Browsing by Author "Hoffman, L. C."
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- ItemAnalysis of carcass characteristics and fat deposition of Merino, South African Mutton Merino and Dorper lambs housed in a feedlot(South African Society for Animal Science, 2018-02-15) Brand, T. S.; Van der Westhuizen, E. J.; Van der Merwe, D. A.; Hoffman, L. C.The objective of this study was to determine the effect of time spent in a feedlot on the size of the various fat depots and the distribution of the main tissues (muscle, bone, and fat) of three common South African sheep breeds. Lambs were supplied with a balanced diet (16% protein, 10 MJ ME/kg feed) ad libitum and had free access to water. Lambs from each breed were divided into six groups, which were slaughtered at 21-day intervals until a production period of 105 days had been reached. During carcass dressing, visceral and renal fat was removed and expressed as a percentage of carcass weight. The subcutaneous fat (SCF) depth was measured on the longissimus lumborum at the 13th rib position using an electronic calliper. The proportion of muscle, bone and fat was determined by dissecting a three-rib cut made on the prime rib between the 9th and 11th ribs. The percentage of visceral and renal fat increased throughout the production period for all breeds. The percentage of renal fat was up to 2.9% higher than the percentage visceral fat in both SAMM production groups. Dorper lambs tended to have high SCF levels (5.6 mm fat after 42 days) due to the early maturing nature of the breed. They reached a maximum fat depth of 20.4 mm fat after 105 days. The SAMM lambs tended to deposit SCF at a slower rate and the late maturing Merino breed was found to be much leaner, and did not reach the high fat levels of the SAMM or Dorper lambs. The percentage of muscle and bone in all carcasses decreased with an increase in the number of days in the feedlot, while the percentage of carcass fat increased during this period. The increase in late maturing adipose tissue in all breeds as they become older is amplified by the restricted movement in the feedlot and high energy diet that the lambs receive.
- ItemAnti-nutritional factors in canola produced in the Western and Southern Cape areas of South Africa(South African Society for Animal Science, 2007) Brand, T. S.; Smith, N.; Hoffman, L. C.ABSTRACT: The development of low erucic acid, low glucosinolate cultivars of canola seed has led to the availability of a feed ingredient with considerable potential to replace soyabean meal in diets for all classes of farm animals. The sinapine and glucosinolate content of various canola cultivars cultivated in two areas of the Western Cape, South Africa were compared. There were no significant differences in sinapine content between the canola produced in the Western and Southern Cape (mean value of 9.95 mg sinapine/g grain). There were cultivar differences, with Varola 54 and Rainbow cultivars having significantly higher sinapine concentrations than Varola 50. There were no significant differences between the aliphatic, indolyl or aromatic glucosinolate content of the canola originating from either the Swartland or the Ruens areas in South Africa (mean value of 17.84 umol total glucosinolates/g grain). There were significant differences in the total glucosinolate content of the various canola cultivars. Varola 44 and Hylite 200TT had the lowest total glucosinolate concentration and Varola 50 had the highest glucosinolate concentration. The results obtained seem to indicate a maximum dietary inclusion level of up to 14% for South African produced canola with an average of 17.83 umol glucosinolates per gram to ensure optimal animal production.
- ItemApplication of European standards for health and quality control of game meat on game ranches in South Africa(AOSIS, 2011) Van der Merwe, M.; Jooste, P. J.; Hoffman, L. C.The health and quality compliance of game carcasses (n = 295) intended for the South African export market and aspiring to comply with the strict hygiene requirements of the European Union were compared with game carcasses (n = 330) available for the local market and currently not subjected to meat safety legislation. Samples were collected in similar seasons and geographical areas in South Africa from 2006 to 2009. Aerobic plate counts (APC) of the heart blood verified that both groups possessed similar ante mortem bacterial status. For health compliance APC, tests for Escherichia coli, Salmonella spp. and Staphylococcus aureus were performed on the carcasses. Surfaces of the local carcasses were swabbed using the European Enviro-biotrace sponge technique at 3 and 72 h post mortem. Unskinned but eviscerated export carcasses in the abattoir were skinned and sampled by incision using a cork borer 72h post mortem. Temperature andpHreadings were recorded at 3 and 72 h post mortem from the longissimus dorsi muscle and the readings at 3 h differed (P = 0.035). Temperatures at 72 h were lower for export than local carcasses (P < 0.001) because of earlier introduction and maintenance of the cold chain. The pH readings also differed between groups at 3 and 72 h (P<0.001). APC results for the local group exceeded the maximum permissible count (<105). S. aureus results showed differences (P <0.001), with readings from the local group being higher. The same tendency was exhibited for E. coli (P = 0.008). Imposition of hygiene guidelines for game ranchers producing meat for the local market is therefore recommended.
