Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science


After the discovery and identification of vitamin A as an essential nutrient, the role of the vitamin and its precursor carotene in the nutrition of animals came under widespread study. Many experiments have been designed in the past to examine the interrelationships concerning vitamin A and carotene in animal feeding. In view of the similarity of digestive systems between cattle and sheep, it was reasonable to assume that vitamin A and carotene might function much the same in the two species. As numerous investigators have demonstrated, there are many similarities in vitamin A metabolism between cattle and sheep. However, there are also important differences and some conflicting reports. Generally, among the like characteristics of vitamin A and carotene nutrition are source and method of administration, deficiency and toxicity symptoms, metabolic functions of the vitamin and site of major storage of vitamin A in the body. Differences occur in the conversion of carotene to vitamin A, storage of carotene in the body and length of time for deficiency symptoms to occur when consuming diets low in vitamin A or carotene. An apparent greater efficiency in utilization of vitamin A and carotene by sheep as compared to cattle has not been fully explained. This difference coupled with limited evidence as to the full role of vitamin A and carotene in metabolism leaves the story of vitamin A nutrition far from complete. The experiments conducted and reported in this thesis were designed to study the. value of supplemental vitamin A and carotene for feedlot lambs. The diets used were balanced for known required nutrients except vitamin A. Various levels of vitamin A palmitate or carotene from dehydrated alfalfa meal formed the treatments. The level of vitamin A or carotene intake was based on amount of feed consumed. The objectives of these experiments were to study the length of time involved in depleting vitamin A reserves of sheep consuming diets low in carotene and to provide information as to the effects of feeding supplemental vitamin A or carotene to -either previously depleted or apparently normal sheep. Evaluation criteria were blood and liver vitamin A and carotenoid levels considering sex differences and length of time involved in depleting and repleting liver vitamin A stores. Blood and liver samples were collected periodically throughout the course of the experiment for evaluation of the vitamin A status.

Library of Congress Subject Headings

Lambs -- Feeding and feeds

Vitamin A in animal nutrition

South Dakota State University Theses



Number of Pages



South Dakota State University