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Transient changes in intestinal properties in piglets due to weaning and inclusion of PHA lectins in the piglet diets

Experiments were conducted in weaned piglets with or without PHA lectins from Phaseolus vulgaris beans included in the diet in various levels and periods post weaning. PHA lectins adhere to the mature cells of the villi in the digestive tract thus reducing the absorptive capacity of the villi. This increases the amount of substrate in the small intestine and induces bacterial growth, especially proliferation of E. coli. In this respect PHA lectins increase the intestinal damage as caused by the weaning process. PHA was included as a model substance to induce and standardise the intestinal damage in newly weaned piglets.

The development of the digestive tract was recorded on days 0, 7 and 14 post-weaning. In general, the parameters suggest a decrease in integrity and digestive capacity during the first week post weaning and a gradual recovery of the gut in the second week post weaning. Villus height, villus/crypt ratio, enzyme activity and fat digestibility were reduced on day 7 and increased up to day 14 post weaning. The development of the microflora in this period was confirmed by an increase in the number of DGGE bands in ileal chyme and feaces and a decrease in number of E. coli bacteria.

The weaning process caused a transient decrease in colonisation resistance and digestive capacity of the digestive tract, as indicated by morphological, physiological and bacterial characteristics. Partial recovery took place from day 7 to day 14 post-weaning. In our experiments, villus height, enzyme activity and fat digestibility were the most responsive parameters. Feed intake was very low in the first week post weaning and correlated to the reduced villus height and digestive capacity. A gradual increase in feed intake in week 2 to avoid bacterial overgrowth improved faecal fat digestibility and increased the number of DGGE bands, suggesting an improved colonisation resistance.

The inclusion of PHA lectins reduced the villus height and tended to reduce ileal fat digestibility and increase the number of E. coli bacteria in the faeces on day 7 post weaning. Voluntary feed intake of the piglets decreased with the inclusion of PHA lectins in the diet. This decrease relative to the control diet was 5-15% in the first week and 25-35% in the second week of PHA inclusion respectively. Feed intake decreased with increasing inclusion of Phaseolus vulgaris in the diet. Furthermore, the reduction in feed intake was relatively higher when lectins were included in week 3-4 post weaning compared to inclusion in week 2-3 post weaning.

Daily gain of the piglets was drastically reduced by inclusion of PHA lectins by 30-50% and 50-70% in the first and second week of PHA inclusions respectively. This decrease resembles the lower feed intake with lectins. In addition, the feed conversion ratio was drastically increased with lectins in the diet. The faecal consistency was lower with inclusion of lectins in the second week of inclusion, but not in the first week.

PHA lectins were included in some treatments to induce a relatively standardised damage of the digestive tract, as previously described. This destructive effect of lectins was confirmed by a reduced villus height, fat digestibility and sucrase-isomaltase activity. However, PHA lectins in the diet also reduced voluntary feed intake compared to the control diet. This indicates that PHA lectins may have a direct effect and an effect mediated by feed intake, since a lower feed intake by itself also influences intestinal parameters. Results of a growth experiment demonstrated a reduced growth performance and feed utilisation with PHA lectin inclusion in the diet. This indicates a lower digestion of the feed because of intestinal malfunctioning due to lectin inclusion.

The lower faecal consistency is in agreement with this result.

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Reported by

Schothorst Feed Research
Meerkoetenweg 26
8218 NA Lelystad
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