Soya saponin fails to improve the antioxidation and immune function of laying hens with antibiotics treated

Soya saponin (SS) helps to improve antioxidant and immune function of body, and intestinal bacteria might play an important role here. In the present study, the co-occurring network of the ileal flora was analyzed with 50 mg/kg SS supplemented to the diet, and Romboutsia was found to have evolved into a dominant flora. In addition, the co-occurring network of the flora was changed with the combined antibiotic treated, and the unidentified-cyanobacteria developed into the dominant flora, whereas the relative abundance of Romboutsia was dropped. Dietary SS failed to elevate the relative abundance of Romboutsia with antibiotics treated, at the same time, it was not helpful for the antioxidant and immune function of laying hens. While dietary SS had a little help on the egg-laying performance. Intestinal bacteria did play a key role in the biological functions of SS on laying hens. In conclusion, SS failed to improve the antioxidation and immune function of laying hens with antibiotics treated.

Dietary soya saponin improves the lipid metabolism and intestinal health of laying hens

Soya saponin (SS) is a natural active substance of leguminous plant, which could improve lipid metabolism and regulate immune function. Intestinal flora might play a key role in the biological functions of SS. The objective of this study was to measure the effects of dietary SS on immune function, lipid metabolism, and intestinal flora of laying hens with or without antibiotic treated. The experiment was designed as a factorial arrangement of 3 dietary SS treatments × 2 antibiotic treatments. Birds were fed a basal diet (CON) or a low-SS diet (50 SS) containing 50 mg/kg SS, or a high-SS diet (500 SS) containing 500 mg/kg SS. Birds were cofed with or without antibiotics. The growth experiment lasted for 10 wk. Results showed that birds fed the 50 mg/kg SS diet tended to have lower abdominal fat rate. The gene expression of liver X receptor-α (LxR-α) in liver and serum total cholesterol (TC) were dropped, and the gene expression of acyl-CoA thioesterase 8 (ACOT8) in liver were upregulated. Compared with CON group, the levels of lysozyme, IL-10, and transforming growth factor (TGF-β) in the serum were elevated as along with gene expression of IL-10, TGF-β, and LYZ in ileum of both 50 and 500 SS group. However, the level of secretory immunoglobulin A (sIgA) and Mucin-2 in the ileum were downregulated in the 500 SS group. Additionally, Lactobacillus and Lactobacillus gasseri were the dominant bacteria in the 50 SS group, whereas the relative abundance of Lactobacillus was dropped in the 500 SS group. With combined antibiotics treatment, the α-diversity of bacteria was reduced, and the biological effects of SS were eliminated. In conclusion, the lipid metabolism, immune function, and intestinal flora of the laying hens were improved with the dietary supplementation of 50 mg/kg SS. But dietary 500 mg/kg SS had negative effects on laying hens.