Effect of immunocastration with Bopriva on carcass characteristics and meat quality of feedlot Holstein bulls

Castration procedures and feed management in the finishing phase affect the performance, carcass traits, and meat quality of grazing steers

The objective of this study was to evaluate the effects of different castration methods, body weights at castration, and feeding management practices on the performance, carcass traits, and meat quality of grazing Nellore steers. 60 male cattle were randomly distributed among the following treatments: surgical castration (SC) at 350 kg body weight (BW) and finished in semiconfinement; immunocastration (ImC) at 350, 400, and 450 kg BW and finished in semiconfinement; and ImC at 450 kg BW and finished receiving protein-energy (P-E) supplementation. All steer production phases were carried out in a grazing system with tropical grass, and only the level of supplementation was varied. The animals were subsequently slaughtered, their carcasses were qualitatively and quantitatively evaluated. The measures of animal performance, carcass traits, composition, and physicochemical quality of aged and unaged meat were considered dependent variables. Immunocastration promoted greater (P < 0.05) average daily weight gains (ADG) postweaning, final BWs postweaning, final BWs at finishing, hot carcass weights, carcass lengths, and internal carcass depths. There was no effect (P > 0.05) of ImC weights on the animal performance variables; however, the ImC weight factor influenced (P < 0.05) carcass conformation and the L* component of aged and unaged meat. Semiconfinement promoted greater (P < 0.05) ADGs, final BWs, hot carcass weights, carcass yields, carcass fattening, rib eye areas, subcutaneous fat thicknesses, and L* components of aged and unaged meat. Immunocastration at 450 kg BW and semiconfinement at the finishing phase is recommended for grazing beef cattle production systems that involve the castration of males.

Reproductive parameters of lambs immunocastrated with anti-GnRH vaccine

The objective of this study was to evaluate the testicular biometric, seminal, and plasma testosterone levels in lambs subjected to an anti-GnRH vaccine as a method of castration. Thirty entire, crossbred Santa Inês male lambs were randomly distributed into three treatment (T): T1 was the control group, with the administration of 1 mL of saline solution subcutaneously (SC); 1.0 and 0.5 mL of an anti-GnRH vaccine were administered SC in T2 and T3, respectively. Testicular biometric variables, physical and morphological variables of semen, and plasma testosterone concentrations were evaluated. At D60, there was a reduction in testicular length, width, thickness, and scrotal circumference of the immunocastrated animals regardless of the vaccine dose used (P < 0.05). A reduction in semen physical variables at both dosages (P < 0.05) was observed, with azoospermia, in 80% and 70% of animals in the T2 and T3 groups, respectively. At D60, the immunocastrated animals also showed an increase in spermatozoa defects (P < 0.05), whereas plasma testosterone concentration decreased (P < 0.05). Immunocastration of lambs using the Bopriva vaccine at doses of 1.0 and 0.5 mL is efficient in inducing azoospermia in up to 80% of animals, although two doses in a 30-day interval are necessary for it to be an effective and safe method. Efficacy was demonstrated through a reduction in serum testosterone levels, testicular biometry, and seminal fluid analysis. Considering the efficacy of both doses in this study, we recommend using the lower dose (0.5 mL), which will allow for a 50% reduction in vaccine costs.

Effectiveness of a New Recombinant antiGnRH Vaccine for Immunocastration in Bulls

Simple Summary

Castration of males is a common procedure in cattle production. Surgical procedures are most commonly used, but there is an increasing interest in non-invasive alternatives to avoid risk of infection, bleeding, pain, stress and to improve animal welfare. Immunization against gonadotropin-releasing hormone is currently being used in livestock, but there is only one commercially available vaccine for cattle and results regarding the number of doses needed to maintain castration are variable. The efficacy, safety, and production parameters of a new antigen for immunocastration in bulls was assessed. Results showed that two doses of the vaccine to 40 10-month-old bulls achieved testosterone suppression below productive performance. Live weight at slaughter and carcass yield was greater in immunized animals than in surgically castrated cattle. Castration effects of the vaccine were maintained until the end of the trial at 24 weeks.

Abstract

Castration by surgical techniques is common in livestock; however, post-surgery complications and concerns for animal wellbeing have created a need for new non-invasive alternatives. The objective of this study was to evaluate immunocastration in bulls using antigen GnRX G/Q; a recombinant peptide proved to be effective in laboratory and companion animals. A nine-month trial with 80 9-month-old Normand x Hereford bulls, kept in a pastured system, was conducted. The herd was divided in half with 40 bulls surgically castrated (SC) and 40 castrated by immunization against GnRH (IC). The antigen was injected on days 0 and 40 of the experiment. After the second dose, the IC group had elevated GnRH antibodies and decreased testosterone levels (below 5 ng/mL) that were maintained for 23 weeks. At slaughter on day 190, the immunocastrated group obtained a higher weight, hot carcass, and dressing percentage than the SC group. There was no difference in pH, color of meat, fat coverage, cooking loss, or tenderness between groups. The bulls showed no inflammatory reaction at the injection site or adverse side effects from the vaccine. Our results demonstrate that immunocastration with GnRX G/Q is an efficient and safe alternative to surgical castration in livestock. Additional work evaluating antigen effects over a longer period is needed to validate commercial viability.

