Freezing Bovine Semen. V. Practicability of Collecting and Freezing a Large Number of Successive Ejaculates

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Abstract
From six to 37 successive ejaculates were collected during 12, 2 hr. depletion trials with 8 dairy bulls, and used to investigate (a) the proportion of ejaculates acceptable for freezing and (b) the freezability of the acceptable ejaculates. Only ejaculates showing an initial motility of 30% or more and a minimum of 150 million motile spermatozoa were frozen. On this basis, the percentage of culled ejaculates increased as the number of consecutively collected ejaculates increased. Considering the first 5 consecutive ejaculates, only 6.7% were culled; among the first 10 consecutive ejaculates, 11.6% were culled; whereas, among all 257 ejaculates collected, 35.8% were culled. There was no significant difference in freezability of the acceptable ejaculates among the 1st 5 or 1st 10 individual ejaculates, and freezability was comparable with that obtained with ejaculates collected from the same bulls when on a frequency of 2 or 6 ejaculates per week. Beyond the 10th ejaculate, freezability was generally, but not significantly poorer and collection of more than 10 consecutive ejaculates probably would be of no practical value. Pooling acceptable ejaculates from a depletion trial resulted in freezability comparable to freezing the ejaculates separately. With adequate sexual preparation, the collection of 6 or 7 consecutive ejaculates from a given bull should make available large numbers of sperm at 1 time, which should freeze satisfactorily.