Energy and protein requirements and feeding of the suckling foal

Suckling foals have a very high growth rate. Body weight doubles between birth and first month of age and at weaning body weight is five times heavier than birth weight. A curvilinear growth model (X-3: age in days) fits the weight-age data. Similarly, body size rises quickly with withers height reaching 80% of adult height at weaning. This dynamic rate of growth dictates the nutrient requirements of the foal. Energy and protein intakes are the primary dietary components influencing growth. Mare's milk supplies the sole source of energy and protein for the suckling foal in the first weeks of life. Daily gain of the foal is linearly related to milk, energy and protein intake up to two months of age whereas grazing time increases linearly with age and body weight between birth and weaning. Gross energy and protein intake of the foal per metabolic body weight from milk at 1, 4 and 8 weeks of age are: 1.90 - 1.42 - 1.05 MJ GE and 21g - 14g - 12 g protein, respectively. NEm for maintenance would be 200 kcal/kgBW(0.75) from birth to 4 months of age. NEg / kgBW gain / kgBW(0.75) would rise from 85 to 110 kcal. NEm % ME would rise from 56 to 69 and NEg % ME would decrease from 44 to 31 between birth and 4 months. Feeding regimes of the mare during lactation (and the last trimester of pregnancy) play an important role in the early development of the foal (0-3 months) whereas the quantity and quality of grass and concentrate have a strong influence on foal growth between 3 months of age and weaning (at 6 months). Grass intake would represent 8-10% and 50-60% of total energy requirements during these periods. Creep feed intake before weaning plays an important role in maintaining daily gain pre and post weaning. Providing quality protein in the form of essential amino acids, particularly lysine and threonine is important. Type of carbohydrates (starch or other vs. lactose) is also of importance. Forage and concentrate management systems for young growing foals vary with breed, age, growth rate and forage quality. The objective when feeding foals is to optimise feed efficiency and maintain a steady rate of growth thus minimising DOD. Ensuring access to quality protein and a well-balanced intake of energy is key to achieving this.