Metabolomic markers of fertility in bull seminal plasma

Abstract

Metabolites play essential roles in biological systems, but detailed identities and significance of the seminal plasma metabolome related to bull fertility are still unknown. The objectives of this study were to determine the comprehensive metabolome of seminal plasma from Holstein bulls and to ascertain the potential of metabolites as biomarkers of bull fertility. The seminal plasma metabolome from 16 Holstein bulls with two fertility rates were determined by gas chromatography-mass spectrometry (GC-MS). Multivariate and univariate analyses of the data were performed, and the pathways associated with the seminal plasma metabolome were identified using bioinformatics approaches. Sixty-three metabolites were identified in the seminal plasma of all bulls. Fructose was the most abundant metabolite in the seminal fluid, followed for citric acid, lactic acid, urea and phosphoric acid. Androstenedione, 4-ketoglucose, D-xylofuranose, 2-oxoglutaric acid and erythronic acid represented the least predominant metabolites. Partial-Least Squares Discriminant Analysis (PLSDA) revealed a distinct separation between high and low fertility bulls. The metabolites with the greatest Variable Importance in Projection score (VIP > 2) were 2-oxoglutaric acid and fructose. Heat-map analysis, based on VIP score, and univariate analysis indicated that 2-oxoglutaric acid was less (P = 0.02); whereas fructose was greater (P = 0.02) in high fertility than in low fertility bulls. The current study is the first to describe the metabolome of bull seminal plasma using GC-MS and presented metabolites such as 2-oxoglutaric acid and fructose as potential biomarkers of bull fertility.

Expression dynamics of Integrin Subunit Beta 5 in bovine gametes and embryos imply functions in male fertility and early embryonic development

“…Using Probit.F90 software (Chang, Gianola, Heringstad, & Klemetsdal, ), fertility prediction of each sire was calculated according to the average conception rates from more than 300 breeding outcomes along with their per cent deviation from the conception rates. The method to determine bull fertility used in our study is also similar to those from previous investigations about fertility biomarkers in bulls, conducted by several authors in the last decades (de Oliveira et al, ; Killian, Chapman, & Rogowski, ; Moura, Chapman, & Killian, ; Peddinti et al, ; Velho et al, ). The calculation of fertility scores was based on the actual conception rates confirmed by either veterinary palpation or ultrasound of cows inseminated with hundreds/thousands frozen‐thawed semen straws from each bull.…”

Amino Acids of Seminal Plasma Associated With Freezability of Bull Sperm

“…In a recent study aimed at analyzing metabolomes of seminal plasma from bulls with somewhat higher vs. lower fertility, researchers have identified 63 metabolites, in seminal plasma, of which 21 are amino acids that can be potential biomarker of fertility. Abundances of Lleucine and ornithine differed between the fertility groups, and the levels of fructose were correlated with those of glutamic acid and amino-butyrolactone (Velho et al, 2018). In other studies, researchers have determined different numbers of amino acids and peptides, in seminal plasma of bull, where glutamic and aspartic acid were the most abundant, and were associated with fertility and pregnancy rates (al-Hakim et al, 1970;Holden et al, 2017).…”

“…Recently, we have identified 63 seminal plasma metabolites of which 21 were amino acids from bulls with different field fertility scores (Velho et al, 2018) demonstrating the importance of metabolite profiles between low and high fertility bulls. Seminal plasma addition before freezing also influenced on post-thaw bull sperm kinematics (Nongbua et al, 2018).…”

Untargeted metabolomic profiling of accessory sex gland fluid from Morada Nova rams

“…The use of both GC/MS and LC/MS for analysis of AGF allowed the identification of 371 metabolites, some of which have been previously described in sperm and seminal plasma of humans (Paiva et al, 2015; Qiao et al, 2017) and bulls (Velho et al, 2018). GC/MS identified fewer compounds than LC/MS, but this was an expected result because LC analysis does not require the separation of thermally stable and volatile molecules, or large metabolites (Issaq et al, 2008).…”

“…In this regard, seminal plasma metabolites identified by GC/MS have been listed as potential markers of nonobstructive azoospermia in men (Gilany et al, 2017) and other studies also confirm the importance of seminal and sperm metabolites for evaluation of subfertility and infertility in humans (Davalieva et al, 2012). Comprehensive analyses of seminal plasma and sperm metabolomes from farm animals are still incipient, but recent reports have shown meaningful associations between seminal fluid metabolites and bull fertility (Kumar, Kroetsch, Blondin, & Anzar, 2015; Velho et al, 2018). In this regard, the goal of the present study was to characterize the major metabolome of accessory gland fluid (AGF) of Morada Nova rams using two complementary techniques, that is, gas chromatography coupled to mass spectrometry (GC/MS) and high‐performance liquid chromatography‐mass spectrometry (LC/MS).…”