Impact of dietary replacement of soybean meal with high-protein wheat on gut microbial metabolism in chickens

The study examined the potential use of high-protein wheat (AW) as an alternative to soybean meal (SBM)-based diet for poultry. One-day-old broiler chickens were divided into 4 groups: control (C), fed a standard mixture, and three experimental groups (W50, W75 and W100) in which 50, 75 and 100%, respectively, of SBM was replaced by AW. Performance and caecal parameters (body weight, caecal morphometry, short-chain fatty acids – SCFAs) of the birds were measured at days 14, 21, 35 and 42 of age. Selected groups of microorganisms in the ileum and caecum were assessed quantitatively. Microbial metabolites (SCFAs and methane) were analysed in vitro, using caecal inocula collected from another group of control chickens, incubated with substrates containing SBM and AW in the proportions corresponding to those in the feeding protocols. The W100 chickens had a distinctly lower body weight than control animals. The development of caecal parameters was also slower, though physiologically correct, in this group. The microbial colonization of the caeca (especially by lactic acid bacteria) and changes in their activity took a longer time in chickens receiving the highest dose of AW. The W50 group was most similar to the control group with respect to performance and caecal parameters, as well as microbial metabolites. However, in the in vitro experiment, no major differences in the SCFA profile or methanogenesis were observed. Based on the obtained results, it can be recommended to replace 50% of soybean meal with high-protein wheat in the diet of broiler chickens, preferably from day 21 of age.