Seasonal changes in spermatogenesis in rams : Their relation to plane of nutrition and to vitamin A status

Abstract

Observations have been made on the seminal characters, body weights, and plasma vitamin A status of rams fed on carotene-deficient diets, at higher and lower levels of food intake. Carotene supplements were provided for a number of the rams at each level of dietary intake. The seminal characters exhibited a seasonal variation, characterized by a reduction in the total number and longevity of spermatozoa during the summer months. Within this period, a temporary increase in the number of morphologically abnormal spermatozoa occurred in the rams of low plasma vitamin A status, or on the lower plane of nutrition. Plasma vitamin A levels fell more rapidly in the rams on the higher plane of nutrition than in those on the lower plane. Morphological abnormality of spermatozoa attributed to vitamin A deficiency appeared at an earlier date in the high-plane group except when rams with presumably low liver stores of vitamin A were fed on the deficient diets. Vitamin A deficiency, if sufficiently severe, resulted in the appearance of a high percentage of morphologically abnormal spermatozoa in the semen of rams on both planes of nutrition. The addition of pure carotene to the diet prevented or reduced this degree of abnormality.