Disappointing Fertility in Modern Dairy Cows: What About their Oocyte and Embryo Quality?

作者：Leroy J L M R^*; Langbeen A; Van Hoeck V; Bols P E J

来源：Cattle Practice, 2010, 18: 6-12.

Along with increasing milk yield, modern dairy cows have become less fertile. Poorer ovarian functioning with disturbed ovulations together with reduced oocyte and embryo quality are recognized as major factors in this problem of disappointing fertility outcome. Changes in follicular growth patterns during a period of negative energy balance (NEB) can indirectly affect oocyte quality. The endocrine and biochemical changes, which are associated with NEB, are reflected in the microenvironment of the growing and maturing female gamete, and may result in the ovulation of a developmentally incompetent oocyte. Even after an oocyte is successfully ovulated and fertilized, a full term pregnancy is still not guaranteed. Inadequate corpus luteum function, associated with reduced progesterone, and probably also low insulin-like growth factor concentrations, can cause a suboptimal microenvironment in the uterus that is incapable of sustaining early embryonic life. This may partly account for the low conception rates and the high incidence of early embryonic mortality in high yielding dairy cows.
Oocytes and embryos are highly sensitive to dietary induced changes in their microenvironment, possibly leading to a disturbed maturation, fertilization or early cleavage. Several nutrition-linked mechanisms, through which oocyte and/or embryo quality can be affected in modern dairy cows, well after the period of NEB, are recognized and should be taken into account when proposing solutions for this subfertility problem.

• 出版日期2010-3