INFLUENCE OF SEMEN COLLECTION INTERVAL AND TACTILE STIMULI ON SEMEN QUALITY AND SPERM OUTPUT IN BULLS

Most semen characteristics of eight Holstein bulls 28 to 36 months old were significantly affected (P<.01) by intervals between semen collections. First and second ejaculates, and ejaculates after five and two days of sexual rest were, respectively: ejaculate volume (ml), 5.55, 5.24, 5.69, and 5.09; sperm concentration (109/ml), 1.72, 1.08, 1.53, and 1.27; initial sperm motility (%), 52.5, 52.3, 52.2, and 52.6; post-thaw motility (%), 36.5, 37.5, 36.7, and 37.3; and total sperm per ejaculate (109), 9.59, 5.55, 8.76, and 6.38. Bull differences were highly significant (P < .01) for all criteria studied. The length and temperature of the artificial vagina had little effect on any characteristics studied. Sperm output per week averaged 30.3 billion, and when adjusted for losses averaged 35.4 billion. Sperm output was positively correlated with maximum testes-scrotal circumference, r = .76 (P < .05). A concurrent experiment showed that ejaculation of sperm directly into a centrifuged tris-egg yolk extender caused a slight but significant (P < .001) increase from 36.2 to 37.5% in motility after freezing and thawing. © 1969, American Dairy Science Association. All rights reserved.