Research Articles (Animal Sciences)

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Across flock genetic parameter estimation for yearling body weight and fleece traits in the South African Dohne Merino population
(South African Society for Animal Science, 2008) Van Wyk, J. B.; Swanepoel, J. W.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Olivier, J. J.; Delport, G. J.
Accurate genetic parameter estimates are needed upon which to perform multiple-trait across flock breed analyses. Genetic parameters for yearling body weight (BW), clean fleece weight (CFW) and mean fibre diameter (MFD) were estimated using records of 107 389 individuals (the progeny of 1 530 sires and 45 178 dams) collected between 1992 and 2004 in the South African Dohne Merino population. Fixed effects included in the model were flock-year-season-sex- management group (1 594 classes), type of birth (singles, multiples), age of dam (2 - 7+ years) and age at measurement, fitted as a linear covariate (385 ± 12 days). Six different single-trait animal models were fitted, where different combinations of the following random effects were fitted: direct additive, the sire-flock interaction, the sire-flock-year-season interaction (SFYS), the dam genetic effect, the direct-maternal correlation and the dam permanent environmental effect. These analyses were followed by a three-trait analysis structured according to the log likelihood ratios obtained for the single-trait analysis. This analysis allowed the calculation of relevant correlations among traits together with their respective standard errors. Direct heritability estimates from the three-trait analysis were 0.17 for BW, 0.19 for CFW and 0.45 for MFD. Maternal heritability estimates were 0.01 for BW and 0.006 for CFW, with corresponding dam permanent environmental ratios of respectively 0.03 and 0.02. The genetic correlation between animal effects amounted to 0.48 for BW. Derived proportions of the total phenotypic variance due to SFYS were 0.02, 0.02 and 0.02, respectively. Genetic correlations of BW with CFW and MFD were 0.11 and 0.13, respectively, and of CFW with MFD 0.16. It was concluded that the inclusion of some form of a genotype by environmental interaction as part of the national evaluation is essential, although it controlled only a modest portion of the overall phenotypic variation.
The adaption of the South Africa sheep industry to new trends in animal breeding and genetics : a review
(South African Society for Animal Science, 2014-10-11) Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Olivier, J. J.; Sandenbergh, L.; Snyman, M. A.
The history of sheep breeding research in South Africa can be divided roughly into four eras, namely the research and development phase, the commencement of recording and evaluation, the expansion of recording schemes, and, most recently, the adaptation of schemes to international benchmarks. The most recent era has presented scientists with the greatest challenges, namely the inclusion of genomic breeding values in routine sheep recording and of disease-resistance traits during routine evaluation. The establishment of reference populations for the major South African sheep breeds to estimate genomic breeding values is an immediate challenge. This process may be facilitated by a number of genetic resource flocks that are phenotyped for traits that are not routinely recorded in the national evaluation. A limited number of these animals are also genotyped. There is strong evidence that resistance of sheep to external and internal parasites is heritable, and may be improved by purposeful selection. Efforts should be concentrated on the inclusion of disease resistance traits in national analyses where appropriate. However, seen against the background that South African investment in research is appreciably less than in developed countries, lack of funding and high-capacity manpower may impede rapid progress. There thus seem to be many challenges for future generations of sheep breeding scientists.
Analysis 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.
Anti-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.
Application 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.
Application of fat-tailed sheep tail and backfat to develop novel warthog cabanossi with distinct sensory attributes
(MDPI, 2020-12-08) Mahachi, Leo Nyikadzino; Rudman, Monlee; Arnaud, Elodie; Muchenje, Voster; Hoffman, Louwrens Christiaan
This study compared the use of pork backfat (PF) and fat-tailed sheep tail and backfat (SF) on the physicochemical, fatty acids and sensory attributes of warthog cabanossi. There were no differences between weight loss during drying, moisture content, pH, water activity, salt content and lipid oxidation between the cabanossi types. However, protein and ash contents were higher in PF cabanossi whilst fat content was higher in SF cabanossi. The PF cabanossi had higher polyunsaturated fatty acids (especially n-6), lower monounsaturated fatty acids whilst the saturated fatty acid content was similar between the two cabanossi products. The n-3:n-6 ratio was more beneficial in the SF cabanossi. The descriptive sensory analysis showed two distinct products where PF cabanossi scored higher for most attributes. Although SF cabanossi scored less for these attributes, this cabanossi had unique and acceptable sensory attributes. This study concluded that fat-tailed sheep tail and backfat could be used to produce a unique cabanossi product of acceptable quality.
