Effects of rye inclusion in grower diets on immunity-related parameters and performance of broilers

An experiment was conducted to investigate the effects of dietary inclusion of three levels (0, 5, and 10%) of rye between 14 and 28 days of age on gut health and performance in broilers. A total of 960 one-day-old male Ross 308 chicks were allocated to 24 pens (40 birds per pen). The inclusion of 5 or 10% rye in the diet between day 14 and 28 in a broiler diet resulted in decreased performance and litter quality, but in increased villus height and crypt depth in the small intestine (jejunum) of the birds. Relative bursa and spleen weights were not affected by dietary treatments. In the jejunum, no effects on number and size of goblet cells, and only small effects on microbiota composition in the digesta were observed. Dietary rye inclusion affected expression of genes involved in cell cycle processes of the epithelial gut cells, thereby influencing cell growth, cell differentiation and cell survival. This observation is consistent with the observed differences in the morphology of the gut wall. Whether this also affected the barrier function of the epithelial layer, cannot be concluded. The complement and coagulation pathways, which are also affected by providing rye-rich diets, are parts of the innate immune system. These pathways are involved in eradicating invasive pathogens. Overall, it is concluded that inclusion of 5% or 10% rye to the grower diet of broilers in the current study had limited effects on performance. Ileal gut morphology, microbiota composition of jejunal digesta, and gene expression profiles of jejunal tissue, however, were affected by dietary rye inclusion levels.