The consequences of metabolic changes in high-yielding dairy cows on oocyte and embryo quality

Abstract

Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high b-hydroxybutyrate (b-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading to reduced cryotolerance of day 7 embryos. Only b-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.

Parturition to resumption of ovarian cyclicity: comparative aspects of beef and dairy cows

“…2005;Garnsworthy et al, 2008a), and in vitro embryo production from overfed, superstimulated heifers (Freret et al, 2006). In contrast, lipogenic diets increased the oestradiolsecreting capacity of preovulatory follicles, thus providing enhanced substrate for progesterone production (Leroy et al, 2008) and improved blastocyst development rates. Garnsworthy et al (2008b) proposed a strategy of glucogenic diets during the early postpartum period to hasten the onset of regular oestrous cycles followed by more lipogenic diets to lower circulating insulin and improve oocyte quality at breeding.…”

Influence of Common Saturated and Unsaturated Fatty Acids on Development of Ovine Oocytes in vitro

“…The high circulating NEFA levels, associated with NEB were reflected in the follicular fluid of dominant follicles in ruminants early postpartum (Roth et al, 2001;Asian J. Anim. Sci., 9 (6): 420-426, 2015Leroy et al, 2008a. The saturated long chain fatty acids in particular (such as: palmitic and stearic acid) aggravated an inhibition of maturation rate, leading to comparatively low fertilization, cleavage and blastocyst formation rates.…”

“…During postpartum period high yielding animals face metabolic stress condition which leads to Negative Energy Balance (NEB) because of energy loss by high production which cannot be reimburse by energy intake (Van Knegsel et al, 2005) and follicular fluid (Leroy et al, 2008a). This change and increase free fatty acid concentration affects oocyte quality which leads to impair fertility (Leroy et al, 2008b).…”

Correlations among oocyte quality, hepatic triacylglycerols, and some blood metabolites in Carora breed cows during early postpartum

“…All of these metabolic features of fatty liver may also directly affect oocyte quality and compromise oocyte developmental capacity (11,12). Additionally, liver TAG accumulation may compromise the ability of liver to detoxify ammonia, contributing to elevated plasma urea nitrogen (PUN).…”