Effects of Partial Replacement of Soybean Meal With Rapeseed Meal, Narrow-Leaved Lupin, DDGS, and Probiotic Supplementation, on Performance and Gut Microbiota Activity and Diversity in Broilers

This study examines the impact of soybean meal (SBM) substitutes, including solvent-extracted 00 rapeseed meal (RSM), narrow-leaved lupin (LUPIN), and distillers dried grains with solubles (DDGS) (each used at a ratio of 250 g/kg⁻¹ in the diet), as well as administered probiotic (L. casei, L. plantarum, Rhodopseudomonas palustris, S. cerevisiae), on gut microbiota activity, diversity and performance. The experimental treatments were arranged in a 4 × 2 factorial design, with the factors being protein source in the diets (SBM only, RSM, LUPIN or DDGS) given from 8 to 35 days of age, and with or without a probiotic preparation administered in drinking water during the entire rearing period. The performance declined in birds fed with SBM substitutes (P≤0.01). The RSM diet decreased concentration of short chain fatty acids (SCFAs) (P<0.01) in ileal and caecal digesta as well as decreased bacterial enzymes activity in the caeca. The LUPIN diet increased viscosity and decreased SCFAs concentration in ileum, while the DDGS diet increased butyrate concentration in caeca. SBM substitutes and probiotic were involved in changing the Clostridiales and Lactobacillales diversity in the ileal and caecal digesta. Probiotic administration did not affect performance, but it did alleviate some negative effects of SBM substitutes on microbiota activity and diversity.