Sperm quality parameters of cryopreserved bovine semen and its relationship to pregnancy rate in timed-AI program

Semen cryopreservation results in damage to sperm structure, and it is important to evaluate the semen batches before being submitted to timed artificial insemination (TAI). However, conventional semen evaluations are not always sufficient to identify batches that may result in lower pregnancy rate in the field, requiring a more thorough and accurate investigation. The aim of this study was to evaluate the relationship of bovine sperm quality parameters on pregnancy rate in a timed-AI program. Six frozen semen samples that were used in a program of artificial insemination were evaluated and classified in high fertility (HF, ≥ 55% pregnancy rate) and medium fertility (MF, 0.05). Interestingly, it was detected that the HF group (55.3±6.7%) exhibited higher APM (p<0.05) than MF group (33.03±5.3%). We concluded that the routine semen evaluation are useful in eliminating samples of very poor quality, but others characteristics are also associated with the fertilizing capacity of the spermatozoa. The method of semen analyses by fluorescent probes is more accurate and reliable to detect of real semen fertilization capacity in cryopreserved bovine semen than conventional analysis. Moreover, the relationship between field fertility and mitochondrial activity could be an interesting tool for predicting the fertility.