BEHAVIORAL-CHANGES IN STABLED HORSES GIVEN NONTHERAPEUTIC LEVELS OF VIRGINIAMYCIN

Abnormal behaviour commonly develops in intensively managed horses. A possible cause is the change in diet occurring when the horse is stabl ed. An experiment was performed to examine this possibility by manipul ating the diet with the feed supplement virginiamycin, as Founderguard . During 4 weeks, 18 horses were fed diets ranging from hay alone to c oncentrate plus hay in the ratio of 3:1. The rations of half the horse s given concentrate were supplemented with Founderguard. Horses eating high concentrate rations displayed abnormal oral behaviours at a high er frequency than those eating only hay The incidence of these behavio urs was reduced when diets were supplemented with Founderguard. The dr op in faecal pH of animals on concentrate diets was also reduced by Fo underguard. Animals on concentrate diets had an average of 21 kg less gut fill post mortem. Dietary supplementation with virginiamycin as Fo underguard apparently lessens some behavioural problems associated wit h management of stabled horses and the intake of grain. It may allow c oncentrate to be fed at higher levels than customary without adverse b ehavioural side effects. The suggested mechanism for the improved beha viour due to Founderguard supplementation is reduced fermentative acid osis in the hindgut.