- ItemApplication of immunocastration in a commercial Dohne Merino ram flock before weaning(South African Society for Animal Science, 2019-01-03) Needham, T.; Lambrechts, H.; Hoffman, L. C.The influence of pre-weaning immunocastration on the growth, incidences of reaction to vaccination, serum testosterone concentration and slaughter performance of ram lambs was determined and compared to that of physically castrated lambs. Immunocastration was performed using two doses of 2 mL Improvac® administered subcutaneously in the shoulder, alternating sides per vaccination, using a Sterimatic® needle guard system. The first vaccination was administered to 50 lambs with an average weight (± SD) of 16.0 ± 3.05 kg, and the second vaccination was carried out six weeks later, when the lambs weighed on average (± SD) 20.5 ± 4.11 kg. An additional 50 lambs were physically castrated using elastrator bands at the same time as the primary vaccination given to the immunocastrates. Data were collected during four sessions over the 25-week period, at time points which fitted into the normal management activities of the commercial operation (Weeks 1, 6, 16 and at slaughter). During these sessions, all lambs were weighed, and blood samples were collected from immunocastrates. The immunocastration injection site was also scored for adverse reactions. Immunocastration was successful in preventing testosterone secretion for the duration of the trial and no differences were reported regarding weight gain or slaughter performance between the treatments. The Sterimatic® and Stericap® system, as used in this study, proved to be an easy-to-use and safe system for the commercial administration of Improvac®, with no adverse reactions to vaccinations recorded at the injection sites. Pre-weaning immunocastration in lambs is thus possible, and the growth rate, carcass weight and carcass fatness of immunocastrates are similar to that of elastrator-castrated lambs.
- ItemCarcass and meat quality attributes of Malawi Zebu steers fed Vachellia polyacantha leaves or Adansonia digitata seed as alternative protein sources to Glycine max(South African Society for Animal Science, 2019-05-09) Chingala, G.; Raffrenato, E.; Dzama, K.; Hoffman, L. C.; Mapiye, C.To enhance smallholder beef farmers' capacity to cope with animal feed shortages, especially dietary protein induced by climate change, it is important to evaluate the feeding value of low-cost protein sources naturally available in the environment. The aim of the study was to evaluate carcass and meat quality of Malawi Zebu steers fed diets containing Adansonia digitata (baobab) seed meal or Vachellia polyacantha (white thorn tree) leaf meal as alternative protein sources to Glycine max (soybean) under feedlot conditions. Thirty Malawi Zebu steers (181 ± 21.4 kg body weight; 29 months old) were individually fed forage-based diets made up of rangeland hay and maize bran, with either baobab seed meal, Vachellia leaf meal or soybean meal as a protein source for 120 days. At the end of the feeding trial, animals were slaughtered and the longissimus thoracis et lumborum muscle sampled for meat quality analyses. Steers fed soybean and baobab diets had higher subcutaneous fat thickness, carcass weights than those fed the Vachellia diet. Meat from steers fed the Vachellia and baobab diets had higher ultimate pH and water-holding capacity, and lower drip and cooking losses than meat from steers fed the soybean diet. Feeding baobab and Vachellia diets produced beef with lower lightness (L*) values than the soybean diet, characteristic of dark, firm and dry (DFD) beef. Steers fed the baobab diet had the highest gross profits followed by those fed the Vachellia and soybean diets, respectively. Overall, feeding the baobab and Vachellia diets improved gross profit but produced DFD beef compared to the soybean diet.
