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OJVRTM
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.
ABSTRACT
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.