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Breeding Behavior, Spermatogenesis, and Semen Production of Mature Dairy Bulls Fed Rations Low in Carotene

Department of Animal Husbandry, Cornell University, Ithaca, New York

ABSTRACT

The present emphasis on extending the use of the desirably proved dairy sire in artificial breeding has focused attention on the need for more information concerning the nutrition of the mature sire, particularly with respect to the role of nutrition in semen production and fertility. In both, spermatogenesis is of primary concern.

The importance of vitamin A and carotene in developing and maintaining the normal germinal epithelium and the breeding ability of young bulls has been demonstrated by Sutton et al. (14), Jones et al. (7), Hodgson et al. (6) and Erb et al. (4, 5). Regeneration of the germinal epithelium following vitamin A and carotene therapy has been observed (4, 6). Similar studies with mature bulls have not been reported.

Roughages are the principal source of carotene for bulls of breeding age. If allowed pasture, mature bulls might be expected to build up body stores of vitamin A sufficient to carry them through periods of relatively low carotene intakes.

¹ Now at the University of Illinois.

² Now at the University of Wisconsin.

³ Now at the Louisiana State University.

⁴ Now at the Ministry of Agriculture, Quebec, Canada.