Effect of Carotene Deficient Rations and Supplemental Vitamin A on Gain, Feed Utilization and Liver Vitamin A of Calves

Six lots of 12 steer calves each were fed a basal ration of cottonseed hulls, cottonseed meal, citrus pulp and mineral mixture during a 140-day depletion period. Daily additions per calf to the basal ration during a 56-day supplemental period were: Lot 1, control; Lot 2, 0.23 kg hay; Lot 3, 0.91 kg hay; Lot 4, 0.23 kg hay+12,000 IU vitamin A; Lot 5, 0.91 kg hay+48,000 IU vitamin A; and Lot 6, 12,000 IU vitamin A. Rations were palatable as shown by the 2.5 kg to 2.8 kg eaten daily per 100 kg body weight. There was no significant difference in daily gain by the six treatments of 12 calves during either the depletion or supplemental periods.Vitamin A per gram fresh liver was reduced (P<.01) from 106 µg intially to 9 µg after 140 days on the basal ration. Livers from Lot 5 during the supplemental period increased (P<.01) from 6 µg to 17 µg per g, the same level as at the 84th day of depletion period. There was a small decrease in level of liver vitamin A in Lots 1, 2, 3 and 4 during the supplemental period with Lot 6 at the same level at end of both periods. Carotene level decreased (P<.01) from 15 µg per g of liver initially to 5 µg after 140 days on basal ration with little change during supplemental period for any lot. Basal ration+combination of hay and vitamin A or vitamin A alone increased (P<.01) plasma level of vitamin A. Calves fed the highest level of both hay and vitamin A had the lowest level of plasma carotene.