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The objectives of this study were to confirm the relationship of apoptosis-associated membrane and nuclear changes in bull spermatozoa with field fertility, to predict the fertility of beef bulls used for natural breeding and to study the role of DNA-nicked spermatozoa in early embryonic development. In Experiment 1, the relationship between fertility and different sperm populations identified by the Annexin V/propidium iodide (PI) and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assays was determined. Bull fertility was related to live (PPPin vitro cleavage and blastocyst rates was evaluated, using 30000 or 300000 spermatozoa per droplet. Cleavage rate was adversely affected (PP<0.05) in high DNA-nicked spermatozoa at the lower sperm concentration. In conclusion, the incidence of DNA-nicked spermatozoa is a useful marker to predict a bull's fertility potential. DNA-nicked spermatozoa showed adverse effects on early embryonic development.

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., (© 2015 Wiley Periodicals, Inc.)

Assessing semen quality is crucially important for the exploitation of genetically superior sires in an artificial insemination (AI) program. In this study, we compare modern and conventional techniques to estimate bovine sperm concentration and membrane integrity. First, the NucleoCounter SP-100 was validated for sperm concentration and provided statistically reliable and repeatable estimates among aliquots and replicates of 25 fresh ejaculates. Sperm concentrations in 78 ejaculates were then determined with hemacytometer, flow cytometer, and NucleoCounter SP-100 and were significantly correlated (P < .001), with regression coefficients among these 3 techniques close to 1 (P < .01). However, the sperm concentration determined by hemacytometer was lower (P < .01) than by flow cytometer and NucleoCounter SP-100. Forty frozen-thawed semen samples were then assessed for sperm concentration and membrane integrity with hemacytometer, flow cytometer and NucleoCounter SP-100. Significant relationships were found for sperm concentration determined by hemacytometer and NucleoCounter SP-100 and for sperm membrane integrity determined by flow cytometer and NucleoCounter SP-100 (P < .01). Finally, the standard curves of sperm concentrations in 6 spectrophotometers, comparing optical density against counts drawn by hemacytometer and NucleoCounter SP-100 (n = 94 fresh ejaculates) showed different (P < .01) intercepts and regression coefficients (linear, quadratic, cubic). It was calculated that a breeding station can improve its production potential by 13% with the use of NucleoCounter SP-100 instead of hemacytometer for calibration of spectrophotometers. Flow cytometer and NucleoCounter SP-100 can be used with equal confidence to estimate sperm concentration and membrane integrity in domestic animals and human semen.