Gastrointestinal morphology and function in turkeys fed diets diluted with whole grain wheat

The aim of this study was to verify the hypothesis that moderate dilution of turkey diets with whole grain wheat (up to 22.5%) improves gastrointestinal function, thus contributing to sustained growth performance. A total of 900 male turkeys were allocated to 5 dietary treatments: basal diet (BD), BD diluted with low levels of ground and pelleted wheat or whole wheat, and BD diluted with high levels of ground and pelleted wheat or whole wheat (GH and WH, respectively). At successive stages of the experiment, diets containing 5 and 15%, 7.5 and 17.5%, 10 and 20%, 12.5 and 22.5% of wheat in different physical form were fed to turkeys aged 5 to 8, 9 to 12, 13 to 16, and 17 to 18 wk, divided into subgroups with low and high dietary levels of wheat, respectively. Dietary dilution with different levels of wheat did not reduce the BW gain of turkeys and did not deteriorate feed conversion despite a decrease in the amino acid content of diets. In comparison with BD, diet GH increased the thickness of the muscularis externa and the depth of cecal crypts (P < 0.05), increased Bacteria domain, and decreased Salmonella counts (P < 0.001), increased butyric acid concentrations, and decreased the levels of putrefactive compounds in the cecal digesta (P < 0.001). In comparison with BD, diet WH improved feed efficiency (P = 0.002) and contributed to significant (P < 0.01) changes in the parameters of gastrointestinal function, including lower pH of gizzard digesta, increased depth of jejunal crypts, lower ammonia concentrations, and lower pH of intestinal digesta, increased Bacteria and Bifidobacterium counts, decreased Salmonella counts, and higher concentrations of butyric acid and total short-chain fatty acids. In comparison with diet GH, diet WH enhanced the activity of bacterial α-glucosidase and β-glucosidase as well as α-galactosidase, reduced the activity of β-glucuronidase, and increased total fatty acid concentrations, mainly acetic acid levels, in the cecal digesta (P < 0.01). The observed changes indicate that diet supplementation with wheat grain enhances gastrointestinal function, thus improving feed conversion in turkeys.