Effects of Sexual Preparation on Sperm Output, Semen Characteristics and Sexual Activity of Beef Bulls with a Comparison to Dairy Bulls

Abstract

Two trials were conducted with Angus and Hereford bulls to determine the effects of sexual preparation by false mounting upon sperm output, semen traits and sexual activity. Two successive ejaculates were collected by artificial vagina on 1 or 2 days per week and either three false mounts (3FM) or none (0FM) preceded each ejaculation. The data were compared to data for Holstein bulls collected twice in succession on 1 day per week after either 3FM or one false mount (control). Use of three false mounts effectively increased (P<.01) the number of sperm obtained in first ejaculates from beef and dairy bulls and in second ejaculates from dairy (P<.05) but not beef bulls. The higher sperm numbers in first ejaculates after false mounting reflected significant (P<.01) improvements in both sperm concentration and semen volume. For second ejaculates, semen volume was greater (P<.01) with 3FM only for dairy bulls; sperm concentration was lower (P<.05) for beef after 3FM than after 0FM and not different for dairy bulls. A third trial with Angus bulls tested all combinations of OFM and 3FM for first and second ejaculations collected 2 days weekly. The total number of sperm in second ejaculates from beef bulls was improved(P.01) by false mounting. for obtaining sperm output data from beef bulls to be used as an index of sperm production, 3FM might preced each ejaculation.For commercial bulls studs, however, this third trial with Angus showed that use of 3Fm before both first and second ejaculates (3FM-3FM) did not enable collection of significantly more sperm in two successive ejaculates (15.1 x 10 sperm) than a combination of 3FM-0FM (13.4 x 10 sperm).It required 35% less time (P.05) to collect about the same number of sperm in two ejaculates with 3FM-0FM (29.8 min.) as with 3FM-3FM (46.0 min.) It is concluded that a combination of three false mounts before firts and no false mounts before second ejaculates is practical for increasing sperm output of beef bulls used in commercial artificial insemination. Copyright © 1973. American Society of Animal Science. Copyright 1973 by American Society of Animal Science.