Browsing by Author "Needham, Tersia"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Effects of immunocastration on the nutrient responses, carcass traits and meat quality of growing pigs (Sus crofa domesticus)
    (Stellenbosch : Stellenbosch University, 2014-12) Needham, Tersia; Hoffman, Louwrens C.; Pieterse, E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: Increased consumer awareness has motivated the industry to find alternative methods to surgical castration for controlling boar taint and aggression in male pigs. Immunocastration has been identified as a solution, however; little research has been done into the nutritional requirements of immunocastrated pigs. Thus the objective of this study was to determine the optimal protein levels for immunocastrated pigs with regards to growth performance, carcass traits and yields as well as meat quality when supplemented with or without ractopamine hydrochloride (RAC). The study involved 120 male pigs following a 2 x 2 x 3 factorial design. The main effects evaluated were sex (immunocastrated versus entire), RAC supplementation (0 versus 10 mg/kg and dietary balanced protein level (7.50 {low}, 9.79 {medium} and 12.07 {high} g lysine/kg). Vaccination occurred at 16 and 20 weeks of age and from 20 weeks each pig was allocated to one of the balanced protein diets with RAC supplementation at either 0 or 10 mg/kg for the last 28 days of growth. Slaughtering occurred at 24 weeks at which time carcass traits were measured and carcasses were processed, commercial cuts were weighed, deboned and trimmed into muscle, bone and fat portions which were then weighed individually. Immunocastration increased the average daily gain, average daily feed intake, feed conversion ratio (FCR) and backfat deposition after the second vaccination. The FCR was improved by RAC supplementation, with the best FCRs seen at the medium and high balanced protein diets. Immunocastration and RAC increased live weight at slaughter and calliper backfat thickness but no differences were seen for the dressed hot carcass weight or Hennessey Grading Probe backfat thickness. Supplementation of RAC increased the percentage of the hot carcass weight, comprising of the shoulder, hindquarter, loin and belly, as well as the shoulder muscle, hindquarter muscle and loin muscle percentages, while decreasing the fat percentage of the belly and hindquarter. Chemical composition analysis of the Longissimus thoracis (LT) muscle indicated differences (p ≤ 0.05) for crude protein content but they were considered biologically negligible. The cooking loss of the LT was decreased by immunocastration and feeding medium protein. Feeding RAC decreased the a* and b* colour values and increased the Warner Bratzler shear force (WBSF) values, resulting in less red and less tender meat. Entire males fed low dietary protein had the lowest L* values, while entire males fed medium protein diets had the highest L* values. Immunocastrates fed the low protein diet had the most tender meat, whereas immunocastrates fed the high protein diet had the least tender meat. Immunocastration decreased the androstenone levels to below 0.5 μg/g fat and although it did not significantly affect the testicle size, it influenced the morphology and increased the lightness (L*), yellowness (b*) and decreased the redness (a*) of the testicle’s cut surface colour. The results from this study indicated that the balanced dietary protein requirements for immunocastrates differ both with and without RAC supplementation and thus the correct dietary protein level needs to be provided so that growth performance and leanness is not compromised. The return per carcass can also be improved by supplementing RAC, owing to improved cutting yields and lean yields of carcasses. Together, immunocastration, RAC supplementation and the correct balanced protein diet may allow pig producers to efficiently produce heavier male carcasses without boar taint while conforming to the animal welfare expectations of the consumer. However, an incentive for producers in terms of immunocastration needs to be provided by the possible modification of the current carcass classification system so that heavier immunocastrated male carcasses are not penalised.
  • Thumbnail Image
    Item
    Immunocastration and its application in ram lambs
    (Stellenbosch : Stellenbosch University, 2018-03) Needham, Tersia; Hoffman, Louwrens C.; Lambrechts, Helet; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: In South Africa, Dohne Merino sheep are farmed extensively for wool and meat production. Ram lambs are typically castrated to enable easier management of mixed-sex flocks by manipulating reproduction and associated behaviour, while promoting fattening and improving meat quality. Due to various welfare concerns regarding the pain associated with castration and healing complications, the practice is under scrutiny, which necessitates producers to investigate alternatives to physical castration. International pork and beef industries have successfully applied immunocastration in commercial enterprises; however, no formal recommendations regarding its commercial application in the lamb industry are available. Improvac® was administered at two doses during the interval from weaning until slaughter and was sufficient in supressing testes growth and functioning in Dohne Merino ram lambs. Varying the interval between the two doses (two, three or four weeks) and the interval between second vaccination and slaughter (four or six weeks) did not influence growth performance or slaughter performance of ram lambs after weaning. The primary vaccine dose decreased serum testosterone concentrations, which resulted in a decrease in scrotal circumference, semen quality and seminiferous tubule size for all immunocastration vaccination schedules. Testes cut surface colour was redder and more yellow in immunocastrated than in intact rams, providing a possible on-line detection method for vaccination success after slaughter to ensure correct sex classification. An inter-vaccination period of two weeks and a six-week interval after second vaccination until slaughter, had the most pronounced and sustained effect on reproductive capacity of the rams, as well as the lowest frequency of injection site reactions. The recommended injection protocol for the commercial application of Improvac® in lambs involves subcutaneous administration on the flat surface of the shoulder area, and alternating shoulder sides per dose. Immunocastration resulted in improved welfare of ram lambs, when compared to rams castrated using the Burdizzo-method. The latter method resulted in increased serum cortisol concentrations, abnormal behaviours in response to pain experienced during the procedure, despite the use of pain mitigation, and tissue necrosis. Minor differences in offal yields were observed in immunocastrated lambs but no influence on carcass cutting yield or meat quality, other than cut surface colour, was reported. Thus, immunocastration can be considered a feasible alternative to physical castration in the commercial production of Dohne Merino ram lambs. However, further investigation is recommended into the application of immunocastration within a feedlot environment to further elucidate the effects on feed intake, nutrient requirements, differential fat deposition and behaviour in Dohne Merinos and other important meat-producing breeds in South Africa.
  • Thumbnail Image
    Item
    Physical changes during post-mortem ageing of high-value impala (Aepyceros melampus) steaks
    (MDPI, 2020-06-29) Needham, Tersia; Engels, Retha A.; Hoffman, Louwrens C.
    Antelope meat production is rapidly growing, not only due to their adaptation to marginal land usage, but also because of its favorable nutritional properties and free-range production. However, limited information is available on the meat quality and processing potential of game meat for commercial consumption. The objective of this study was to determine the ageing period to achieve maximum tenderness of longissimus thoracis et lumborum (LTL) muscles of impala. The LTL muscles of 11 male and 11 female impala were harvested, and divided into eight portions. Each portion was randomly allocated to 1, 2, 4, 6, 8, 10, 12, or 14 days of wet-ageing (4 °C) in vacuum packaging. The meat pH, color, weep loss, cooking loss, and Warner–Bratzler shear force were measured throughout ageing. Initially the ageing profile differed depending on the sex of the animal from which the muscle was harvested; however, after 8 days of ageing, maximum tenderness was reached (13.5 ± 0.91 N) and no further sex differences were seen. Ageing improved the surface color of all meat until day 8, after which discoloration occurred. Therefore, it is recommended that impala LTL steaks should be wet-aged at 4 °C for eight days to achieve maximum tenderness and minimize sex variability.