The use of pea seeds is limited due to the content of antinutritional factors that may affect gut physiology. Heat treatment such as extrusion may reduce heat-labile antinutritional factors and improve the nutritional value of pea seeds. This study determined the effect of partial replacement of soybean meal in pig diets by raw or extruded pea seeds on growth performance, nitrogen balance and physiology of the ileum and distal colon. The experiment was carried out in 18 castrated male piglets of initial body weight of 11 kg, divided into three groups. The animals were fed cereal-based diets with soybean meal (C), which was partly replaced by raw (PR) or extruded pea (PE) seeds. Nitrogen balance was measured at about 15 kg body weight. After 26 days of feeding, tissue samples were taken from the ileum and distal colon for histological measurements, and colonic digesta samples for analyses of microbial activity indices. The animals fed the PE diet had a significantly greater average daily gain than those fed the C diet and better apparent protein digestibility than those on the PR diet. Pigs fed the PR diet had a significantly greater butyric acid concentration and lower pH in the colon than pigs fed PE and C diets. There was no significant effect of the diet on other indices of microbial activity or morphological parameters. In conclusion, feeding a diet with extruded pea seeds improved growth performance of pigs, did not affect intestinal morphology and had a negligible effect on microbial activity in the distal colon.

The effects of indigestible carbohydrates, protein type, and protein level on large intestine health were examined in rats. For 21 days, 12 groups of six 12-week-old male Wistar rats were fed diets with casein (CAS), or potato protein concentrate (PPC), providing 14% (lower protein level; LP), or 20% (higher protein level; HP) protein, and containing cellulose, resistant potato starch, or pectin. Fermentation end-products, pH, and β-glucuronidase levels in cecal digesta, and ammonia levels in colonic digesta were determined. Cecal digesta, tissue weights, cecal and colon morphology, and colonocyte DNA damage were also analyzed. Digesta pH was lower, whereas relative mass of cecal tissue and digesta were higher in rats fed pectin diets than in those fed cellulose. Cecal parameters were greater in rats fed PPC and HP diets than in those fed CAS and LP diets, respectively. Short-chain fatty acid (SCFA) concentrations were unaffected by protein or carbohydrate type. Total SCFA, acetic acid, and propionic acid concentrations were greater in rats fed LP diets than in those fed HP. Cecal pool of isobutyric and isovaleric acids was greater in rats fed PPC than in those fed CAS diets. PPC diets decreased phenol concentration and increased ammonia concentration in cecal and colonic digesta, respectively. Cecal crypt depth was greater in rats fed PPC and HP diets, and was unaffected by carbohydrates; whereas colonic crypt depth was greater in rats fed cellulose. Myenteron thickness in the cecum was unaffected by nutrition, but was greater in the colon of rats fed cellulose. Colonocyte DNA damage was greater in rats fed LP diets than in those fed HP diets, and was unaffected by carbohydrate or protein type. It was found that nutritional factors decreasing cecal digesta weight contribute to greater phenol production, increased DNA damage, and reduced ammonia concentration in the colon.

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