- ItemCarcass and muscle yields of ostriches as influenced by genotype(South African Society for Animal Science, 2007) Hoffman, L. C.; Brand, M. M.; Muller, M.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe)ABSTRACT: Live, carcass, leg and muscle weight (kg) as well as dressing percentage were compared between South African Black (Struthio camelus var. domesticus) ostriches, purebred Zimbabwean Blue Neck (Struthio camelus australis) ostriches and the progeny of Zimbabwean Blue Neck males crossed with South African Black females, commercially slaughtered at 14 months of age. South African Black ostriches had the lowest live (84.9 kg) and carcass (43.3 kg) weights, compared to Zimbabwean Blue Necks (100.9 and 51.2 kg, respectively). In general, crossbred birds resembled Zimbabwean Blue Necks more closely for the quantitative meat traits. However, dressing percentage (51.1%) and yields of different carcass components (bone, leg) did not differ between genotypes. Six of the major muscles present in the ostrich leg (M. gastrocnemius, M. femorotibialis accessorius, M. iliotibialis cranialis, M. iliotibialis lateralis, M. iliofibularis and M. iliofemoralis) showed significant weight differences between genotypes, with South African Black ostriches yielding the lowest values.
- ItemCarcass traits and cutting yields of entire and immunocastrated pigs fed increasing protein levels with and without ractopamine hydrochloride supplementation(American Society of Animal Science, 2015) Needham, T.; Hoffman, L. C.The objective of this study was to determine the effects of increasing balanced protein, with and without ractopamine hydrochloride (RAC), in the finisher diets of immunocastrates on their carcass cutting yields and respective muscle, fat, and bone proportions. Carcass traits and yields of 120 individually housed entire male pigs and immunocastrates were evaluated following a 2 × 2 × 3 factorial design. Vaccination occurred at 16 and 20 wk of age and slaughtering at 24 wk. Up until 20 wk of age, all pigs received a commercial grower diet. Low-, medium-, and high-protein (7.50, 9.79, and 12.07 g standardized ileal digestible [SID] lysine/kg, respectively) diets were then fed for the last 28 d with RAC supplemented at 0 or 10 mg/kg. Immunocastration and RAC supplementation increased (P = 0.003 and P = 0.017, respectively) the live weight at slaughter. The interaction between sex and protein (P = 0.039) for caliper backfat depths showed greater backfat depths in immunocastrates fed medium protein whereas RAC decreased (P = 0.027) the caliper backfat depth. Feeding RAC increased the trotters (P = 0.040), tenderloins (fillets; P < 0.001), shoulder (P = 0.002), hindquarter (P = 0.026), loin (P = 0.028), and belly (P = 0.044) percentages. The shoulder (P < 0.001), hindquarter (P < 0.001), and loin (P = 0.005) muscle percentages were increased and the hindquarter fat percentages were decreased (P = 0.032) with RAC supplementation. Immunocastration increased the belly cut (P = 0.006), loin fat (P < 0.001), and belly fat (P < 0.001) percentages. Therefore, carcass cutting and lean yields can be improved by RAC supplementation while decreasing the backfat depth, and the increase in backfat due to immunocastration could be avoided with the correct dietary protein level.
- ItemCastration of male livestock and the potential of immunocastration to improve animal welfare and production traits : invited review(South African Society for Animal Science, 2017-09-15) Needham, T.; Lambrechts, H.; Hoffman, L. C.Growing consumer awareness about animal welfare has led to the assessment of the impact of common farming practices, such as physical castration, on animal well-being under production conditions. Physical castration is used in livestock industries to prevent indiscriminate breeding, control aggression, and improve meat and carcass quality. In terms of animal welfare, physical castration causes pain, decreased growth performance, infection, and mortality. An alternative approach to castration is thus warranted that will ensure optimal growth without compromising the castrated animal’s wellbeing. Immunocastration has proved to be an effective method of suppressing the development and functioning of the reproductive system in various domesticated and wildlife species. The effect of immunocastration on production performance is well-documented for both swine and cattle. Although ram lambs used for meat production are often physically castrated, information regarding the potential application of immunocastration in sheep is limited. However, immunocastration may potentially improve the welfare, performance, and meat quality of ram lambs used in commercial meat production systems. The purpose of this review is to compare the application and the effects of immunocastration on male livestock to highlight and motivate the need for further research into its use on ram lambs.