Application 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.
Bioavailability and bioefficacy of hemp by-products in ruminant meat production and preservation: a review.
(2020) Semwogerere, Farouk; Katiyatiya, Chenaimoyo L. F.; Chikwanha, Obert C.; Mapiye, Cletos
Plant by-products obtained from agro-industrial processes require valorisation to demonstrate their potential for enhancing animal health, meat production, and shelf life extension. One example is the fast-growing hemp industry, which produces seeds, leaves, seed oil, and cake. Studies on the nutritional value of hempseed cake have shown it can be a valuable source of protein in ruminant diets. However, there is limited documentation on the bioavailability and bioefficacy of hemp phytochemicals for improving ruminant health, production, and extending meat shelf life. The current review provides an overview of existing information on nutrient and phytochemical composition of hemp by-products, their bioavailability, and bioefficacy, and explores current limitations and prospects regarding their valorisation.
Carcass 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, Cletos
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.
Carcass 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.
Carcass 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.
Carcass yields and physiochemical meat quality of semi-extensive and intensively farmed impala (Aepyceros melampus)
(MDPI, 2020) Needham, Tersia; Engels, Retha A.; Bures, Daniel; Kotrba, Radim; Van Rensburg, Berndt J.; Hoffman, Louwrens C.
The effects of sex and production systems on carcass yield, meat quality and proximate composition of sub-adult impala were evaluated by culling 35 impala from intensive (12 males) and semi-extensive (12 males and 11 females) production systems within the same game farm. While no sexual dimorphism was found for carcass weights, male impala had a higher dressing percentage than females, indicating a higher meat production potential. Few differences were observed for yields between the male impala from the different production systems, but physical meat quality parameters indicated possible stress for those kept intensively. Minor differences existed in physiochemical parameters between various impala muscles for the two sexes and production systems, providing little motivation for these factors to be considered when processing sub-adult impala carcasses. Impala meat from both sexes, all muscles and all production systems produced meat with shear force values below 43 N, and thus may be considered as tender. Furthermore, the proximate composition of all impala meat in this study ranged from 74.7 to 77.0 g/100g moisture, 20.7 to 23.5 g/100g protein, 1.2 to 2.2 g/100g fat and 1.1 to 1.3 g/100g ash content. These values compare favorably to other game species, indicating that impala meat may serve as a lean protein source.
Castration 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.
Characterization of pigeon paramyxoviruses (Newcastle disease virus) isolated in South Africa from 2001 to 2006
(AOSIS OpenJournals, 2008) Abolnik, C.; Gerdes, G. H.; Kitching, J.; Swanepoel, S.; Romito, M.; Bisshchop, S. P. R
Pigeon paramyxovirus type 1 (PPMV-1), a variant of Newcastle disease virus that primarily affects doves and pigeons has been isolated in South Africa since the mid-1980s. Phylogenetic evidence indicates that pigeon paramyxovirus type 1 viruses were introduced into South Africa on multiple occasions, based on the presence of two separate lineages, 4bi and 4bii, that have been circulating in Europe and the Far East since the early 1990s. During 2006, a PPMV-1 virus was isolated from an African ground hornbill (Bucorvus leadbeateri) which became acutely infected with PPMV-1 and died, probably after scavenging off infected dove carcasses in the region, since a closely-related PPMV-1 strain was also isolated from doves collected nearby. The hornbill isolate had ICPI and MDT values characteristic of PPMV-1 strains. The threat of PPMV-1 to poultry production and biodiversity in southern Africa highlights the importance of monitoring the spread of this strain.
