Influence of Follicular Growth Stimulation on Fertility of Beef Cows Treated with eCG or FSH in FTAI Protocols

Abstract

Background:The pregnancy rate in fixed-time insemination (FTAI) programs in beef cattle is affected by several factors, including the size of ovulatory follicle (OF). Induced ovulation of small OF (≤11 mm) reduces the chance of pregnancy after FTAI when compared to ovulation of larger follicles (≥12 mm). Hormonal treatments to enhance the follicle growth have been widely used in comercial beef cattle systems, aiming to improve the development of a dominant follicle. The objective of this experiment was to evaluate the effect of treatment with eCG or FSH at the time of progesterone implant removal on the diameter of OF, final follicle growth and pregnancy rate in beef cows. Materials, Methods & Results: Three hundred and seven suckled beef cows with body condition score 2.80 ± 0.24 (1 to 5 scale) and 45 to 70 days postpartum were synchronized to FTAI. On day 0, intravaginal implants containing 1 g of progesterone, were inserted and administered 2 mg of estradiol benzoate (EB), i.m. On day 7, intravaginal implants were

Influence of nutritional and ovarian parameters on pregnancy rates of Nelore cows artificially inseminated at fixed time

“…In this context, the FTAI protocols are very useful, and are frequently performed in acyclic cows during the postpartum period, a condition in which the cow has a low LH support and reduced follicular development (Meneghetti et al, 2009;Roche, Crowe, & Boland, 1992). Thus, the administration of Equine Chorionic Gonadotropin (eCG) is an alternative that can be used in hormonal protocols, as it has an activity similar to FSH and LH in ruminants, promoting follicular growth and oocyte maturation (Ferraz et al, 2019;Thedy et al, 2018). In the present study, the 350 IU eCG administration at the moment of the P4 device removal, may have positively influenced the cows' pregnancy rates.…”

Recombinant bovine somatotropin in the synchronization of ovulation in crossbred dairy cows (Bos taurus indicus × Bos taurus taurus)

“…Studies indicate that the administration of eCG in the protocol increases follicular growth rate since it improves the ovarian follicular development due to follicle-stimulating hormone and luteinizing hormone-like activity [21]. In this context, the present study suggests that all treatments were affected by eCG since the follicular growth rate observed is similar to those reported by other authors, who observed rates ranging from 1.3 to 1.8 mm/day in B. t. taurus using ovulation synchronization protocols [22,23].…”