Effect of dietary supplementation of butyric acid glycerides on performance, immunological responses, ileal microflora, and nutrient digestibility in laying hens fed different basal diets

• Supplemental butyric acid improved egg production and egg mass in laying hens.
• Supplementation of butyric acid glycerides was more affective in wheat-based diets.
• Dietary inclusion of butyric acid glycerides improved antibody response to SRBC.
• Feeding wheat-based diets increased ileal populations of total bacteria and E. coli.
• Dietary supplementation of butyric acid glycerides improved fat and ash digestibility.

A total of 150 laying hens (55-wk-old) were used to investigate the effect of different levels of butyric acid glycerides (BAG) on performance, egg quality, ileal microbial populations, and nutrient digestibility in hens fed different basal diets. Dietary treatments consisted of 2 different basal diets (corn- or wheat-based diets) and 3 supplemental BAG levels (0, 2.5, and 5.0 g/kg) in a 2×3 factorial arrangement with 5 replicate cages and 5 hens per cage. The study lasted for 77 d, including 7 d for adaptation and 70 d as the main experimental period. In addition to performance variables, antibody responses to different antigens were assessed after the inoculation. Furthermore, ileal digesta was collected from 3 euthanized hens per replicate at the end of the study to determine microbial count and ileal nutrient digestibility. Results showed that dietary BAG supplementation (2.5 and 5.0 g/kg) increased egg production and egg mass, but it had more impact in hens fed wheat-based diets (basal diet×BAG, P<0.05). Dietary supplementation of BAG increased both egg production and egg mass, but those response criteria were greater with 5.0 g/kg compared with 2.5 g/kg. The heavier egg weights were observed for the hens fed corn-based diets (P=0.001), however, feed intake was not influenced by dietary treatments. Supplemental BAG (2.5 and 5.0 g/kg) improved feed conversion ratio and it was lower in hens fed 5.0 g/kg than those fed 2.5 g/kg of BAG, especially in those hens fed the wheat-based diets (basal diet×BAG, P=0.022). Yolk color index was greater (P<0.001) in eggs produced by hens fed on corn-based diets. In contrast to Newcastle antibody titer, dietary inclusion of BAG (2.5 and 5.0 g/kg) increased (P=0.011) antibody response against sheep red blood cell during primary response. Serum concentrations of triglycerides and cholesterol were lower (P<0.01) in hens fed wheat-based diets, and they increased (P<0.01) as supplemental BAG level was increased. Total bacterial count and Escherichia coli (E. coli) population were greater (P<0.05) when hens were fed wheat-based diets, and dietary BAG supplementation (2.5 and 5.0 g/kg) reduced (P<0.05) total bacteria and ileal E. coli enumerations. Supplemental BAG (2.5 and 5.0 g/kg) increased digestibility coefficients of ether extract (P=0.009) and also total ash, even though there was the interaction on total ash (P=0.045). The present findings indicate that BAG supplementation of diets could increase production performance of laying hens, probably because of the decreased intestinal E. coli count, and this effect was more obvious in wheat-based diets.