Chemical composition of wild fallow deer (Dama Dama) meat from South Africa : a preliminary evaluation
(MDPI, 2020) Cawthorn, Donna-Maree; Fitzhenry, Leon Brett; Kotrba, Radim; Bures, Daniel; Hoffman, Louwrens C.
The effects of sex and production systems on carcass yield, meat quality and proximate composition of sub-adult impala were evaluated by culling 35 impala from intensive (12 males) and semi-extensive (12 males and 11 females) production systems within the same game farm. While no sexual dimorphism was found for carcass weights, male impala had a higher dressing percentage than females, indicating a higher meat production potential. Few differences were observed for yields between the male impala from the different production systems, but physical meat quality parameters indicated possible stress for those kept intensively. Minor differences existed in physiochemical parameters between various impala muscles for the two sexes and production systems, providing little motivation for these factors to be considered when processing sub-adult impala carcasses. Impala meat from both sexes, all muscles and all production systems produced meat with shear force values below 43 N, and thus may be considered as tender. Furthermore, the proximate composition of all impala meat in this study ranged from 74.7 to 77.0 g/100g moisture, 20.7 to 23.5 g/100g protein, 1.2 to 2.2 g/100g fat and 1.1 to 1.3 g/100g ash content. These values compare favorably to other game species, indicating that impala meat may serve as a lean protein source.
Citrus and winery wastes : promising dietary supplements for sustainable ruminant animal nutrition, health, production, and meat quality
(MDPI, 2018-10-16) Tayengwa, Tawanda; Mapiye, Cletos
Citrus and grapes are the most widely grown fruits globally, with one-third of total production used for juice and wine making. The juice and winemaking processes generate large quantities of solid organic wastes including citrus pulp and grape pomace. These fruit wastes pose serious economic, environmental, and social challenges, especially in low-to-middle-income countries due to financial, technological, and infrastructural limitations. They are, however, rich in valuable compounds which can be utilized in the ruminant livestock industry as novel, economical, and natural sources of cellulose, polyunsaturated fatty acids, and phytochemicals, which have nutritional, anthelmintic, antioxidant, and antimicrobial properties. Despite citrus and grape fruit wastes having such potential, they remain underexploited by the livestock industry in low-to-middle-income countries owing to lack of finance, skills, technology, and infrastructure. Inclusion of these fruit wastes in ruminant diets could combine the desirable effects of enhancing animal nutrition, health, welfare, production, and meat quality attributes with the prevention of challenges associated with their disposal into the environment. The current review explores the valorization potential of citrus and winery wastes as dietary supplements to sustainably enhance ruminant animal nutrition, health, welfare, production, and meat quality.
Combined effect of dietary protein, ractopamine, and immunocastration on boar taint compounds, and using testicle parameters as an indicator of success
(MDPI, 2020-11-14) Needham, Tersia; Gous, Rob M.; Lambrechts, Helet; Pieterse, Elsje; Hoffman, Louwrens C.
This study investigates the combined effect of immunocastration, dietary protein level (low, medium or high) and ractopamine hydrochloride supplementation (0 or 10 mg/kg) on the adipose concentrations of androstenone, skatole and indole in pigs, and explores whether body mass, carcass fatness or testicular parameters may be indicators of boar taint in these carcasses. Immunocastration was successful in decreasing testicle functioning, and adipose androstenone and skatole concentrations, in all individuals. Immunocastration decreased testicle weight and length, seminiferous tubule circumference and epithelium thickness. Testicle tissue from immunocastrates was also paler, and less red in color, in comparison to non-castrated controls. Dietary protein level and ractopamine hydrochloride supplementation had no influence on the adipose concentration of androstenone, skatole and indole. Testicle size and color were moderate to strong indicators of androstenone and skatole concentrations in the carcasses, and thus vaccination success. Immunocastration together with the adjustment of dietary protein and ractopamine hydrochloride supplementation, is successful in preventing boar taint while maintaining growth performance.
A 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.
A 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.
Comparison 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

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