Vitamin D₃ Nutritional Status Affects Gut Health of Salmonella-Challenged Laying Hens

Salmonella enterica serovar Enteritidis (SE) is one of the most common pathogens associated with poultry health and foodborne Salmonellosis worldwide. The gut plays a pivotal role in inhibiting SE transintestinal transmission and contaminating poultry products. The nutritional status of vitamin D (VD) is involved in gut health apart from bone health. However, the impact of VD₃ nutritional status on the gut health of Salmonella-challenged hens is rarely investigated. This study investigated the impact and possible mechanisms of VD₃ nutritional status on the gut health of hens challenged with SE. Hens were fed basal diets with either 0 (deficient) or 3000 IU (sufficient) VD₃/kg of diet, respectively. After 10 weeks of feeding, half of the hens were orally inoculated with either SE (1 × 10⁹ CFU /bird). Results indicated that VD₃ sufficiency reversed the disruptive effects on the laying performance of hens caused by Salmonella challenge or VD₃ insufficiency by promoting VD₃ metabolism. In addition, VD₃ sufficiency ameliorated gut injury induced by either Salmonella or VD₃ deficiency, shown by reducing Salmonella load and histopathological scores, suppressing TLR4-mediated inflammatory responses, and increasing expression of TJs along with decreasing pro-apoptotic protein expression and the number of TUNEL-positive cells in the jejunum. Besides, VD₃ enriched the abundance of probiotics, such as Lactobacillus and Bacilli, and restored the balance of gut microflora. Collectively, dietary VD₃ sufficient supplementation could alleviate Salmonella or VD₃ deficiency-induced intestinal damage of hens via modulating intestinal immune, barrier function, apoptosis along with gut microbiota composition, revealing that VD₃ could act as a novel nutritional strategy defending Salmonella invasion in hens.