Relationship between nutrient intake, growth and body composition of the nursing foal

The milk and nutrient intakes of 21 nursing foals of heavy breeds (adult weight : 800 kg) were determined at 1, 4 and 8 weeks of age.Lactose intake increased (P < 0.01) from 1 300 g/day at 1 week of age to 1 800 g/d at 8 weeks ; fat decreased (P < 0.01) from 400 g/d to 300 g/d and protein did not vary (600 g/dl.Energy and nitrogen intakes did not depend on the source of energy in the mother's diet.Milk, energy and nitrogen intakes were well related (r = 0.74 to 0.81) with foal growth between 1 and 4 weeks, but not between 4 and 8 weeks.The composition of weight gain showed a greater deposition of protein than of lipids until 8 weeks.Lipid and protein contents in empty body weight were 5.3 and 19.2 %, respectively, at 1 week and 9.0 and 19.9 % at 8 weeks. Introduction.During the first months of postnatal life, the foal eats only a few solid feeds (Martin-Rosset, Doreau and Cloix, 1978).Almost all the nutrients needed to meet maintenance and growth requirements come from the mare's milk.Preliminary studies on a few animals (Doreau, Martin-Rosset and Dubroeucq, 1982) have shown a weak relationship between milk intake and foal growth.This relationship is stronger in other species such as cattle (Le Neindre, 1974) or rabbits (Lebas, 19691.In the present trial, we took into consideration milk composition and analyzed relationships between milk, energy and nitrogen intakes on the one hand, and foal liveweight gain and lipid and protein retention in vivo on the other. Material and methods.Animals and experimenial diets.― Twenty-one mare/foal pairs of heavy French breeds (Bretonne, Comtoise), weighing on an average 800 kg when adult, were studied during the first two months of nursing.In 1983 ten mares were divided