Effect of low vitamin A status on fat deposition and fatty acid desaturation in beef cattle.

摘要: A group of Angus beef cattle was removed from temperate pastures and fed a very low β-carotene cereal-based ration in feedlot for over 300 d. Half the supplemented weekly with retinyl palmitate (at rate 60,000 IU vitamin A/100 live weight (LW)/day), sufficient to offset clinical deficiency; other half received no supplement. Blood sampled all animals at biweekly intervals assess status. Adipose tissue by biopsy on three occasions throughout experimental period slaughter FA composition. Muscle determine intramuscular fat content. The mean plasma concentration fell an initial value 20.1 5.2 μg/mL 14 d, 1.4 35 zero 105 Mean not significantly different between treatment groups initially. values then rose almost twice their but subsequently below day 119. Thereafter, greater than that unsupplemented (P<0.05). samples contained (P<0.01) more lipid (13.0 vs. 9.6%). Major changes occurred time composition both groups. Saturated decreased as monounsaturated increased first 60 An index desaturation lower (P<0.001) A-supplemented nonsupplemented group. M.P. adipose 32.3°C, less (P<0.05) (34.1°C). Feeding associated desirable (less unsaturated, solid) profile.