Masters Degrees (Animal Sciences)

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Die aanwending van die CPM dairy model in formulering van voerrantsoene in 'n melkkudde
(Stellenbosch : Stellenbosch University, 2005-04) Vermaak, Jacobus Vermaak; Cruywagen, C. W.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: CPM Dairy was developed to maintain amino acid balance. because the correct amino acid relationship has an influence on milk production and milk composition (Schwab e/ af. 1992, Rulquin e/ af. 1993). Rulquin e/ af. (1993) found that an increase in lysine and methionine concentration in the diet had no meaningful effect on milk production and milkfat production. However, milk protein production is described as a function of lysine and methionine concentration. In order to balance the amino acid relationships, the CNCPS model has been adopted, using the following guidelines: I. a dairy cow feed characteristic scheme, described by Van Soest e/ af. (1991) and Sniffen e/ aI. (1992), II. a model for rumen fermentation and bacterial growth in the dairy cow, described by Russel e/ af. (1992), Ill. feed val ues for dairy cow feeds, described by Sniffen e/ af. (1992). IV. a set of formulas describing the feeding needs of dairy cows under different circumstances, assembled by Fox e/ af. (1992). Bateman e/ af. (2001) studied the accuracy of formulation models according to crude protein (CP) and amino acid (AA)-flow to the duodenum in lactating dairy cow diets. CPM Dairy does not calculate direct flow of CP to the duodenum, but the following adjustment was made: the change-over of metabolizable protein (MP) to CP is done by increasing bacterial protein from 60% to 100% of bacterial-CP. Intestinal digestion of fraction B3-protein is increased from 80% to 100%, whereas fraction C-protein is increased from 0 to 100% to change feed-MP to feed-CP. CP from feed and microbes are summed to indicate total CP-flow to the duodenum. AA-flow, as calculated by CPM Dairy, is used without adjustments. A rise in MUN-Ievels are typical to spring and summer months. which can be ascribed to high soluble protein and low soluble carbohydrates in grasses and legumes. This gives rise to an excess N-uptake in the bloodstream. Grass silage, when fed as primary feeding source. has the same reaction. Blood-urea-nitrogen (BUN) is the amount of urea-N found in the blood of the cow. MUN is the fraction ofN in the milk in the form of urea. MUN is normally 85% the concentration of BUN. Studies show that an increase in BUN/MUN levels leads to a negative effect on the reproductive ability of the cow. An increase in BUN-levels leads to an increase in urea in the reproductive tract of the animal. Urea passes between the blood plasma and the reproductive tract. It is therefore obvious that a high BUN-concentration leads to high levels of urea in the reproductive tract. In order to eradicate this problem. the use of deodorise in the supplemental feed of the lactating dairy cow \vas recommended. Deodorise is a natural product manufactured by Alltech. The product is derived from the Yuccha Schidigera plant. Two glycocomponents (CI and C II) of this plant binds gasses such as N1-I3. (Alltech information sheet) During .June to August 2002 data were collected regarding the effect of deodorise on lactating dairy cows. No meaningful difference between the two groups in this experiment was found.
Actual and predicted performance of broiler chickens
(Stellenbosch : Stellenbosch University, 2004-03) Van Niekerk, S. J. (Sarel Johannes); Ekermans, L. G.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this study was to evaluate the performance and profitability of different dietary specifications for broiler chickens slaughtered at 35 days of age. Two trials were performed to evaluate different production parameters. The results of these trials were compared to the predicted results of the EFG broiler model. No carcass data were available for the two trials mentioned above. Therefore, in order to evaluate the accuracy of the broiler model when predicting carcass characteristics, two published data sets (Leeson et al., 1996a) were used. Predicted and actual values were compared, evaluated and discussed. Two broiler trials were performed. In Trial One the amino acid density decreased throughout the range of three treatments from prestarter to finisher diets. In Trial Two the amino acid density decreased only in the four finisher diets. The main difference between predicted and actual results was the response to body weight. The model predicted a steady increase in feed intake to compensate for the lower dietary specifications while body weight did not change significantly. This increase in feed intake seems to be enough to maintain body weight. Trial birds also increased their feed intake as dietary amino acid density decreased, but this compensation seemed to be too low to maintain body weight compared to the control diet. The birds may find it easier to compensate when they have time to adapt to the specification. There is evidence in the literature that birds need seven days to adapt their feed intake to a lower feed specification (Leeson et al., 1996a). It can be speculated that the trial birds started to loose body weight due to a lower amino acid intake in this period. The model seems to adapt feed intake immediately after a change in diet specification. The simulation on literature data lead to the following conclusions: 1) Broilers posses the capacity to increase their feed intake with at least 65% should finisher diets with lower amino acid and energy concentrations be supplied. If only the energy concentration of finisher diets were decreased, the increase in feed intake will be around 30%. (see Table 16 and 23) 2) The accurate prediction of feed intake from the given dietary specification has a major influence on the accuracy of the prediction of broiler performance. 3) Amino acid density and DLys:ME ratio plays a significant role in the control and prediction of feed intake. The EFG broiler model is based on sound scientific principles. The model is comprehensive and can be used for a wide range of environmental and management conditions as well as dietary conditions. The nutritionist can use the model with confidence to assist in practical feed formulation. The actual strength of the model lies in the time and money being saved compared to practical trials.
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.
Alternatives to replace antibiotics in broiler diets : effects on protein utilization and production performance
(Stellenbosch : Stellenbosch University, 2008-12) Kritzinger, Magdel; Lambrechts, Helet; Ciacciariello, Mariana; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Different substances were evaluated and compared to an antibiotic, in terms of their effect on nitrogen - and amino acid digestibilities. Two digestibility trials and one performance trial were conducted. Trials one and two apparent nitrogen (AND)- and amino acid (AAD) digestibilities were determined from digesta collected at the terminal ileum (ileal digestibility method). In Trial 3 the substances were evaluated in terms of their potential to improve production performance. Broilers were fed a maizesoya based diet throughout the three trails. In the first trial, garlic and a commercial prebiotic (Bio-Mos®), were tested and compared in terms of AND and AAD, to an antibiotic (doxycyclin, Doxyvete-SOS). A starter and finisher diet were fed as either mash or pellets. The garlic was included at 8g/kg, 13g/kg and 18g/kg to the starter and finisher diets. Bio-Mos® was added at 1g/kg, 2g/kg and 3g/kg to the starter diet, and 0.5g/kg, 1g/kg and 1.5g/kg to the finisher diet. The doxycyclin was added at 0.3 g/kg. None of the treatments had any beneficial effects in terms of AND. Feeding a pellet seem to have some negative effects in terms of AND. In general most of the treatments did not show any improvement in AAD at any determination period (day 21, 28 or 35). At day 21 and day 35, the mash diet supplemented with 18g/kg garlic had a negative effect on AAD, when compared to the negative and positive control. It doesn’t seem that feeding either a mash or a pellet had an influence on the effects exerted by the different treatments. In the second trial the influence of Bio-Mos®, a blend of organic acids, probiotics and electrolytes (Acid-Pak 4-way®) and a medium-chain triglyceride (MCT) were evaluated and compared in terms of AAD and AND, to the effect of an antibiotic, doxycyclin. The starter and finisher diets were fed as a mash. Bio-Mos® was included at 1g/kg, 2g/kg, and 3g/kg in the starter diet, and at 0.5g/kg, 1g/kg, 1.5g/kg in the finisher diet, respectively. Acid-Pak 4-way® was included at 0.4g/kg, 1g/kg and 1.6g/kg for both the starter and finisher diets. Medium-chain triglycerides (MCT) were allocated at 3g/kg, 3.6g/kg, 4.2g/kg for the starter diet, and 2.1g/kg, 2.7g/kg and 3.4g/kg for the finisher diet. An antibiotic, doxycyclin, was included at 0.3 g/kg. With AND, no treatment had any significant effect for the entire experimental period. At day 21, the treatment supplemented with MCT (3.4g/kg) had the most significant beneficial effect on AAD, when compared to the negative- and positive controls, as it increased AAD for the majority of the amino acids. The treatment with Acid-Pak 4-way® (1g/kg) had the most significant negative effect on AAD when compared to the positive control. At day 28, the treatments with Bio-Mos® (0.5g/kg and 1.5g/kg) and Acid-Pak 4-way® (0.4g/kg) had the most significant beneficial effect on AAD when compared to the positive control. It increased AAD for more than half of the 17 amino acids evaluated. The treatment supplemented with MCT (2.7g/kg) has shown the most significant negative effect on AAD, when compared to the positive control. In the third trial the effect of Bio-Mos®, Acid-Pak 4-way® and MCT on production performance was evaluated, and compared to the effects of the presence or absence of doxycyclin. Body weight (BW), body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured. The starter and finisher diets were fed as a mash. Bio-Mos®, MCT and Acid-Pak 4-way® were included at 3.0g/kg, 4.2g/kg and 1.6g/kg, respectively in the starter and finisher diets. Birds were weighed (per pen) on arrival and on days 7, 14, 21, 28, 35. Feed intake (FI) per pen was measured at days 7, 14, 21, 28 and 35, and mortality was recorded daily. In terms of BWG, Acid-Pak 4-way® had a higher BWG, when compared to the negative control, Bio-Mos® and MCT. It can be concluded that Bio-Mos®, Acid-Pak 4-way®, as well as MCT can be a possible alternatives to antibiotic supplementation. These three treatments did not necessary prove to be more effective than antibiotics, but are definitely competitive alternatives.
