Impact of Watermelon Rind and Sea Buckthorn Meal on Performance, Blood Parameters, and Gut Microbiota and Morphology in Laying Hens

Natural ingredients from fruits and fruit-derived by-products have gained special interest as dietary supplements in poultry because of their health-promoting effects. The present work aims to evaluate the impact of the dietary inclusion of watermelon rind and sea buckthorn meal on performances, blood parameters, and gut microbiota and morphology of laying hens. A 4-week trial was conducted on 90 Tetra SL layers (32 weeks old), assigned to three dietary treatments (C, E1, and E2). The C group hens were fed a basal diet based on corn-soybean meal. The experimental diets included 10 g of watermelon rind/kg fed (E1) and 20 g of sea buckthorn meal/kg fed (E2). During the feeding trial, we monitored the performances. Blood samples, intestinal tissue, and intestinal content were collected to assess the effect of dietary ingredients on health status, digestive enzyme activity, intestinal morphology, and gut microbiota characterization. From the blood samples, cholesterol and triglycerides significantly (<i>p</i> < 0.05) decreased in E1 and E2 compared with the C group. Dietary watermelon rind and sea buckthorn meal positively impacted villus height. Maltase and invertase activity increased only in the duodenum of the E2 group, while alpha-amylase decreased in the duodenum and jejunum of both E1 and E2 groups. The two supplements tested triggered Firmicutes and <i>Lactobacillus</i> spp. multiplication, while reducing harmful bacteria such as Bacteroidetes and Enterobacteriaceae. The study provides the first evidence that the dietary inclusion of watermelon rind and sea buckthorn meal can be used in laying hens’ diets with a beneficial impact on hens’ biochemical parameters, gut microbiota, and gut morphology.