Small intestine development in chicks after hatch and in pigs around the time of weaning and its relation with nutrition: A review

The period after hatch in broilers and around the time of weaning in pigs is critical for development and for adaptation of the small intestine to the nutritional changes. In broilers, the small-intestinal weight relative to body weight and villous height increase rapidly during the first week after hatch. After the first week, the relative small-intestinal weight decreases gradually, but the villous height continues to increase. In pigs, at 4 d after weaning, villous height decreases to about 60% of the pre-weaning height when weaned between 1 and 4 wk of age. Two weeks after weaning, this recovers to similar values as in unweaned control animals independent of weaning age. Small-intestinal development after hatch and after weaning consistently deteriorates at low feed intake levels and with suboptimal protein nutrition. These findings stress the importance of applying an optimal nutritional strategy in these phases of life to reach optimal small-intestinal development.