-fat canola containing diet. The feed conversion ratio of the 25.00% lupin containing diet was significantly poorer than the feed conversion ratio of the 16.75% lupin containing diet, 8.25% lupin containing diet, 16.75% full-fat canola containing diet, 25.00% canola oilcake containing diet and the control diet. In a choice feeding trial growing pigs were offered four diets with four different protein sources: sweet lupins (25% inclusion level), canola oilcake (25% inclusion level), full-fat canola (25% inclusion level) and soybean oilcake (25% inclusion level), while their daily intakes were recorded. In a second choice feeding trial pigs were offered ten different diets with increasing levels (6.6%, 13.2%, 20%) of either sweet lupins, canola oilcake meal or full-fat canola meal. The pigs consumed significantly more of the soybean oilcake containing diet compared to diets containing the alternative protein sources. Pigs consumed significantly less of the full-fat canola diet compared to the sweet lupin and canola oilcake diets. Ten different canola cultivars were collected from two different locations in the Mediterranean rainfall area of South Africa namely the Western Cape (Swartland) and Southern Cape (Rûens) grain producing areas. The sinapine and glucosinolate content of various canola cultivars was compared and the influence of locality on the sinapine and glucosinolate content of the canola cultivars was determined. There were no significant differences (P < 0.05) in sinapine content when the canola produced in the Western and Southern Cape were compared. Varola 54 and Rainbow cultivars had significantly higher (P < 0.05) sinapine contents compared to the Varola 50 cultivar. Samples of lupins, field peas, faba beans and narbon beans were collected and analysed for amino acids, alkaloids, non-starch polysaccharides, tannin and starch. The digestible energy value of these alternative protein sources for pigs was determined. Significant differences were found in the amino acid content of the various crops. The alkaloid content of the lupins varied significantly between the sweet and bitter lupin varieties. Sweet L. angustifolius cultivars contained ca 50mg/kg and the bitter L. angustifolius cultivars ca 15000mg/kg alkaloids. The mean alkaloid content of L. albus cultivars was ca 1300mg/kg. The faba beans, narbon beans and peas had significantly higher values for tannins and starch, compared to lupins.
The effect of transport on live weight loss, meat quality and blood haematology in slaughter ostriches
(Stellenbosch : University of Stellenbosch, 2011-03) Wolmarans, Wilhelm J.; Hoffman, Louwrens C.; Brand, T. S.; Smith, Carine; University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The production and export of ostrich meat from southern Africa, to especially the European Union, are increasing rapidly due to the healthy nature of ostrich meat. The European Union has very high standards when importing food products, and it is inevitable that more emphasis is being placed on the production of high quality ostrich meat. Another aspect also of concern to consumers, is the welfare of animals prior to slaughter, and this forces producers to look at ways to decrease stress of animals during the ante-mortem period. Research regarding the effect of stress during the ante-mortem period, and as a result, on meat quality, haematology and weight loss in ostriches, is lacking and thus the purpose of this study was to investigate the effect of various transport distances, travel conditions and different birds on these factors. Ante-mortem stress was measured using serum corticosterone levels (ng/ml), heterophil: lymphocyte (H:L) ratio, white blood cell (WBC) count, aspartate aminotransferase (AST) and creatine kinase (CK), as well as the rate and extent of pH decline in the M. gastrocnemius. Special emphasis was also placed on the meat quality parameters drip loss, cooking loss, colour and Warner-Bratzler shear force (kg/1.27 cm diameter). Live weight losses, as well as carcass weight and weight of bruises cut off from each bird were also recorded during various stages of the trials. The effect of transport distance on the meat quality of ostriches was investigated. Ultimate pHu measurements were taken at 24 hours post-mortem. The muscles of the ostriches from the control group (i.e. birds that were not transported prior to slaughter) had a lower mean pHu (5.77 ± 0.053) than birds that travelled 60 (5.93 ± 0.053) and 600 km (6.11 ± 0.053), respectively. Differences in meat drip loss percentage were also observed between the three treatments. The birds in the control group (0.40 ± 0.07 %) had the lowest meat drip loss percentage compared to the birds that travelled 60 km (treatment C) (1.36 ± 0.07 %) and 600 km (treatment B) (0.97 ± 0.07 %), respectively, to a commcerical ostrich abattoir. Ostriches that were transported for 600 km (8.13 ± 1.16 %) had a greater percentage live weight loss during the antemortem period than birds that travelled a distance of 60 km (2.4 ± 2.185 %) to