A COMPARISON OF WEANING DAIRY CALVES BY BODY WEIGHT VERSUS AGE FROM WHOLE MILK OR MILK-REPLACER

Abstract

Ayrshire bull calves were weaned from whole milk or milk-replacer at 7 weeks of age, and at two different body weights, namely 55 and 46 kg. A maximum of 1.82 kg starter was fed daily to 15 weeks of age and 1.82 kg grower concentrate to 180 days of age.Calf performance did not differ significantly by weaning at 7 weeks or 55 kg. Weight gains to weaning and to 15 weeks were significantly lower for calves weaned at 46 kg. The average 180-day body weights for calves weaned at 7 weeks, 55, and 46 kg were 150, 146, and 140 kg, respectively.Whole milk or milk-replacer feeding produced identical calf growth to 180 days of age. Milk-replacer tended to increase preweaning and decrease post-weaning growth of calves weaned at 46 kg compared with whole milk. The augmented preweaning starter intake by calves fed replacer is discussed in relation to the digestible energy content of milk-replacers. It is suggested that energy supplied by plant carbohydrates should not be included in replacers for early-weaned calves, due to the low digestibility of starch by calves until 3 or 4 weeks of age.