Amino acid requirements of feedlot cattle according to the duodenal and whole empty body essential amino acid profile
(Stellenbosch : Stellenbosch University, 2001-12) Erasmus, Morné; Ferreira, A. V.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The purpose of this study was to determine the essential amino acid requirements of beef cattle under feedlot conditions through evaluation of the duodenal and whole empty body essential amino acid compositions. To define the ideal protein required for growth, the whole empty body essential amino acid compositions of 8 beef steers (Simmental and Hereford crosses) was investigated. The amino acid composition of the components (carcass, metabolic organs and residual fraction), was pooled relative to their respective mass and protein contribution, resulting in the calculated whole empty body amino acid composition: arginine 6.81; histidine 2.69; isoleucine 4.02; leucine 6.96; lysine 7.43; methionine 2.01; phenylalanine 4.03; threonine 4.01; valine 5.30; tryptophan 0.82. Variations in profiles were found between scientific reports, either indicating that ratios change with growth and implants or possibly through genotype. The present study's body amino acid ratios were used to estimate dietary amino acid requirements through evaluation of the duodenal essential amino acid compositions from three different maize based feedlot diets. Although there was a general increase in the biological value of protein after rumen fermentation, the duodenal essential amino acids in comparison with the whole empty body recorded deficient/unbalanced profiles of essential amino acids for growth. The chemical scores suggested that the first-to-thirdlimiting amino acids in the duodenal digesta of beef cattle, that received three different commercially available feedlot diets, were: histidine, lysine, methionine/arginine (Diet 1), histidine, arginine, lysine (Diet 2) and arginine, methionine, histidine (Diet 3). Thedisproportionate duodenal amino acid concentrations obtained from the three diets, emphasise the necessity to enhance the intestinal delivery of amino acid profiles through different undegradable protein sources, with the objective to maximise protein utilisation and obtain the genetic potential for optimal growth in feedlot cattle. When amino acid requirements and flows to the duodenum were simulated using the Cornell Net Carbohydrate and Protein system (CNCPS), predictions indicated that lysine amino acid flow was limiting the metabolizable allowable average daily gain in Diet 1 and 3. Predicted profiles indicated that the order of limitation was: lysine, arginine, histidine (Diet 1), lysine, arginine, histidine, methionine (Diet 2) and lysine, arginine, histidine (Diet 3). The predicted profiles were in accordance with observed duodenal values, except for methionine that was observed limiting in Diet 1 and 3; however, the sequence and extent of limitation varied. Results indicate that prediction models have potential in predicting requirements; however there are still limitations for use to accurately define requirements for particular EAA's. From the present study, it is clear that the protein accretion was constrained by quantity and/or disproportionality of amino acids available for absorption. Further research should therefore be directed towards obtaining a more desirable array of amino acids to the lower digestive tract that is digestible, absorbable and an economically viable option for the feedlot operator.
Analysis of genetic diversity and population structure of indigenous (fat-tailed) sheep in South Africa
(Stellenbosch : Stellenbosch University, 2022-03) Malan, Isaack Nichol; Molotsi, Annelin H.; Cloete, Schalk W. P. ; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: Indigenous fat-tailed sheep breeds are primarily kept by rural peoples, especially in developing countries. These livestock species contribute to household income, is a source of food security, plays a role in social and crop production (fertilizer) systems. The diversity within these indigenous breeds allows them to be productive under harsh environmental conditions, thus genetic and phenotypic characterization is pivotal for future sustainable farming practices. The aim of this study was to elucidate the genetic structure of indigenous fat-tailed sheep in South Africa and to trace selection pressure applied to fat-tailed sheep for adaptation. The first objective was to elucidate the genetic variation and population structure of indigenous fat-tailed sheep in South Africa. The second objective was to determine if selection pressure has been placed on these indigenous sheep breeds for adaptation traits. The first objective was achieved by sampling blood from indigenous sheep breeds (30 Damara, 30 Pedi, 30 Zulu, 20 Meatmaster and 54 Karakul animals). The extracted DNA was genotyped using the OvineSNP50K BeadChip. Genotype data from 48 Namaqua Afrikaners and 98 Merinos were included for comparative purposes. Several genetic parameters were analysed to determine the genetic diversity within and between the sheep populations: observed heterozygosity (Ho), expected heterozygosity (He), inbreeding coefficients (F) and Linkage disequilibrium (LD). The highest and lowest observed heterozygosity was seen in the Pedi and Damara sheep (0.4 and 0.34 respectively). The Merino exhibited the highest expected heterozygosity of 0.38 and the Namaqua Afrikaner the lowest at 0.345. The highest LD was reported in the Namaqua Afrikaner at r²= 0.45 and the lowest LD was observed in the Merino at r²= 0.37. The population structure of the indigenous sheep breeds was studied by conducting a Principal Component Analysis (PCA), where PC1 (6.8%) and PC2 (5.0%) describes the total genetic variation. A Bayesian approach was used to calculate maximum likelihood estimates in the FastSTRUCTURE program, which elucidate the true ancestral populations (K= 8) of the sheep breeds. Lastly, through hapFLK analysis, Reynolds genetic distances between the different sheep populations were calculated and a neighbour-joining population tree was generated. These could be used to determine the relatedness and dissimilarities (dendogram) found between the indigenous fat-tailed sheep. A close relationship could be seen between the Zulu and Damara sheep breeds. Despite the lower diversity, the Namaqua Afrikaner displays the highest genetic distance from the other indigenous fat-tailed breeds. The Pedi and Karakul populations also exhibited distinct clustering and separation. Admixture within the Meatmaster breed with the Merino was observed. This is to be expected as the Merino could have been used as a parental breed in the make-up of this composite (Meatmaster) sheep. To determine selection sweeps in the indigenous sheep breeds, the hapFLK approach was used and 13 regions were found to be under selection, spanning a total of 11 chromosomes. The candidate genes associated with the SNPs of interest was linked to traits involved in metabolic process such as DNA synthesis and transcription (CEP41, TLL1, EIF1B, SCN5A, SCN8A, SCN10A, SCN11A), immune response (BPIFC, CLDN12, CLDN14, TRL4), ultraviolet exposure and thermoregulation (SLX4, ASCL4, KCNJ5, LAMB1, GPR26, CX3CR1), energy metabolism (MYH9) and meat production (PDEZA, UTRN). These candidate genes give an insight into the adaptive traits of indigenous sheep in South Africa and further genotyping is needed to elucidate more of the robust characteristics exhibited by these locally acclimated genetic resources.
