Abstract
The effects of the growth promoters avoparcin and avilamycin and the ionophore anticoccidials maduramicin, narasin and monensin on the growth of Clostridium perfringens (Cp) in the caeca and on performance of broiler chickens were tested in 2 experiments. The supplements were fed as single feed additives or in some combinations. No clinical signs or lesions caused by coccidia were observed in any of the studies. All supplements had an antibacterial effect on Cp and improved growth rate significantly. Carcass yield of birds fed growth promoters avilamycin or avoparcin was significantly higher compared with birds fed anticoccidials. These data indicate that, what concerns bird performance, during good hygienic conditions supplementation with antibiotic growth promoters may not be necessary when the diet is supplemented with an anticoccidial with antibacterial effects.