- ItemChemical characteristics of red hartebeest (Alcelaphus buselaphus caama) meat(South African Society for Animal Science, 2010) Hoffman, L. C.; Smit, K.; Muller, N.The aim of this study was to determine the effect of region (Qua-Qua, Maria Moroka, Sandveld and Tussen die Riviere) and gender on carcass characteristics and chemical composition of meat from the red hartebeest. The parameters measured on 29 red hartebeest included body weight, carcass weight, dressing percentage, proximate composition, fatty acid, cholesterol, amino acid and mineral content. The average carcass weight of males (79.3 kg) was significantly higher than that of females (56.0 kg); however, there was no difference in dressing percentages. The animals obtained from the Qua-Qua region had the highest lipid content (1.3 g/100 g meat sample) compared to hartebeest sampled in other regions. Differences in concentrations of individual fatty acids, amino acids and minerals were minor and of no practical value. The ratio of polyunsaturated to saturated fatty acids (0.78) is above the recommended 0.7 and therefore has positive implications for human health. These nutrient values determined in meat from red hartebeest could be incorporated into human food composition tables. These results will also be of value to the South African game meat exporters who may wish to market their products in terms of their nutritional value in order to compete with meat from domestic livestock or international venison products. In such cases, it is required by law (both locally and internationally) to provide adequate nutritional labelling.
- ItemA comparison between the body composition, carcass characteristics and retail cuts of South African mutton Merino and Dormer sheep(South African Society for Animal Science, 2004) Cloete, J. J .E.; Hoffman, L. C.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Fourie, J. E.The body composition, carcass characteristics and retail cuts of 61 Dormers (21 rams and 40 ewes) and 35 South African Mutton Merinos (SAMM) (17 rams and 18 ewes) were determined. A range of carcass measurements was recorded. Since there was no sex x breed interaction, only main effects of breed and sex were considered. There were no differences in slaughter weight between Dormer and SAMM sheep at 18 months of age. Dormers had a 2.7% point higher dressing percentage and a 6.2% higher carcass weight than the SAMM. The Dormer had a higher fat content (kidney fat, back-fat depth) than the SAMM. The eye-muscle area of the Dormers was 13% larger than that of the SAMM sheep. Rams were heavier than the ewes at slaughter. All the traits measured, indicated advantages in favour of rams. Only the saturated, mono-unsaturated fatty acids and polyunsaturated fatty acids to saturated fatty acids ratio differed significantly between the Dormer and SAMM sheep. Based on the fatty acid profile, SAMM meat is slightly healthier than that of Dormer sheep. The higher retail cut weights of Dormers suggested that they were superior to the SAMM as far as meat production was concerned.
- ItemA comparison between the effects of two cropping methods on the meat quality of impala (Aepyceros melampus)(South African Society for Animal Science, 2003) Kritzinger, B.; Hoffman, L. C.; Ferreira, A. V.Impala (Aepyceros melampus) constitute one of the most commercially important species in game farming in South Africa. The purpose of this study was to compare the effects of day and night cropping on the meat quality characteristics of impala. Emphasis was placed on the influence of the cropping method on muscle pH45 (45 minutes post mortem), pHu (ultimate pH), pH decline, and the related influence on drip loss, cooking loss, toughness and colour of the meat in the M. longissimus lumborum. Measurements taken from 16 animals cropped at night were compared to those taken from 24 animals cropped in daytime. A mean PH45 of 6.67 ± 0.11 was recorded for the night cropped animals compared to a mean pH45 of 6.55 ± 0.23 for the day cropped animals. A mean pHu of 5.39 ± 0.08 for animals cropped at night was recorded compared to a mean pHu of 5.45 ± 0.11 for the animals cropped in the day. Regression analysis showed the rate of pH decline to be slower in the night cropped animals compared to those cropped in the day. This persisted when the pH values were adjusted to correct for ambient temperature. The cooling rate of the M. longissimus lumborum was twice as fast in the night cropped group. Shear force values and drip losses respectively, for the night-cropped animals were 19.11 ± 5.68 g/mm2 and 2.93 ± 1.59%, whereas for the day cropped animals the values were 23.42 ± 8.13 g/mm2 and 4.15 ± 2.34%. The results of this study indicate that night-time cropping does have a beneficial effect on certain meat quality parameters.
