Protein and Energy Requirements of the Young Calf

Three experiments were conducted to study the protein and energy requirements o£ the young calf and the relative efficacy of various milk replacers, by using 88 three-day-old male Holstein calves from 4 to 60 days o£ age.The energy requirement for maintenance was 48.2 kcal digestible energy daily per kilogram of body weight; the requirement for growth was 370 kcal per 100 g gain in body weight.The nitrogen retention was 2.56 g per 100 g gain in weight.The digestibilities of nitrogen, ether extract and energy; weight gains and fecal consistency showed significant (P ~ 0.01) lineax decreases when increasing levels o£ corn distillers dried solubles were substituted for dried skimmilk and lactose.When the substitution of corn distillers dried solubles was on the basis o£ digestible protein (as determined in this study), differences in growth rates of calves on diets providing 0, 20, and 35% of the digestible protein from corn distillers dried solubles were nmch smaller and not statistically significant at P ----0.05.Milk replacers are used extensively to reduce the cost of raising dairy calves.Even though present and potential ingredients have been subjected to much experimentation, there is still a lack of conclusive data regarding the nutritional value of many of them.While the value of milk by-products in replacers has been clearly established, certain ingredients from plant sources (which generally are lower in cost than animal products) are less efficiently used (7,8).Recent studies (4, 10) indicate satisfactory results with replacers in which fish flour supplied part of the protein.To determine the substitution value of various ingredients, nmre information is needed on the digestible protein and energy supplied by each ingredient.