the abattoir, although both groups were deprived of feed for the same period. When the haematology of the groups that travelled different distances was compared at various time intervals in the ante-mortem period, both groups of birds experienced significant increases in WBC, s-AST and s-CK. An increased H:L ratio from pre-transport to post-transport was only evident in the birds that travelled 600 km (treatment B). However, the birds that travelled 60 km were the only group of birds that had significant elevated serum corticosterone levels during the ante-mortem period. The increase in the various blood parameters indicates severe physical stress, which negatively affected meat quality. Another trial also investigated the effect of various farming systems and transport on meat quality and bruising of ostrich carcasses. Ostriches were raised in three different farming systems, i.e. feedlot -, semiintensive - and free range conditions. Other factors that could maybe impact on stress susceptibility, such as road conditions, floorspace and floor type were also investigated. A significant difference in meat pHu was found between ostriches that were raised in a feedlot (5.95 ± 0.018) and semi-intensive (6.04 ± 0.033) environment. The feedlot birds also had the greatest percentage of carcass weight removed due to bruising. The free range birds were the birds that had the lowest floor density per birds and also had the least amount of bruising on their carcasses. Incidently the other two groups (feedlot and semi intensive) were the birds that travelled on the same type of road (mountain pass) in a truck with rubber flooring whilst the free range birds travelled on a straight road in trucks with metal grid floors.The results indicate that the type of farming system didn’t have a significant influence on meat quality of ostriches, but that factors such as road conditions, flooring and bird density did play a significant role in the incidence of bruises and injuries obtained during transport.
The evaluation of locally produced canola oilcake meal as an alternative protein source in the diets of slaughter ostriches (Struthio camelus var. domesticus)
(Stellenbosch : Stellenbosch University, 2019-04) Van der Merwe, Johanet; Brand, T. S.; Hoffman, Louwrens C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Feeding costs make out ~75% of all expenses in an intensive ostrich production system. Protein is one of the major components in ostrich diets. Currently, the main source of protein used in animal feed is soybean oilcake meal (SOCM). This protein source is, however, expensive as it is an imported raw material. In order to decrease feeding costs a locally produced alternative source of protein; canola oilcake meal (COCM) was identified. It is important to evaluate the possible influence alternative raw materials might have on the production and slaughter traits of animals as nutrition has a direct influence on production. The use of COCM is limited in animals’ diets due to its glucosinolate content. Glucosinolates are anti-nutritional factors that reduce palatability. Therefore, a study to determine whether or not the glucosinolate content has an influence on ostriches’ feed intake was conducted. Grower ostriches in a free-choice system had access to five iso-nutritious diets with different inclusion levels of COCM, replacing SOCM in increments of 0%, 25%, 50%, 75% and 100%. The control diet (the diet with 0% inclusion of COCM) showed to be the preferred diet by having the highest average intake per bird per day over the entire trial period (736.1 ± 74.1 g/bird/day). The intake of this diet made up to 35% of the total daily intake while the diets containing COCM were consumed at levels lower than 18% of the total DMI per bird. As the preference trial showed that the inclusion of COCM in ostrich diets might have a negative influence on feed intake in a free-choice system, production and slaughter traits were evaluated in the following trial. Ostriches were reared from 77-337 days of age on five iso-nutritious diets, each with a different inclusion level of COCM, replacing 0%, 25%, 50%, 75% and 100% of SOCM, respectively. Bird weight and feed intake were measured over the entire growth period. Results showed that the replacement of SOCM with COCM had little effect on the performance of ostriches. The ostriches that were reared on the diet replacing 75% of SOCM had the best performance in terms of slaughter and production traits. Typically, production of the end-products (feather, leather and meat yield and quality) is directly influenced by nutrition. The replacement of SOCM with COCM had no influence on the production and quality characteristics of feathers, skin or meat. This study concludes that the COCM can be used as a cheaper alternative protein source in the diets of slaughter ostriches without having any detrimental effect on growth, production parameters and slaughter traits. This will not only be beneficial to the ostrich industry but it will also benefit the local grain industry.
