Protease and Bacillus coagulans supplementation to a low-protein diet improves broiler growth, promotes amino acid transport gene expression, strengthens intestinal barriers and alters the cecal microbial composition

A low crude protein (CP) diet has several advantages including reduced feed costs, improved protein utilization rates for livestock and poultry, and decreased environmental pressures. However, broilers on amino acid-fortified low-protein (LPRO) diets show poorer growth perfor-mance than those on normal protein diets. We therefore examined whether the addition of a pro-tease (PRO) in the presence and absence of the probiotic bacterium Bacillus coagulans (BC) could provide additional amino acids (AA) from LPRO to satisfy growth requirements of Arbor Acre chicks. We utilized one day old chicks that were fed control (CON) conventional diet, an LPRO diet enhanced with lysine, methionine, and threonine, a PRO group that consumed an LPRO diet fortified with PRO and PRO with added BC (PAB) incorporated at .