Impacts of Dietary Protein and Prebiotic Inclusion on Liver and Spleen Gene Expression in Hy-Line Brown Caged Layers

SIMPLE SUMMARY: Eggs are one of the most affordable and nutritious animal proteins available, and with increasing human population, there is an increased demand for production. As feed is the main expense in poultry production, novel protein sources and feed additives need to be evaluated for their benefits for poultry health and performance. In this study, we evaluated the standard soybean-based diets against an alternate source—cottonseed meal, in the context of prebiotic addition. Prebiotics putatively improves health and production. We assessed the homeostatic and immune balance by assaying the expression of select marker genes. We find that the inclusion of yeast cell wall products as prebiotic alters homeostatic balance. Particularly, the upregulation of apoptosis—a normal cell process—suggests that these products may promote homeostatic balance. ABSTRACT: The ingredients of poultry feeds are chosen based on the least-cost formulation to meet nutritional requirements. However, this approach can lead to the introduction of anti-nutritional ingredients in the feed. The objective of this study was to evaluate the impacts of two diets (with or without prebiotic) on homeostatic genes in the liver and spleen of laying hens. Hy-Line Brown layers were raised either on a soybean meal or cottonseed meal-based diets with and without an added prebiotic (yeast cell wall), totaling four experimental diets. A total of 120, 63-week old layers were housed individually in a wire cage system. We investigated differences in the expression of select homeostatic marker genes in the liver and spleen of hens from each treatment. We then used the ΔΔCT and generalized linear models to assess significance. Results show that the inclusion of prebiotic yeast cell-wall (YCW) increased the expression of the BAK gene in the liver tissue for both the soybean meal (SBM) and cottonseed meal (CSM) diets. For splenic tissue, the combination of YCW with the CSM diet increased the POR gene over six log2 fold. Altogether, our results suggest altered homeostasis, which can have consequences for health and performance.