Nutrient limits in diets for growing dairy goats

Dry matter intake and nutrient requirements of young growing dairy goats were reviewed in this paper to derive nutrient limits applicable for diet optimization through minimum cost linear programming. The diets offered to growing goats should be optimized from both nutritional and economic view. To get those objectives, the nutritionist has to estimate accurately forage and total dry matter intake, and the nutrient supply and requirements. The reviewed literature suggests that intake of young growing goats ranges between physical and physiological limits imposed by gut fill and energy requirements. The filling effect of the diet is related to its structural carbohydrate content, whereas the physiological satiety effect is related to diet metabolizable energy content. The minimum intake of forage required to keep rumen health is low, whereas maximum forage intake is probably related to the neutral detergent fibre content of the total diet. The energy and protein supply and requirements calculated according to the two most recent feed evaluation systems are similar, what makes no difference using any of both to optimize diets. Recent proposals to calculate calcium and phosphorus supply and requirements provide greater accuracy than the older ones.