Effect of faba bean seeds with different content of proanthocyanidins on growth of rats, caecal enzyme activity and metabolism indices

Rats were fed for 6 weeks with diets containing seeds or their fractions (cotyledons and hulls) of two types of faba bean: colour-flowered varieties (dark seeds) and white-flowered strain (light seeds). Compared to dark seeds, the light seeds contained more crude protein (29.68% vs. 26.96) and less fibre (CF: 7.79 vs. 8.54% and DF: 24.74 vs. 28.93%). The light seeds contained also more a-galactosides (3.88%) than the dark seeds (3.37%). Amino acid composition, e.g. the content of lysine, methionine and cystine in the seeds and cotyledons of different types of faba bean was similar. The content of total polyphenols in light seeds of white flowered faba bean (2.79 g kg -1) was about five times lower than in dark seeds of colour-flowered varieties (10.95 g kg -1). Proanthocyanidins (condensed tannins) consist about 65% of the content of total polyphenols in dark seeds and about 1% of polyphenols in light seeds. The content of proanthocyanidins in the diet (about 2.7 g kg -1) significantly lowered the body weight gain of rats and protein efficiency ratio (PER). Proanthocyanidins decreased also the activity of ß-glucuronidase in the caecal digesta, without affecting the activity of a- and ß-glucosidase and a- and ß-galactosidase. Different proanthocyanidin content in the diet had no effect on the content of glucose, triglycerides and total cholesterol in the serum and activity of selected enzymes: aspartate aminotransferase, alanine transferase, superoxide dismutase and glutathione peroxidase.