Animal performance from natural pastures and the effects of phosphorus supplementation
(Stellenbosch : Stellenbosch University, 1984-03) Read, Marion Victoria Pearl; Smith, W. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
INTRODUCTION: This study was initiated by the various reports of improved animal performance resulting from supplementary feeding of grazing ruminants and in this respect, it may be regarded as a feasibility study of the ability of the natural pasture at the applied stocking rates, to supply the animal with its nutrient requirements, since before providing the animal with supplementary nutrients, it is necessary to identify those which may possibly limit animal production. The criti= cal test of such a limiting nutrient would be an improved animal performance, resulting from supplementation of the nutrient suspected as being limiting, under grazing conditions.
Ante- and post-mortem factors influencing impala (Aepyceros melampus) meat quality
(Stellenbosch : Stellenbosch University, 2019-04) Engels, Retha Annette; Hoffman, Louwrens C.; Needham, T.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this research was to investigate the influence of sex, muscle (Longissimus thoracis et lumborum/LTL, biceps femoris/BF, semimembranosus/SM, semitendinosus/ST, infraspinatus/IS, and supraspinatus/SS), production system (intensive, semi-extensive and extensive), and post-mortem ageing on the meat quality of impala (Aepyceros melampus) to provide baseline data for the South African game industry. This was done by gathering data on the carcass yields, overall meat quality (physical attributes and chemical composition) and sensory meat quality of impala, as well as investigating the optimum post-mortem ageing period for maximum tenderness of LTL steaks. The sex-muscle comparison (Trial 1) consisted of 11 male and 11 female impala that were culled from a semi-extensive production system in the Central Sandy Bushveld region near Modimolle in Limpopo, South Africa. No sexual dimorphism (P > 0.05) was recorded for the undressed (36.4 ± 1.30 kg males; 37.8 ± 1.30 kg females) or dressed carcass weights (21.6 ± 0.82 kg males; 21.0 ± 0.82 kg females). However, male impala had a higher (P = 0.004) mean dressing percentage than females (59.1 ± 0.76 % vs. 55.6 ± 0.76 %). For the production system comparison (Trial 2), 12 sub-adult (±15- 18 months old) male impala were culled per production system (n = 36). The intensive and semiextensive production systems were also located near Modimolle, and the extensive production system was located in the Central Rûens Shale Renosterveld region near Bredasdorp in the Western Cape of South Africa. Extensive system impala had higher (P ≤ 0.05) undressed and dressed carcass weights (46.5 ± 1.12 kg and 26.6 ± 0.79 kg) than intensive (37.9 ± 0.92 kg and 21.9 ± 0.65 kg) and semiextensive system impala (36.4 ± 0.96 kg and 21.3 ± 0.68 kg, respectively), while the latter two systems did not differ significantly from each other. No differences (P = 0.364) were recorded between production systems for the dressing percentages (57.9 ± 0.58 % pooled mean) or total offal yields (39.7 ± 0.48 % pooled mean) of sub-adult male impala. The physical meat quality attributes of impala were significantly influenced by sex, muscle, and production system. Sex-muscle interactions were found for the CIE a* values, drip loss percentages and cooking loss percentages (Trial 1). Higher (P = 0.021) ultimate pH (pHu) values and lower (P = 0.002) Warner-Bratzler shear force (WBSF) values were recorded in male impala than in females. The IS and SS muscles from the forequarter were the most tender, whereas the BF and SM muscles from the hindquarter were the least tender. The pHu of both sexes, all muscles (Trial 1) and both intensive and semi-extensive system impala (Trial 2) fell within the acceptable normal range (5.6- 5.9), but the extensive system impala produced meat with an exceptionally high pHu (6.2 ± 0.06) due to extrinsic factors caused by the production and culling process. Consequently, extensive system impala produced meat with DFD-like (dark, firm, dry) characteristics, such as the lowest drip loss percentage (0.9 ± 0.14 %), cooking loss percentage (28.1 ± 0.79 %) and darkest, least red and least saturated surface colour (L* = 26.8; a* = 10.0; b* = 5.2; chroma = 11.4). With the exception of the extensive system impala, impala from both sexes, all muscles and both the intensive and semiextensive systems (Trial 1 & 2) had CIE Lab colour measurements within the acceptable range of expectation for game meat (L* = 30.9-36.8; a* = 11.4-13.6; b* = 6.0-8.8). Furthermore, all fresh impala meat in this study (Trial 1 & 2) produced meat with shear force values < 43 N (range of 19.2-39.3 N) at 24 hours post-mortem and may thus be classified as tender. The chemical meat quality of impala was also significantly influenced by sex, muscle and production system. Sex-muscle interactions were recorded for all four chemical components (moisture, protein, intramuscular fat/IMF and ash), while a strong negative correlation (r = -0.49; P < 0.001) was observed between the protein and IMF content of the muscles (Trial 1). Extensively produced impala were recorded to have LTL muscles with the lowest (P ≤ 0.05) mean IMF (1.5 ± 0.06 g/100 g) and the highest protein (23.4 ± 0.12 g/100 g) content, whereas intensive system impala had the highest IMF content (2.0 ± 0.05 g/100 g). The proximate composition of all impala meat in this study (Trial 1 & 2) ranged from 74.7-77.0 % moisture, 20.7-23.5 % crude protein, 1.2-2.2 % IMF and 1.1-1.3 % ash content. While the differences between sex, muscle and production system were significant, the differences were marginal and thus may not be of biological consequence with regards to human nutrition. Regardless, all impala meat had a high protein and low IMF content which is considered desirable by health-conscious consumers. With the differences in dietary regime, management strategies and daily activity between production systems, it can be expected that the sensory profile and fatty acid composition of impala meat will also be influenced by differences in these factors. The influence of production system on sensory meat quality was significant (Trial 2), with the highest (P ≤ 0.05) sensory ratings for gamey, beef-like, herbaceous and sweet-associated aromas and flavours found in extensive system impala during descriptive sensory analysis (DSA). However, the sensory meat quality of the intensive and semi-extensive system impala from the same production region did not differ (P > 0.05) except for a few textural attributes and a higher (P < 0.05) gamey flavour intensity found in semi-extensive system impala. The ideal post-mortem ageing period of impala LTL steaks was also determined. The LTL muscles of 11 male and 11 female impala (Trial 1) were divided into eight portions each, with each portion was randomly allocated to age for 1, 2, 4, 6, 8, 10, 12, or 14 days, vacuum-sealed and stored at 4°C. This research found that maximum tenderness (13.5 ± 0.91 N) and improvement of bloomed surface colour of impala LTL steaks was reached at eight days post-mortem, whereas prolonged ageing beyond this point resulted in some discolouration and no further improvement in meat tenderness. The ageing of meat to eight days post-mortem also successfully negated the initial significant differences in tenderness between the sexes. Therefore, it is recommended that impala LTL steaks should be vacuum-aged at 4°C for eight days to achieve optimum tenderness and minimize variability between individual animals irrespective of sex.
