Partial to complete replacement of soybean meal with high-protein wheat in broiler diets: Effects on growth and blood parameters

The aim of this study was to evaluate the replacement of soybean meal (SBM) with high-protein wheat (HPW; 163 g kg^–1 crude protein) in broiler chicken diets. Birds were fed isoenergetic diets with reduced crude protein content, supplemented with crystalline essential amino acids to meet nutritional requirements. Growth performance, selected blood biochemical parameters, and rearing costs were assessed. A total of 196 broilers were randomly assigned to four dietary groups with varying HPW inclusion levels across feeding phases. The control group received the lowest HPW levels and SBM as the primary protein source, while in groups II–IV, SBM concentration was decreased simultaneously with HPW concentration – starting at 50% increments until complete replacement was achieved. No significant differences in body weight or feed conversion ratio were observed between the control group and group II. In contrast, growth performance and the European production efficiency factor were significantly reduced (P < 0.01) in groups III and IV, indicating lower profitability at high HPW inclusion levels. Total costs of feeding decreased with increasing HPW inclusion from 3.1% (group II) to 33.7% (group IV). The biochemical parameters fluctuated, although the alterations were relatively minor and statistically significant changes were observed only in certain groups and on selected days. While HPW serves as an effective partial protein substitute, the decline in performance at higher inclusion levels suggests that further research into exogenous enzyme combinations is necessary to unlock the full nutritional potential of high-wheat broiler diets.