Interactions of Amino Acids, Crude Protein and Necrotic Enteritis in Meat-Chickens

Abstract

A third experiment investigated the extent of the roles of essential amino acid and extra amino acid supplementation in reduced protein diets with glycine considered essential. Ross 308 cockerels were fed one of three protein levels; standard, reduced, or low protein, with one of three amino acid profiles; 100% amino acids (100% AA), 115% essential amino acids (115% EAA), or 115% amino acids (115% AA). Differences in crude protein and non-essential amino acids existed between the 115% EAA and 115% AA treatments. Performance, nitrogen digestibility and blood parameters were measured. Birds fed diets with greater non-essential amino acids but similar essential amino acids to 115% EAA had greater performance irrespective of protein level. Additionally, no difference was observed between standard and reduced protein treatments. Blood parameters indicated reduced uric acid synthesis, despite glycine supplementation. The results from this study indicate that non-essential amino acids play key roles in growth and development that cannot be overcome with extra essential amino acid supplementation. Finally, a fourth experiment assessed interactions between sub-clinical necrotic enteritis, dietary crude protein and amino acid levels using standard and low protein treatments with 100% AA, 115% EAA, and 115% AA profiles from the previous experiment. Ross 308 cockerels were fed one of six dietary treatments with half challenge with sub-clinical necrotic enteritis using Eimeria spp. and Clostridium perfringens. Differences in bird performance between those fed the standard and low protein diets were not apparent in challenged birds. Increasing the non-essential amino acids increased body weight gain after the challenge, however, low protein diets delayed recovery. Increasing the crude protein and non-essential amino acids can improve the rate of recovery from necrotic enteritis challenge and not essential amino acids alone. The work completed has been highly industry-relevant and has highlighted the complex relationships between amino acids and the effects they have on meat-chicken performance, biochemistry, and physiology. The Australian chicken meat industry now has a dataset of Australian diets for assessment to consider implementing reduced protein diets to improve industry sustainability and access potential diet cost savings.