Browsing by Author "Lambrechts, H."

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Extending the interval between second vaccination and slaughter : I. effects on growth, scrotal size and stress responses of immunocastrated ram lambs
    (Elsevier, 2019-01-18) Needham, T.; Lambrechts, H.; Hoffman, L. C.
    Immunocastration provides a less invasive means of castrating lambs. Considering increasing consumer awareness, the efficacy of this technique on commercial slaughter lambs needs to be further investigated and its effects on growth and stress responses need to be established. This study compared the growth rate, testes size and stress responses of immunocastrated lambs with that of lambs physically castrated with a Burdizzo clamp, as well as intact rams. A total of 40 Dohne Merino ram lambs (average live weight = 45.4±3.68 kg) were randomly allocated to the following four treatment groups: control (intact; R), Burdizzo-castrated (on day 2; B), immunocastrated with a 4-week (ICS4), or a 6-week (ICS6) interval between the second immunocastration vaccination and slaughter. Within the immunocastration treatments, the reaction to vaccination was assessed through injection site scoring, recording the local injection site surface temperature and assigning a walking score. The response to Burdizzo castration was assessed by scoring the reaction during the procedure, testes palpation reaction, walking gait and measuring testis temperature. Additional parameters recorded included BW, serum cortisol concentration, scrotal circumference and rectal temperature. Pain behaviours were described for the short-, medium- and long-term effects after the two methods of castration. Predominantly, tissue-hardening and bruising occurred at the injection sites of immunocastrates, but little effect was observed on walking comfort and no effect on injection site temperature or rectal temperatures. After Burdizzo castration, lambs spent more time in abnormal postures, and from day 3 (D3) to D8 of the trial, discomfort was observed during testes palpation and walking in B lambs. Serum cortisol concentrations were elevated in B lambs on D3 and D15, indicating physiological stress. Thus, immunocastration improved the welfare of castrated lambs as assessed by cortisol secretion, scrotal swelling and pain behaviours, without influencing growth rate.
  • Thumbnail Image
    Item
    Extending the interval between second vaccination and slaughter : II. changes in the reproductive capacity of immunocastrated ram lambs
    (Elsevier, 2019-01-17) Needham, T.; Lambrechts, H.; Hoffman, L. C.
    Immunocastration improves the welfare of castrated commercial slaughter lambs; however, the time-point at which this technique influences semen quality and sperm production has not yet been established for various vaccination schedules. Furthermore, the effect of extended intervals between second vaccination and slaughter needs to be investigated regarding continued testosterone suppression in immunocastrated lambs. The effect of extending the interval between second immunocastration vaccination and slaughter from four to six weeks on the reproductive capacity of Dohne Merino lambs was examined. A total of 40 Dohne Merino lambs were stratified according to initial weight (45.4±3.68 kg) and randomly assigned to four treatments that included intact control rams (R), Burdizzo-castrated lambs (B) and lambs immunocastrated with either four (ICS4) or six (ICS6) weeks between second vaccination and slaughter. Blood and semen samples were collected throughout the study period to determine serum testosterone concentrations, evaluate semen quality and assess sperm viability. Semen samples from R showed improvement over the trial. Throughout the collection period, B lambs had low serum testosterone concentrations, poor sperm motility and sperm viability, as expected. However, a slight increase in the percentage of live sperm in semen samples from B lambs towards the end of the collection period indicated poor success rates of the technique in some lambs. Burdizzo-castration also caused testes tissue necrosis and abscessing, indicating physiological stress. Semen appearance scores varied for both immunocastrated treatments, but the mass motility scores decreased over time. The ICS6 lambs showed a consistent and continuous decline in serum testosterone concentrations and sperm viability, with an increased percentage of dead abnormal sperm in the semen samples at the end of the study. The ICS4 treatment was successful in interrupting serum testosterone production and reducing semen quality; however, not as consistently as the ICS6 treatment. Primary immunocastration vaccination influenced serum testosterone concentrations but consistently low levels were only realised for both treatments after secondary vaccination. Although all castration treatments influenced testes size and colour, the six-week vaccination-to-slaughter interval caused a greater decrease in testes cut surface L* (lightness) colour values and in seminiferous tubule circumference. Extending the interval between second immunocastration vaccination and slaughter resulted in a more consistent and reliable influence on reproductive capacity of immunocastrated lambs. Thus, immunocastration is a suitable alternative to Burdizzo-castration regarding the interruption of testosterone production and testis functioning.
  • Thumbnail Image
    Item
    A novel flush technique to simulate natural dispersal of spermatozoa in the female reproductive tract and expedite motility assessment of fresh ejaculated Merino (Ovis aries) sperm
    (South African Society for Animal Science, 2018-02-15) Boshoff, N. H.; Lambrechts, H.; Maree, L.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Van der Horst, G.
    Motility is an important criterion in the assessment and quantification of the quality of ejaculated and epididymal sperm samples. Ovine sperm spermatozoa are particularly susceptible to cryodamage, and shortening the interval from collection to cryostorage may potentially minimize the negative effects of cryopreservation, thereby improving the post-thaw viability of ram spermatozoa. The use of the swim-up technique (SUT) in quantifying spermatozoa motility is well documented, especially for the isolation of highly motile spermatozoa for assisted reproductive purposes. However, this technique is time consuming and involves a swim-up period of 10 minutes before the motility of a sample is recorded by using computer-assisted sperm analysis (CASA) software such as the Sperm Class Analyser® (SCA®). The novel flush technique (FT) allows for capturing of sperm motility tracks via the SCA® system shortly after semen collection, that is, within a minute. This study compared fresh ejaculated sperm motility traits by using the SUT and FT. Motility evaluations were performed using 45 semen samples obtained from 15 adult Merino rams (Ovis aries) at weekly intervals. Motility recordings were captured at 100 frames per second, using a calibrated 20 µm deep Leja slide. The percentage total motile spermatozoa of samples subjected to the FT was 89.2%, which was significantly higher than that recorded by the SUT (83.9%). The results also indicated that the wobble (WOB) parameter showed significantly higher values when using the FT, and parameters curvilinear velocity (VCL) and amplitude of the lateral head displacement (ALH) indicated significantly higher values when using the SUT. Establishing the ideal spermatozoa concentration and analysis of sperm subpopulation motility characteristics would assist in the optimization of the FT, and its use in CASA motility analysis of ovine spermatozoa. Standardization of CASA analysis of ovine semen samples, which would enable the selection of quality spermatozoa samples for use in field insemination (fresh samples) or in vitro fertilization programs, and laparoscopic AI cryopreserved samples warrants further investigation.