Application of exogenous enzymes in Haliotis midae diets with soybean meal as fish meal replacement
(Stellenbosch : Stellenbosch University, 2012-03) De Villiers, Christopher Murray; De Wet, Lourens; Pieterse, Elsje; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: A 240-day growth study was conducted to determine the suitability of soybean meal (SBM) as an alternative protein source to fish meal (FM) in the diet of commercially produced South African abalone (Haliotis midae). The suitability of SBM was determined by a close evaluation of the following key factors: feed water stability, morphological impact on the abalone intestine and the effect on the growth performance of abalone. The study was comprised of two phases: a fish meal replacement phase (Phase A) and an enzyme treatment phase (Phase B). Diets used in Phase A consisted of a control fish meal diet (Control=22%FM, 0%SBM), a fish meal-soybean meal diet (FMSBM=20%FM, 15%SBM), a soybean meal-low diet (SBMlow=0%FM, 15%SBM) and a soybean meal diet (SBM=0%FM, SBM30%). In Phase B, the FM diet and SBM diet were used as basal diets (FME0 and SBME0). These diets were then treated with three commercial enzyme products, namely, a β- glucanase (FME1 and SBME1), xylanase (FME2 and SBME2) and α-D-galactosidase (FME3 and SBME3). Subsequently, all three enzymes were combined to make two treatments (FME123 and SBME123). With regard to the gut morphology and growth trials, a thirteenth energy enhanced commercial animal protein-free diet (ECO) was used. In Phase A (fish meal replacement), the findings revealed that water stability did not differ significantly between treatments. In Phase B (enzyme treatment) however, the water stability of β- glucanase treated feeds was significantly lower than that of the control FM diet. It was also observed that in comparison to the control FM diet, soybean meal based diets have a significantly greater effect on intestinal morphology. With reference to Phase A (fish meal replacement), by the end of the 240 day growth trial period, it was evident that animals fed on the commercial (ECO) diet were significantly heavier than those given the control FM diet. With regard to final length in mm, feed conversion ratio (FCR) and specific growth rate (SGR) for mass and length, no differences between the treatments were noted. It was also found that the condition of the ECO fed animals was significantly better in comparison to the other treatment fed animals. No significant differences were observed between the FM and three FMreplaced diets however. With reference to Phase B (enzyme treatment), it was noted that once again, after the 240 day period, abalone fed on the ECO diet were significantly heavier in terms of their final weight when compared to those fed on the other diets. As in Phase A, no differences in FCR and SGR for mass and length were observed. Measurements of the animals’ final length (as observed on day 240) revealed that those fed on the ECO diet were significantly longer than those given the FME1, SBME1 and SBME3 diets. At the end of the trial, abalone fed on the ECO diet were also in significantly better condition than those fed on the SBM, FME3 and FME123 diets. In terms of production performance, no significant difference was found between the SBM diets and FM diets and enzyme supplementation did not significantly increase the production performance either. The results of this study therefore show that SBM has great potential to be used as a FM-replacement diet. The improved performance of the ECO diet was expected due to its energy content.
Application of the condition factor in the production of African sharptooth catfish Clarias gariepinus
(Stellenbosch : University of Stellenbosch, 2005-03) Luckhoff, Paul Daniel; De Wet, Lourens; Brink, Danie; University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences.
In recent years there has been a renewed interest in the commercial culture of African Sharptooth Catfish. Its robust characteristics and its air breathing capabilities makes the African catfish a good candidate for culture in intensive recirculating systems. In light of the size variation in offspring spawned from undomesticated fish, that may eventually increase cannibalism, suitable methods for the quantification of some production performance parameters such as growth and health measurements need to be established for application in intensive catfish culture. In fish the condition factor (CF) reflects information on the physiological state of the fish in relation to its welfare. This factor is expressed as Fulton’s condition index, or the K-factor. African Sharptooth Catfish fry with average weight of 1.9g ± 0.7867 and average length of 59.375mm ±8.812 were equally allocated into ten 1000L-recirculating tanks. The fish were fed a commercial feed to apparent saturation at a frequency of 5 times per day. Sixteen fish were sampled out of each treatment. Weight (g) and length (mm) of each fish were recorded every seven days over a trial period of 175 days from which Fulton’s condition index K was calculated. Results were analysed for significant differences using one-way ANOVA and Tukey’s pair wise comparison test for the various parameters. Growth parameters (a = -5.083, b = 3.004, R2 = 99.4%) derived from the logarithmic relationship between body weight (W) and standard length (L) indicated an isometric growth through the duration of the trail. No significant differences (P>0.05) in condition factors between treatments were found at the beginning of the trail. Significant differences (P<0.05) were found at the end of the trail for weight between ponds and condition factor between treatments. No significant difference (P> 0.05) between length and treatments were found at the end of the trial. Mean condition factor was 0.856 ± 0.187. By using this information on condition factor for African catfish a K-factor calculation chart for African catfish could be calculated, to be used as a practical measurement tool to measure performance goals on catfish farms.
