Beef heifers with diminished numbers of antral follicles have decreased uterine protein concentrations

Maternal age influences the number of primordial follicles in the ovaries of yearling Angus heifers

“…All procedures were approved by the U.S. Meat Animal Research Center (USMARC) Animal Care and Use Committees in accordance with the FASS guidelines for the care and use of agricultural animals in research. Commercial Angus heifers (n = 116/year; total 464) were evaluated for antral follicle count at an average of 325, 355, and 385 d of age as described previously (McNeel et al, 2017). Briefly, heifers that were born between March and May in 2012-2015 were weaned and moved to the USMARC feedlot in the fall.…”

“…In this previous study, Holstein heifers that were born to heifers had fewer antral follicles detectable by ultrasonography at a year of age than Holstein heifers that were born to multiparous cows. Similarly, Angus heifers with diminished numbers of antral follicles detectable by ultrasonography (14.5 ± 0.8 follicles) had dams that were younger than the dams of Angus heifers with increased numbers of antral follicles (31.1 ± 0.8 follicles, McNeel et al, 2017). More recently, it was reported that heifer born to mature beef cows had greater circulating concentrations of anti-Müllerian hormone (AMH), a blood marker of size of the ovarian reserve, and greater fertility than heifers with primiparous dams (Akbarinejad et al, 2018).…”

“…One proxy that can be used to estimate the size of the ovarian reserve is ultrasonographic determination of antral follicle number (Cushman et al, 2009). The number of antral follicles detectable by ultrasonography is highly repeatable (Burns et al, 2005;McNeel et al, 2017;Morotti et al, 2018), and the number of antral follicles is positively correlated with the number of microscopic primordial follicles in cattle ovaries (Cushman et al, 1999;Ireland et al, 2008). Walsh et al (2014) reported that maternal age affected the number of antral follicles detectable by ultrasonography in the ovaries of the daughters at a year of age.…”

Recuento de folículos antrales y concentraciones de hormona anti-Mülleriana: dos potenciales herramientas de selección de reemplazos

“…En vacas lecheras se encontró una asociación positiva entre RFA y performance reproductiva Mossa et al, 2012). La mayor calidad ovocitaria, mayor concentración de proteínas en el fluido uterino y las mayores concentraciones de progesterona (Figura 6) podrían explicar el mayor desarrollo del concepto y mayores porcentajes de preñez en vacas de alto respecto a bajo RFA (Jimenez-Krassel et al, 2009;McNeel et al, 2017;Tessaro et al, 2011). Por lo tanto, existe suficiente evidencia de que los mecanismos que determinan la calidad ovocitaria y viabilidad del embrión en sus primeras fases de desarrollo se ven favorecidos en vacas con alto respecto a bajo RFA.…”

“…Trabajos previos en ganado para carne no encontraron una relación beneficiosa entre el RMFA y la pubertad (Cushman et al, 2014;Mossa et al, 2013), pero si se ha descrito que vaquillonas con alto RMFA tienen mayores concentraciones de progesterona (presente estudio, (Jimenez-Krassel et al, 2009)). Además, vaquillonas con mayor RFA presentan un mayor tamaño uterino y contenido de proteína uterina, lo que indica la existencia de un ambiente más auspicioso para el desarrollo embrionario, variables que podrían explicar la concepción más temprana respecto a vaquillonas con menor RFA (Cushman et al, 2014;Jimenez-Krassel et al, 2009;McNeel et al, 2017;McNeel y Cushman, 2015). El incremento en las concentraciones de progesterona en vaquillonas con alto RMFA después del día 10 del ciclo estral, podría contribuir a un incremento en el elongamiento del embrión y favorecer el reconocimiento materno de la preñez (Diskin y Niswender, 1989).…”