Effects of Glyceryl Monolaurate on Production Performance, Egg Quality, Oviduct Cytokines and Intestinal Microflora of 66 Weeks Old Laying Hens

SIMPLE SUMMARY: It has been proved that glyceryl monolaurate is a safe and green additive in food and feed. The purpose of this experiment was to study the potential application value of glyceryl monolaurate in the diet of laying hens in the late laying period. Our results indicate that the dietary supplementation of glyceryl monolaurate could significantly improve laying performance and egg quality, reducing inflammation, promoting immune function and intestinal barrier function as well as regulating the intestinal flora of laying hens. ABSTRACT: The principal purpose of this research was to study the effects of glycerol monolaurate (GML) on the production performance; egg quality; health state of the oviduct, ovary and ileum; and gut microbiota of laying hens in the later stage. The laying hens were randomly assigned to two groups: a control group and an experiment group, for which 1000 mg/kg of GML was added to a control diet. The results showed that GML increased the laying rate, average egg weight, albumen height, yolk color and Haugh unit and decreased the feed conversion ratio and defective eggs (p < 0.05). GML increased the intestinal villi height and the ratio of villus height to crypt depth (p < 0.05). Moreover, GML improved the contents of cytokines in the oviduct, ovary and ileum mucosa; ameliorated the expression of TLR2, TLR4, MyD88, IL-4, IL-1β and TNF-α; and increased the expression of Occludin and Muc-2 in the ileal mucosa. The supplementation of GML increased the volatile fatty acids in the cecal contents, such as acetic acid and propionic acid, and up-regulated Bacteroides (p < 0.01) and Alistipes (p < 0.05) richness in the cecal contents. In summary, GML improved production performance, egg quality and immunity; ameliorated the health status of the oviduct, ovary and ileum; enhanced the intestinal barrier function; improved the content of intestinal volatile fatty acids; and regulated the abundance of cecal flora.