Butyric acid-based products, alone or in combination with hydroxy-selenomethionine, improve performance of laying hens in post-peak period by modulating their antioxidant, metabolic and immune status

This study aimed to evaluate the effects of butyrate, butyric glycerides (BG) and their combination with sodium selenite (SeNa) or hydroxy-selenomethionine (OH-SeMet) on the performance and egg quality of the laying hens in post-peak period as well as the potential mechanism. A total of 900 45-week-old Hy-Line brown laying hens were randomly allocated to 5 treatment groups (n = 10 replicates/diet, 18 hens/replicate). The hens were fed the basal diet supplemented with 0.3 mg/kg selenium from SeNa (Control), Control plus 240 mg/kg butyric acid from coated butyrate (CB), Control plus 240 mg/kg butyric acid from butyric glycerides, basal diet supplemented with 0.3 mg/kg selenium from OH-SeMet plus coated butyrate (CB+OH-SeMet) or butyric glycerides (BG+OH-SeMet), respectively, for 20 weeks. Serum, liver, isthmus, uterus, and jejunum were collected at the end of the trial for biochemistry, histology, redox status, and gene expression analysis. Compared with Control, diets supplemented with BG, CB+OH-SeMet and BG+OH-SeMet increased (p < 0.05) the average egg weight (0.6-2.2 %), while only BG+OH-SeMet increased (p < 0.05) the total egg weight (7.1 %) and egg-laying rate (4.6 %) and decreased (p < 0.05) the feed/egg ratio (5.0 %) throughout the whole experiment. Furthermore, BG+OH-SeMet reduced (p < 0.05) the content of IL-6 and alanine aminotransferase (15.4-32.5 %), while elevated (p < 0.05) the content of IgA, IgY, IgM and total protein (18.7-26.8 %) in the serum in comparison to the Control. Notably, dietary supplementation of BG+OH-SeMet performed more effective antioxidant capacity in decreasing (p < 0.05) malondialdehyde (16.4-27.9 %) content and increasing (p < 0.05) the activity of total antioxidant capacity and glutathione peroxidase (17.6-36.3 %) in various tissues. Further experiment revealed that dietary BG+OH-SeMet regulated the lipid metabolism by increasing (p < 0.05) the expression of Carnitine palmitoyltransferase 1A (CPT1A) and Lipoprotein lipase (LPL) in liver. In conclusion, diets supplemented with BG and OH-SeMet could improve the laying performance via the enhancement of antioxidant capacity and regulation of lipid metabolism.