The evaluation of locally produced full-fat canola seed (Brassica napus) as an alternative protein source in the diets of slaughter ostriches (Struthio camelus var. domesticus)
(Stellenbosch : Stellenbosch University, 2018-03) Niemann, Gert Jacobus; Hoffman, Louwrens C.; Brand, T. S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Ostriches are multi-purpose animals, producing feathers, leather and meat that contribute to the income generated from slaughter ostrich production. Compared to other domesticated farm animals, knowledge of the nutritional requirements of ostriches has been very limited, until recently. Together with simulation models this knowledge gained is being used to formulate least cost, nutrient specific rations for ostriches in different production phases. In an effort to reduce feeding costs, which make up the largest expense (ca. 75%) in an intensive ostrich production unit, the use of alternative protein sources are being explored to replace the more expensive protein sources that make up a large portion of the diet. Full-fat canola seed (FFCS) is one such locally produced protein source that has the potential to replace current protein sources such as soybean oilcake meal. However, it is unclear whether ostriches will readily consume canola, due to its anti-nutritional factors, and what effect its consumption may have on animal performance. The feeding preference (Chapter 3) of ostriches towards canola was established by placing 60 South African Black ostriches (82.2 ± 1.06 kg in live weight, 233 days of age) in ten camps of six birds per camp. Each camp had five identical feed troughs, each containing diets, where FFCS incrementally (0, 25, 50%, 75 and 100% of protein source) replaced the soybean oilcake meal (9.8% of the total diet composition in control diet) as protein source. Feed and water were made available ad libitum. Dry matter intake (DMI) was measured on a daily basis and feed colour characteristics were measured based on CIE L*, a* and b* colour attributes. Only the 25%FFCS (25% soybean oilcake meal replacement diet) showed a higher DMI (817.4 ± 81.98 g/bird/day) than the other diets (average of 488.8 ± 81.98 g/bird/day). While there were slight differences between some of the colour attributes, it is believed to have had no effect on DMI. Based on the results of this study, FFCS can be used to replace 25% soybean oilcake meal without any negative effect on DMI; resulting in an inclusion level of 6.8% FFCS in ostrich diets. To evaluate to what extent FFCS can be utilised in the diets of slaughter ostriches, 187 day old South African Black ostrich chicks were randomly divided into 15 groups (9 - 12 animals per group). The growth trial (Chapter 4)commenced at the onset of the starter phase when the chicks were 84 days of age weighing 24.7 ± 0.36kg. Five iso-nutritional treatment diets with varying levels of FFCS were randomly allocated to the groups with three replications per treatment diet. Birds were reared according to standard practises and slaughtered at 309 days of age (93.2 ± 1.82 kg). Within each feeding phase, FFCS incrementally (0%, 25%, 50%, 75% and 100% of protein source) replaced the soybean oilcake meal as protein source. Feed and water were supplied ad libitum. Dry matter intake, average daily gain (ADG), feed conversion ratio (FCR) and end weights were recorded with in each phase and over the entire trial period, as well as slaughter traits. No differences were observed regarding production traits during the starter and finisher phases. Dry matter intake during the grower phase was lowest (P =0.01) for the 100% replacement of soybean oilcake meal (100%FFCS) (1.52 kg/bird/day). The rest of the diets with an average DMI of 1.80 kg /bird/day did not differ. The 100%FFCS also showed the slowest growth (P =0.01) (152.0 g/bird/day) during the grower phase, and did not differ from 25%FFCS (208.9 g/bird/day) and 75%FFCS (209.5 g/bird/day) diets. With the 0%FFCS (236.2 g/bird/day) and 50%FFCS (267.8 g/bird/day) diets resulting in higher ADG. End weights during the grower phase for the 0%FFCS, 25%FFCS, 50%FFCS and 75%FFCS (74.8, 72.2, 76.8 and 72.5 kg respectively) did not differ from each other. The 100%FFCS resulted in lower end weights (67.4 kg), although not differing from the 25%FFCS and 75%FFCS. For the overall trial period the only differences observed, were within ADG, with the 0%FFCS, 50%FFCS and 75%FFCS replacement diets showing the fastest growth and the 100%FFCS, although not differing from the 25%FFCS and 75%FFCS diets, resulted in the slowest growth. Fat pad weight was the only slaughter trait that revealed differences between diets, with the 50%FFCS resulting in the heaviest fat pad weights. Based on these results, it is recommended that a maximum of 20.6% inclusion (75%FFCS) of FFCS be used in diets during the grower phase as it may lead to reduced performance when exceeded. Although in the other phases, FFCS can be included up to the maximum levels evaluated (100% replacement of soybean oilcake meal) without any detrimental effects. The aim of the study in Chapter 5 was to evaluate the effect of different dietary FFCS inclusion levels on the feathers, leather and meat composition of slaughter ostriches. The end products of the South African Black ostriches