Effect of segregated early weaning on postweaning small intestinal development in pigs

The effect of segregated early weaning (SEW) on postweaning small intestina l development was investigated in SEW and control(CON) pigs. Small intestin es were collected from a total of 15 pigs killed at 11 (preweaning), 15 (3 d postweaning), and 34 d of age. At 3 d postweaning, the SEW and CON pigs h ad shorter villi (P < .01), deeper crypts (P < .01), and reduced (P < .01) ratios of villus height:crypt depth (V:C) compared with preweaning. Weaning also reduced specific activities of lactase (P < .01) in duodenum and ileu m and alkaline phosphatase (ALP) (P < .05) in duodenum and jejunum. Sucrase activity in the three regions of the small intestine marginally decreased in both groups at 3 d postweaning. The mucosal protein:DNA ratio in duodenu m and jejunum increased (P < .05) in SEW and CON pigs at 3 d postweaning co mpared with preweaning pigs. The SEW and CON treatments resulted in differe nces in postweaning gut development. At 15 d of age in SEW pigs, the mucosa l protein:DNA ratio in duodenum and jejunum were 20 and 25.5% (P < .05) les s, respectively, than those in CON pigs. However, at 34 d, these ratios in duodenum, jejunum, and ileum were 43.5 (P < .05), 24.3, and 32.9% (P < .05) greater, respectively, in SEW pigs than in CON pigs. Longer villi, shorter crypts (P < .01), and higher V:C ratios (P < .01) in jejunum and ileum wer e observed in SEW pigs vs CON pigs at 34 d of age. The specific activities of lactase in duodenum (P < .01) and jejunum (P < .05) and of ALP in duoden um (P < .01) were higher in SEW pigs. Sucrase activity in duodenum, jejunum , and ileum was 21.7, 46.3 (P < .05), and 11.2% greater in SEW pigs at 34 d of age. These results demonstrate differences in postweaning gut developme nt between SEW and CON pigs. Furthermore, the number of intraepithelial lym phocytes in jejunum was greater (P < .001) in 34-d-old SEW pigs compared wi th CON pigs. Microscopy revealed a thick mucus coating over epithelial cell s in the ileum of 34-d-old CON pigs that was not apparent in the SEW pigs. These observations are consistent with reduced pathogen exposure associated with SEW. We suggest that segregated early weaning advances postweaning gu t maturation, which is consistent with improved growth and feed efficiency observed in SEW pigs.