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Dietary zinc deficiency has little effect on the architecture, enzyme activities and the microflora of the small intestine of weaned piglets

Zinc deficiency in rats has been shown to alter the villous-crypt architecture and enzyme activities of the small intestine. This model proved valuable in demonstrating the positive effects of probiotic on the restoration of intestinal alterations. Therefore, we conducted an experiment with this model of zinc deficiency in weaned piglets in order to develop it for studying alternatives to in-feed antibiotics. Two weaning diets supplemented (control) or not supplemented (Zn-) with zinc were formulated. The diets were pair-fed for three to four weeks to 32 piglets weaned at 21 days of age and placed in individual plexiglass-covered cages.

They had free access to demineralised water. Feed intake, bodyweight and consistency of faeces were recorded throughout the trial. At the end, the piglets were sacrificed. Blood was collected for zinc and alkaline phosphatase (a Zn-dependent metalloenzyme) determination. Organs and the gastrointestinal tract and its segments (full and empty) were weighed. Mucosal tissues from the small intestine were sampled for histomorphometry and determination of enzyme (maltase, amino-peptidase A, dipeptidyl peptidase IV and alkaline phosphatase) activity.

Jejunal digesta were sampled for bacteriology (total counts of anaerobes and aerobes, lactobacilli, enterococci and coliforms). Plasma levels of zinc and alkaline phosphatase were two and three-fold lower in the Zn-deficient group, showing the depression of the circulating pool of zinc and consequences on a Zn-dependent metalloenzyme. No diet effects were observed for feed intake, growth performance or consistency of faeces throughout the trial or on the weights of organs and gastrointestinal tract, except a tendency for a lighter pancreas in the Zn-deficient piglets.

However, the weight of fresh digesta in the stomach was higher, and that in the caecum and colon lower, with the Zn-deficient diet. No significant effect was observed on the villous-crypt architecture and enzyme activities of the mucosa of the small intestine, except a tendency for a smaller villous area in the Zn-deficient piglets. The intestinal microflora was little influenced by the diet. In conclusion, feeding a Zn-deficient diet for three to four weeks to weaned piglets had little effect on the villous-crypt architecture, enzyme activities and the microflora of the small intestine in this study. This limits the interest of the model for investigating alternatives to in-feed antibiotics in the weaned piglet.


Jean-Paul LALLES, (Senior Scientist, coordinator of the whole project)
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