DIETARY YEAST CULTURE SUPPLEMENTATION OF MARES DURING LATE GESTATION AND EARLY LACTATION - EFFECTS ON DIETARY NUTRIENT DIGESTIBILITIES AND FECAL NITROGEN PARTITIONING

This study explored the hypothesis that dietary supplementation of mares during late gestation and early lactation with small amounts of a concentrated dried live yeast culture preparation would increase the digestibility of the components of their feed. Ten pregnant mares were randomly allotted to 2 groups which were fed the same diets, except for supplementation of one group with 20 g/day of yeast culture, from 4 weeks before foaling to 8 weeks after foaling. After 2 weeks of supplementation, the supplemented mares exhibited increases (p < .05) in the digestibilities of dietary energy, dry matter, NDF, ADF, hemicellulose, cellulose, calcium and phosphorus, compared to the digestibilities of these nutrients before supplementation began. In addition, the digestibilities of crude protein, NDF-bound nitrogen and the nutrients listed above were increased (p < .05) when compared to the digestibilities exhibited by the unsupplemented mares. Increased nutrient digestibilities (p < .05) were observed in the supplemented mares 4 weeks after foaling. These data indicate that the supplementation of gestating and lactating mares with yeast culture will increase the nutritional value of a 50% roughage, 50% concentrate diet.