Barley inclusion and avoparcin supplementation in broiler diets. 1. Effect on small intestinal bacterial flora and performance.

Diets based on barley or corn without avoparcin supplementation were associated with high counts of Clostridium perfringens in the contents of the small intestine of the birds at the age of 2 to 4 wk. The weight gain of birds younger than 2 wk and the body weight of 4-wk-old birds were significantly lower, and the feed conversion ratio at slaughter was significantly higher, in birds on barley diets than in birds on corn diets. The frequency of birds with sticky droppings on Day 21 was significantly higher for barley diets. The number of C. perfringens, and the feed conversion ratio at slaughter were significantly lower but the number of coliform bacteria, weight gain during the 3rd wk, and body weight of 4-wk-old chickens were significantly higher when the diets were supplemented with 7.5 mg avoparcin/kg feed. The effect of avoparcin on the feed conversion ratio was statistically significant only on a barley diet.