The assessment of black soldier fly (Hermetia illucens) pre-pupae, grown on human faecal waste, as a protein source in broiler and layer diets
(Stellenbosch : Stellenbosch University, 2017-03) Van Schoor, Anton Lourens; Pieterse, Elsje; Hoffman, Louwrens C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this study was to investigate the effect of processing of black soldier fly (Hermetia illucens) pre-pupae meal (BSF), grown on human waste, as a protein source in broiler and layer hen diets (10% inclusion level). For the broilers, the diets were iso-nitrogenous and iso-energetic, containing 10% pre-pupae meal. The potential of these (BSF) as a protein source in broiler diets were evaluated, along with the production parameters, carcass quality (physical and chemical), possible toxicities, feed safety and digestibility of the pre-pupae were investigated in broilers. Eight different processing treatment methods were used on the BSF in the broiler trials. The methods included: washed in water at 62°C for 30min (Trt1), 62°C for 60min (Trt2), 72°C for 5min (Trt3), 72°C for 15min (Trt4), 100°C for 2min (Trt5), 100°C for 5min (Trt6), rinsing in 5% propionic acid (Trt7) and rinsed in 5% formic acid (Trt8).The production trial indicated no treatment differences for cumulative feed intake and average daily gain (ADG). Treatment differences were observed between the BSF diets and the control, with the BSF diets achieving better results regarding feed conversion ratio (FCR), protein efficiency ratio (PER), european protein efficiency factor (EPEF) and final live weight. The organ weights and the gut toxicity were measured. The analysis indicated no treatment differences with regards to the gut pH, organ weights and neither with the histomorphology of the duodenum and jejenum. No significant treatment differences were observed regarding the slaughter weight, breast muscle yield and the proximate analysis. However, significant differences were observed in the dressing percentage, with the control diet achieving higher dressing percentages than most of the BSF diets. The breast muscle of broilers receiving BSF diets produced meat that was redder than that of the control diet. Significant differences were observed between Trt2 and Trt8 with regards to pH of the meat (pH of 6.4 and 6.0 respectively). For the total tract digestibility study the following were evaluated: protein, fat, fiber, ash, amino acids and apparent metabolisable energy (AME). There were significant differences among all the treatments with regards to AME and the other nutrients. Trt1, Trt2, Trt3 and Trt5 had the highest coefficient of total tract digestibility (CTTD) over all the nutrients analysed. These treatments had CTTD's over 0.9 for crude protein and the essential amino acids. The layer trial only investigated four out of the initial eight treatment methods of the pre-pupae (Trt1, Trt3, Trt5 and Trt8), with two housing methods for each treatment (naturally ventilated and free range). The eggs were stored at room temperature at different time intervals before analysis: 1) the same day, 2) one day after collection, 3) one week later, 4) two weeks later and 5) one month later. The data collected were egg weight, shell weight, yolk weight, yolk colour and albumen height. The albumen height was used to determine the Haugh unit (HU). It was concluded that there were no significant differences between the dietary treatments with regards to shell weight, HU, shell thickness and colour. There were, however, observed differences between dietary treatments for egg weights and yolk weight. Trt3 house (naturally venitlated) differed significantly from the other treatments with regards to egg weight. While Trt3 house (naturally venitlated) and Trt5 house (naturally venitlated) differed significantly from the control group regarding yolk weight. It was observed that with increased storage time the quality of the eggs degraded (egg weight, yolk weight and HU). There were significant differences between treatments with regards to egg weight and yolk weight in storage group 1. There were also significant differences in storage group 2 as pertaining to egg weight, Trt3 house being significantly heavier than the other treatments except for Trt1 house. Trt1-3 free range also differed significantly from the other treatment groups. It can be concluded that BSF grown on human waste can successfully be used as a protein source in broiler and layer diets. Good production values along with carcasses of acceptable physical and chemical quality can be produced in broilers, with no measurable toxic effects. The BSF are also highly digestible irrespective of treatment. It was also concluded that eggs produced from diets containing BSF grown on human waste were still of good quality with no adverse effects to be found.
An assessment of the contributions of Afrikaner, Hereford and Simmentaler in composite breed development in beef cattle
(Stellenbosch : Stellenbosch University, 2000-12) Skrypzeck, Heidi; Schoeman, S. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The objective of this study was to obtain more information regarding the characterisation of Afrikaner (A), Hereford (H) and Simmentaler (S) breeds in an initial crossbreeding programme and subsequent composite development. This involves the estimation of breed additive effects, breed maternal, individual heterotic effects and maternal heterotic effects in the initial crossbreeding phase and the estimation of genetic parameters and prediction of breeding values in later generations for birth weight (BW), weaning weight (WW) and cow efficiency (CE; WW/dam weight" 75 x 100) in an intensive environment under high stocking rates. In the analysis of the initial crossbreeding phase, the S breed direct effects, expressed as deviation from the general mean, were positive (P :s; 0.01) for both BW and WW. Hereford and A breed direct effects were negative (P :s; 0.01) for both BW and WW. Afrikaner direct maternal effects were positive (P :s; 0.01) for both BW and WW. The H direct maternal effect was negative (P :s; 0.05) (- 2.8%) for WW. Simmentaler maternal effect was negative (P :s; 0.01) for BW but non-significant (P ;:::0:.05) for WW. Individual heterotic effects for BW were significant (P:S; 0.01) in H x S (3.5%) and S x A (11.0%) only. Individual heterotic effects were positive (P :s; 0.01) for WW, with that of the H x A (9.8%) and S x A (6.7%) crosses exceeding the H x S (3.1%) cross. Maternal heterotic effects were non-significant (P ;:::0:.05) for both BW and WW. Investigations of the contributions of the A, Hand S during composite development in later generations, respectively, were made to estimate direct heritabilities (h2 a) and maternal heritabilities (h2 m) for BW and WW of the calf and CE of the dam. Calves were born between 1968 and 1993 (n = 52628). Calves of this composite population had varying levels of A, Hand S genes ranging from o to 75%, 0 to 100% and 0 to 96.9%, with an average of 4.3,19.3 and 33.4%, respectively. For the A, direct heritabilities fitting unitrait models were 0.67, 0.53 and 0.19 for BW, WW and CE, respectively, with corresponding estimates of h2mbeing 0.22, 0.36 and 0.58. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.62. Direct breeding values for BW increased and reached a maximum value at 0.11 proportion of A. The maternal breeding values for BW decreased linearly between 1.6 to 37.5% A proportion and increased linearly between 37.5 to 75% A proportion. For WW, the direct breeding values decreased linearly with increasing A proportion, while the maternal breeding values were not affected by proportion of A. Cow efficiency was unaffected by an increase in proportion of A. For the H, direct heritabilities fitting unitrait models were 0.67,0.52 and 0.21 for BW, WW and CE, respectively, with corresponding estimates of h2mbeing 0.22, 0.36 and 0.60. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.64. Direct breeding values and maternal breeding values for BW and WW decreased with increasing proportion of H. Direct breeding value for CE increased, while the maternal breeding value for CE reached minimum value at 0.62 proportion ofH. For the S, direct heritabilities fitting unitrait models were 0.66, 0.53 and 0.21 for BW, WW and CE, respectively, with corresponding estimates of h2m being 0.22, 0.36 and 0.59. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.63. Direct breeding values for BW and WW decreased and maternal breeding values increased with increasing proportion of S. Cow efficiency was unaffected by an increase in proportion of S. The study suggests that in the initial crossbreeding phase, purebred S breeding seems to be the best breeding practice for this environment and that during composite development, high A and H contributions could lead to low BW and WW (except the maternal contribution of the A for BW and WW). The advantage of the S lies more in the maternal contribution than in the direct contribution suggesting that the S is a large-framed maternal line rather than a terminal sire line.
