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Online Journal of Veterinary Research


Volume 26 (6): 387-392, 2022.

Effect of cosynch and ovsynch with or without estradiol on fertility in dairy cows.

S. Kothandaraman, R. Gnanasekar, A. Varadharajan, R. Vijayalakshmi and K. Saravanan*


Division of Animal Husbandry, Department of Genetics & Breeding, Faculty of Agriculture, Annamalai University, Annamalai Nagar 608 002, Tamil Nadu, India.



Kothandaraman S, Gnanasekar R, Varadharajan A Vijayalakshmi, Saravanan K., Effect of cosynch and ovsynch with or without estradiol on fertility in dairy cows, Onl J Vet Res., 26 (6): 387-392, 2022. Groups of 45 repeat breeders in estrus at day 34 were given Ovsynch protocol of gonadotrophin (GnRH) at day 46, prostaglandin (PGF2α) day 53, estrogen (E2) day 55 at 8 and 48h and GnRH again 16h after insemination at day 56 (Group = OV-56+E2). Controls (n =45) were given same treatment except without estrogen at day 55 and gonadotropin at time of insemination (TAI) at day 56 (Group = CO-72). Groups consisted of 30 heifers and 60 multiparous cows. We assessed effect of treatment on fertility. In cows subjected to OV-56+E2 estrus was 74.8% compared with 57.5% in CO-72 controls not given estrogen (P < 0.05). Pregnancy due to artificial insemination (P/AI) at days 45 to 50 was 60% in OV-56+E2 cows compared with 42% in controls 41.6% (P < 0.05). In cows without estrus these values were 43.3 and 6.6%, respectively (P < 0.05) Moreover, P/AI was 60% (P < 0.05) in OV-56+E2 and 36.6% in controls with body condition score >2.5 compared with <2.5 (44.3 and 16.6%, respectively. Results suggest that OV-56+E2 protocol boosted estrus compared with controls but had no effect on fertility by artificial insemination. However cows with high body condition score exhibited more estrus and pregnancy.

Keywords: Modified Ovsynch, Cosynch, Repeat breeders, Estradiol, Fertility.