Effects of energy reduced diets including alternative protein sources and a phytogenic supplement on performance, carcass traits and digestibility in broiler chickens

Protein sources obtained from co-products might provide an alternative to soybean meal (SBM), counteracting the dependency on other countries and increasing the sustainability. In an energy reduced broiler diet (−0.72 MJ AMEN), a mixture of DDGS, sunflower meal and rapeseed meal was applied as alternative fiber rich protein source (APS) to replace 100% of SBM. Furthermore, the diets were supplemented with 0.04% of a lignan-rich phytogenic component derived from bark to improve the performance. The experimental diets were fed to 3,600 broilers (Ross 308, mixed sex) from day 11 to 36 posthatch (grower and finisher phase). Overall, the broilers responded to APS diets with a significantly increased daily feed intake and decreased body weight (P < 0.05), which resulted in an impaired F:G ratio (P < 0.05). The apparent total tract digestibility of dry matter, organic matter, and gross energy with APS diets decreased significantly. The replacement of SBM by APS resulted in higher gizzard weights (P < 0.05), proventriculus weights (P < 0.05) together with a decreased gizzard pH (P < 0.05) and improved foot pad dermatitis score of broiler chickens (P < 0.05). These findings suggest that the replacement of soybean meal with alternative protein sources in energy reduced diets destined for broilers negatively affects performance and digestibility, however, improves food pad health and upper intestinal tract characteristics. The supplementation with a phytogenic component, decreased feed intake in finisher phase, however improved F:G ratio and increased the breast weight (P < 0.05). Furthermore, it indicated a positive statistical interaction with APS diets regarding certain digestibility values (P < 0.05).