Beef production, quality and fatty acid composition of non-descript crossbreed steers fed natural pasture-based diets
(Stellenbosch : Stellenbosch University, 2018-12) Dezah, Tatenda; Mapiye, Cletos; Dzama, Kennedy; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: The broad objective of the current study was to assess beef production and quality of steers fed diets formulated using locally available feed resources in communal areas of Eastern Cape Province, South Africa. A survey to identify locally available feed resources was conducted using pretested structured questionnaires administered to 47 and 48 participants from Ncorha and Gxwalibomvu communities, respectively. Crop residues (65% of all respondents), maize stover in particular, were common in both areas, with more farmers from Ncorha (70%) using crop residues than those in Gxwalibomvu (59%). Few farmers (<5%) from both communities used cereal grains and exotic herbaceous legumes (i.e., lucerne) as feed supplements. Farmers also mentioned that cattle browsed indigenous and exotic leguminous tree species, especially Acacia mearnsii (Black wattle) during the dry season. Most abundant feed resources in Ncorha and Gxwalibomvu communities were collected in two seasons and their nutritional composition analysed. Lucerne hay and A. mearnsii had the overall highest protein in both seasons while maize grain and natural pasture hay were the overall best energy sources. Cultivated pasture hay had the highest neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) and consequently had the least in-vitro dry matter digestibility (IVDMD) compared to feed ingredients. Among the crop-based feed resources, Glycine max-based commercial ration had the highest crude protein content followed by maize grain. The growth performance, carcass attributes, meat quality and fatty acid composition of crossbred steers fed Acacia mearnsii-based, Medicago sativa-based and Glycine max-based diets were assessed. Thirty-six 12-month-old steers were randomly allocated to the three diets (n = 12 per treatment) under feedlot conditions for 120 days. The steers fed A. mearnsii-based diet had lower (P < 0.05) average daily feed intake and average daily gain (ADG) than steers fed M. sativa-based and G. max-based diets. Steers fed the A. mearnsii-based diet, however, had a higher (P < 0.05) feed conversion ratio than steers fed M. sativa- and G. max-based diets. Steers fed M. sativa-based diet had the highest (P > 0.05) warm and cold carcass weights followed by those fed the G. max-based and A. mearnsii-based diets, respectively. The G. maxbased and M. sativa-based diets had positive effects on growth performance and carcass characteristics of the steers compared to the A. mearnsii-based diet. Diet had no effect (P > 0.05) on meat colour (L*, a*, b*, chroma and hue), pH, temperature, drip loss, shear force, crude protein and fat. Meat from steers finished on A. mearnsii-based diets had higher (P ≤ 0.05) moisture and ash content than meat from those finished on G. max-based and M. sativabased diets. Meat from steers fed A. mearnsii-based diets had the highest cooking losses followed by those fed and M. sativa- and G. max-based diets, respectively (P ≤ 0.05). Meat from steers fed the M. sativa-based diet had higher (P ≤ 0.05) proportions of individual and total SFA and (n-) 3 PUFA and lower (P ≤ 0.05) proportions of linoleic acid and total n-6 PUFA than G. max and A. mearnsii- based diets. Steers finished on A. mearnsii-based diet had lower feedlot performance, greater gross margins, better n-3 PUFA profile and comparable meat quality to those finished on M. sativa- and G. max-based diets. The M. sativa-based diet had better potential to be used as alternative feeding resources for finishing cattle in a conventional feedlot system than the A. mearnsii-based diet.
Die beheer van rooikatte (Felis caracal) en bobbejane (Papio ursinus) in Kaapland met behulp van meganiese metodes
(Stellenbosch : Stellenbosch University, 1989-12) Brand, D. J.; Nel, J. A. J.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
AFRIKAANSE OPSOMMING: Die wye verspreiding van rooikatte oor Kaapland in al die hoofplantegroeitipes en in 'n wye verskeidenheid van terreintipes is aangetoon. Rooikatte blyk heterogene habitatte, geskep deur gebroke terrein en/of verskeidenheid van plantgemeenskappe, te verkies bo homogene habitatte, terwyl die grootste kleinveeverliese (deur rooikatte) in eersgenoemde habitatte voorkom en die meeste rooikatte ook daar gevang is. Die doeltreffendheid en selektiwiteit van rooikatbeheeroperasies met vanghokke en slagysters is hoofsaaklik beïnvloed deur die opleiding en motivering van operateurs, en die teikendierdigtheid, terwyl beheeroperasiekoste grotendeels deur studiegebiedgrootte bepaal is. Temperatuur, relatiewe humiditeit en reenval blyk nie 'n effek op beheerresultate te he nie, terwyl sterk wind, windrigting en maanfase moontlik 'n effek, en habitat en veldtipe 'n statisties betekenisvolle effek daarop het. Meer rooikatmannetjies as wyfies, waarvan 'n klein persentasie dragtig of lakterend was, is gevang. Die meerderheid rooikatte wat gevang is, was jonger as twee jaar. Ses-en-dertig persent van die rooikatte is in die eerste vier dae van 'n beheeroperasie gevang waarna 'n geleidelike daling in die aantal rooikatte gevang met 'n toename in vangdae plaasgevind het. In Suidwes- en Suid-Kaapland is bobbejane, veral in besproeiingsgebiede, tot die gebroke en bergagtige terrein beperk. Bobbejaanskade in hierdie dele is hoofsaaklik tot gewasse beperk alhoewel bobbejane ook kleinveeverliese veroorsaak en skade aan draadheinings, waterkrippe en pypleidings aangerig het. Die gebruik van bobbejaanvanghokke kon in die algemeen as 'n doeltreff ende en ekonomiese beheermetode (in vergelyking met ander probleemdierbeheermetodes) beskou word mits die voorgeskrewe vanghokke gebruik en die aanbevole vangprosedure gevolg is. Doeltreffende bobbejaanbeheer kon ook deur menslike aktiwiteite, ongure weersomstandighede, alternatiewe voedselbronne, Iokaaskeuse en alternatiewe beheermaatreels beïnvloed word, terwyl tropsamestelling nie beheerresultate blyk te beïnvloed nie. Bobbejaanvanghokke is hoogs selektief in beheeroperasies aangewend en 'n minimum nie-teikendiere is gevang. Hierdie inligting dra by tot kennis om verbeterde voorligtings- en opleidingsprogramme oor die beheer van rooikatte en bobbejane daar te stel.
'n Beoordeling van prestasie-evalueringsprosedures van Dorperramme onder ekstensiewe bestuurstoestande
(Stellenbosch : Stellenbosch University, 2007-03) Von Schauroth, Erich Dieter Friedrich; Schoeman, S. J.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: AN ASSESSMENT OF PERFORMANCE EVALUATION PROCEDURES OF DORPER RAMS UNDER EXTENSIVE MANAGEMENT CONDITIONS. During 1988 to 2000, Dorper rams (n=2565) maintained on the Kalahari Experimental Farm during performance test periods of approximately 180 days, were subjected to evaluation according to specific body measurements and breed standards. The respective body measurements included live weight, shoulder height, body length, body width, scrotal circumference and average daily weight gain (ADG). The measurements were recorded at the beginning and end of each evaluation period. The rams were evaluated visually by breed inspectors and classified according to breed standards. Live weight recorded at the beginning of evaluation periods, was moderate to high, and positively correlated with most of the body measurements recorded in the study. The exception was ADG, which was negatively correlated (-0.25) with live weight. Live weight recorded at the end of evaluation periods was moderately and positively correlated with scrotal circumference (0.57), and highly correlated with body width (0.76). Average daily weight gain was high and positively correlated with live weight (0.63) recorded at the end of the evaluation periods. Large variations within test periods, that could be attributed to age differences and variation between the respective groups of rams, necessitated correction of the data for the effect of year/season. The rams were divided into above- and below average groups according to their weight at the beginning of the test period. Analysis of the growth patterns of rams during the study period, using the adjusted end data, indicated that 75% of the rams remained in their respective groups. This finding supports the above-mentioned positive correlation of 0.58 that was reported for live weight at the beginning and end of evaluation periods. Body measurements recorded at the beginning of the evaluation periods were in most cases moderately to high and positively correlated (P<0.0001) with measurements recorded at the end of the evaluation periods. The exception was ADG, which was low and negatively correlated with the respective body measurements that were recorded at the beginning of evaluation periods. After each body measurement was quantified by the sum of squares, it became evident that year/season had the greatest influence on the body measurements recorded at the end of an evaluation period. Year/season influenced live weight, body width, shoulder height, scrotal circumference and ADG, with the largest effect on live weight and the least influence on ADG (R2 = 31.62). After correction for year/season, the contribution of the respective measurements to live weight recorded at the end of evaluation periods were still in the same order. After a step-wise procedure for adjusted live weight at the end of evaluation periods was performed, it was found that body width contributed the most to live weight. Average daily gain made the third largest contribution, i.e. with respect to body width (largest) and body length (second largest), to corrected live weight recorded at the end of evaluation periods. The high correlations reported between the respective body measurements necessitated the analysis of the data for multi-colinearity to determine whether the partial contribution of the respective body measurements would differ from the initial values. The partial contribution of the respective body measurements, however, was not affected by the analysis. Regression analysis indicated that the respective body measurements and weights recorded at the beginning of evaluation periods decreased significantly (P<0.0001) over the entire period (1988-2000). The largest annual decreases were reported for ADG (- 2.5%) and body width (-1.1%), respectively. The decreases in ADG and body width are indications that Dorper sheep decreased in size during the period of this study. The value of visual appraisal methods therefore need to be seriously considered to determine whether this is a valuable management tool to assess the production performance of Dorper rams under extensive conditions. The influence of corrected body measurements and ADG, i.e. after selection by breed inspectors and according to breed standards, was plotted on scatter plots. The plots indicated that the breed inspectors selected larger and heavier rams throughout. It is however, still the case in the Dorper industry that rams that perform below average are sometimes classified and used as stud breeding material. Body width and shoulder height were the body measurements that received the highest and lowest approval as visual selection criteria, respectively. A possible reason for this is that the tendency of a smaller Dorper sheep can be attributed to the decreasing shoulder height, as the latter is an indication of body frame size. Visual appraisal should therefore be used in conjunction with scientific methods. Optimum size for the Dorper should be established.
