Evaluation of amino acid digestibility values of protein feedstuffs and dietary protein content in combination with probiotic supplementation in growing pigs

During the last decade, the concept of standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) has been used in diet formulation for pigs. However, there is limited data on the nutritional composition and SID of CP and AA in home-grown European soybean and rapeseed products. For full-fat soybeans (FFSB), the presence of heat-labile trypsin inhibitors may cause problems in protein digestion of pigs. Therefore, the optimization of heat treatment for FFSB is a need to reduce trypsin inhibitor activity for improving SID of CP and AA. However, excessive heat treatment may have a negative effect on protein digestion. Furthermore, reducing dietary protein levels in combination with the supplementation of Bacillus spp. may reduce feed costs and improve pigs' gut health. As a result of the present study, home-grown European soybean and rapeseed products can be considered as a suitable alternative to imported soybean products for pigs raised in organic and conventional farming systems. Wet heating at 100°C for 16 min, together with autoclaving at 110°C from 15 to 45 min reflects optimal heat treatment for FFSB resulting in greater SID of CP and AA with lower destruction of AA. Reducing the dietary CP level is an alternative strategy to improve SID of some AA, thereby decreasing feed cost and nitrogen excretion. The supplementation of Bacillus spp. promoted gene copy numbers of Roseburia spp., which may be beneficial due to ascribed health promoting properties of this butyrate producer.