Increasing diet viscosity using carboxymethylcellulose in weaned piglets stimulates protein digestibility

Ileal indigestible protein may be an important factor for the occurrence of post weaning diarrhoea in piglets. Depending on the quantity of indigested protein, an imbalance in the microbial community can occur, resulting in an overgrowth of pathogens. Diet viscosity may influence nutrient digestibility and substrate availability for microbial growth. Therefore, we examined the effect of dietary viscosity in piglet nutrition. Carboxymethylcellulose (CMC) was added as a model substance in order to increase diet viscosity. The effect of 1% supplemented CMC on nutrient digestibility, morphological and physiological parameters was measured in piglets 3 weeks post weaning at 26 days of age. The main effects of inclusion of CMC were:–A 10% slower gastric emptying rate (P = 0.18).–An increased protein hydrolysis in the gastric fraction, measured as increased nitrogen concentration in the liquid phase of gastric contents (26% in control vs. 34% in experimental group; P = 0.13).–An increased production of the protein hydrolysing enzyme amino-peptidase from 359 U/g protein for the control diet to 516 U/g protein for the experimental diet (P < 0.01).–A numerical increase in apparent ileal protein digestibility by 6% from 75.2% to 79.5% (P = 0.22) and a significant increase in faecal protein digestibility by 5% (P = 0.044).These results indicate that an optimized diet viscosity might be one factor exerting a beneficial influence on protein digestibility. We hypothesize that the effect of diet viscosity on gastric emptying rate is the major factor.