Investigations on dominant follicle development, estrus response, ovulation time and fertility in PRID–treated anestrous buffalo heifers

Abstract

In this study, the aim of progesterone releasing intravaginal device (PRID) insertion in anestrous buffalo heifers was to induce estrus, to see ovulation time subsequent to PRID removal, and to find out reason(s) for poor fertility in PRID– treated buffalo heifers by investigating dominant follicle development during and after PRID period and post–ovulation luteal profile. True anestrous buffalo heifers (6) during summer were inserted PRID (containing 1.55 g progesterone but capsule of estradiol removed) for 15 days. Subsequent to PRID removal onset of estrus was confirmed and heifers were inseminated at 24 h interval till ovulation. During PRID period, rectal ultrasonography and jugular vein blood sampling was done on every alternate day. After PRID removal, these procedures were carried out at 24 h interval till the day of ovulation and thereafter, on days 5, 10, 15, 21 and 42 post–ovulation. Compared to initial concentrations, all treated heifers had high (P<0.05) plasma progesterone during the period of PRID placement. All the heifers exhibited estrus which persisted for 48 or 72 h subsequent to PRID removal. All the heifers ovulated by 48 (n=4) or 72 h (n=2) after PRID removal. Fertility (FSCR) after PRID treatment observed in this study was dependent upon the life span of ovulatory follicle. Heifers (n=3) only with short life span of ovulatory follicle became pregnant. Compared to ovulatory follicle of long life span, the one with short life span produced better post–ovulation luteal profile (CL size and plasma progesterone). In conclusion, ovulatory estrus can be successfully induced following PRID treatment of anestrous buffalo heifers and heifers can be bred at 48 h and 72 h (if dominant follicle present) subsequent to PRID removal. Fertility depends upon the life span of ovulatory follicle during and post–PRID period.