Productive performance, feed digestibility and gut microbiome of broiler chickens (Gallus gallus L.) fed diets with native and extruded carbohydrate containing ingredients

Extrusion, as a thermal and mechanical processing method combining high temperatures and pressure, increases the nutritional value of feed ingredients and it is widely used to improve the functional properties of food products. However, it is unclear how diets containing extrudates interact with the intestinal microbiota and influence the nutritional physiology of broiler chickens. In this work, it was established for the first time that replacing up to 10 % of wheat with bran and corn does not affect poultry productivity. A decrease in fat absorption during bran extrusion and an increase in this indicator during corn processing were revealed. It has been shown that the cecal microbiome is formed differently at different ratios of soluble and insoluble carbohydrates. Our goal was to evaluate the effects of replacing the grain portion of the broiler chicken diet with native and extruded wheat and corn bran on growth performance, digestibility, and gut microbiome composition. The research was carried out in 2023 in the vivarium of the Federal Research Centre of Biological Systems and Agrotechnologies of the Russian Academy of Sciences. The Arbor Acres cross broiler chickens (Gallus gallus L.) were divided into four experimental groups (n = 5 each) using the analogue pair method. The birds were fed with complete feed in accordance with the recommendations of the All-Russian Scientific Research and Technological Institute of Poultry Farming (RSRTIPF). Starting from day 21, 10 % of wheat grain (100 g/kg of feed) in the diet of chickens in group I was replaced with wheat bran (B), in group II with bran extrudate (BE), in group III with corn (C), in group IV with corn extrudate (CE). The crude fiber content in the studied components was as follows: 7.7 % for B, 2.7 % for BT, 4.29 % for C, and 1.67 % for CE. Live weight gain was measured by weekly weighing during 21-42 days of life. The chemical composition of diets and droppings was studied. The dry matter content was measured according to GOST 31640-2012 (M., 2012), the mass fraction of crude fat according to GOST 13496.15-2016 (M., 2016), crude protein according to GOST 13496.4-93 (M., 2011), crude fiber according to GOST 31675-2012 (M., 2014). At the end of the experiment, on day 42, the birds were slaughtered. The digestive organs (muscular and glandular stomachs, intestines) were removed, freed from contents and weighed. The contents of the cecum were collected at slaughter. Preparation of DNA libraries, DNA sequencing and bioinformatic processing were performed. Visualization of the bioinformatics data and statistical analysis were carried out using MicrobiomeAnalyst (https://www.microbiomean-alyst.ca/). The resulting OTUs, after filtering and assigning taxonomic affiliation, were used to calculate alpha diversity (Chao1 index, Fisher index, Shannon diversity index, ACE abundance-based coverage estimate, Simpson diversity index; ANOVA statistical method) and beta diversity (NMDS ordination method, distance method, Bray-Curtis index; statistical method PERMANOVA). On day 14 after the start of the experiment, there was a tendency to increase live weight in the groups of chickens receiving extruded products; they had a weight superiority of 8.5 % for EB and 9.9 % for EC compared to similar feeds without extrusion. By the end of the test period, the difference for the same groups in live weight was 8.3 and 10.4 %, respectively, without significance of the differences. The addition of extruded corn to diets led to a statistically significant increase in the digestibility of crude fat (CF): this indicator was 5.1 % (p ≤ 0.05) higher compared to EB and 6.4% (p ≤ 0.05) higher compared to C. The addition of extruded bran to the diet o reduced the digestibility of CF by 3.5 % when compared to group I. When assessing the digestibility of crude protein (CP), the effect was opposite with a statistically significant decrease in groups III and IV, respectively, by 6.6 % (p ≤ 0.05) and 13.2 % (p ≤ 0.05) compared to group I. The remaining indicators of nutrient absorption did not have significant differences. The development of the digestive organs was influenced by the higher fiber content in the native components of bran and corn. The weight of the muscular stomach in group I was 7.02 % (p ≤ 0.001) higher than in birds fed EB, in group III it was 22.04 % (p ≤ 0.05) higher than when fed EC. Intestinal weight decreased in group IV by 22.12 % (p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }