What should we feed calves? Extra colostrum and discarded milk from antibiotic-treated cows . The amount of liquid (milk or replacer) you feed daily should be 8 to 10 percent of the body weight. Many calves perform well when fed all their milk at one feeding a day. Y ou may provide a handful of calf starter in a shallow bucket and gradually increase the amount of starter as calves grow. For optimal calf growth and nutrition, feed fresh calf starter and water daily. Calves ranging in age from 1 day to 12 weeks old have different nutritional needs, and calf starter needs are no exception.