- ItemComparison of shear force tenderness, drip and cooking loss, and ultimate muscle pH of the loin muscle among grass-fed steers of four major beef crosses slaughtered in Namibia(South African Society for Animal Science, 2016) Strydom, P.; Luhl, J.; Kahl, C.; Hoffman, L. C.The authors investigated the effects of breed (Brahman, Bonsmara, Simbrah and Simmental crosses) and post-mortem ageing on meat tenderness, purge, cooking loss and ultimate pH of the longissimus muscle under commercial production and slaughter conditions of the Namibian beef export industry. Fifty steers of each breed cross, at an average age of 2½ years and with an average subcutaneous fat cover of 2 mm over the 9th–10th thoracic vertebrae, were included in this study. The Brahman (BRX) differed significantly (P < 0.05) from all other breed crosses in all ageing treatments, recording higher Warner-Bratzler shear force values. The Bonsmara (BNX) steers showed the highest rate of tenderization and maintained this advantage up to day 30 post mortem. Purge and cooking loss increased initially and then tapered off over ageing time. BNX steers recorded the highest cooking loss
- ItemComposition of rabbit caecal microbiota and the effects of dietary quercetin supplementation and sex thereupon(Universidad Politecnica de Valencia, 2019) North, M. K.; Zotte, A. Dalle; Hoffman, L. C.The purpose of this study was to add to the current understanding of rabbit caecal microbiota. This involved describing its microbial composition and linking this to live performance parameters, as well as determining the effects of dietary quercetin (Qrc) supplementation (2 g/kg feed) and sex on the microbial population. The weight gain and feed conversion ratio of twelve New Zealand White rabbits was measured from 5 to 12 wk old, blood was sampled at 11 wk old for the determination of serum hormone levels, and the rabbits were slaughtered and caecal samples collected at 13 wk old. Ion 16STM metagenome sequencing was used to determine the microbiota profile. The dominance of Firmicutes (72.01±1.14% of mapped reads), Lachnospiraceae (23.94±1.01%) and Ruminococcaceae (19.71±1.07%) concurred with previous reports, but variation both between studies and individual rabbits was apparent beyond this. Significant correlations between microbial families and live performance parameters were found, suggesting that further research into the mechanisms of these associations could be useful. Negative correlations with the caecal flavonoid content were found, but the latter was not affected by diet, and the effects of quercetin supplementation on the microbiota were very limited, possibly due to the absorption of the quercetin-aglycone from the gastrointestinal tract prior to the caecum. Nonetheless, Clostridiales Family XIII. Incertae Sedis was more abundant in the quercetin-supplemented rabbits (Control: 0.003±0.003%; Qrc: 0.020±0.000; P=0.005), as was the genus Anaerofustis (Control: 0.000±0.002; Qrc: 0.010±0.002; P=0.003). Serum cortisol levels were higher in females, and several microbial families differed between the sexes. Most were more abundant in female rabbits, including the most abundant, the family Eubacteriaceae (Male: 2.93±0.40; Female: 4.73±0.40; P=0.01).
- ItemComposition of rabbit caecal microbiota and the effects of dietary quercetin supplementation and sex thereupon(Universidad Politécnica de Valencia, 2019) North, M. K.; Zotte, A. Dalle; Hoffman, L. C.The purpose of this study was to add to the current understanding of rabbit caecal microbiota. This involved describing its microbial composition and linking this to live performance parameters, as well as determining the effects of dietary quercetin (Qrc) supplementation (2 g/kg feed) and sex on the microbial population. The weight gain and feed conversion ratio of twelve New Zealand White rabbits was measured from 5 to 12 wk old, blood was sampled at 11 wk old for the determination of serum hormone levels, and the rabbits were slaughtered and caecal samples collected at 13 wk old. Ion 16STM metagenome sequencing was used to determine the microbiota profile. The dominance of Firmicutes (72.01±1.14% of mapped reads), Lachnospiraceae (23.94±1.01%) and Ruminococcaceae (19.71±1.07%) concurred with previous reports, but variation both between studies and individual rabbits was apparent beyond this. Significant correlations between microbial families and live performance parameters were found, suggesting that further research into the mechanisms of these associations could be useful. Negative correlations with the caecal flavonoid content were found, but the latter was not affected by diet, and the effects of quercetin supplementation on the microbiota were very limited, possibly due to the absorption of the quercetin-aglycone from the gastrointestinal tract prior to the caecum. Nonetheless, Clostridiales Family XIII. Incertae Sedis was more abundant in the quercetin-supplemented rabbits (Control: 0.003±0.003%; Qrc: 0.020±0.000; P=0.005), as was the genus Anaerofustis (Control: 0.000±0.002; Qrc: 0.010±0.002; P=0.003). Serum cortisol levels were higher in females, and several microbial families differed between the sexes. Most were more abundant in female rabbits, including the most abundant, the family Eubacteriaceae (Male: 2.93±0.40; Female: 4.73±0.40; P=0.01).
