Effects of sperm cryopreservation extenders and estrus in pregnancy of Bos indicus cows submitted to TAI

The objective of this study was to evaluate the relationship between estrus behavior of cows and the semen’s cryopreservation extenders on the fertility of B. indicus cows subjected to timed artificial insemination (TAI). In this study, 505 postpartum B. indicus Nelore beef cows were enrolled in a TAI program and separated into groups according to the estrus detection on the Day of the TAI procedure, into: Cows detected in estrus (E, n = 307), and cows not detected in estrus (NE, n = 198). The semen used in this study was cryopreserved with 2 different extenders: Optixcell (OPT), and the egg yolk-Tris-glycerol (EYTG), and were distributed to inseminate E and NE cows. The pregnancy per AI (P/AI) of the groups EOPT (69.5 %), and EEYTG (60.1 %) were greater (P ≤ 0.05) in comparison with groups NEOPT (46.0 %), and NEEYTG (42.9 %). The group EOPT tended (P = 0.08) to have greater P/AI in comparison with the group EEYTG. In conclusion, among cows exhibiting estrus, those inseminated with semen diluted in OPT showed a tendency toward higher pregnancy per AI compared to those inseminated with EYTG-diluted semen.