Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

The effects of weaning age (weeks 4 versus 7), social stress, and creep feed intake on the gut integrity in piglets

This study was assigned to confirm if:

- A delayed weaning results in a better performance, gut integrity and welfare of weaned piglets;

- Antibiotic-free, creep-feed intake improves the gut integrity;

- Developing a pig specific ELISA for determination of intestinal fatty acid binding protein (I-FABP) as a potential serological marker for intestinal damage and assessment of welfare in both intensive and extensive management systems.

The first two objectives were targeted in an experiment involving in total 16 litters (160 sucking piglets at 2 days of age). Eight litters were offered creep feed (barley-based) from day 12 of age, and the remaining not. A half of those animals (fed without and with creep feed) was weaned at 4 weeks of age, and the other half at 7 weeks of age. After weaning all piglets were offered the same creep feed. At day 1 pre-weaning, and days 3 and 6, post-weaning seven piglets from each group were euthanized to obtain intestinal tissue slices for studies of macromolecular transport in Ussing chambers. Besides, the morphological indices (villous heights and crypt depths) were measured in these intestinal slices.

Although prolonging the sucking period of piglets from 4 to 7 wk of age resulted in a milder weaning stress (=lower cortisol levels in blood) and slightly longer epithelial villi, no significant differences due to the weaning age could be found in the gut integrity (as measured in terms of net fluid absorption from the intestinal lumen or paracellular transport and I-FABP levels). Despite the consumption of creep feed by piglets up to 4 weeks of age was rather limited, the intestinal paracellular fluxes and villous heights were greater (P<0.05) in comparison to their littermates, which were deprived of the creep feed. Both groups did not differ in cortisol levels (=weaning stress) and the gut integrity (=net fluid absorption and I-FABP levels). Post-weaning growth retardation could be observed in piglets, which received no access to creep feed during 7-week sucking periods.

Another objective of this study was to develop a pig specific ELISA for determination of I-FABP as a potential serological marker for intestinal damage and rapid assessment of welfare in both intensive and extensive management systems. As demonstrated in human and rat studies, this biomarker is exclusively expressed in intestinal epithelial cells, is a small intracellular protein, has a high level of expression, and is detectable in the circulation and urine.

For this purpose were used 6 young boars (20-25 kg BW). They were anaesthetized to place catheters in the carotid artery + blood flow probe (around the arteria mesenterica cranialis, AMC). After initial blood sampling (t=0), three jejunal segments (10-20cm) were ligated, and again blood sampling was carried out (t=30 min and further in 15min intervals). At t=60min was a clamp placed around AMC (to get 90% ischemia). At t=60, 120 and 150min the ligated loops were removed, and the mucosal layer was removed. Afterwards, the measurements of macromolecular permeability using horse radish peroxidase (HRP) were carried out in Ussing chamber for 2 h. After 90 min clamping, the intestines were re-perfused and blood flow re-established as normal.

The EDTA-plasma was tested with ELISA test kit for humans with rabbit polyclonal antibodies, and purified human I-FABP as standard. During 60min of surgery plasma I-FABP appeared to be stable (=no intestinal damage). At 90% ischemia, a rapid increase of I-FABP during 30min, and plateau after 60min (at t=120min). Reperfusion at 150min had no impact on plasma I-FABP (whereas in rodents ischemic injury is exacerbated).

In conclusion, we found that a rise of I-FABP in plasma coincides with increased intestinal permeability due to ischemia. Alike in humans, plasma I-FABP concentrations in pigs can be used as sensitive biomarker of (mild) damage of the intestinal mucosa. The porcine I-FABP cDNA sequence has been determined and it appeared to be of a high identity with homologous genes from other species. This sequence allows us to clone and purify recombinant porcine I-FABP in order to raise specific antibodies and develop an assay for porcine I-FABP. A key innovative feature is that the established values of I-FABP can serve as as a rapid diagnostic tool for monitoring "on site" the pig intestinal health status and welfare.

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Reported by

Animal Sciences Group Lelystad
Edelhertweg 15
8200 AB LELYSTAD
Netherlands
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