Fertility of Holstein Dairy Heifers after Synchronization of Ovulation and Timed AI or AI after Removed Tail Chalk

Abstract

Nonlactating Holstein dairy heifers (n=352) 13 mo of age were managed using a 42-d artificial insemination (AI) breeding period in which they received AI after removed tail chalk evaluated once daily. At AI breeding period onset (d 0), heifers were randomly assigned to receive synchronization of ovulation (100 microg of GnRH, d 0; 25 mg of PGF2alpha, d 6; 100 microg of GnRH, d 8) and timed AI (TAI; d 8) and AI after removed tail chalk for the entire AI breeding period (GPG; n=175), or AI after removed tail chalk for the entire AI breeding period (TC; n=177). As expected, 17.7% (31/175) of GPG heifers received AI after removed tail chalk before scheduled TAI. Pregnancy rate per artificial insemination (PR/AI) at approximately 30 d after first AI tended to be greater for TC (46.5%) than for GPG (38.3%) heifers. No treatment x inseminator interaction was detected; however, overall PR/AI was low for heifers in both treatments due to variation among the 3 inseminators (24.8, 30.0, and 58.0%). Pregnancy loss from approximately 30 to approximately 75 d after first AI was 10% and did not differ between treatments. Based on survival analysis, days to first AI was greater for TC than for GPG heifers, whereas days to pregnancy across the 42-d AI breeding period did not differ between treatments. Overall, 81.2% of GPG heifers receiving TAI synchronized luteal regression and ovulated within 48 h after the second GnRH injection. We conclude that this synchronization protocol can yield acceptable fertility in dairy heifers if AI to estrus is conducted between treatment with GnRH and PGF2alpha and AI efficiency is optimized.

Effects of presynchronization and postinsemination treatments on pregnancy rates to a timed breeding Ovsynch protocol in dairy cows and heifers

“…Studies using Ovsynch TAI in heifers have reported that a high proportion (18 to 24%) come into estrus before the day of timed insemination (Rivera et al 2004(Rivera et al , 2005. Although our study found a similar proportion of heifers that came into estrus before scheduled timed breeding as other studies, our PR were far superior compared with these studies and others (Pursley et al 1997a), and are similar to those achieved with breeding at natural estrus (Pursley et al 1997a).…”

“…Although our study found a similar proportion of heifers that came into estrus before scheduled timed breeding as other studies, our PR were far superior compared with these studies and others (Pursley et al 1997a), and are similar to those achieved with breeding at natural estrus (Pursley et al 1997a). Other studies using Ovsynch TAI observed PR that were 20 to 40% less than that of heifers receiving AI to a natural estrus (Pursley et al 1997a;Rivera et al 2004). The establishment, maintenance of pregnancy, and embryo growth are related to the ability of the CL to secrete P 4 (Schmitt et al 1996).…”

“…Previous work using Ovsynch protocol on heifers has found unsatisfactory PR compared with that of natural estrus (Pursley et al 1997a). These results have been attributed to a high proportion of heifers expressing estrus before TAI (Pursley et al 1997a;Rivera et al 2005), resulting from an inconsistent response to the first GnRH treatment of the Ovsynch protocol and differences in their follicular wave pattern compared with lactating dairy cows (Rivera et al 2004). Presynchronization before the initiation of Ovsynch may help to overcome these premature ovulations in heifers.…”

Ovarian Response of Dairy Cows to Progesterone Combined On

“…Progesterone concentrations below 1.0 ng/ml were considered low and indicative of the absence of CL, while progesterone concentrations of 1.0 ng/ml or higher were considered as an indicative of functional CL and were referred as high (Cordoba and Fricke, 2002;Rivera et al, 2004;Yusuf et al, 2010). Cows showed high progesterone concentrations on day-7 were considered to have positive response to GnRH treatment, and cows showed high progesterone concentrations on day-7 and low on day-10 were considered to have positive response to GnRH and PGF2α treatments.…”

Efficacy of Intravaginal Progesterone Administration as an Additional Treatment on Two Types of Timed AI Protocols in a Commercial Herd of Holstein Heifers

“…However, these TAI protocols have not been utilized in heifers due to impaired pregnancy rate compared with AI at detected estrus [8,14]. One of the major reasons in heifers that estrus was observed before TAI and thus it failed in fertile inseminations [8,16,17]. This may occur due to early maturation of follicles compared with lactating cows [13] and results in premature estrus or ovulation [4,9,18,19].…”