- ItemThe effect of age on the carcass composition, portion yield and proximate composition of two rabbit genetic types in South Africa(Universidad Politécnica de Valencia, 2017) North, M. K.; Nkhabutlane, P.; Hoffman, L. C.This study investigated the carcass component yields and meat proximate composition of 2 rabbit genetic types (Californian and hybrid New Zealand Red×Californian), with 5 rabbits per genetic type being slaughtered every 2 wk throughout the study period (9-17 wk) to evaluate the effect of age on these traits. Slaughter weight, reference yield, portion yield (hind leg, foreleg and fore part, as percentage of slaughter weight), meat yield, skin weight and the fat content of the meat (percentage of wet weight) increased significantly with age, while the full gastrointestinal tract, liver, head and feet decreased significantly. This is likely a reflection of the early-maturing nature of bone and viscera and later maturing nature of muscle and fat. These results indicate that delaying slaughter to 13 wk tends to improve yields for valuable carcass components. The Californian had a significantly higher total meat yield at 11 and 17 wk and higher portion meat yields at 9 (hind leg), 11 (hind leg and fore part) and 13 (foreleg) weeks than the hybrid. This was likely due to the later maturation of the hybrid and the influence of the New Zealand Red on carcass quality. It therefore appears that the Californian may be more favourable for meat production, from a carcass and meat quality perspective.
- ItemEffect of chronological age of beef steers of different maturity types on their growth and carcass characteristics when finished on natural pastures in the arid sub-tropics of South Africa(South African Society for Animal Science, 2004) Du Plessis, I.; Hoffman, L. C.In the arid sweetveld regions of South Africa producers are marketing beef steers increasingly as long weaners (ca. 12 months of age) or finishing them on the natural grazing to a ready-to-slaughter stage at between 18 and 30 months of age. Limited production norms in this regard are available since most growth and carcass studies have been conducted in the sourveld regions of the country. In this study steers from four different beef maturity types which differ in body frame size were used, viz. Simmentaler crosses (large, >500 kg mature weight), Bonsmara crosses (large-medium, 450-500 kg mature weight), the Afrikaner (small-medium, 400-450 kg mature weight) and the Nguni (small, <400 kg mature weight). After weaning the steers in each type were randomly allocated to three groups, viz. groups slaughtered at 18, 24 or 30 months of age after raising them on natural sweetveld pasture. Live weight, cold carcass weight, carcass fat classification code and number of visible incisors were recorded. Growth rates from weaning to 24 months of age were similar for the different maturity types, though the Afrikaner steers gained significantly less than the Bonsmara crossbreds. Periods where high growth rates occurred (at 12 to 18 months of age and 24 to 30 months of age) coincided with the rainy season. Relatively low dressing percentages were noted and could be attributed to the fact that all internal organs and fat were removed at slaughtering, as well as a possible high level of gut fill. Due to genetic variation within maturity types it was not possible to predict the market readiness of a particular individual from its live weight. The carcass weights were heavier for steers slaughtered at 24 months of age than those at 18 months of age, but had a lower fat classification code. This seems to be due to the fact that these steers were slaughtered at the end of the winter period when the quality of the grazing was at its lowest. The carcasses of all maturity types had the highest fat classification codes at 30 months of age. However, the carcasses of 77.8% of the Simmentaler crossbreds were graded 1 (lean) in the fat classification. Furthermore, at 30 months of age 23.8% of all steers had more than two permanent incisors. This increases their carcass age classification, which lowers their carcass grading according to the South African grading standards, and thus their price per kg relative to the younger ages. The results of this investigation indicated that steers of all frame sizes would have to be fed additional energy to ensure that they finish with a fat classification code of at least 2 before the age of 30 months to ensure optimal financial returns.
