ESTIMATED WATER AND FORAGE INTAKES IN NURSING RANGE CALVES

Abstract

The intakes of water and forage dry matter by Angus calves on range before weaning were estimated from total water intake, milk intake, and digestible energy (DE) requirement. Water intake, including that in milk, as estimated by injection of tritiated water, rose from 8.3 kg/day at 44 days of age to 17.5 kg/day at 114 days and then fell to 13.7 kg/day at weaning. Milk supplied 90% of the water at 44 days and 25% at weaning. About 600 kg of free water would have been consumed over the pre-weaning period. Milk supplied 86% of DE intake at 44 days of age and 19% at weaning. Over this period, the forage dry matter intake, estimated from the difference between DE requirement and DE obtained from milk, rose from 0.5 kg/day to 5.5 kg/day and an estimated 450 kg would have been consumed between birth and weaning. Water intake per unit forage dry matter intake fell below 3.5 in late August or early September at which time siliceous urinary calculi could begin to form. Plant fiber residues in feces of calves increased as a consequence of the increasing forage intake and declining milk intake. It is suggested that the fiber content of feces could be used as an index of the relative importance of grass and milk in the nutrition of nursing calves on different types of range.