Dynamic changes in digestive capability may contribute to compensatory growth following a nutritional insult in newly weaned pigs

We have previously demonstrated that feeding low complexity diets (LOW) compromises growth performance of pigs during the first 3 wk after weaning and induces compensatory growth and improved feed efficiency thereafter. A study was undertaken to explore physiological mechanisms involved in compensatory growth following a nutritional insult. Fifty-six pigs were weaned at 21 +/- 2 d of age and fed high complexity diets (HIGH) for 6 wk. All pigs received the same grower diet thereafter. Pigs were killed at weeks 2, 4, and 8 after weaning and proximal jejunum and distal ileum were sampled for evaluation of histology and enzyme activity. In the proximal jejunum, villus height was lower (P = 0.03) at week 2 in pigs on LOW than HIGH but not different at week 4. There was no effect of diet on crypt depth; villus height: crypt depth ratio increased (P = 0.02) from week 2 to week 4 in pigs on LOW but was not changed in pigs on HIGH. Diet did not impact gut morphology at the distal ileum. Enzyme activity was lowest (P < 0.05) at week 2 for sucrase and aminopeptidase N (APN) and lowest (P < 0.06) at week 8 for lactase. Sucrase activity was numerically higher at week 4 in pigs fed LOW but numerically higher at week 8 in pigs fed HIGH. Lactase and APN activity were not affected by diet. Compensatory growth observed in pigs following a nutritional insult after weaning may be due in part to improved digestive capability.