Background: To design a pre-Ovsynch hormonal strategy in yaks in order to increase the ovulatory response to the first GnRH injection of Ovsynch so that overall synchronization rate to Ovsynch could be improved. Materials and Methods: Non-lactating cyclic yak cows (n=33) were assigned to receive either no treatment before Ovsynch (control) or 0.375mg of PGF2(PreP) followed 2 d later by 10 g of ...

The objective of this study was to determine the effect of GnRH (100 microg i.m.) treatment 5 and 15 days after timed insemination (TAI) on pregnancy rate and pregnancy loss in lactating dairy cows subjected to synchronization of ovulation. The study included 831 lactating dairy cows subjected to a Presynch-Ovsynch protocol for first service. On the day of TAI (Day 0), cows were randomly assign...

Nonlactating dairy cows were used to examine effects of bovine somatotropin (bST) on components of the insulin-like growth factor (IGF) system. Estrus was synchronized in cows with a Presynch + Ovsynch protocol and timed AI (TAI; n = 55) or not TAI (cycling, C; n = 23) on d 0 (time of synchronized ovulation). On d 0 and 11, cows received bST (500 mg) or no bST, and were sacrificed on d 17. Preg...

We compared synchronization and pregnancy rates, and the increase in blood progesterone concentrations during luteal development, between (1) Ovsynch plus an intravaginal controlled internal drug release (CIDR) device protocol followed by timed embryo transfer (timed ET), and (2) a conventional estrus synchronization method using PGF(2 alpha) and ET in suckled postpartum Japanese Black beef cow...

Lactating dairy cows have unique reproductive responses compared to when they were heifers that result in distinctly different reproductive measurements and pregnancy outcomes that can be partially overcome with pharmacological strategies. These parameters include circulating progesterone and estradiol concentrations, ovulatory follicle and corpus luteum diameter, incidence of anovulation and d...

Introduction Reproductive physiologists had long searched to develop a synchronization program that could overcome the problems and limitations associated with visual estrus detection. Such a program was developed at the University of Wisconsin-Madison in 1995 (Pursley et al., 1995) and is now commonly referred to as Ovsynch. Ovsynch synchronizes follicular development, luteal regression and ov...