Chlortetracycline and aflatoxin interaction in two lines of chicks.

To determine if feed contaminants and feed additives interact, day-old chicks from lines bred for high and low antibody response to sheep erythrocytes were fed aflatoxin at a level of 3,000 ppb, chlortetracycline at a level of 550 ppm, or a combination of aflatoxin and chlortetracycline for a period of 6 wk. Weight gain in both lines of chicks was adversely affected by the aflatoxin treatment. There was a synergistic adverse effect in chicks of the low antibody response line when given chlortetracycline as well as aflatoxin, an effect not noted in chicks of the high antibody response line. Chlortetracycline alone had no effect on weight gain of low antibody response birds but increased the weight gain of chicks from the high antibody response line. Bursa to body weight ratios were adversely affected by aflatoxin in both lines of chicks, but chlortetracycline further adversely affected this parameter only in the low antibody response line. These results indicate that adverse effects of aflatoxin may be enhanced by addition of antibiotics to feed.