Effect of prostaglandin treatment on the estrus behaviour, follicular and luteal morphometry and serum hormone profile in sub-estrus buffaloes during non-breeding season

Sub-estrus buffaloes do not exhibit estrus signs despite being cyclic contributing to extended service periods and inter-calving intervals causing significant economic loss. The present study described the effect of synthetic prostaglandin (PGF(2 alpha)) on estrus behaviour, follicular and luteal morphometry, and serum estradiol (E-2) and progesterone (P-4) profile in sub-estrus buffaloes during the non-breeding season. The incidence of sub-estrus was 38.4% during the non-breeding season. The sub-estrus buffaloes (n = 33) were divided into two groups, viz., Control (n = 16) and PGF(2 alpha) treatment (Inj. Cloprostenol 500 mu g, i.m., n = 17). Estrus induction response was significantly greater in the treatment (100 vs. 18.75%, p < .001), and a relatively greater proportion of animals conceived in the treatment group (29.41 vs. 6.25%, p = .08). The time elapsed to induction of estrus and insemination following treatment was significantly lower in the treatment group than control. A significant increment in the follicle diameter (9.72 +/- 0.45 vs. 13.00 +/- 0.45 mm, P < .0001) and serum estradiol (E-2) concentration (66.01 +/- 11.92 vs. 104.9 +/- 13.21 pg/mL, p = .003) observed at the post-treatment period in the PGF(2 alpha) treatment group. At the same time, CL diameter was reduced significantly at a higher regression rate in the PGF(2 alpha) treated buffaloes than those of control. Of the responded buffaloes, only 30% showed high-intensity estrus attributed to the expulsion of cervico-vaginal mucus (CVM), uterine tonicity, micturition, and mounting response by a teaser bull. From this study, it can be concluded that the administration of PGF(2 alpha) could induce estrus in the sub-estrus buffaloes during the non-breeding season. Behavioural changes, along with sonographic observation of POF, regressing CL, and serum E-2 and P-4 concentration would be useful to determine the right time of insemination in sub-estrus buffaloes during non-breeding season.