The effect of the age of the ovulatory follicle on fertility in beef cows was investigated. Multiparous (n = 171) and primiparous (n = 129) postpartum beef cows in 2 groups (G1 and G2) received estradiol benzoate (EB; 1 mg/500 kg BW, intramuscular [i.m.]) 5.5 d (G1; n = 162) and 6.5 d (G2; n = 138) after the final GnRH of a synchronization program (5d CO-Synch + CIDR) to induce emergence of a n...

Since its formation, the Beef Reproduction Task Force (BRTF) has worked to enhance productivity and profitability of US beef herds by integrating research and extension efforts with the intent of more effectively transferring the use of reproductive technologies to the field. A key early step was to coordinate efforts in identifying effective breeding management protocols for beef cattle and to...

The production of embryos by superovulation is often reduced in periods of heat stress. The associated reduction in the number of transferable embryos is due to reduced superovulatory response, lower fertilization rate, and reduced embryo quality. There are also reports that success of in vitro fertilization procedures is reduced during warm periods of the year. Heat stress can compromise the r...

Fifty-three mature Hereford-cross heifers, which were between day 0 and 3 of the estrous cycle, each had silastic coils containing 2.1 g progesterone inserted into the vagina where they remained for 12 days. Animals were assigned to treatment groups and were injected with (1) 5 mg estradiol benzoate, (2) as (1) + 50 mg progesterone or (3) as (1) + 200 mg progesterone at the time of insertion of...

The objective of this study was to determine whether administration of hCG approximately 5 d after AI would increase plasma progesterone concentrations and conception rates in beef heifers. Heifers from two locations (Location 1: n = 347, BW = 367 +/- 1.72 kg; Location 2: n = 246, BW = 408 +/- 2.35 kg) received melengestrol acetate (0.5 mg.heifer(-1).d(-1)) for 14 d and an injection of PGF2alph...

Background: Recent studies have been conducted with the aim of improving fertility rates in FTAI programs beef females. The observation estrus expression constitutes an important indicator zebu Therefore, this work has as objective to evaluate impact on follicular, luteal and morphofunctional characteristics Nelore females synchronized for FTAI.Materials, Methods & Results: Sixty five lacta...

Introduction The development of methods to synchronize estrus in beef cattle has been refined to a point that is feasible as well as reasonable to obtain pregnancy rates in mixed populations of cycling and anestrous cows that exceed 50% to a single fixed-time artificial insemination, provided a progestin based estrus synchronization protocol is used (Lamb et al., 2001; Kojima et al., 2002; Perr...

Abstract Korean black goat (Capra hircus coreanae) populations are dwindling and facing genetic erosion due to artificial insemination. Here, we introduced an estrus synchronization method for goats enable crossbreeding with non-native breeds on small farms investigated the application of insemination in goats. Semen was obtained using electro-ejaculation preserved a conventional simple freezin...

Abstract The objective of this study was to evaluate the uterine microbiota composition cows on day 15 estrous cycle. Non-pregnant Bos taurus beef (n = 23) were exposed a pre-synchronization step followed by 7-d CO-Synch estrus synchronization protocol. On days -10, -3, 0 (exogenously induced ovulation), 7 and 14, transrectal ultrasonography performed ovarian structures, ensure synchrony, deter...