Effects of dietary protein source and level on intestinal populations of Clostridium perfringens in broiler chickens.

Two experiments were conducted to examine the effect of the level of dietary crude protein and protein source on intestinal populations of Clostridium perfringens in broilers. In experiment 1, 6 groups of 12 birds were fed diets containing 230,315 or 400 g/kg crude protein with soy protein concentrate (SPC) or low-temperature-dried fishmeal as the major protein sources in a 2 x 3 factorial arrangement of treatments. A significant interaction between protein source and level was observed where the number of C. perfringens present in the ileum and cecum increased as the level of crude protein in the diets increased from 230 to 400 g/kg in the birds fed fishmeal-based diets (P < 0.05) but not in the birds fed SPC-based diets. In experiment 2, the dietary treatments used were arranged in a 2 x 2 factorial arrangement with 2 levels of crude protein (230 and 400 g/kg) and 2 protein sources (SPC or fishmeal). The main effects of protein source and protein level significantly (P < 0.05) affected numbers of C. perfringens without interaction. Amino acid analysis of the diets showed that the glycine and methionine contents of the fishmeal diets were elevated compared with the SPC diets. This suggests that the level of crude protein, protein source, and amino acid content of diets affect the growth of C. perfringens in the lower intestinal tract of the broiler chicken and might be predisposing factors to outbreaks of clinical necrotic enteritis.