Observations on Vitamin A Deficiency in Young Dairy Bulls

Abstract

Summary 1.The effects of varying levels of vitamin A on the reproductive development of 13 Holstein, 4 Jersey, and 3 Guernsey bulls were studied. 2.Complete blindness developed in bulls receiving 2,000 I.U. of vitamin A daily. Following supplementation of the ration with 4,000 and 6,000 I.U. of vitamin A daily, very slight spermatogenesis was observed; only moderate sperm production was found following 5 months of therapy with 100,000 I.U. of vitamin A daily. 3.Bulls which received 4,000 and 6,000 I.U. daily of vitamin A until 300lb. in weight, and then 8 and 16 I.U. daily per lb. of body weight, exhibited convulsions, showed evidence of night blindness, and three became totally blind. Sexual maturity was delayed, sex drive inhibited, and spermatogenesis limited. Cystic pituitary glands were observed in all bulls except the controls. Histological differences were observed, however, in both the anterior pituitary glands and the adrenal glands of the bulls. 4.Although moderate prepubertal vitamin A deficiency did not completely inhibit sperm production, fertility and reproductive capacity appeared to be seriously impaired, since sexual drive and spermatogenesis as measured by laboratory procedures and histological examination were reduced. The possibility that prepubertal damage may be permanent, especially when cystic pituitaries develop or total blindness occurs, should not be overlooked.