slaughtered in Chapter 4 were used during this trial. The only differences between diets regarding feather yields were within chick body short (P =0.021) and unmarketable feathers (P =0.011). The 50%FFCS resulted in the heavier yields of chick body short feathers (283.2 ± 14.84 g), however, it did not differ from the 0%FFCS, 25%FFCS and 75%FFCS. The 100%FFCS resulted in lighter yields (202.3 ± 14.84 g) of chick body short feathers, although not differing from the 75%FFCS. The 50%FFCS had the lightest yield (97.1 ± 13.18 g)of unmarketable feathers, differing from all the other diets. The rest of the diets did not differ and yielded anaverage of 161.2 ± 13.18 g unmarketable feathers. Skin thickness was the only leather trait showing differences (P =0.038) between diets. With the 0%FFCS resulting in thicker skins (0.65 ± 0.027 mm), not differing from the 25%FFCS and 50%FFCS diets. The 100%FFCS resulted in thinner skins (0.53 ± 0.027 mm), not differing from the 50%FFCS or 75%FFCS diets. Moisture and protein concentration of the meat were the only chemical components showing differences (P =0.008 and P =0.004, respectively) between diets. Meat from the 100%FFCS was found to have higher moisture concentrations (77.0 ± 0.29%). The 25%FFCS meat resulted in the lowest mean moisture concentration (75.2 ± 0.24%), not differing from the 0% and 50%FFCS meat. The inverse of moisture concentration could be seen with regards to protein concentration where the 25%FFCS diet resulted in the highest meat protein concentration (22.6 ± 0.19%), not differing from the 0%FFCS and 50%FFCS diets’ meat. The 100%FFCS diet resulted in the lowest (20.9 ± 0.23%) meat protein concentration. Dietary FFCS inclusion had beneficial effects on the fatty acid profile of the abdominal fat tissue. Total saturated fatty acids concentrations decreased from 37.8% (0%FFCS) to 20.3% (100%FFCS) of total identified fatty acids. Total MUFA concentrations increased from 39.7% for the 0%FFCS fed birds to 51.0% for the 100%FFCS fed birds. The total PUFA concentrations also increased from 22.1% for the 0%FFCS fed birds to 28.7% for the 100%FFCS fed birds. These changes resulted in the PUFA:SFA ratios to increase from 0.60 (0%FFCS) to 1.43 (100%FFCS). Both n-6 and n-3 fatty acids increased with an increase in FFCS inclusion, however the n-6:n-3 ratio showed a beneficial decrease from 3.20 for the 0%FFCS fed birds to 2.28 for the 100%FFCS birds. Overall it is recommended that full-fat canola seed can be used to replace up to 75% (not exceeding inclusion levels used within each growth phase in this trial) of the soybean oilcake meal in slaughter ostrich diets. Prescribed replacement of soybean oilcake meal with FFCS can be done without affecting growth of ostriches or the quality of end products, and achieve similar results as current standard commercial diets.
The evaluation of lupins (Lupinus angustifolius) as alternative protein source in ostrich (Struthio camelus var. domesticus) diets
(Stellenbosch : Stellenbosch University, 2016-12) Jacomina Aletta, Engelbrecht; Hoffman, Louwrens C.; Brand, T. S.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: In an intensive ostrich production unit, one of the highest cost components is nutrition, contributing ca. 75% to the total input costs. Energy and protein are the two most important and abundant nutrients found in a balanced diet, with the protein component being the most expensive per unit weight. This study was conducted to evaluate the inclusion of lupins (Lupinus angustifolius) as an alternative protein source to soybean oilcake meal in ostrich (Struthio camelus var. domesticus) diets. In the first study (chapter 3) production performance and slaughter traits were studied at different dietary lupin inclusion levels that replaced soybean oilcake meal. There were five dietary treatments with three replications of between 15 – 17 chicks each. The chicks all received the same pre-starter diet. Five iso-nutritional diets were formulated for each feeding phase (starter, grower and finisher) using Mixit2+ software according to specifications set out for each of the different feeding phases Within each feeding phase these diets contained either soybean oilcake meal (control diet; 0LD) or sweet lupins (alternative protein source; diets 25LD, 50LD, 75LD and 100LD) as the primary protein source. The 100 lupin diet (LD) was formulated to include the maximum amount of sweet lupins according to the specifications for the specific species and the feeding phase. The maximum amount of lupins included in the 100LD therefore differs between the three feeding phases. The remaining three diets were formulated by mixing the diets to determine the gradual increase in lupins in the diets from 0LD up to 100LD. Soybean oilcake meal was thus gradually replaced by sweet lupins in the following ratios: 100:0 (0LD), 75:25 (25LD), 50:50 (50LD), 25:75 (75LD) and 0:100 (100LD) to make up the five dietary treatments for each feeding phase. No differences were found in the live weight of the birds at the end of each feeding phase or in the dry matter intake (DMI), average daily gain (ADG) or feed conversion ratio (FCR). The end weight (P = 0.07) and ADG (P = 0.09) for the starter phase tended to be higher for the birds on the 75LD. Birds fed the 50LD and 75LD tended (P = 0.08) to have the heaviest cold carcass weights, although dressing percentages did not differ. Birds receiving the 50LD diet had somewhat heavier (P = 0.05) thighs than those on the other diets. No differences were found for the weight of the big drum muscles of the birds. It was concluded that soybean oilcake meal can be replaced by sweet lupins in starter diets by up to 15% lupin inclusion in the diet (75LD) and in grower and finisher diets by up to 30% lupin inclusion in diet (100LD) without any significant detrimental effect on the production and slaughter traits. The second study (chapter 4) evaluated the three primary ostrich products (leather, meat and feathers) to clarify whether the lupin inclusion levels had any effect on these products. Birds used in this study were the same birds as described in chapter 1. No differences were found for the marketable feather classes and measured leather traits, but the leather was thicker (P < 0.05) for birds fed the 25LD. This corresponds with the heavier slaughter weight of the birds on the 25LD, although this was not significant. No differences were found in the chemical composition of the meat, apart from a higher (P < 0.05) intra-muscular fat content being found for birds on the 50LD. It can be concluded that the sweet lupin inclusion levels evaluated in this study had little influence on the leather traits, chemical composition of the meat of the birds measured (ten birds per treatment were selected around the median for chemical analysis of their meat) and the feather classes. In the third study (chapter 5), 60 South African Black growing ostriches were randomly divided into 10 paddocks with six birds per paddock. Three trials with five experimental diets per trial were conducted to investigate the effect of sweet and/or bitter lupins on the feed preference of growing ostriches in a free-choice system. In Trial 1 (sweet) and Trial 2 (bitter), lupins replaced soybean oilcake meal in a step-wise manner for inclusion levels of 0%, 7.5%, 15%, 22.5% and 30%. In Trial 3, the soybean oilcake meal was replaced with 0%, 15% sweet, 15% bitter, 30% sweet and 30% bitter lupin inclusion levels. The position of the feeders containing each diet in successive paddocks changed by rotating the five feed troughs in a clockwise direction, but within each paddock the specific position of each feeder and diet stayed the same throughout the three trials. No interaction was found between day and diet for the three trials. The DMI per diet did not differ between the five treatments in any of the three trials. However, in trial 2 the birds showed a tendency (P = 0.11) to prefer the 7.5% bitter lupin diet to the 15% and 30% diets. The results showed that soybean oilcake meal can be replaced in the diets of growing ostriches by sweet lupin inclusion of up to 30% without any significant detrimental effect on feed preference and intake. The tendency (P = 0.11) of the birds to discriminate to some extend against the 15% and 30% bitter lupin diets may warrant further research. This study found that lupins can be used without compromising growth or product quality in ostriches, making them a viable economic alternative.
Studies on the environmental and genetic parameters for lamb survival, growth and wool traits of the Elsenburg Dormer and SA Mutton Merino flocks
(Stellenbosch : Stellenbosch University, 2020-12) Muller, Anieka; Cloete, Schalk W. P.; Brand, T. S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Environmental and genetic parameters and trends of the Elsenburg South African Mutton Merino (SAMM) and Dormer resource flocks were estimated. The breeds were also compared for lamb survival, growth, wool, carcass and meat quality traits. Early growth and lamb survival data over a 64-year period (1955 - 2019) and yearling weight and wool data over a 36-year period (1983 - 2019) were used in the study for SAMM sheep. Single-trait heritability estimates of SAMM lambs amounted to 0.07 for birth weight (BW), 0.03 for weaning weight (WW), 0.02 for lamb survival (LS), 0.24 for yearling weight (YW), 0.58 for clean yield (CY), 0.37 for clean fleece weight (CFW), 0.34 for staple length (SL), 0.55 for coefficient of variation of fibre diameter (CVFD) and 0.68 for fibre diameter (FD). Maternal heritability estimates were 0.15 for BW, 0.06 for WW and 0.01 for LS. Multi-trait heritability estimates compared well with the single-trait estimates. Genetic correlations among weight traits ranged from 0.04 for BW and YW to 0.81 for WW and YW. Low to moderate correlations among yearling traits accorded with previous literature for wool breeds. Genetic trends showed favourable but extremely slow genetic responses. Data from 1943 to 2019 were used to investigate genetic and environmental parameters and trends for early growth traits and LS in the Dormer flock. Yearling live weight- and wool traits were recorded for a shorter period from 2008 to 2018. Direct single-trait heritability estimates were 0.15 for BW, 0.06 for WW, 0.02 for LS, 0.19 for YW, 0.63 for CY, 0.56 for CFW, 0.59 for SL, 0.59 for SS, 0.60 for CVFD and 0.80 for FD. Maternal genetic effects amounted to 0.21 for BW, 0.08 for WW and 0.06 for YW. Genetic correlations among live weight traits ranged from low (-0.11) between BW and YW to very high (0.93) for WW and YW. Genetic correlations among wool traits were mostly low. Genetic trends for all weight traits suggested significant positive trends with time. Expressed relative to the overall phenotypic mean, these trends amounted to 0.12% for BW, 0.16% for WW and 0.45% for YW. Selection from 2013 for direct-, maternal- and a combination of direct and maternal breeding values up to 2019 resulted in genetic trends amounting to 0.07% for BW, 0.79% for WW and 1.01% for YW in the line selected on direct breeding values for WW. Corresponding genetic trends amounted to respectively -0.51%, 0.17% and 0.27% in the line selected on maternal breeding values for WW and respectively -0.20%, 0.41% and 0.58% in the line selected for a combination of direct and maternal breeding values. Maternal genetic trends were markedly smaller in magnitude even in those lines were selection was based on maternal breeding values. Results indicated that SAMM lambs were heavier at birth compared to their Dormer contemporaries (4.19 vs. 4.13 kg). Dormers were heavier than SAMMs at weaning (27.3 vs. 25.0 kg) and also when weighed as yearlings (49.7 vs. 47.8 kg). Dormer lambs had a higher survival rate than SAMM lambs at 0.89 and 0.81, respectively. Clean fleece weight was the only wool trait not affected by breed. Dormer yearlings had a higher CY and SL than SAMM yearlings. In contrast, SAMM yearlings had a lower CVFD and finer wool than their Dormer contemporaries (respectively 22.4 vs. 28.6 μm). The two breeds did not differ for slaughter weight, carcass weight or dressing percentage. Dormers had a thicker subcutaneous fat cover at the rump than SAMM contemporaries (5.00 vs 4.18 mm). It was concluded that all traits considered were variable and heritable, although selection responses to traits such as lamb survival and weaning weight in SAMMs may be slow. Breed differences for economically important traits were consistent with the roles of the two breeds, with the Dormer as a coarse-woolled terminal sire breed and the SAMM as a dual-purpose breed.
Studies on the response of lambs and ewes to changes in the ambient climate owing to climate change
(Stellenbosch : Stellenbosch University, 2022-12) Steyn, Shannong; Cloete, Schalk W. P.; Brand, T. S.; Van Zyl, Johan Hendrik Combrink ; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: This study investigated the impact of climate instability on neonatal lamb behaviour as a proxy for lamb survival in a winter lambing season in the Western Cape, as well as the impact of increased temperatures on heat stress indicator traits in mature ewes in the Western and Eastern Cape. Historic data were used to establish the relationship of neonatal lamb behaviour with cold stress and to derive genetic parameters for early lamb behaviour. Merino lambs of the Elsenburg flock were phenotyped for behaviour latencies from birth to first standing (LTBS) and from standing to first suckling (LTSS). These data were analysed in relation to a cold stress gradient (CSG) derived from a combination of wind, rain, and temperature. The flock consisted of a line selected for number of lambs weaned per ewe mated (NLW; the High or H-Line) and a line selected against NLW (Low or L-Line). H-line lambs progressed faster from standing to first suckling than L-line lambs. Increased CSG-levels resulted in 18% faster progress in LTBS when mild conditions at 800kJm⁻²h⁻¹ were compared to stressful conditions at 1200kJm⁻²h⁻¹. LTSS was compromised by 76.0% as CSG-values increased from 800kJm⁻²h⁻¹ to 1200kJm⁻²h⁻¹. Heritability estimates were 0.22 for LTBS and 0.06 for LTSS. The maternal heritability for LTBS was 0.06 and the dam permanent environment variance ratio 0.09 for LTSS. The traits were not genetically correlated. Further research is required to understand the responses of lambs to cold stress. Average temperatures are likely to increase, resulting in hotter and dryer conditions in South Africa. The impact of these changes on animal production and welfare is not well-defined. Three trials were conducted on 10 to 20 mature, dry ewes at 2 locations to determine the homeothermic response of nine sheep breeds between 2016 and 2022. These breeds were the Dohne, Dormer, Dorper, Ile de France, Meatmaster, Merino, Namaqua Afrikaner, South African Mutton Merino (SAMM) and White Dorper. They were studied in different combinations across trials. On days forecast to be hot at noon, animals were assessed under cool conditions in the morning and hot conditions at noon/afternoon by monitoring individual rectal temperature, eye temperature (thermal imaging), spot temperature, and respiration rate. The increased heat in the afternoon sessions markedly increased all traits across trials. In general, hair breeds (Dorper, White Dorper, Meatmaster, and particularly Namaqua Afrikaner) were able to maintain lower basal respiration rates compared to the wool breeds originating from temperate regions (Dohne, Dormer, Ile de France, Merino, and SAMM). These results suggest that hair sheep and hardy indigenous breeds such as the Namaqua Afrikaner may cope better with the anticipated higher heat load in the future when compared to the breeds originating from temperate regions. Rectal temperature was low- moderately repeatable across trails, while outcomes for respiration rate and spot temperature were more variable and commonly affected by the reranking of ewes across sessions as well. Eye temperature was not repeatable. There is still marked scope for research on ovine adaptation to heat stress conditions in South Africa.
