Seasonal changes may cause vitamin A deficiency in range heifers
Range cattle obtain vitamin A from carotenoids in green plants. In northern California's foothill ranges, carotenoids are destroyed as forage dries in the summer. Tests of liver and blood plasma in grazing cattle indicated that mature breeding cows can store enough vitamin A during the green season to meet later needs. Heifers on their first calf, however, may need vitamin A supplementation.