- ItemEffect of days in feedlot on growth performance and carcass characteristics of Merino, South African Mutton Merino and Dorper lambs(South African Society for Animal Science, 2016-12-08) Brand, T. S.; Van der Westhuizen, E. J.; Van der Merwe, D. A.; Hoffman, L. C.This study investigated the effect of feedlot production on lamb growth characteristics of three common South African breeds: Merino, South African Mutton Merino (SAMM) and Dorper. Lambs were supplied with a balanced diet (16% crude protein, 9.41 MJ ME/kg feed) ad libitum and had free access to water. Lambs from each breed were divided into six groups. One group of each breed was slaughtered every three weeks until 105 days under feedlot production were reached. The weights of the lambs were recorded weekly, along with feed intake, to obtain the individual daily intake, average daily gain (ADG) and feed conversion ratio (FCR) for each lamb. The ADG for the SAMM 2007 and Dorper lambs increased throughout their production period, while that of the SAMM 2008 and Merino lambs tended to decrease with time, although the SAMM 2008 group achieved the highest ADG of 350.2 g/lamb/day of all the breeds. The Dorper and SAMM 2007 lambs had higher FCR (7.52 and 7.58, respectively). The average FCR achieved by the SAMM 2008 and Merino lambs was 5.54 and 5.14, respectively. However, the FCR of Merino and SAMM 2008 lambs increased throughout the production period. The Dorper lambs produced fatter carcasses and therefore exhibited the highest average dressing percentage of 49.7% compared with the SAMM 2007 (48.4%) and 2008 lambs (45.6%), followed by the Merino lambs (43.9%). The results confirm that the Merino is a late maturing breed that is recognised for its wool rather than meat production, and therefore exhibits weaker growth characteristics. The SAMM is a dual-purpose breed that has also been selected for growth and meat production, and therefore exhibits desirable production characteristics, while the Dorper is an early maturing breed that deposits localized fat at an earlier age as it grows, thereby producing fatter carcasses than SAMM and Merino lambs. Therefore, Dorper lambs should be slaughtered at lower live weights so that carcasses are not graded as over-fat.
- ItemEffect of dietary vitamin E on the performance of broilers and quality of broiler meat during refrigerated and frozen storage(South African Society for Animal Science, 2001) Coetzee, G. J. M.; Hoffman, L. C.Experiment 1 was carried out with 220 one-day-old broiler chicks to evaluate the effect of 11 different levels of vitamin E supplementation (viz. 0 to 200 mg a-tocopheryl acetate/kg diet) on the production performance of broilers and oxidative stability of frozen broiler carcasses. The diets with vitamin E levels of 0 to 100 mg were fed from day-old to 42 days of age, and the diets with vitamin E levels of 120 to 200 mg were fed from 21 to 42 days of age. The oxidative stability, evaluated by thiobarbituric acid reactive substances (TBARS), was determined after 30, 90, 120 and 150 days of storage at –20 °C. There were no differences in weight gain (2.29 ± 0.397 kg) or feed conversion ratios (1.85 ± 0.111 kg feed/kg gain) between dietary treatments. TBARS values increased with increasing time of storage (basal diet: day 30 = 1.71 ± 0.51; day 150 = 4.89 ± 0.51), but decreased with increasing vitamin E levels (day 150: basal = 4.89 ± 0.51; 100 mg/kg = 1.09 ± 0.27). Experiment 2 was carried out with day-old broiler chicks to evaluate the effect of five levels of vitamin E supplementation (viz. 0 to 160 mg a-tocopheryl acetate/kg diet) on performance parameters and the oxidative stability of refrigerated carcasses. The experimental diets were fed from dayold to 42 days of age. Oxidative stability, evaluated by TBARS, colour deterioration and microbiological stability was determined after 0, 4, 8, 10 and 12 days of storage at 4 °C. Fatty acid analysis was done on samples obtained on days 0 and 12. There were no differences in total weight gain (2.37 ± 0.467 kg) or feed conversion ratio (1.88 ± 0.117 kg feed/kg gain) between dietary treatments. TBARS values increased with increasing storage time, but decreased with increasing vitamin E levels. There were no differences between treatments for colour measurements for L* (44.97 ± 0.662), a* (5.23 ± 0.315) or b* (12.76 ± 0.321) values. Microbiological counts increased over time, but dietary vitamin E concentration had no effect. There were no differences between dietary treatments for any of the groups of fatty acids measured (SFA: Day 0 = 26.1 ± 1.13 %, Day 12 = 26.1 ± 1.17 %; MUFA: Day 0 = 41.4 ± 1.46 %, Day 12 = 40.2 ± 2.28 %; PUFA: Day 0 = 32.4 ± 1.95 %, Day 12 = 33.8 ± 2.52 %). Similarly, fatty acid proportions did not change over time. There were no differences between dietary groups for mean muscle pH (6.01 ± 0.206).