Studies to develop a mathematical optimisation model to describe the effect of nutrition on the growth of ostriches (Struthio camelus var. domesticus)
(Stellenbosch : Stellenbosch University, 2013-12) Carstens, Petrus Daniel; Brand, T. S.; Hoffman, Louwrens C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The first study (Chapter 3) evaluated the growth response of ostrich chicks on diets containing three different levels of protein and amino acids. Linear and nonlinear models were fitted to the data and compared by using Akaike’s information criterion (AIC). The linear polynomial of the third degree had the lowest AIC value for all three treatments thus making it the most suitable model for the data. Significant differences were found between treatments for growth data. The results from this study can aid in describing the growth of ostriches subjected to assumed optimum feeding conditions. In the second study (Chapter 4), a range of diets was formulated for the five growth stages of ostriches (pre-starter, starter, grower, finisher and maintenance) according to their nutrient requirements. The diets were diluted with wheat straw. Three dilution levels (0%, 10% and 20%) were used for the pre-starter and starter phases, five dilution levels (0%, 15%, 30%, 45% and 60%) were used for the grower and the finisher phases, and five dilution levels (0%, 20%, 40%, 60% and 80%) were used for the maintenance phase. Weekly intake data were collected throughout each phase. Feed bulk restricted intake by 21% and 52% at the 10% and 20% dilution level, respectively (P < 0.05) in the pre-starter phase, whereas intake was not restricted during the starter phase(P > 0.05). Intake was constrained by 39% and 42% at the 45% and 60% dilution levels in the grower phase, respectively (P < 0.05), and by 17% and 39% at the 45% and 60% dilution levels (P < 0.05) in the finisher phase, respectively. Feed bulk restricted intake by 60% and 69% for the 60% and 80% dilution levels (P < 0.05), respectively, in the maintenance phase. Defining the bulk density that will constrain feed intake, as established in this study, will aid in least-cost feed formulations, feed intake modelling and growth predictions. In the third study (Chapter 5) the effect of three different dietary protein (with a specific associated amino acid content) concentrations on certain production parameters in growing ostriches were investigated. Significant differences were found for the final live weight of birds, cold carcass weight, thigh weight as well as for most of the weighed muscles at slaughter (350 days old). Concerning the growth and feed related parameters, only average daily gain (ADG) was influenced by dietary treatment (P < 0.05). Results indicated that birds on the diet with the medium protein performed optimally. One exception is the starter phase (26 – 47 kg) where chicks on the high protein diet outperformed those on the medium protein diet. In the fourth study (Chapter 6) the effects of different dietary energy concentrations on ostrich production parameters were examined in two different trials. The first trial included measurements from the pre-starter phase through the starter phase until the grower phase. The second trial was based on the finisher phase per se. Overall dietary levels provided in the pre-starter, starter and grower phases indicated better growth, FCR, skin size and grade, thigh weight, live weight, and carcass weight for the birds fed the medium energy diet. Dietary energy levels provided during the finisher phase indicated that the energy level above the medium level used improved growth rate and tanned skin size. The gender of the birds influenced carcass weight, growth rate, and certain feather parameters (P < 0.05). In the fifth study (Chapter 7) the effect of feather clipping at six to eight months of age on the production parameters of ostrich chicks were investigated. The study was conducted in three different trials. In each of the trials the feathers of half the amount of birds were clipped at six to eight months of age. Significant differences (P < 0.05) were found for the feed conversion ratio (FCR), the average daily gain (ADG) and for the quantity of valuable feathers. Results indicated that the growth rate and FCR was better for the birds which had their feathers clipped at six to eight months of age. Results also showed that the quantity of feathers with commercial value were significantly higher for the clipped group. This study showed that there may be an advantage for ostrich producers concerning the harvesting of feathers at six to eight months of age. The work in this thesis is a follow up on the framework set by Kritzinger (2011) and is part of the same project. Most of the results obtained in these studies will be incorporated in to the mathematical optimisation model of Gous and Brand (2008) for more accurate predictions concerning feed intake and other production parameters that may lower feeding costs.