Black soldier fly (Hermetia illucens) pre-pupae as a protein source for broiler production
(Stellenbosch : Stellenbosch University, 2015-03) Uushona, Tulimo; Hoffman, Louwrens C.; Pieterse, E.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of the study was to investigate the potential of black soldier fly (Hermetia illucens) pre-pupae meal (BSM) as a protein source in broiler chicken diets. The first part of the study determined the digestibility of black soldier fly pre-pupae meal in a trial where four treatment diets, i.e. 100% maize (control diet), BSM dried at 100 °C (BSM100), BSM dried at 65 °C (BSM65), and defatted BSM dried at 65 °C (DF-BSM) were fed to Cobb 500 broiler chicks, 43 days of age, for a period of three days. The chicks (n=64) allocated to the treatment groups were acclimatized to the treatment diets for a period of three days prior to the experimental feeding period. The chicks received a commercial diet, according to the guidelines of Cobb-Vantress, up to an age of 39 days. The DF-BSM diet was found to be more digestible than the BSM65 diet, and acceptable digestibility values (i.e. above 70%) were reported for all the treatment diets. The apparent metabolisable energy of the BSM65 diet was 16.52, with a crude protein coefficient of total intestinal tract digestibility (CTTD) of 86%, which is higher than that reported for soya bean meal. In the second part of the study, the inclusion of BSM65 in chicken diets and the effect on broiler production parameters; organ, gut and skeletal parameters, were investigated. Black soldier fly pre-pupae meal, dried at 65 °C (BSM), was included in broiler diets at levels of 0, 5, 10, and 15%, respectively and fed to 320 day-old Cobb 500 broiler chicks for a period of 35 days. For most of the production parameters studied, no significant differences were reported for average daily intake, live weight gain, feed conversion ratio and European protein efficacy factor. A significant effect was observed for average weekly feed intake and cumulative feed intake at day 18 of age. This part of the study indicated that BSM65 levels included at 15% sustained normal growth in birds used in the study, which indicated the viability of BSM to be used as a protein source in broiler diets. The findings also indicated that the inclusion of BSM in broiler diets did not influence organ weight, gizzard erosion score, tibia ash percentage, tibia breaking strength, tibia mineral content, small intestine pH, and histomorphology of the duodenal and jejenal regions. In the third part of the study, the inclusion of BSM65 in broiler diets on carcass characteristics and meat quality of broilers was investigated. Black soldier fly pre-pupae meal dried at 65 °C did not compromise the physical, sensory and chemical quality of the broiler meat. No significant effects were also found in terms of live slaughter weight, cold carcass weight and the commercial portions (i.e. breast, thigh, drumstick, wing and back). Overall, the study indicated that BSM, which is considered a non-traditional protein source, can be included in broiler diets at levels as high as 15%, without any adverse effect on normal broiler production, organ and skeletal parameters. The inclusion of BSM in broiler diets did not affect the quality of the meat nor compromised the eating quality of the meat produced, when compared to meat of broilers fed the control diet (commercial broiler diet).
Breed differences in ruminal digestibility of forages in dairy cows receiving high concentrate diets
(Stellenbosch : Stellenbosch University, 2000-11) Retief, Nicky; Schoeman, S. J.; Cruywagen, C. W.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science .
ENGLISH ABSTRACT: Statistical analysis was conducted on data from two Elsenburg herds, containing 105 Jersey and 232 Holstein cows. The data was examined for external factors which may affect milk yield and milk composition. The data consisted of 337 first lactation records, taken over a 20 year time period. Breed of cow had an effect on milk yield, butterfat and protein production, as did the year in which the cows were born and the age of the heifer at first calving. There was a significant interaction between the breed and year of birth. There are other external factors, which are difficult to quantify, which may have an effect on production. In the following trials, eight ruminally cannulated dairy cows (four Jerseys and four Holsteins) were used to determine the effect of breed on forage digestibility in the rumen. All cows received a high concentrate mixed ration, with supplementary wheat straw. An in situ rumen degradability trial was conducted with three different forages, viz. lucerne, wheat straw and NaOH-treated wheat straw. The bags were incubated in the rumen for time intervals of 2,4, 8, 12, 16,20,24, 36,48, 72 and 96 hours and samples were analysed for dry matter (DM) and neutral-detergent fibre (NDF). Higher rumen degradability values (P<0.01) ofDM and NDF were observed in Jerseys for all three forages. Differences were more apparent for wheat straw and treated wheat straw than for lucerne. The rate of passage of digesta from the rumen was measured in both breeds by a chromium mordanted wheat straw marker. The Holsteins manifested a higher rate of passage (P<0.05) than the Jerseys, while daily feed intakes were also higher (P
Breed, transport and lairage effects on animal welfare and quality of Namibian beef
(Stellenbosch : University of Stellenbosch, 2010-03) Luhl, Juljane; Hoffman, Louwrens C.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Namibia by nature is very well suited for livestock production and is a net exporter of beef. Beef is currently exported to South Africa, the European Union (EU) and Japan while market access to the United States of America is being explored. Food safety, traceability and lately animal welfare are all aspects which are requested by Namibians trading partners when exporting meat to those countries. The first two aspects have been addressed with the introduction of the Farm Assured Namibian Beef scheme (FAN Meat) which also provides basic guidelines for animal welfare. Beef in Namibia is produced from extensively managed enterprises which are privately owned and managed, or state owned and communally utilized. The events of handling and transport are considered stressful to all animals but especially so to extensively raised animals and their reaction to these events has the potential to severely infringe on their welfare. The aim of this study was to determine the effect of pre-, during, and post-transportation handling on animal welfare status under Namibian transport conditions. The study also investigated the influence of breed on the meat quality of Namibian beef. The level of bruising recorded on slaughter was used to measure animal welfare. Interviews with producers were conducted to describe the pre-transport handling. Questionnaires that included variables considered as important indicators of animal welfare during transport were distributed to truck drivers. Observations of the off-loading event and animal behaviour were completed in lairage at the export abattoir in Windhoek. The variables that were identified as high risk factors and had a significant influence on the level of bruising under Namibian transport conditions include animal factors (i.e. breed type, age, sex, condition and subcutaneous fat cover), pre-transport handling (i.e. re-branding of animals), transport related risks (loading density and animals lying down during transit) as well as lairage factors (i.e. fit of truck floor to off-loading ramp, the way animals moved to holding pens, pen size and minimum environmental temperatures). The influence of breed on meat tenderness and water-holding capacity of the Longissimus dorsi muscle of the four main beef breeds (i.e. Brahman, Bonsmara, Simbrah and Simmental), as well as the effect of different aging periods on meat quality (i.e. 2, 9, 16, 23, 30 & 37 days post mortem) were investigated. The Brahman differed significantly (p < 0.05) from the other three breeds in terms of all aging treatments; with higher Warner-Bratzler shear force values reported for this breed. Interactions between days post mortem and breed were found for the Simbrah, and Simmental breeds, which may be indicative of a delayed response to aging of meat samples obtained from Simbrah animals. This can possibly be ascribed to an increased calpastatin activity in these animals. Meat samples obtained from the Bonsmara steers showed the highest rate of tenderization, with this effect retained until day 30 post mortem. Recommendations as pertaining to the ante mortem handling of cattle are made.