Effect of Kisspeptin-54 immunization on performance, carcass characteristics, meat quality and safety of Yiling goats

This study aimed to evaluate the effects of kisspeptin-54 immunocastration vaccine on performance, carcass characteristics, meat quality, and safety of Yiling goats. Thirty buck goats were randomly assigned into three groups: PVAX-B2L-Kisspeptin-54-asd immunized (PBK-asd), control, and surgically castrated. PBK-asd immunization significantly stimulated serum anti-kisspeptin antibody production and reduced testosterone hormone compared with the control group (p < .05). Interestingly, PBK-asd plasmid did not integrate into the host genome and had no significant effect on growth hormone, body weight, and average daily gain (ADG). Conversely, surgical castration significantly reduced ADG and carcass weight compared to the control group. Furthermore, PBK-asd immunization did not affect carcass characteristics (dressing percentage, loin area, and fat thickness) and meat quality traits (pH, color, cooking loss, drip loss, and shearing force). These results indicate that the Kisspeptin-54 DNA vaccine is safe and has potential to be used as an alternative to surgical castration for goats without negatively affecting carcass and meat quality.

Effects of an anti-gonadotrophin releasing hormone vaccine on the morphology, structure and function of bull testes

Castration reduces aggressive and sexual behaviour and provides better carcass quality in bull calves. Vaccination against gonadotrophin-releasing hormone (GnRH) is used as an alternative to surgical castration for the purposes of reducing pain and distress in the animals. Currently, no anti-GnRH vaccine has been authorized for use in cattle in the European Union. The aim of the present study was to assess the effect of an anti-GnRH swine-specific vaccine (Improvac®, Zoetis, USA) on the morphology, structure and function of bull testes. Animals were vaccinated at days 1, 21 and 104 of the experimental period and were classified based on their live weight into the following two groups: LIGHT (172.9 ± 30.00 kg) and HEAVY (323.8 ± 37.79 kg). The scrotal circumference was measured on day 1 and prior to slaughter (day 164). At slaughter, the sperm motility and concentration in the caudae epididymis were assessed. Testes were weighed, measured and examined using ultrasound, and then tissue samples were collected and fixed in formalin. Histological and immunohistochemical studies were performed on the testes to measure the diameter of the seminiferous tubules and assess the testicular cell populations. The results revealed that suppression of testicular development was associated with the use of the Improvac® vaccine, which resulted in a smaller size of the testes and impaired spermatid production. However, the effect of Improvac® was more pronounced and consistent in calves vaccinated at a low live weight than at a heavy live weight, which suggested that vaccination is more effective when calves are vaccinated before or early during puberty. However, testes from calves vaccinated at a low live weight were more prone to the development of intraluminal concretions in the seminiferous tubules.

Gender status effect on carcass and meat quality traits of feedlot Angus × Nellore cattle

The study evaluated the effect of gender status on carcass and meat quality of feedlot Angus × Nellore cattle. A total of 176 cattle, 20 months old, were confined for 190-days and assigned to four treatments: bulls, immunocastrated, steers, and heifers. Bulls had greater rib eye area and HCW (p = 0.0001). Heifers had increased fat thickness (p = 0.0001). Steers and heifers had higher marbling scores (p = 0.0001). There was interaction between gender and aging time for Warner-Bratzler Shear Force (p = 0.0002), L* (p = 0.0118), and b* (p = 0.0113) values of beef. The sensory panel results showed that beef from bulls had the lowest consumer overall acceptance (p = 0.0278). Especially, regardless tenderness, steers and immunocastrated beef were considered tender, independent of aging time. Beef produced by heifers, steers, and immunocastrated is considered to be of higher quality than bulls. Thus, it is may be an interesting alternative to produce high-quality beef than bulls, to attend the consumer demand for high-quality products. Additionally, the low fatty acids n6 levels and low n6:n3 ratio, high levels of CLA, MUFAs, and oleic acid suggests that the heifer meat is favorable for human health.

