Mohan Gawai ¹ Brijesh Kumar ^1* S Mehrotra ¹ Pradeep Chandra ¹ Kalpendra Kohli ¹ Manoj Donadkar ¹ Vandana Yadav ¹ Brijesh K. Yadav ² Chinmay Warghat ¹ Nitish Kharayat ¹ Dushyant Yadav ³ Sumit Singhal ³ VIKRANT S. CHOUHAN ¹ S K. Singh ¹ M H. Khan ¹

• ¹ Indian Veterinary Research Institute (IVRI), Bareilly, Uttar Pradesh, India
• ² U.P. Pandit Deen Dayal Upadhyaya Veterinary University, Mathura, Uttar Pradesh, India
• ³ Bihar Veterinary College, Bihar Animal Sciences University, Patna, Bihar, India

The study aimed to evaluate the effect of antral follicle count (AFC) on follicular and luteal development during the estrous cycle and superovulatory period, superovulatory response, and also in vivo embryo quality and in MOET program. A total of 48 estrus induced (500 µg PGF2α, Single dose, IM) Sahiwal cows (Bos indicus) with a BCS between 3.5 -4.0 were selected for the study. On the day of wave emergence, the animals were divided into two groups based on AFC i.e. low AFC (≤18) and high AFC (>18). Both the groups were monitored daily using B mode ultrasonography (USG) for one cycle and the superovulation protocol was initiated on the 9 th day of the subsequent estrous cycle. A total of 240 µg of FSH in eight divided doses were given in a tapering sequence for 4 days and simultaneous administration of 500 µg PGF2α, along with the 5 th dose of FSH. Donors were inseminated at superovulatory estrus using a double dose of quality frozen semen thrice at 12 h. intervals and nonsurgical flushing was performed on the day 7 th of the superovulatory estrus followed by embryo searching and evaluation under a stereo zoom microscope. Ovulatory waves of high AFC Sahiwal cows have significantly (P ≤ 0.05) larger sizes of preovulatory follicles (POF) (12.06±0.19 mm vs 11.56±0.16 mm), and corpus luteum (CL) (19.57±0.28 mm vs 18.26±0.35 mm), as compared to low AFC. The ovarian size was significantly (P < 0.0001) larger in cows with high AFC during the superovulatory protocol. The number of large, medium, and small follicles were significantly (P < 0.0001) high on the day of superovulatory estrus (SOE), PGF2α administration, and initiation of superovulatory protocol respectively in high AFC. Donors with high AFC had a notably greater (P < 0.0001) count of CL and embryos retrieved per flushing, including excellent and fair quality embryos. A strong association (P <0.0001) between high AFC and ovarian size (r=0.9136) , superovulatory response (r=0.9350), and embryo quality ( x 2 = 8.788; P= 0.032) and number ( r=0.9858) were also recorded.