THE ROLE OF PROTEIN AND AMINO ACID NUTRITION IN CONTROLLING CLOSTRIDIUM PERFRINGENS IN THE GASTROINTESTINAL TRACT OF BROILER CHICKENS
A series of experiments were conducted to examine the effect of dietary protein and amino acids (AA) on intestinal Clostridium (C.) perfringens proliferation and necrotic enteritis (NE) in broiler chickens. The effects of dietary protein level and protein digestibility on the growth performance and carcass characteristics of broilers were evaluated first. Low protein (LoPro) diets supported growth performance equal to high protein (HiPro) diets when highly digestible protein supplements were incorporated. Birds fed HiPro yielded more breast meat than those fed LoPro while birds fed diets with highly digestible (HiDig) protein supplements accumulated more abdominal fat than those fed diets containing low digestible (LoDig) protein ingredients. The next experiment focused on the development of a feasible experimental model to induce NE experimentally in broilers to investigate potential dietary approaches. Different modes of challenge (oral gavage, in-feed and in-water) with different doses of C. perfringens inoculums (2 or 4 ml) were tested using microbiological, pathological and hematological parameters. The findings suggested the possibility to applly any of the evaluated treatments to induce the disease in broilers raised on litter. The next experiment was conducted to examine the effects of dietary protein level and digestibility on the growth performance and intestinal ecosystem of C. perfringens challenged and unchallenged broilers. The results of this experiment again revealed the ability of LoPro diets to maintain the growth performance of broilers as with HiPro diets, when HiDig protein supplements were included. The findings further demonstrated significant reduction in the intestinal C. perfringens numbers and severity of intestinal lesions of infected broilers when LoPro diets and HiDig protein supplements were fed. The last experiment was performed to assess the methionine requirement for optimum growth in broiler chickens fed diets supplemented with either DL-methionine (DLM) or 2-hydroxy-4-methylthiobutanoic acid (HMB) under C. perfringens infected and uninfected situations. None of the methionine sources affected the growth of C. perfringens in the broiler GIT, however, infected birds needed more dietary methionine to achieve maximum growth when DLM, but not HMB, was included in the diet. Based on the overall findings it can be concluded that the dietary approaches tested in this project may support our efforts in the development of nutritional strategies to minimize the impact of C. perfringens on broiler production in an antibiotic free livestock industry.
protein, amino acid, Clostridium perfringens, Necrotic enteritis, broiler
Doctor of Philosophy (Ph.D.)
Animal and Poultry Science