Article

Disruption of Bovine Oocytes and Preimplantation Embryos by Urea and Acidic pH

Department of Animal Sciences, University of Florida, Gainesville, 32611-0910, USA.
Journal of Dairy Science (Impact Factor: 2.55). 05/2003; 86(4):1194-200. DOI: 10.3168/jds.S0022-0302(03)73703-5
Source: PubMed

ABSTRACT Feeding cattle diets high in degradable crude protein (CP) or in excess of requirements can reduce fertility and lower uterine pH. Objectives were to determine direct effects of urea and acidic pH during oocyte maturation and embryonic development. For experiment 1, oocytes were matured in medium containing 0, 5, 7.5, or 10 mM urea (0, 14, 21, or 28 mg/dl urea nitrogen, respectively). Cleavage rate was not reduced by any concentration of urea. However, the proportion of oocytes developing to the blastocyst stage at d 8 after insemination was reduced by 7.5 mM urea. In addition, the proportion of cleaved oocytes becoming blastocysts was decreased by 5 and 7.5 mM urea. For experiment 2, putative zygotes were collected -9 h after insemination and cultured in modified Potassium Simplex Optimized Medium (KSOM). Urea did not reduce the proportion of oocytes developing to the blastocyst stage, although 10 mM urea reduced cleavage rate slightly. For experiment 3, dimethadione (DMD), a weak nonmetabolizable acid, was used to decrease culture medium pH. Putative zygotes were cultured in modified KSOM containing 0, 10, 15, or 20 mM DMD for 8 d. DMD reduced cleavage rate at 15 and 20 mM and development to the blastocyst stage at all concentrations. Results support the idea that feeding diets rich in highly degradable CP compromises fertility through direct actions of urea on the oocyte and through diet-induced alterations in uterine pH.

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    • "Las vacas alimentadas con una dieta con el 20% de PC tuvieron una media de US de 21,0 mg/dl en comparación con una media de 8,6 mg/dl en vacas alimentadas con una dieta con el 13% de PC. Sin embargo, parámetros reproductivos como el intervalo al primer celo y la ovulación, la tasa de concepción al primer servicio, servicios por concepción y días abiertos no fueron afectados por el nivel de proteína en la dieta.. El efecto negativo de una dieta con elevada proteína sobre el tracto reproductivo podría deberse a un efecto sobre el pH uterino (Elrod et al., 1993) aunque otros estudios in vivo e in vitro sugieren que el amoníaco y la urea tendrían un efecto directo sobre el ovocito y el embrión (Blanchard et al., 1990; Sinclair et al., 2000; Ocon and Hansen 2003; Rhoads et al., 2006). "
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    ABSTRACT: En los sistemas de producción de leche intensiva, el aumento de la producción de leche por vaca y del tamaño corporal de las vacas, en los últimos años, ha sido traducido en un aumento de las necesidades de energía y proteína bruta, que indirectamente impacta en la fertilidad general de la granja. Además, la ingesta insuficiente de vitaminas y micro y macro minerales ha sido asociada con el pobre rendimiento reproductivo del ganado lechero. El balance energético negativo (BEN) es, quizás, el factor nutricional más importante relacionado con una mala función reproductiva en vacas lecheras. Aunque las vacas de carne no experimentan un período de balance energético negativo tan severo como las vacas lecheras, tienen que mantener una buena condición corporal en el periparto para reanudar rápidamente los ciclos estrales de alta fertilidad después del parto. Por lo tanto, la ingesta insuficiente de nutrientes y/o las reservas corporales inadecuadas antes del parto y durante la lactancia temprana son los principales factores que afectan el comportamiento reproductivo en las vacas de carne. Esta revisión se centrará principalmente en la información disponible proveniente de las investigaciones sobre la nutrición y la reproducción en bovinos y proveerá discusiones sobre el suministro de diferente nutrientes durante el pre y posparto que podrían contribuir a una mejora de la eficiencia reproductiva del ganado.
    Primer Simposio Internacional de Avances en Reproduccion Bovina, Guadalajara, Mexico; 07/2015
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    • "The combination of high dietary energy and increased urea concentration exacerbates the deleterious effects of urea alone on embryo development (Papadopoulos et al. 2001). Similarly, in cattle, in vivo exposure to high levels of ammonia or urea inhibited oocyte capacity to develop to blastocysts in vitro (Sinclair et al. 2000; Ferreira et al. 2011) and likely also has a negative effect on oocyte potential through acidification of uterine pH (Ocon and Hansen 2003). Embryos derived from a maternal environment with high concentrations of urea show compromised long-term potential with reduced pregnancy rate after transfer (Rhoads et al. 2006). "
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    ABSTRACT: Maternal periconceptional (PC) nutrition, coupled with maternal physiological condition, can impact on reproductive performance and potential across mammalian species. Oocyte quality and embryo development are affected adversely by either nutrient restriction or excess. Moreover, the quality of maternal PC nutrition can have lasting effects through fetal development and postnatally into adulthood. Chronic disease, notably cardiovascular and metabolic disease, and abnormal behaviour have been identified in adult offspring in small and large animal models of PC nutrient restriction. These long-term effects associate with compensatory responses that begin from the time of early embryo development. This review assesses the field of PC nutrition in vivo on short- and long-term developmental consequences in rodent and ruminant models and considers the implications for human health.
    Reproduction Fertility and Development 12/2011; 24(1):35-44. DOI:10.1071/RD11905 · 2.58 Impact Factor
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    • "However, in these studies no concentration gradients between serum and FF were mentioned, there is now enough evidence to conclude that the growing and maturing oocyte is directly exposed to the typical biochemical changes that occur in highyielding dairy cows early post partum. It has furthermore been established that high urea concentrations, also found in FF (Hammon et al., 2005), can be toxic to oocytes during maturation (Ocon and Hansen, 2003; Iwata et al., 2006), probably through an inhibition of the polymerization of tubulin into microtubules (De Wit et al., 2001). The same is true for the lowered glucose concentrations observed. "
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