FAT DEPOSITION, β- CAROTENE, AND VITAMIN A METABOLISM IN BULLS, STEERS, AND HEIFERS

Research highlights the impact of Vitamin A on cattle growth and meat quality. Supplementing Vitamin A early in life has been linked to enhanced IMF content and growth rates in calves, especially when administered at birth or during early developmental stages. This is attributed to the role of the ZFP423 gene in adipocyte formation, with studies noting its involvement in the development of IMF during the finishing phase. This study aims to add to the present research by evaluate the effect of calves’ sexual class on blood β-carotene and Vitamin A before weaning. The second study evaluated the β- carotene metabolism in bulls, steers, and heifers following an orally administered dose of a β- carotene supplement. The first study showed blood β-carotene increased from week 2 to 30 (P < 0.01) and it was also affected by the sexual class (P = 0.05), showing that bulls had a lower β- carotene level compared to steers and heifers. Blood Vitamin A was not affected by the sexual class (P = 0.38). The second study showed that sexual class-by-day interaction was found for plasma β-carotene, showing that bulls had lower concentrations than steers and heifers only on days 3, 4, and 12 post-oral administration (P < 0.05). Plasma vitamin A was not affected by sampling day (d 3 vs. 24; P = 0.33) but it was affected by sexual class (P = 0.01), and steers had greater concentration (179 ng/mL) than bulls (155 ng/mL) while heifers had an intermediate plasma vitamin A (168 ng/mL) and did not differ from bulls and steers. Our results suggest that β- carotene metabolism differs among sexual classes in cattle, and bulls will have lower β- carotene and vitamin A than steers and heifers under the same feeding regimen.