Retinol is involved in the intestinal regeneration and strengthens the intestinal barrier during refeeding in broiler chickens

Fasting is typically used before feeding metabolizable energy assessment in broilers. Previous studies have shown that fasting cause atrophy of the intestinal villus. Whether fasting affects intestinal permeability during refeeding by altering barrier function and nutrient absorption is of concern. Here, 23-d-old broilers were randomly assigned to 5 treatments, fasted for 0, 12, 24, 36, and 48 h, respectively, and then refed for 2 d, to study the impact of different duration of fasting on the intestinal regeneration and barrier function during refeeding. Results showed that the intestinal morphology in fasted birds was recovered in 2 d of refeeding at most. As fasting durations increased, enterocytes per intestinal villus were linearly and quadratically increased (both P