A study on certain factors that may affect the production and feed intake of breeding ostriches
(Stellenbosch : Stellenbosch University, 2015-03) Tesselaar, Ger-Mari Alice; Brand, T. S.; Hoffman, Louwrens C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: A large amount of research has gone into developing growth models for other monogastric animals, incorporating various biological and animal related factors, feed factors, the environment as well as the interaction between these factors. In order to develop a mathematical optimization model for breeding ostriches, all possible factors that can influence feed intake and production needs to be investigated. Therefore this study was conducted to identify and quantify the possible factors that affect feed intake and production of breeding ostriches. In the first study (Chapter 3), the effect of certain nutrients on feed intake and production of breeding ostriches was evaluated. No specific effect of any one of the tested parameters (additional vitamins, minerals, fatty acids and amino acids) was seen on the production parameters considered. Significant differences were found in the quantity of feed ingested indicating a possibility that breeding ostriches may adjust feed intake to satisfy mineral requirements. The supply of additional vitamins and minerals during the resting period might have an effect on the results. Therefore, the second study (Chapter 4) determined the effect of the addition of minerals and vitamins during the resting and breeding period on the production of breeding ostriches. The presence of a vitamin and mineral premix during the resting period decreased body condition lost by female breeding ostriches with 31.2% and decreased the presence of DIS eggs with 8.1%. The supply of vitamins and minerals in the breeding period decreased the body condition lost by breeding females with 5.3%. Overall it can be concluded that the presence of a vitamin and mineral premix is essential in resting as well as the breeding period. The commonly used protein source in the diet of breeding ostriches, soya oilcake (SOC), has become so expensive that an alternative protein source, cottonseed oilcake (CSOC), was investigated for its possible use in the third study (Chapter 5). Cottonseed oilcake as a protein source had no significant effect on most of the production parameters (total number of eggs, DIS eggs, infertile eggs or chick production), but led to a significant decrease in the quantity of chicks hatched. Until more research results are available, it is suggested that producers follow the precautionary approach and not use CSOC to feed breeding ostriches. With the development of a simulation model for ostriches, the immediate effect of dietary energy content on feed intake as well as its long term effect on breeding ostrich production was determined in the fourth study (Chapter 6). One hundred ostrich breeding pairs were divided into five groups of twenty breeding pairs each for two consecutive breeding seasons and received one of the five experimental diets ad libitum. Although previous studies of Brand et al. (2002, 2003) have indicated that production in the current breeding season can be affected by nutrition of previous breeding seasons, no such effect was seen on the production parameters measured (total egg production, DIS eggs, infertile eggs, chick production, breeding female ostrich weight change or feed intake). Breeding ostriches also showed no indication of regulating feed intake according to the energy content of the feed. Literature revealed that breeding ostrich feed intake may be influenced by the bulk density of the feed. Due to lack of differences in production parameters measured, possible future studies can include the effect of low and high levels of basal energy supplied over three or more consecutive breeding seasons. Egg production is a costly process for female breeding ostriches, requiring high levels of quality feed and often causing loss of body condition. In study five (Chapter 7), the egg laying pattern for breeding ostriches was evaluated. Results from this study indicated that the days until first egg and total days in lay are strongly influenced by the age of the female ostrich. However, due to the egg production of female breeding ostriches being highly variable, and a vast number of factors influencing the production of ostrich eggs, a specific egg laying pattern over the breeding season could not be identified. This thesis makes a significant contribution towards quantifying the factors affecting production and quality parameters in breeding ostriches. Most of the results obtained in these studies can be incorporated into a mathematical optimization model for more accurate predictions concerning feed intake and other production parameters.

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