Dietary glycine concentration affects intestinal Clostridium perfringens and lactobacilli populations in broiler chickens

Previous studies have reported that intestinal populations of Clostridium perfringens, the causative agent of necrotic enteritis (NE), are correlated with diets high in glycine. To establish a direct causative link, 3 trials were conducted to examine the effect of dietary glycine levels on gut populations of C. perfringens, alpha-toxin production, and NE lesion scores in broiler chickens. In trials 1 and 2, 12 groups of 4 birds were fed 4 different ideal protein-balanced diets formulated to contain 0.75, 1.58, 3.04, or 4.21% glycine from d 14 to 28 of age. In trial 3, 24 groups of 4 birds were given 6 different ideal protein-balanced diets formulated to contain 0.50, 0.75, 1.00, 1.50, 2.00, or 4.00% glycine. All birds were orally challenged with a broth culture of C. perfringens type A on d 1 and between d 14 and 21 of age and killed on d 28. The majority of birds showed clinical signs of NE with 4.16 to 8.33% mortality in the 3 trials. The highest mortality and intestinal lesion scores were observed in chickens receiving 3.04% glycine in trials 1 and 2, and 4.00% glycine in trial 3. Clostridium perfringens populations in the cecum varied quadratically with increasing dietary glycine, with the maximal response seen at 3.30, 3.89, and 3.51 % dietary glycine in trials 1, 2, and 3, respectively. Numbers of lactobacilli in cecum declined significantly (P < 0.05) with increasing levels of glycine. The results suggest that dietary glycine level has a significant effect on C. perfiringens and lactobacilli populations and may be a predisposing factor for NE in broiler chickens.