Immunocastration with recombinant GnRH6-CRM197 fusion protein improves reproductive suppression and meat tenderness in roosters

This study evaluated the potential of the recombinant GnRH6-CRM197 fusion protein as an immunocastration vaccine for roosters. Forty 4-week-old roosters were divided into two groups: the immune group and the control group that received a saline injection. The vaccine (1 mg/mL) was administered at 4 and 8 weeks of age. Body weights and blood samples were collected at 4, 8, 12, 16, and 20 weeks of age, with culling performed at 20 weeks. Serum anti-GnRH antibody titers and testosterone concentrations were measured. The testicles were collected for morphological analysis, while pectoral and thigh muscle samples were assessed for muscle fiber characteristics, intramuscular fat, and meat quality indicators. The results demonstrated that the immune group exhibited a significant induction of anti-GnRH antibodies (P < 0.05). Vaccination significantly suppressed comb and wattle development (persisting until week 16) and markedly reduced testis size, weight, and serum testosterone levels (P < 0.05). Histological examination confirmed a severe reduction in germ cell numbers at all developmental stages. Regarding the quality of the meat, the tenderness of the breast exhibited a significant enhancement in the group that had been immunized. However, no significant differences were observed among groups in live weight, carcass yield, muscle pH, meat color, or intramuscular fat content (P > 0.05). In summary, the GnRH6-CRM197 vaccine effectively suppresses reproductive function in roosters while enhancing meat tenderness, demonstrating potential for application as an immunocastration agent in poultry without adversely affecting key production indicators.