The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1 × 1010 (T1, n = 41), 1 × 109 (T2, n = 37), 1 × 108 (T3, n = 37) or 0 (C, n = 43) CFU/ml bacteria delivered inhibin vaccine in 10 ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5 mg PGF2α on day 30 and 200 μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P < 0.01). The number and diameter of large follicles (≥10 mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P < 0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P < 0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.