Metabolite concentrations in follicular fluid may explain differences in fertility between heifers and lactating cows

Abstract

There has been a marked decline in the fertility of dairy cows over the past decades, and metabolomic analysis offers a potential to investigate the underlying causes. Metabolite composition of the follicular fluid, which presents the intrafollicular environment, may be an important factor affecting oocyte maturation and subsequent early embryo development. The aim of the present study was to investigate the metabolic differences between follicular fluid from the dominant follicle of lactating cows and heifers using gas chromatography mass spectrometry (GC-MS)-based metabolomics. Follicular fluid and serum were collected from cows and heifers over three phases of follicle development: newly selected dominant follicles, preovulatory follicles prior to oestrus and post-LH surge follicles. Analysis of the fatty acids revealed that there were 24 fatty acids and 9 aqueous metabolites significantly different between cows and heifers. Of particular interest were the higher concentrations of saturated fatty acids (palmitic acid, PZ0.001; stearic acid, PZ0.005) in follicular fluid from cows and higher docosahexaenoic acid levels (PZ0.022) in follicular fluid from heifers. Analysis of the metabolite composition of serum revealed that follicular fluid had a unique lipid composition. The higher concentrations of detrimental saturated fatty in cows will have a negative impact on oocyte maturation and early embryo development. Overall, the results suggest that the follicle microenvironment in cows potentially places their oocytes at a developmental disadvantage compared with heifers, and that this may contribute to well-characterised differences in fertility.

Effect of Linolenic acid during in vitro maturation of ovine oocytes: embryonic developmental potential and mRNA abundances of genes involved in apoptosis

“…Lipid analysis of follicular fluid revealed that ω-6 and ω-3 fatty acid families are the most abundant polyunsaturated fatty acids (PUFAs) in the follicle [6]. These findings strengthen the hypothesis that dietary supplementation of ω-6 and/or ω-3-fatty acids has an important role in oocyte quality and development [7].…”

Lipids and oocyte developmental competence: the role of fatty acids and β-oxidation

“…By day 44 post-partum, follicular fluid NEFA levels have increased to match that in serum, yet follicular fluid is selectively enriched with palmitic, oleic and linoleic fatty acids (Leroy et al 2005a). These studies highlight that serum NEFA levels are dynamic, increasing dramatically at parturition; and that during lactation follicular fluid NEFA also increase but display a distinct fatty acid profile compared with serum (Leroy et al 2005a, Bender et al 2010. Oocytes of repeat breeder dairy cows were also shown to contain significantly more lipid than oocytes from virgin heifers, even though the COCs isolated from both types of animals were classified as normal good quality (Awasthi et al 2010).…”

“…The follicular fluid of both heifers and lactating cows was shown to contain primarily linoleic, oleic, stearic and palmitic acids: however, compared with heifers, the cows had higher levels of at least 24 different fatty acids in follicular fluid, particularly palmitic acid and stearic acid and lower levels of docosahexaeonic acid (Bender et al 2010). In dairy cows, circulating triglyceride levels decrease at parturition, while NEFA levels increase dramatically, relative changes that are also reflected in the follicular fluid (Leroy et al 2004b).…”

Selected molecular and microfluidic aspects of mammalian oocyte maturation-perspectives: a review

“…In addition, Bender et al (2010) suggested that the metabolites present in the follicular fluid might be used as markers of oocyte maturation ability as well as of the subsequent embryo development. They investigated the metabolomic profile of follicular fluid obtained from the dominant follicle of lactating cows and heifers using gas chromatography mass spectrometry.…”