关键词: 生长猪, 饲粮组成, 小肠消化环境, 氨基酸消化率, 相关性

Abstract:

This experiment was conducted to investigate the variability of digestive environment in different sites of the small intestine of pigs and its correlation with dietary standardized ileal digestibility of amino acids, and to provide a reference for the development of rapid evaluation of nutritive of amino acid for pig diets. In this experiment, 18 Duroc×Landrace×Yorkshire barrows with an initial body weight of (21.6±3.5)kg were randomly divided into 3 groups with 6 pigs in each group. A T-cannula was surgically equipped at the end of duodenum, the middle of the jejunum-ileum and the end of the ileum, respectively. Each group of pigs was allotted to a replicated 3×3 Latin square design with 3 diets (3 kinds of semi-homozygous diets with corn, soybean meal and wheat bran as the only protein source, respectively) and 3 phases. In each phase, there was a 5-d adaption to experimental diet, followed by a 3-d determination of digesta passage time, a 2-d collection of digesta, and a 2-d of recovery period. The pH, ion concentration, digestive enzyme activity and the passage time of digesta in each sites of small intestine were determined. The effects of intestinal sites and diets on the digestive environment were analyzed, and the simple correlation analysis was conducted between the standardized ileal digestibility of amino acid in diets and the digestive environment parameters in small intestine. The results showed that: 1) Intestinal sites and diets had significantly interactions (P < 0.05) on the K⁺ and Cl^- concentrations and chymotrypsin activity of intestinal fluid. The intestinal sites had extremely significant effects (P < 0.01) on pH, amylase and trypsin activities and Na⁺ concentration, and diets had significant effects (P < 0.05) on pH, trypsin activity and Na⁺ concentration. 2) Taking the average time of appearance and disappearance of digesta indicator as the passage time, the passage time of corn diet in duodenum, middle jejunum-ileum and terminal ileum was significantly longer (P < 0.05) than that of wheat bran diet, but there was no significantly difference (P>0.05) compared to soybean meal diet in duodenum. 3) Pigs fed the corn diet had no significant correlation (|r|≤0.68, P>0.10) between the pH, Na⁺ concentration, K⁺ concentration, passage time of digesta, digestive enzyme activities and the standardized ileal digestibility of amino acids. Pigs fed the soybean meal diet showed significantly negative correlation (|r|=0.86, P < 0.05) between the amylase activity and standardized ileal digestibility of glutamate. Feeding pigs with wheat bran diet, there was a significantly positive correlation (|r|≥0.87, P < 0.05) between Na⁺ concentration and proline, passage time of digesta and standardized ileal digestibility of methionine, histidine, arginine, aspartic acid, glutamic acid, glycine and alanine. In summary, the intestinal sites and diets of growing pigs have a significant influence and interaction on the digestive environment of small intestine. The correlation between pH, ion concentration and digestive enzyme activity and the standardized ileal digestibility of amino acids is weak, but the passage time of digesta affects protein digestion in wheat bran diet.

Key words: growing pig, diet composition, digestive environment, amino acid digestibility, correlation