Genetic basis of vitamin A and its role in lipid deposition and fatty acid desaturation of ruminant livestock

Abstract

Cellular forms of vitamin A, derived either from β-carotene of plant origin or pre-formed as retinol or retinyl ester from animal origins, are known to have a range of potent biological effects. Different species of livestock (e.g. sheep versus cattle) show distinct differences in the manner they metabolise-carotene. Within cattle as a species, breeds differ in the degree that they metabolise this molecule. These differences, apart from the fact that fat depots become yellow in color when-carotene is not cleaved to retinal, are brought about by a further-carotene metabolite, retinoic acid. Our studies have concentrated on a number of aspects of lipid metabolism as related to-carotene metabolism. In cattle that metabolise-carotene to vitamin A, the degree of intramuscular lipid deposition and desaturation of fatty acids is limited. Studies over 10 years have defined the circumstances in which the level of vitamin A causes these effects. Recent molecular studies have defined a DNA variant in a gene thought to be responsible for the accumulation of-carotene in cattle. This finding may partially explain breed differences in fat colour, fatty acid desaturation and intramuscular fat deposition. © 2011 by Nova Science Publishers, Inc. All rights reserved.