THE EFFECT OF WEANING AGE ON FOAL GROWTH AND RADIOGRAPHIC BONE-DENSITY

Seven foals weaned at 4.5 months were compared to eight foals weaned a t 6.0 months at three-week intervals before and after weaning to asses s the effect of weaning and weaning age on growth and bone density. Av erage daily gain (ADG) declined (P < .01) in the first week after wean ing in both weaning groups, and remained lower (P < .05) than preweani ng gain in foals weaned at 6.0 months at three weeks' postweaning. Can non circumference (CC) growth was depressed at three weeks (P < .05) a nd six weeks (P < .10) postweaning when foals were weaned at 4.5 month s, but not when foals were weaned at 6.0 months. Withers height (WH) a nd radiographic bone density were not affected by weaning or weaning a ge. By 203 days of age, there were no differences in body weight, CC, WH or bone density between weaning groups. Therefore, weaning foals at 6.0 months of age seems to pro vide little growth advantage over wean ing foals at 4.5 months of age. Radiographic analysis across treatment s revealed that the medial density of the left third metacarpal (MCIII ) was greater (P < .01) than the right MCIII, thereby suggesting that both forelimbs should be included when assessing dietary or exercise e ffects on radiographic bone density.