PRE-WEANING GROWTH AFFECTS COLONIC MUCOSA RESPONSE TO STRESS LONG-AFTER WEANING

Weaning-induced stress is associated with intestinal dysfunction and impaired piglet growth. In addition, body weight at weaning has life-long effects on pig performance. Therefore, the aim of this work was to elucidate if variation in pre-weaning growth correlate with differences in intestinal sensitivity to stress long after weaning. . To this end, 18 piglets ((LW x LD) x Pietrain) were weighed and identified at birth. At weaning (21 d of age) piglets were divided into two groups (n = 9): fast growers (FG) or slow growers (SG) according to their growth rate from birth to weaning. Thereafter, piglets were housed individually and fed ad libitum non-medicated pre-starter (21 – 35 d) and starter (35 – 56 d) feeds. Individual BW and feed intake were registered. On day 56 ascendant colon samples were harvested to measure the protein concentration of cortisol, TNF-α, CRH and the mRNA abundance of glucocorticoid receptor (GR), 11β-hydroxylase (CYP11B1), and 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1) in colonic mucosa. Performance data were analyzed with a mixed-effect model with repeated measures in which pig was treated as random and treatment, week, and its interaction were considered fixed effects. Colonic measurements were analyzed using a Student’s t tests. Pigs in the SG group had a lower pre-weaning growth rate (181 vs. 208 g/d; P < 0.04) and BW at d 21 (6.0 vs. 6.3 kg; P < 0.05) than FG counterparts. At d 56, no differences were observed in colonic CYP11B1, CRH, and GR between groups. Compared to SG, however, FG pigs had lower levels of colonic cortisol (20 vs. 2.5; P < 0.001) and TNF-α (0.15 vs 0.09; P < 0.01). In addition, the expression of HSD11B1 gene, which encodes for the enzyme that reduces cortisone to the active hormone cortisol, awas was downregulated (1 vs 0.68; P < 0.004) in the FG group. In conclusion, higher pre-weaning growth rate is associated with decreased intestinal sensitivity to stress , which partly may explain the long-lasting effects in animal performance. tech.service@fad.com