The effects of necrotic enteritis, aflatoxin B<|, and virginiamycin on growth performance, necrotic enteritis lesion scores, and mortality in young broilers.

The effects of increasing aflatoxin Bi con-centration (0, 0.75, 1.5 mg/kg) on broilers with or with-out necrotic enteritis or virginiamycin were determined. In the 23-d study, 22 male Cobb 500 chicks per pen were allotted to 12 treatments (3×2×2 factorial ar-rangement) with 8 replications. Intestines of 5 birds per pen were examined for lesions on d 21. Birds were al-lowed to consume feed and water ad libitum. Aflatoxin was included in the diets from d 0. All birds received a 10x dose of coccidiosis vaccine on d 10. Pens of birds where necrotic enteritis was being induced were on Clostridium perfringens pathogen (CPP) contaminated litter from d 0. Aflatoxin decreased gain and feed intake and resulted in poorer feed:gain, increased mortality, and higher lesion scores. Inducing necrotic enteritis in-creased lesion scores and decreased feed intake and gain. Adding virginiamycin to the diets improved gain, feed intake, feed conversion, and decreased mortality. There was a 3-way interaction (aflatoxin x virginiamycin x CPP) on gain; increasing aflatoxin decreased gain and the effects of CPP and virginiamycin were dependent on aflatoxin concentration. In the absence of aflatoxin virginiamycin increased gain but was unable to prevent the growth suppression caused by CPP. At 0.75 nig/kg of aflatoxin virginiamycin no longer increased growth in non-CPP challenged birds but was able to increase growth in CPP-challenged birds. At the 1.5 mg/kg of aflatoxin concentration, virginiamycin increased gain in non-CPP-challenged birds but challenging birds with CPP had no effect on gain. Virginiamycin improved overall feed conversion with the greatest improvement at 1.5 mg/kg (aflatoxin x virginiamycin, P < 0.05). Af-latoxin increased lesion scores in unchallenged birds but not in challenged birds (aflatoxin x CPP, P < 0.001). Aflatoxin and necrotic enteritis decrease broiler perfor-mance and interact to decrease weight gain, virginia-mycin helps improve gain in challenged birds at 0.75 mg/kg of aflatoxin, but, not at 1.5 mg/kg of aflatoxin. [ABSTRACT FROM AUTHOR]