Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows II: Strategies and factors affecting fertility

Effects of Equine Chorionic Gonadotropin on Follicular, Luteal and Conceptus Development of Non-LactatingBos IndicusBeef Cows Subjected to a Progesterone Plus Estradiol-Based Timed Artificial Insemination Protocol

“…Despite being the first report regarding the effects of exogenous administration eCG associated to the conceptus length, no differences were found in blood P4 concentrations or the length of the conceptus. Cows treated with eCG had greater final follicular development, which is in agreement with studies by other authors who used eCG in postpartum Nelore cows (Sá Filho et al, 2009, 2010aSales et al, 2011). Additionally, the results of the present trial showed a greater diameter of the LF at TAI after eCG treatment.…”

“…In particular, TAI programmes have been applied in postpartum anovular beef cows, anticipating the first postpartum insemination and improving reproductive efficiency under tropical conditions (Baruselli et al, 2004;Sales et al, 2012). The use of equine chorionic gonadotropin (eCG) has improved the efficacy of TAI protocols and increased ovulatory responses and pregnancy rates (Cutaia et al, 2003;Sá Filho et al, 2009, 2010cSales et al, 2011). Equine chorionic gonadotropin is a long half-life molecule produced by mare's endometrial cup cells (Murphy and Martinuk, 1991), and it has a stimulatory effect on FSH and LH hormones, leading to increased follicular growth and ovulation (Sá Filho et al, 2010a;Sales et al, 2011).…”

Synchronization of ovulation and fixed-time artificial insemination in beef cattle

“…On the contrary, the absence or little effect of CR on pregnancy rates contrasts with data from other studies conducted on Nelore (B. indicus) cows (Penteado et al, 2004;Sá Filho et al, 2009. Yet in another study conducted in Colombia on suckled Brahman cows (B. indicus) that were mostly in postpartum anoestrus (i.e.…”

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

“…Além disto, o maior tamanho do FO está correlacionado com a concentração sérica de estradiol, a manifestação de estro, a taxa de ovulação e com o sucesso na concepção [11]. A indução da ovulação de folículos dominantes pequenos, com diâmetro menor que 11 mm, está associada a menores taxas de prenhez e maiores perdas gestacionais em novilhas [11] e vacas de corte [14,15]. Novilhas que apresentam folículos menores que 10,7 mm ou maiores que 15,7 mm no momento da inseminação possuem menor chance de conceber quando comparadas àquelas com FO de 12,8 mm de diâmetro na IA [13].…”