The effect of dietary protein on reproduction in the mare. II. Growth of foals, body mass of mares and serum protein concentration of mares during the anovulatory, transitional and pregnant periods.

The effect of 4 different diets, in terms of protein quantity and quality, on total serum protein (TSP), albumin and globulin was investigated. Non-pregnant mares that were not lactating (n = 36), pregnant mares that had foaled (n = 24) and their foals (n = 24) were used in this study. Daily total protein intake had no effect on blood protein concentrations in the mares. Total protein intake and quality (available essential amino-acids) did affect the body mass of mares during lactation. When mares were fed the minimum recommended (National Research Council 1989) total daily protein, foal mass decreased by approximately 25% at weaning compared to the foals whose dams were on a higher level of protein intake. The TSP concentrations of foals at birth were on average 10 g/l lower than those of the mares. Albumin concentrations of foals during the first 60 days of life were on average 2-3 g/l lower than those of the mares. Globulin concentrations of foals were approximately 5 g/l lower than those of mares at weaning.