Large intestine morphology and microflora activity in piglets fed diets with two levels of raw or micronized blue sweet lupin seeds

Abstract

Legumes are important protein source in human and animal nutrition. The experiment was performed on 32 weaned piglets divided into four groups. Animals were fed cereal-based diets with 109 g/kg of soybean meal and 150 g/kg of raw (LLR) or micronized (LLM) blue sweet lupin seeds or diets without soybean meal and with 300 g/kg of raw (HLR) or micronized (HLM) lupin seeds for 21 days. At the end of experiment tissue samples and digesta were taken from the caecum, proximal, middle and distal colon for histological measurements and analyses of dry matter, pH, short chain fatty acids, ammonia, phenolic compounds and bacterial enzyme activity. The animals fed diets with high lupin level had significantly smaller body weight gain (P = 0.001) than those fed diets with low lupin level aside from the micronizing process. Both, level and form of lupin had small effect on morphology of the large intestine. Dry matter content increased in caecum (P = 0.021) and in proximal colon (P = 0.048) in pigs fed diets with high level of lupin and in middle colon (P = 0.040) in pigs fed diets with micronized seeds. Only valeric acid concentration in caecum (P = 0.021) and proximal colon (P = 0.005) was affected by micronizing process. In distal colon valeric (P < 0.001), acetic (P = 0.008), propionic (P = 0.025) and butyric (P = 0.007) acids concentration increased in pigs fed diets with high lupin level. Ammonia concentration was also affected mainly by the level of lupin seeds. Concentration of phenolic compounds did not depend on the lupin level in the diets and in a small extent depended on the form of lupin. Pigs fed diets with high level of micronizing lupin seeds had significantly lower p-cresol concentration in proximal colon (P = 0.026) than pigs fed diets with raw seeds. The reverse relationship for p-cresol concentration was observed in middle colon. High lupin level decreased β-glucuronidase activity in proximal (P = 0.020) and in middle colon (P = 0.032). Mucinase was not significantly affected by experimental factors. The level and form of blue sweet lupin seeds had a small effect on histological parameters of the large intestine and might improve microbial activity in the pigs colon.