Effect of weaning in the pig on ileal ion transport measured in vitro.

Early weaning in pigs results in small intestinal malabsorption and an increased susceptibility to E. coli infections. This is closely associated with villus shortening and crypt hyperplasia of the small intestine. The present study compared piglets either weaned at 3 weeks of age onto a high soya diet (n = 12) or an egg-based diet (n = 12) with piglets that remained on the sow (n = 12). Prior to weaning, care was taken to ensure that piglets only had access to sows milk. Serum anti-soya IgG was measured 7 days after weaning and sections of the mid-ileum excised and fixed for determination of crypt depth and villus height. Four pieces of 'stripped' mucosa were mounted in Ussing chambers in Krebs-phosphate Ringer (with indomethacin) for determination of short circuit current (SCC) and unidirectional fluxes of Na22 and Cl36, half in mucosa-serosa (MS), and half in serosa-mucosa (SM) direction. After basal measurements of absorptive capacity of Na, supramaximal doses of prostaglandin E2 (PGE2) and theophylline were added to measure the intestinal secretory capacity for Cl. Anti-soya IgG was elevated in the group weaned onto soya when compared either with the group weaned onto egg or the unweaned group. All intestinal transport and histological parameters were similar in both the weaned groups, although some were different from the unweaned. The SCC (equal to Na absorption) and the villus height were reduced two-thirds by weaning, whereas crypt depth and Cl secretion were similar in all groups. It is suggested that weaning per se is causal for the observed changes in intestinal transport and morphology, but they are not influenced by whether the weaning diet is soya or egg based.