Pattern of induced estrus and conception rate following Ovsynch and Ovsynch based gonadotropin-releasing hormone treatments initiated on day 6 of estrous cycle in repeat breeding crossbred cows

Abstract

Aim:The aim was to evaluate the estrus response, incidence of accessory corpus luteum formation and fertility following different hormonal protocols in repeat breeding crossbred cows.Materials and Methods:This study was carried out on 24 repeat breeding crossbred cows allotted into four groups. Cows of Group I was not given any treatment, Group II was treated with gonadotropin-releasing hormone (GnRH) injection on day 6 post-estrus, Group III was treated with Ovsynch protocol, and Group IV was treated with Ovsynch based GnRH treatment. Estrus responses such as duration, onset, percentage, and intensity of estrus were recorded during the study. The incidence of accessory corpus luteum was recorded per rectally on day 7 after first and additional GnRH of Ovsynch treatment. The conception rate for all groups was calculated by the absence of estrus and on day 45 after artificial insemination (AI) per rectum. Serum samples were collected at AI and day 12 post-AI in Group I and II. Serum samples were also collected at GnRH, Prostaglandin F2α (PGF2α), timed AI (TAI) and day 12 post-TAI in Group III and IV.Results:Ovsynch and Ovsynch based GnRH treatments are resulted in 100.00% induction of estrus after the PGF2α injection. Onset of induced estrus after the PGF2α injection for Group III and IV was recorded as 48.750±0.713 and 51.472±1.989 h, respectively, and it was not significant. There was no significant difference in duration of estrus among the groups. The incidence of intermediate estrus intensity was found to be highest. All the cows showed the incidence of formation of accessory corpus luteum subsequent to GnRH treatment on day 6 of the estrous cycle in Group II, III, and IV. The conception rate was 0.00%, 16.67%, 50.00%, and 50.00% in Group I, II, III, and IV, respectively.Conclusion:Ovsynch and Ovsynch based GnRH treatments initiated on day 6 of estrous cycle capable of responding with a higher percentage of ovulation and formation of accessory corpus luteum which helped in higher conception rate over single post-AI GnRH treatment in repeat breeders. These treatments responded with better estrus response but did not significantly improve estrus intensity.

Efficacy of different estrus synchronization protocols on estrus induction response and conception rate in acyclic and cyclic crossbred cows

“…Higher estrus induction response (100%) with Ov_synch protocol in acyclic cows as observed in the present study has also been reported by Virmani et al (2013), Buhecha et al (2015) and Ahmed et al (2016). However, relatively lower induction response of 20.0 to 67.0% has been reported by others (Mahour et al, 2012;Naikoo et al 2016).…”

Estrus Performance and Pregnancy Rate in Types of Local Cows on Different Estrus Synchronization Protocols

“…This research selected cattle traditionally raised in the countryside. The onset of estrus in this study was different from 18.43±0.48 hours in Jersey cows (Bhat and Bhattacharyya, 2012), and 20.07 -21.458 hours in India cattle (Ahmed et al, 2016). The onset of estrus in this study was within the normal range, i.e.…”

Ovarian luteal category at the time of exogenous progesterone treatment alters pre-ovulatory follicle size and pregnancy outcome but not initial GnRH treatment in repeat-breeder crossbred dairy heifers submitted to the 7-day fixed-time AI protocol

“…This increase in PR was probably due to the fact that a combination of GnRH and PGF2α in the P4-based fixed-time AI programme results in synchronous follicular wave emergence, timely follicular development, synchronous ovulation following the last injection of GnRH ( Kim et al., 2007 ), and it can overcome the problem of delayed ovulation and anovulation in repeat-breeder dairy cattle ( Bhattacharyya & Hafiz, 2009 ). As stated above, repeat breeder heifers have a smaller preovulatory LH surge than virgin heifers ( Gustafsson et al., 1986 ) and, therefore, an increase in the spontaneous LH surge that results from the treatment of GnRH at onset of the final stage of DF development affects the fertility favourably ( Ahmed et al., 2016 ; Kaim et al., 2003 ).…”