EFFECT OF COCCIDIOSTATS ON NECROTIC ENTERITIS AND PERFORMANCE IN BROILER-CHICKENS

Five anticoccidials, lasalocid, maduramicin, monensin, narasin and halofuginone, were compared in an experiment embracing 3720 Ross broiler chickens. The chickens were raised in 24 floor pens (155 birds per pen). The drugs were incorporated in two different feeds, A and B. Feed A was designed to correspond to optimal nutritional requirements while feed B had higher quantities of animal protein and had been used previously in a trial with an outbreak of necrotic enteritis (NE). There was no evidence of coccidiosis in any group. Necropsy revealed NE in a low number of chickens given feeds A and B and the incidence of necrotic hepatitis at slaughter was noteworthy. Improvement of production performance was observed in chickens receiving anticoccidials. However, this effect of anticoccidials varied. In several aspects narasin gave the best performance. Significant differences were also found regarding the effects of the drugs on water intake and on litter condition. Narasin resulted in drier litter beds than the others.