Buffer supplementation in concentrates for Jersey cows grazing spring ryegrass pasture
(Stellenbosch : Stellenbosch University, 2015-03) Van Dyk, Nelita; Cruywagen, C. W.; Meeske, R.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Pasture is the cheapest available source of nutrients and in the Southern part of the Western Cape of South Africa the most common used pasture system is kikuyu grass, over-sown with ryegrass. For this reason, it is important to optimally utilise the pasture and to ever try to improve pasture based feeding systems. High quality ryegrass creates a risk for subclinical rumen acidosis (SARA) for dairy cows. Supplementing concentrates, which is inevitable as energy is the first limiting nutrient for dairy cows, increases the risk of incidence. The addition of buffers to total mixed ration feeding systems has achieved great success in diets containing high levels of concentrates. Information on buffers regarding pasture based systems is, however, lacking, especially pertaining to SARA. The cost of adding buffers to concentrates fed to grazing dairy cows is a concern. If, however, there is a challenge on the rumen, buffer addition has proved to increase the milk fat content and therefore the increased income might justify the expense. The purpose of this study was to determine whether the addition of buffers to concentrates supplemented to grazing dairy cows could utilise pasture optimally, whilst increasing milk yield and improving milk composition, and maintaining rumen functioning. Fifty four high producing Jersey cows were blocked according to milk yield, days in milk and lactation number. Cows within blocks were then randomly allocated to one of three treatments. Treatments included no buffer inclusion (CON), Acid Buf (AB) at a level of 10 g/kg and sodium bicarbonate (SB) at a level of 20 g/kg of the concentrate DM. Cows received 6.6 kg “as is” concentrate per day, consisting of 62% maize, 15% hominy chop, 11% bran, 4% soybean oilcake, 4% molasses, minerals and vitamins. Buffers were mixed into the concentrates beforehand to ensure intakes of 120 g of sodium bicarbonate or 60 g of Acid Buf per cow/day. Cows grazed high quality ryegrass during spring and were allocated 10 kg DM pasture per cow/day with ad libitum access to fresh water. Milk production was recorded daily and milk composition fortnightly, after an adaptation period of 14 days. Six ruminally cannulated Jersey cows grazed with the production study cows, to be used for a separate rumen study. These cows were divided into three groups of two and were allocated to each treatment. Cows were crossed-over through-out the duration of the trial to ensure that all cannulated cows received each treatment. An in sacco digestibility trial was done and rumen pH and volatile fatty acid (VFA) concentrations were also determined. Milk production (kg/day) was 20.2, 20.3 and 20.5, whereas 4% fat corrected milk production (kg/day) was 20.8d, 21.8cd, 21.9c for the CON, SB and AB treatments, respectively. Milk fat content did not differ among treatments and was 42.4, 45.0 and 45.1 g/kg, whereas milk protein tended to be different at 34.1d, 35.6c and 35.1cd g/kg for CON, SB and AB, respectively. Milk lactose differed among treatments and was 44.9b, 47.6a and 47.6a g/kg, whereas milk urea nitrogen was 10.5a, 9.7ab, 9.6b for CON, SB and AB, respectively. Total VFA and proportions of individual VFA’s did not differ among treatments. Treatment also had no effect on mean ruminal pH and time spent below critical pH values. Pasture DM and NDF digestibility did not differ among treatments. The results indicated that milk production and rumen functioning can be maintained with the addition of buffers to grazing cows, even though no differences were found between control and buffered treatments. The milk composition was, however, favourably affected by buffers and it could be economically viable for farmers using similar production systems.
The caracal, Felis caracal caracal Schreber, 1776, as predator in the West Coast National Park
(Stellenbosch : Stellenbosch University, 1993) Avenant, Nico Loubser; Nel, J. A. J.; Stellenbosch University. Faculty of AgriSciences. Department of Animal Sciences.
ENGLISH ABSTRACT: Small mammals were sampled in eight different plant communities in the West Coast National Park and on two farms adjacent to the Park, and along various slopes in the Postberg Nature Reserve section. Rhabdomys pumilio was by far the most abundant species at all sites, although its density varied between plant communities and seasons. Species diversity, absolute and relative density, cover preference and breeding activity of some small mammals and density, group size and habitat preference of the main bird prey species are also discussed. A low incidence of larger prey, e.g. antelope, hyrax and hares in caracal scats probably reflects their low densities in the study area. Together with caracal, the diet of four other sympatric carnivore species was also examined by analysis of scats collected over a 14-month period in the West Coast National Park. Dietary patterns of all predators studied correlated with fluctuations in densities of main prey species, as well as group size of certain prey species. Food niche widths accordingly changed seasonally, being widest during spring and then contracting gradually towards winter. A considerable amount of food niche overlap existed between carnivore species pairs. The main prey item of all the carnivores examined were rodents (mainly Rhabdomys pumilio and Otomys unisulcatus), which were utilized heavily throughout the year, despite marked declines in rodent numbers towards winter. Habitat use by five transmitter-equipped caracal (Felis caracal Schreber 1776) indicated that they spent most of their time active in specific areas where highest rodent density and species diversity were found. Males were active for 45-180 min. in a given area (patch) before moving, without stopping, to another patch; females covered their ranges more uniformly in space. The mean home range size (26.97 ± 0.750 km2) of two males inhabiting the same area, but at different times, was 3.6 times larger than that of each of three females (7.39 ± 1.68 km2). Home ranges overlapped both within and between sexes. Caracal were mostly nocturnal, but were also active during daytime in the colder winter. No correlation was found between degree of activity and cloud cover, full or dark moon, wind speed, or rain, but a significant correlation existed between degree of activity and temperatures above 22°c or below 20°c. Mean litter size was 2.25 ± 0.96, with kittens staying ca 120 days with their mother in her territory. This four-month period coincided with the time when most springbok were predated on and when the highest stock losses were reported on farms in the surrounding Swartland Divisional Council. The impact of caracal on introduced springbok at Postberg Nature Reserve section of the West Coast National Park was studied to aid in the decision of whether springbok can be kept in that section of the Park or not. This study contributes to the conservation and control of caracal in the West Coast Strandveld.

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