Preliminary study of the effects of an anti-gonadotropin-releasing factor vaccine at two initial liveweights on the carcass traits and meat quality of bulls

The aim of this experiment was to study the effect of the Improvac® anti-gonadotropin-releasing factor vaccine developed for pigs on the carcass quality and shelf life of meat from Serrana de Teruel bulls at two liveweights at the start of immunisation. The anti-gonadotropin-releasing factor vaccine stopped testosterone production regardless of the liveweight. The carcasses of immunised bulls were less heavy and had poorer conformation than those of entire bulls, although the dressing percentages were similar. Immunisation had no influence on the degree of carcass fatness or intramuscular fat content. Immunisation decreased metmyoglobin formation during storage, especially in light bulls. Immunisation reduces the total meat collage, improving tenderness and reducing the ageing time. Minimum toughness was reached 2 weeks earlier than in entire bulls. Quick tenderisation was achieved regardless of the liveweight at immunisation; therefore, the technique studied here could be effective for producing tender meat and avoiding long periods of maturation. In conclusion, immunisation at any of the initial liveweights trialed may be detrimental to animal performance. However, it was effective in delaying metmyoglobin formation and produced more tender meat than that of entire bulls from the first day, thus reducing the ageing time.

Carcass traits and consumer acceptability of striploin steaks from band-castrated, intratesticular zinc-injected, or sexually intact beef cattle

One hundred and eighty beef bulls (BW = 337 ± 10.9 kg) were blocked by BW (6 blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood-restrictive rubber band placed upon the dorsal aspect of the scrotum, and 3) BUL; bulls with testicles remaining intact. Cattle were grouped by weight block in a randomized complete block design (three treatment pens/block and 10 cattle/pen) and harvested by block on three separate dates when blocks reached similar BW and visual subcutaneous fat thickness depth. Striploins were removed from the left carcass sides, vacuum packaged and aged for 14 d, and then frozen at −20 °C. Frozen striploins were sliced into 2.54-cm-thick steaks and remained frozen until analyses. Steaks (n = 3/animal) were used to assess consumer acceptability via consumer taste panel (n = 152 panelists), Warner-Bratzler shear force, percentage cook loss, and cooked color values. Data were analyzed using mixed model procedures; pen was the experimental unit for all dependent variables. Hot carcass weights and LM area were greater (P < 0.01) for the INJ and BUL treatments compared with BAN. Mean yield grade did not differ between treatments (P = 0.12), although BAN carcasses had smaller LM area (P < 0.01) than BUL or INJ carcasses. Percentage of USDA Choice or better carcasses was greater (P < 0.01) for BAN than INJ and BUL treatments. Consumer panelists detected a difference in perceived tenderness; BAN steaks had greater (P = 0.02) tenderness scores than BUL steaks, whereas INJ steaks were intermediate. Panelists rated juiciness of BAN steaks greater (P < 0.01) than either BUL or INJ steaks. Panelists rated beef flavor greater (P = 0.01) for BAN and BUL steaks than INJ steaks. Overall acceptability was greater (P < 0.01) for BAN compared with INJ steaks, whereas BUL steaks were intermediate. Percentage cook loss of striploin steaks (P = 0.47) and Warner-Bratzler shear force values (P = 0.11) did not differ. Cooked color lightness (L*) and redness (a*) values were not affected (P ≥ 0.23) by treatment. Striploin steaks from BAN and BUL treatments had greater (P = 0.02) yellowness values (b*) than INJ steaks. The ratio of red-to-brown (630:580 nm) of cooked striploin steaks was greater (P = 0.05) for INJ than either BAN or BUL treatments. Carcass and palatability outcomes of INJ were more similar to BUL than BAN, suggesting limited efficacy of INJ in mature beef bulls at feedlot entry.

Reversibility and safety of KISS1 metastasis suppressor gene vaccine in immunocastration of ram lambs

Objective

The aim of this study was to investigate the reversibility and safety of KISS1 metastasis suppressor (KISS1) gene vaccine in immunocastration.

Methods

Six eight-week old ram lambs were randomly divided into vaccinated and control groups. The vaccine (1 mg/ram lamb) was injected at weeks 0, 3, and 6 of the study. Blood samples were collected from the jugular vein before primary immunization and at weeks 2, 4, 6, 10, 14, 22, and 30 after primary immunization. All ram lambs were slaughtered at 38 weeks of age, and samples were collected.

Results

The specific anti-KISS1 antibody titers in vaccinated animals were significantly higher and the serum testosterone level was significantly lower than those in the control groups from week 4 to 14 after primary immunization (p<0.05). No significant difference was observed at weeks 22 and 30 after the primary immunization. Similar results were also found for scrotal circumference, testicular weight, length, breadth, and spermatogenesis in seminiferous tubules in week 30 after primary immunization. KS (KISS1-hepatitis B surface antigen S) fusion fragment of KISS1 gene vaccine was not detected in host cell genomic DNA of 9 tissues of the vaccinated ram lambs by polymerase chain reaction.

Conclusion

The effects of KISS1 gene vaccine in immunocastration were reversible and no integration events were recorded.