Antral Follicle Populations and Embryo Production – In Vitro and In Vivo – of Bos indicus–taurus Donors from Weaning to Yearling Ages

Abstract

Interest in indicus-taurus cattle has been increasing, as these animals are likely to present the best characteristics of Zebu and European bovine breeds. The aim of this study was to compare the embryo production of indicus-taurus donors with high vs low antral follicle counts obtained by ovum pickup/in vitro production (OPU/IVP) and superovulation (SOV)/embryo collection. Braford females at weaning age (3/8 Nelore × 5/8 Hereford, n = 137, 9 ± 1 month old) were subjected to six serial ovarian ultrasonographs and were assigned to two groups according to the number of antral follicles ≥ 3 mm as follows: G-High antral follicular count (AFC, n = 20, mean ≥ 40 follicles) and G-Low AFC (n = 20, mean ≤ 10 follicles). When the females (n = 40) reached 24 months of age, they were subjected to both OPU/IVP and SOV/embryo collection. The average number of follicles remained highly stable throughout all of the ultrasound evaluations (range 0.90-0.92). The mean number of COCs recovered (36.90 ± 13.68 vs 5.80 ± 3.40) was higher (p < 0.05) for females with high AFC, resulting in higher (p < 0.05) numbers of total embryos among females with high vs low AFC (6.10 ± 4.51 vs 0.55 ± 0.83). The mean number of embryos per collection was also higher (p < 0.05) for G-High vs G-Low (6.95 ± 5.34 vs 1.9 ± 2.13). We conclude that a single ultrasound performed at pre-pubertal ages to count antral follicles can be used as a predictor of embryo production following IVP and SOV/embryo collection in indicus-taurus females.

Anti-Müllerian hormone (AMH) as a predictor of antral follicle population in heifers

“…The number of recruited follicles in each follicular wave is highly variable between individuals; however, a high level of individual repeatability is observed (Evans et al, 2010;Oliveira Junior et al, 2015;Batista et al, 2014;Gobikrushanth et al, 2017). High correlation of AFP with in vivo and in vitro embryo production may be used as an auxiliary tool to select donor cows for embryos and oocytes (Silva-Santos et al, 2014a;Baruselli et al, 2015;Ghanem et al, 2016).…”

Antral follicles population in heifers and cows of Nelore and Girolando breeds

“…Subsequent counts were performed twice at 35-day intervals without synchronization and in accordance with other studies (CUSHMAN et al, 2009;SILVA-SANTOS et al, 2014a), no influence of stage of estrous cycle on OAFPs was observed. However, based on consideration of ovary characteristics as well as the historical age at puberty for Girolando and Nelore breeds in the study region, heifers were considered to be prepubertal at the time of the study and were therefore not subjected to the estrus synchronization treatment administered to cows.…”

“…For cattle, improved success of in vitro embryo production has been associated with high numbers of recovered cumulus oophorus complexes (COCs) from bovine females (PONTES et al, 2011;SILVA-SANTOS et al, 2014a, 2014b. However, high individual and between-breed variations in oocyte production have been observed and researchers seek to identify mechanisms underlying such variability.…”

Contagem de folículos antrais em fêmeas Nelore submetidas a inseminação artificial em tempo fixo

“…Estes resultados foram suportados por diversos pesquisadores, que também verificaram inter-relação entre estes parâmetros (CUSHMAN et al, 2009;IRELAND et al, 2008;MOSSA et al, 2012). A literatura demonstrou ainda que fêmeas apresentando um maior DOV tiveram maior número de folículos e oócitos saudáveis (IRELAND et al, 2008;SILVA-SANTOS et al, 2014).…”

“…Contagem de folículos antrais (CFA) (Média±EP) P-valor (IRELAND et al, 2007(IRELAND et al, , 2008JIMENEZ-KRASSEL et al, 2009;SILVA-SANTOS et al, 2014). Acreditava-se que os resultados desta pesquisa iriam confirmar estas evidências fisiológicas, porém, neste estudo, o efeito da CFA sobre a fertilidade não foi observado.…”