Many environmental factors can alter the 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 the nutrition of the dam during pregnancy. Many experimental models 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. Although 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 DMI, 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. Foal growth over 150 d 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 area under the curve (AUC) increased with increased concentrate supplementation. Foal
insulin AUC and peak
insulin concentrations were increased when mares were fed concentrate 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 because 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 development of the fetus as well as long-term consequences of developmental programming.