Although natural weaning in the pig occurs at 6 to 8 weeks of age it is common commercial practice to wean at 3 to 4 weeks. This abrupt and early weaning is often associated with a more or less prolonged check in growth, frequent occurrence of gastrointestinal disease and a significant mortality. The transition from a milk diet to a solid diet in the post-weaning period necessitates complex digestive and metabolic adaptations in the piglet. Experiments in small animals have shown that some of the changes brought about by weaning are at least partially controlled by hormones from the adrenal cortex (Henning, 1981).

We have investigated the changes that occur in the mucosa of the small intestine and in the pancreas of pigs weaned at 21 days of age. In addition we have investigated the effects of an orally administered synthetic glucocorticoid (dexamethasone; DEX) given before weaning, on the development of the intestine and pancreas.

Two pigs from each of six litters were killed at 18 days of age, half of the remaining pigs were given DEX (0.4mg/kg ) suspended in agar (0.5%). This dose was divided into four equal aliquots and given by stomach tube on days 19 and 20. Controls received an equivalent volume of agar. Pigs were weaned at 21 days, two control and two DEX treated pigs were killed on the day of weaning and at 28, 35 and 42 days. After weaning pigs were allowed ad libitum access to a commercial starter diet.