Diet composition and gut integrity in weaned piglets

This thesis deals with the effects of dietary modulation of protein and carbohydrates under controlled energy intake on small intestinal integrity in weaned piglets. Small intestinal integrity is assessed on the basis of indicators regarding morphology (villus length, crypt depth), functionality (enzyme secretion and permeability across the gut wall) and inflammation (cell differentiation molecules on T cell lymphocytes and haptoglobin levels in blood plasma). The piglets were offered a predetermined maximum amount of feed in order to prevent entanglement between the effect of feed intake level and the effect of diet composition itself on small intestinal integrity. The effectiveness of protein versus lactose was investigated by changing the ratio of protein to lactose in the diet. Results indicated that lactose seemed more limiting than protein for epithelial cells in contributing to mucosal integrity during the first days after weaning. Therefore the specificity of lactose as carbohydrate source was investigated by feeding the piglets either glucose, lactose or native starch. However, those carbohydrate sources did not differentially affect mucosal integrity. Furthermore, changing protein digestibility or predigestion of protein did not affect mucosal integrity. Across diets, degeneration of the small intestine occurred already after one day postweaning and seemed more pronounced in the proximal small intestine, regeneration during the second week postweaning seemed more pronounced in the mid small intestine. The association between measurements regarding faeces consistency and small intestinal morphology was poor. It was concluded that the effect of the weaning induced low energy intake is in general more pronounced than the effect of diet composition on small intestinal integrity.