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Influence of High Level Vitamin A Supplement on Semen Characteristics and Blood Composition of Breeding Bulls¹

Department of Dairy Science, Louisiana Agricultural Experiment Station, Baton Rouge

ABSTRACT

There has been a considerable number of recent reports of beef cattle showing suggestive vitamin A deficiency symptoms, even though rations apparently contained adequate quantities of carotene (2, 9). Nitrates in the forage and other factors have been reported to reduce carotene conversion to vitamin A as well as absorption of these nutrients (2, 6, 13, 15). Involvement of the decreased thyroid activity with depressed carotene conversion has also been suggested (7, 8). Thus, recommendations for increased vitamin A supplementation of the ruminant ration are being made (3, 4, 5, 11).

The objective of this study was to determine the effects of supplemental vitamin A to an adequate ration for breeding bulls in stud.

EXPERIMENTAL PROCEDURE

Eight mature dairy bulls (two Jerseys, three Holsteins, and three Guernseys) were selected according to adequate semen quality and randomly assigned into two groups, without regard to age or breed. All bulls received the same basal ration, consisting of a 14% protein concentrate and 30:70 amounts of alfalfa and prairie grass hay, approximately ten months in storage.

¹ This investigation was financially supported by the Louisiana Artificial Breeding Cooperative, Incorporated.