Effect of Protein Sources on Early Turkey Performance and Gastrointestinal Tract Development

Abstract

Nutrition during the early life of turkey poults has a long lasting impact on bird performance, as well as gastrointestinal tract (GIT) development. This research focused on understanding the impact of protein source provided in the feed on performance and GIT development. All statistical analysis was completed using Proc Mixed in SAS 9.3 and significant differences were set at P≤0.05, while trends were identified for P≤0.10. The first study (5 x 2 factorial arrangement) evaluated apparent metabolizable energy (AMEn) and apparent ileal amino acid digestibility (AIAAD) of five high protein feed ingredients (soybean meal, SBM; corn gluten meal, CGM; canola protein concentrate, CPC; fish meal, FM; and porcine meal, PM) in male broiler chickens at 5 and 21 d with 6 replications of 30 and 8 chicks, respectively. The AMEn was not affected by bird age for CPC, FM, CGM, and SBM, however, the d 5 value for PM was higher than the d 21 value. The response of AIAAD was variable and dependent on amino acid and protein source, but overall, there was an increase in AIAAD with increasing age, with the largest increase observed for CGM. These AMEn and AIAAD values were then used to formulate the diets for a second experiment. The diets for this experiment consisted of a high SBM control diet, and four additional diets with either CPC, FM, PM, or CGM replacing 25% of the protein that was supplied by SBM in the control diet. This experiment was set up as a completely randomized design with four pens of 23 turkey poults per protein source. Body weights, feed and water intake, and mortality were recorded on a weekly basis. At the same time, four pens of 21 poults per protein source were used to study the impact of these diets on GIT development and blood metabolic profiling. At hatch, placement, d 1, 2, 3, 5, 7, 14, and 21, intestinal tract and tissue weights were collected and recorded (2 poults per replication per time point). Ileal segments were collected at hatch, placement, d 1, 3, 5, and 7 from 2 poults per replicate pen of the SBM and PM diets to study the effect of diet on intestinal morphology, number of goblet cells, and transcript abundance for selected genes relating to barrier function and inflammation. Blood samples were also drawn at these time points for blood metabolite analysis. Data were analyzed as a 5x9 factorial for tissues weights, a 2x5 factorial for histology and gene expression, and a 5x5 factorial for blood analysis. Planned contrasts were used on the performance, tissue, and blood data to compare the SBM diet to the average of the remaining diets, the PM diet to the average of the remaining diets, and the addition of animal or vegetable proteins. Inclusion of an additional protein source increased body weight up to 14 d, in comparison to poults fed the SBM diet, but feed efficiency and water consumption were not affected. The effect of diet on tissue weights were small, with the exception of the pancreas weight, which were higher in the birds fed vegetable protein diets. Age had an effect on all tissue weights, which peaked between d 2 and 7, as well as on digestive tract morphology and gene expression. There was an increase in gene expression between placement and d 1, which could illustrate the importance of feed as an activator of barrier function and the immune system. The goblet cell counts revealed a greater proportion of neutral goblet cells in PM fed birds associated with accelerated mucus maturation. The research shows there are benefits to limiting the amount of SBM provided in early turkey feeds, especially prior to two weeks of age.