Effects of phytosterol ester supplementation on egg weight, biochemical indices, liver immunity and gut microbiota of laying hens during peak laying period

This experiment was aimed to investigate the effects of Phytosterol Ester (PSE) supplementation on egg weight, biochemical indices, liver immunity and gut microbiota of Hy-Line Brown laying hens during peak laying period. A total of 256 healthy Hy-Line Brown laying hens were randomly allocated into four groups. Laying hens in the control group were fed a basal diet (Control), while those in the experimental group received a basal diet containing 10 mg/kg (PSE10), 20 mg/kg (PSE20), or 40 mg/kg (PSE40) mg/kg PSE, respectively. We found that PSE supplementation significantly increased the egg weight in PSE20 and PSE40 groups (P < 0.05) and the serum magnesium (Mg) content in PSE10 and PSE20 groups (P < 0.05), but significantly decreased the serum calcium (Ca) content in PSE40 group (P < 0.05). Moreover, PSE supplementation significantly increased the total protein (TP) content of ovary in all experimental groups (P < 0.01) and decreased the total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) content of ovary in PSE20 and PSE40 groups (P < 0.0001). In serum, PSE supplementation significantly increased TP content in all experimental groups (P < 0.01) and albumin (ALB) content in PSE20 group (P < 0.05). Alkaline phosphatase (AKP) content was significantly decreased in PSE20 group (P < 0.05). TC content significantly decreased in all experimental groups (P < 0.05). LDL-C content was significantly decreased in PSE20 and PSE40 groups (P < 0.05). In egg yolk, dietary PSE supplementation significantly increased TP content in PSE20 and PSE40 groups (P < 0.01) and significantly decreased TC content in PSE20 group (P < 0.01). In liver Immunohistochemistry, PSE supplementation alters the content and distribution of CD163, especially in PSE20 group. Dietary PSE can increase the Alpha diversity of gut microbiota, and change the Beta diversity, indicating that the number and type of intestinal bacteria have changed. PSE significantly decreased Bacteroides and Desulfovibrio, and added Faecalibacterium, g_unclassified_f_Lachnospiraceae, g_norank_f_Ruminococcaceae, g__unclassified_f__Oscillospiraceae, Fournierella, g_Prevotellaceae_UCG-001 and other bacteria. In conclusion, PSE supplementation increased the average egg weight, lowered egg yolk, serum and ovary cholesterol and increased total protein of Hy-Line Brown laying hens during peak laying period. At the same time, the dose of 10-40 mg/kg PSE did not increase the burden on the liver and kidneys, and also promoted serum magnesium levels, enhanced liver immunity, and improved gut microflora.