Abstract :
High dietary threonine extraction by the digestive tract suggests that threonine contributes to maintain gut integrity. The aims
of this study were to investigate the intestine development and the growth performance of early-weaned piglets pair-fed
either a control well-balanced (C: 9.3 g threonine/kg diet) or a low-threonine diet (LT: 6.5 g threonine/kg diet) for 2 weeks.
As expected, LT piglets presented lower plasma free threonine compared with C piglets (118 v. 356612 mmol/l, P,0.001).
Dietary threonine supply altered neither growth performance nor growth of the intestine and of the other portal-drained viscera
(stomach, spleen and pancreas). Nevertheless, villus height was reduced in the ileum of the LT piglets compared with C piglets
(446 v. 714674 mm, P,0.05). This was also associated with a decrease in crypt width (P,0.05) and villus height-to-crypt
depth ratio (P,0.05). Whereas maltase and lactase activities did not change between the two groups, aminopeptidase
nitrogen activity was decreased in the ileum of LT piglets (269 v. 374627 IU/mg protein, P,0.05). The number of mucincontaining
goblet cells was not modified in the ileum and in the proximal part of the large intestine of the LT piglets compared
with the C piglets. In conclusion, despite no alteration of intestinal growth, villus hypotrophy associated with a reduction
of aminopeptidase nitrogen activity suggest an alteration of the structure of the ileum in early-weaned piglets fed a diet
supplying inadequate dietary threonine
