Spermatozoal transcripts expression levels are predictive of semen quality and conception rate in bulls (Bos taurus)

- Spermatozoal RNA transcription levels can be used to assess the events associated with spermatogenic process and fertility.
- Spermatozoal BMP2 and NGF transcripts expressions were higher in good semen producers.
- Spermatozoal UBE2D3, CASP3 and HSFY2 transcripts expressions were negative indicators of post-thaw semen quality.
- Spermatozoal apoptotic genes expression level determines the conception rate of the bull.
- Spermatozoal RNA expression levels can be used to predict bull fertility and cryo-survivability.

Spermatozoal transcripts expression levels could be used to assess fertility potential of a male. The objective of the present study was to elucidate the predictive ability of the expression levels of growth, apoptosis and homeostasis regulating transcripts on sperm functions and fertility. The expression levels of spermatozoal RNA isolated from the neat semen samples were related to the good (discarded ejaculate, <25%; n = 7) and poor (discarded ejaculate, >40%, n = 6) quality semen producer and bulls (n = 12) with known conception rate. The relative fold expression levels of BMP2 were significantly (p < 0.01) higher in good than the poor semen producers and positively associated with post-thaw sperm velocity parameters (LIN and VAP). The NGF expressions fold levels had significant (p < 0.05) positive relationship with mitochondrial membrane potential of neat semen samples. The genes involved in the apoptotic, UBE2D3 (r = −0.61, p = 0.02), CASP3 (r = −0.57, p = 0.03) and homeostatic, HSFY2 (r = −0.61, p < 0.02) regulators had significant negative correlation with the percentage of post-thaw fast progressive motile spermatozoa. The expression level of TRADD had significant negative influence on the mitochondrial membrane potential (r = −0.54, p = 0.05) of neat semen samples and conception rate (r = −0.57, p < 0.05). The expression levels of BMP2 had highly significant positive correlation with NGF (r = 0.99, p < 0.01) and CASP3 (r = 0.56, p = 0.05). The BMP2 expression level might be used to predict the quality of the semen and TRADD determine the conception rate of the bull. The study provides ample evidence that the sperm transcripts expression levels might be used to predict quality semen production and bull fertility.