Nutrition of the Dam Influences Growth and Development of the Foal

A 1996 Kentucky Equine Research (KER) study monitored the incidence of developmental orthopedic disease (Pagan and Jackson, 1996). The results of this study provided early evidence of the importance of nutrition of the mare to the proper growth and development of the foal. The farm in this study produced 271 foals. Ten percent of the foals showed signs of developmental orthopedic disease by radiograpy. The foals were weighed monthly from birth, and those weights were compared to a large data set of weights from other central Kentucky farms. Foals with fetlock lesions tended to be small at 15 days, 3.2 kg below the average. Lesions were most often seen in foals born in January, February and March and were more prevalent in fillies than colts. Approximately 2% of the foals were affected and the average age of diagnosis was 102 days. Foals that developed lesions at a later age (379 days) tended to be normal size up to 120 days but grew faster than average and were heavier after weaning. Foals that developed hock osteochondritis dissecans (OCD) averaged 7 kg heavier than the Kentucky body weight (BW) average at 15 days. By 240 days of age these foals were 14 kg heavier than the population average. Average daily gains were significantly higher in the OCD group. Foals that developed stifle or shoulder lesions averaged 5.5 kg heavier than the Kentucky average at 25 days and 17 kg heavier at 120 days of age. Stifle and shoulder OCD lesions were diagnosed in approximately 2% of the foals at an average age of 336 days. The mare has a tremendous effect on development of the foal through weaning. The size of the foal at birth is determined by genetics, nutrition, and uterine environment. Growth after birth is mostly a result of the mare’s milk production. In utero growth of the foal is governed by actual placental size and competency and available area of healthy endometrium.