Dietary Fat Supplementation and the Consequences for Oocyte and Embryo Quality: Hype or Significant Benefit for Dairy Cow Reproduction?

Abstract

In many countries, fat supplementation in the diet has become common in the dairy industry. There are several ideas as to how dietary fat could influence reproductive performance. Saturated fatty acids, such as palm oil, can increase milk yield but may aggravate negative energy balance and thus may impair fertility when fed during the first week post-partum. However, priming the lipid oxidation in the liver by feeding saturated fats during the dry period has recently been shown to be a potentially promising strategy to mitigate fat mobilization and liver accumulation post-partum. Furthermore, polyunsaturated fats (omega-3 fatty acids and conjugated linoleic acids) are fed to reduce the 'de novo' fat synthesis in the udder and thus the milk fat content, which may be of modest benefit for overall energy balance. Furthermore, omega-6 and omega-3 polyunsaturated fatty acids are reported to alter follicular growth, steroid synthesis and prostaglandin metabolism in the ovary and endometrium, respectively. Omega-6 fatty acids are believed to have pro-inflammatory and thus PGF2α-stimulating properties rendering them extra value as 'nutraceutical' early post-partum, while omega-3 fatty acids can weaken this inflammatory potency, leading to a higher chance of survival of the embryo when supplemented during the periconceptual period. Unfortunately, research results rarely provide a consensus in this perspective. The consequences of these fat-feeding strategies on oocyte and embryo quality remain an intriguing issue for debate. Fat feeding may alter the microenvironment of the growing and maturing oocyte of the early and older embryo and thus may affect reproductive outcome. We recently reported that dietary-induced hyperlipidaemic conditions can be harmful for embryo development and metabolism. However, to date, research results remain somewhat conflicting most probably due to differences in fat sources used, in diet and duration of supplementation and in experimental set-up in general.

Comparison of PUFA Profiles in the Blood and in Follicular Fluid and its Association with Follicular Dynamics after PGF2α Induced Luteolysis in Dairy Cows

“…Since follicular fluid obtains metabolites partly from the serum (14), any dietary alterations that are effectively transferred in the serum may modify the fatty-acid composition of the follicular fluid, which, in its turn can be crucial for altering ovarian activity and oocyte environment (17,35). In this respect, incorporations of PUFA into the rations might improve fertility, since, it has been reported that in general, unsaturated fatty acids tend to have beneficial effects when present in elevated concentrations on early embryo development (36). However, in contrast to our findings, other studies have reported (21,22) that the follicular fluid has a unique lipid composition which does not represent a simple reflection of the serum but significantly depends on the estrogen activity of the follicles.…”

Stimulatory effects of fish oil and vitamin E on ovarian function of laying hen

“…A few studies have shown that the number of follicles in bovine ovaries within the early postpartum period may be increased by dietary PUFA. However, they have not studied the role of dietary antioxidants, especially vitamin E (Leroy et al 2014). Similarly, the number of preovulatory follicles and ovulation rates were notably higher in goats that had fed with fish oil supplement (Mahla et al 2017), but antioxidant roles were ignored in this study.…”

Pre- and postpartum effects of starch and fat in dairy cows: A review

“…The NEB starts a few days before calving until 70 to 84 days post partum, coinciding with the beginning the breeding season (Butler, 2003;Roche et al, 2009). The NEB impairs the general metabolic system in dairy cows and has been identified by a number of researchers (Butler & Smith, 1989;Garnsworthy & Webb, 1999;Butler, 2003;Jorritisma et al, 2003) as an underlying causal factor of poor lifetime milk production and reproductive performance Several reviews have been published regarding the effect of the EB status on reproductive efficiency of dairy cattle (Beam & Butler, 1999;Butler, 2000;Jorritisma et al, 2003;Van Knegsel et al, 2005;Wathes et al, 2007;Santos et al, 2008;Roche et al, 2011;Evans & Walsh, 2012;Leroy et al, 2014). The status of NEB alters the insulin level and the GH-IGF-I axis to decrease the bioavailability of circulating IGF-I (Wathes et al, 2007).…”

“…Vasconcelos et al (2001) reported that an increased follicle size can have advantageous effects on both oocyte quality and corpus luteum function. The resulting high plasma cholesterol concentration improves PGF 2α and P 4 secretion Staples & Thatcher, 2005;Leroy et al, 2014), thus supporting embryo development and pregnancy survival (Ryan et al, 1992;Lammoglia et al, 1996;McNamara et al, 2003).…”