Evaluation of Two Seminal Collection Regimens for Mature Holstein Bulls1

Twenty mature Holstein bulls (3 to 10 yr old) were used to test the effect of two semen collection regimens on spermatozoal output, post-thaw percentage spermatozoal motility, and time needed to make the collections/week. For both regimens, six ejaculates/wk were collected using either three ejaculates/d, 2 d/wk, or two ejaculates/d, 3 d/wk. A three-period switchback experimental design was used. Each collection period for which measurements were taken was 3 wk and was preceded by a 2 wk period of acclimation. The total number of spermatozoa harvested per week was not significantly different (P>.05): 33.2 × 109when the bulls were collected two ejaculates 3 d/wk, compared with 33.9 × 109three ejaculates 2 d/wk. Post-thaw progressive spermatozoal motility was 50.3 and 52.1% (P>.05), respectively. The average time per week to collect each bull was 73.6 and 83.7 min (P<.05), respectively.