- ItemThe effect of different dietary vitamin and mineral levels on certain production parameters, including egg shell characteristics of breeding ostriches(South African Society for Animal Science, 2014-08-24) Brand, T. S.; Tesselaar, G. A.; Hoffman, L. C.; Brand, Z.Earlier studies on breeding birds indicated no effect of dietary energy-content on feed intake. This observation is contradictory to results for other animals and/or poultry where feed intake decreases with an increase in dietary energy level. Literature revealed that a lack of certain nutrients may cause animals to consume more feed than necessary to satisfy their nutrient requirements for these limiting nutrients. In this study eight diet groups were evaluated. A standard commercial diet plus one of the following supplements: (i) Standard diet without a vitamin and mineral premix pack (control diet), (ii) with a normal premix pack, (iii) with normal vitamin and 2 x trace elements (M x 2), (iv) with normal trace elements and 2 x vitamins, (v) with a normal premix pack and limestone added as calcium source; (vi) with a normal premix pack and monocalcium phosphate added as phosphorus source, (vii) with a normal premix pack and soybean oilcake added as crude protein source, (viii) with a normal premix pack and linseed added as a fatty acid source. Significant differences were recorded in the quantity of feed ingested by birds between the diet with surplus minerals (M x 2) (Group 3) (2.3 ± 0.3 kg/bird/day), the diet with no vitamins and minerals added (Group 1) (2.7 ± 0.3 kg/bird/day) and the diet with added fatty acids in the form of linseed (Group 5) (2.9 ± 0.5 kg/bird/day). This indicates the possibility that ostriches may adjust feed intake to satisfy their mineral requirements. No statistically significant relationship was found between the thickness and strength of the shell. Significant differences in shell strength (mean value of 154.7, 109.9, 140.4, 142.7, 153.0, 143.4, 138.4 and 151.1 N/cm2, respectively) were found between all treatments, but no specific pattern could be identified. Results further revealed no effect of dietary treatment on egg production, dead-in-shell eggs (DIS), infertile eggs or chick production. Further experiments that include certain dietary treatments during the five months rest period are currently being done to quantify the effect of the addition of minerals and vitamins during this period on the production of breeding ostriches.
- ItemEffect of hot-deboning on the physical quality characteristics of ostrich meat(South African Society for Animal Science, 2006) Botha, S. St. C.; Hoffman, L. C.; Britz, T. J.The effects of hot-deboning on the physical meat quality characteristics and shelf-life of ostrich m. gastrocnemius, pars interna (gastroc) and m. iliofibularis (iliof) were investigated during 42 days (d) of refrigeration. The hot-deboned gastroc was initially tougher than the cold-deboned muscles, while hot-deboning had no significant effect on the shear force of the iliof. After 14 d of refrigerated storage, there was no difference in tenderness between the hot- and the cold-deboned muscles. Hot-deboning caused significantly more purge (3.4 ± 2.33%) compared to cold-deboning (2.1 ± 2.06%) throughout the 42-day storage period. All muscle samples were acceptable in terms of Aerobic Plate Counts (APC < 104 cfu/g) and E. coli (E. coli < 101 cfu/g), based on the South African Standards for the microbiological monitoring of meat for refrigerated export. It was concluded that hot-deboning did not influence the shelf-life of ostrich muscles negatively.