Effects of Al protocol and time interval from onset of estrus to Al on conception rate in Japanese Black cows

摘要

Two different artificial insemination (Al) protocols were investigated to determine the effect of the time interval from the onset of estrus (as detected by a pedometer) to the Al on the conception rate in Japanese Black cows. Seventy-three cows weredivided into two groups that received Al either after the induction of synchronized ovulation (synchronized Al group; n = 26) or at the time of observed estrus (control Al group; n = 47). Each group was further divided into two subgroups, which were artificially inseminated either 0-12 h (early Al group; n = 21) or 12-24 h (late Al group; n = 52) after the onset of estrus. There was no significant difference in the conception rate between the synchronized Al and control Al groups. The Al protocol and the detection of estrus using a threshold of counted steps (as measured by a pedometer) in this study could be effective for planned reproduction management without the observation of standing estrus in Japanese Black cows.