Fertility‐associated metabolites in bull seminal plasma and blood serum: ¹H nuclear magnetic resonance analysis

Abstract

Early estimation of bull fertility is highly desirable for the conservation of male genetics of endangered species and for the exploitation of genetically superior sires in artificial insemination programs. The present work was conducted as a proof-of-principle study to identify fertility-associated metabolites in dairy bull seminal plasma and blood serum using proton nuclear magnetic resonance ((1)H NMR). Semen and blood samples were collected from high- and low-fertility breeding bulls (n = 5 each), stationed at Semex, Guelph, Canada. NMR spectra of serum and seminal plasma were recorded at a resonance frequency of 500.13 MHz on a Bruker Avance-500 spectrometer equipped with an inverse triple resonance probe (TXI, 5 mm). Spectra were phased manually, baseline corrected, and calibrated against 3-(trimethylsilyl) propionic-2,2,3,3-d4 acid at 0.0 parts per million (ppm). Spectra were converted to an appropriate format for analysis using Prometab software running within MATLAB. Principal component analysis was used to examine intrinsic variation in the NMR data set, and to identify trends and to exclude outliers. Partial least square-discriminant analysis was performed to identify the significant features between fertility groups. The fertility-associated metabolites with variable importance in projections (VIP) scores >2 were citrate (2.50 ppm), tryptamine/taurine (3.34-3.38 ppm), isoleucine (0.74 ppm), and leucine (0.78 ppm) in the seminal plasma; and isoleucine (1.14 ppm), asparagine (2.90-2.94 ppm), glycogen (3.98 ppm), and citrulline (1.54 ppm) in the serum. These metabolites showed identifiable peaks, and thus can be used as biomarkers of fertility in breeding bulls.

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

“…Together, these amino acids modify calcium active transport across the sperm membrane, causing a delay in calcium absorption by ejaculated sperm (Rufo, Singh, Babcock, & Lardy, 1982). In addition, seminal plasma leucine is associated with fertility of bulls (Kumar et al, 2015) and infertile men have low alanine in seminal plasma (Gershbein & Thielen, 1988). The modified amino acid 3‐chlorotyrosine is a marker of myeloperoxidase activity, an enzyme that acts in oxidative and antimicrobial processes (Hazen, Crowley, Mueller, & Heinecke, 1997) and involved in the removal of apoptotic cells (Lessig et al, 2007).…”

“…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).…”

Age-related differences of semen quality, seminal plasma, and spermatozoa antioxidative and oxidative stress variables in bulls during cold and warm periods of the year

“…Historically, emphasis has been focussed on assessing bull fertility by evaluating sperm characteristics, whereas little attention has been paid to physiological function and/or fertility markers, that is, antioxidants/proteins in the blood, seminal plasma and spermatozoa of breeding animals (Kumar et al, 2015). Spermatozoa concentration, motility and morphology are the most common semen metrics used at breeding stations worldwide.…”

Showcasing metabolomic applications in aquaculture: a review

“…), identifying biomarkers for assessment of sperm fertility (Kumar et al . ), assessing oocyte quality and predicting embryo viability (Bertoldo et al . ; Cortezzi et al .…”

“…While not yet realized within the aquaculture industry, metabolomics has benefitted other areas of developmental biology with respect to investigating reproductive disorders (Courant et al 2013), identifying biomarkers for assessment of sperm fertility (Kumar et al 2015), assessing oocyte quality and predicting embryo viability (Bertoldo et al 2013;Cortezzi et al 2013) and identifying the coordination of metabolic traits during selective breeding for stress resistance and longevity (Malmendal et al 2013). Metabolomics will undoubtedly be a useful tool in the progression of future hatchery technologies.…”