STABILIZATION OF INTESTINAL MAST CELLS AT WEANING IMPROVES PERFORMANCE OF EARLY WEANED PIGS

Previous work showed that weaning stress causes gut barrier dysfunction partly by triggering the release of corticotropin releasing factor (CRF) and thereby inducing the degranulation of intestinal mast cell (MC). This study investigated the hypothesis that attenuating the weaning-induced activation of the CRF-MC axis via administration of a MC stabilizing agent (cromolyn) may improve gut permeability and piglet performance after weaning. Twenty piglets (Large White x Landrace x Pietrain) were weaned (20 ± 1 d of age; 6.4 ± 0.4 kg of BW) and injected intraperitoneally with saline (control, n = 10) or 20 mg/kg BW of sodium cromolyn (CR, n = 10) at – 0.5, 8 and 16 h relative to weaning. Piglets were housed individually and fed ad libitum a pre-starter diet from 0 to 14 d postweaning followed by a starter diet until the end of the study on d 35. Body weight and feed intake were measured weekly; the plasma concentration of CRF and MC tryptase (MCT) was measured on d 2; and the plasma recovery of lactulose and Co-EDTA (Permeability markers) was assessed 1 h after intragastric infusion on d 2 and 35. On d 35, 8 pigs/treatment were sacrificed and their intestines were collected for later analyses. Performance data were analyzed with a mixed-effects model with repeated measures in time in which pig was treated as random effect and treatment, week, and their interaction as fixed effects. All other variables were analyzed with the same model without repeated measures. Plasma concentration of CRF, MCT, and permeability markers and mucosal morphology of the ileum were not affected by treatments. Although not significant, CR pigs had 15% more granulated MC in the ileum than control pigs (66.3 vs. 51.7 ± 0.10 cells/mm2; P < 0.20). On average, CR pigs consumed more feed (369 vs. 313 ± 13.6 g/d; P < 0.01), gained more BW (283 vs. 234 ± 11.7 g/d; P < 0.01), and grew more efficiently (0.60 vs. 0.40 ± 0.07; P < 0.05) than their control counterparts. As a result, pigs on the CR group were 1.4 kg heavier than those in the control group by d 35 (16.5 vs. 17.9 ± 0.17 kg; P < 0.01). In conclusion, interventions capable of moderating the weaning-induced activation of the CRF-MC axis may contribute greatly to improve pig performance after weaning. tech.service@fad.com