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Nutritional programming and the impact on mare and foal performance
Many environmental factors can alter phenotype of offspring when applied during critical periods of early development. In most domestic species maternal nutrition influences fetal development, and the fetus is sensitive to nutrition of the dam during pregnancy. Large numbers of techniques have been explored including both under- and overnutrition of the dam. Both nutritional strategies have yielded potential consequences including: altered glucose tolerance, pancreatic endocrine function, insulin sensitivity, body composition, and colostrum quality. While the impact of maternal nutrition on fetal development in the equine has not been thoroughly investigated, overnutrition is a common occurrence in the industry. Work in our laboratory has focused on effects of maternal overnutrition on mare and foal performance, mare intake, mare hormone concentrations, foaling parameters, colostrum quality and passive transfer of immunity, and glucose and insulin dynamics. Over several trials mares were fed either 100% or 140% of NRC requirements for DE and supplemental Se and arginine were added to diets in an attempt to mitigate potential intrauterine growth retardation resulting from dams overfed during the last third of pregnancy. As expected, when mares were overfed BW, BCS, and rump fat values increased. Despite this change in mare body composition, foaling parameters such as time to stand and time to nurse were unaffected. Foal growth over 150 days was also not influenced. Maternal nutrition did not alter colostrum volume, but influenced colostrum quality. Maternal overnutrition resulted in lower colostrum IgG concentrations, but did not cause failure of passive transfer in foals. Supplemental Se and arginine were unable to mitigate this reduction in colostrum IgG. Additionally, mare and foal glucose and insulin dynamics were influenced by maternal nutrition. Mare glucose and insulin AUC increased with increased concentrate supplementation, and in a subsequent trial supplemental arginine was able to decrease mare insulin AUC. Foal insulin AUC and peak insulin concentrations were increased when mares were fed concentrate during the last third of pregnancy, and in a later trial, foal peak glucose values were reduced with arginine supplementation of the mare. This influence of maternal nutrition on glucose and insulin dynamics warrants further investigation as it may be related to athletic performance and metabolic disease in the adult. Further studies will be necessary to fully elucidate the influence of mare nutrition during pregnancy on performance of the mare and resulting foal, as well as, long term consequences of developmental programming.
Keywords: Horse, Nutrition, Foal, Developmental Programming