Effectiveness of Carotene and Failure of Ascorbic Acid to Increase Sexual Activity and Semen Quality of Vitamin A Deficient Beef Bulls

Abstract

Observations are recorded on the reproductive performance of six beef bulls reared on a carotene deficient basal diet supplemented with restricted levels of alfalfa, which furnished 45 to 140 micrograms of crude carotene per kilogram of body weight daily. One bull on the 45 microgram level showed symptoms of vitamin A deficiency as a calf and later failed to demonstrate copulatory ability. Successful semen collections and fertility were established in the other five bulls, all of which received 50 micrograms or more of crude carotene per kilogram of live weight. At the end of a preliminary semen collection period, two of the bulls were subjected to a period of vitamin A depletion, and the other three continued on their respective levels of carotene intake for control observations. The progress of the degree of vitamin A deficiency was followed by chemical determinations of carotene and vitamin A in the blood plasma and ascorbic acid in the blood plasma and semen.Sexual activity and ability decreased rapidly with the development of symptoms of vitamin A deficiency. Semen samples collected as the depletion progressed showed marked increases in percentage of abnormal spermatozoa and cellular debris with progressive decline in motility. Injections of ascorbic acid failed to stimulate sexual activity or modify the quality of the semen produced by the carotene deficient bulls. Carotene feeding, on the other hand, restored the bulls to apparently normal activity and semen production. Histological evidence of previous testicular injury due presumably to vitamin A deficiency was evident after as long as 20 months of carotene feeding.