Effects of reduction or replacement of soybean meal and a combination of compound enzyme preparations supplementation on growth performance and intestinal health of Langshan chickens

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The present study assessed the effects of low protein and alternative protein diets with compound enzyme preparations supplementation on the growth performance and intestinal health of Langshan chickens. A total of 288 Langshan roosters at the age of 30 d were selected, and six diets were prepared according to 3 × 2 factor test: the corn-soybean meal, corn-soybean meal with enzymes, low protein meal, low protein meal with enzymes, corn-soybean-miscellaneous meal, and corn-soybean-miscellaneous meal with enzymes. The experiment lasted for 56 d. Over the entire experiment, the corn-soybean-miscellaneous diet significantly increased average daily gain and significantly reduced the feed-to-gain ratio (p < 0.05). The corn-soybean miscellaneous meal diet significantly decreased the apparent digestibility of protein (p < 0.05), while enzyme supplementation significantly increased the digestibility of crude protein and crude ash (p < 0.05). Intestinal morphology showed that low protein and corn-soybean-miscellaneous meal diets increased the villus height of birds at 58 d of age (p < 0.05). Enzyme-supplemented diets significantly increased amylase activity in the jejunal digesta of broilers at 58 d of age (p < 0.05). Corn-soybean-miscellaneous diet significantly decreased protease activity compared with those fed with corn-soybean meal (p < 0.05). There were significant interactions on mRNA expressions in intestinal tight barriers and amino acid transporters by diet type and enzyme supplementation. A low protein diet and corn-soybean miscellaneous meal diet could destroy the intestinal barrier and reduce amino acid transporter gene expression levels, which could be improved after adding enzyme preparations.