Effects of Hulls of Faba Beans zyxw (Vicia zyxw faba L.) with a Low or High Content of Condensed Tannins on the Apparent Ileal and Fecal Digestibility of Nutrients and the Excretion of Endogenous Protein in Ileal Digesta and Feces of Pigs' A.J.M. Jansman*vtp2, M.W.A. Verstegenf, J. Huisman", and J.W.O. van den Berg* z *TNO Nutrition and Food Research Institute, Department of Animal Nutrition and Physiology (ILOB), P.O. Box 15, 6700 zyxwvu AA Wageningen, The Netherlands; +Agricultural University, Department of Animal Nutrition, Haagsteed zyxwv 4, 6708 PM Wageningen, The Netherlands; and *University Hospital Dijkzigt, Department of Internal Medicine 11, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands ABSTRACT: In three experiments (Exp. 1, 2, and 3) with young pigs (BW 10 to 26 kg), the effects of dietary inclusion of hulls of faba beans zyxwvut ( Vicia zyxwvutsr faba L. (200 g/kg) with a low (<.l% catechin equivalents; LT) or high tannin content (3.3% catechin equiva- lents; HT) on the apparent ileal (Exp. 1 and 2) and fecal (Exp. 3) digestibility of nutrients were deter- mined. In addition, the true digestibility of protein of the diets and the excretion of endogenous protein (N x 6.25) in ileal digesta and feces of pigs were measured, using the 15N isotope dilution technique (Exp.3). Diets contained either casein and faba bean cotyledons as highly soluble (HS) protein sources (Exp. 1 to 3 ) or potato protein, soy concentrate, sunflower meal, meat meal, and fish meal as protein sources with a low solubility (LS) (Exp. 1). Control diets contained cellulose as a fiber source (64 to 73 g/kg). Inclusion of either type of hulls decreased the apparent ileal digestibility forDM, organic matter (OM), and non- protein organic matter (NPOM) (P < ,051. Inclusion of LT hulls instead of cellulose only reduced the apparent ileal digestibility of crude protein (N x 6.25; CP) in Exp. 3 (P .05). Inclusion of HT instead of LT hulls reduced the apparentileal digestibility of CP (by 7 to 10 units) and amino acids (by 4 to 29 units) (P < .05). The LT hulls decreased apparent and true ileal digestiblity of CP from SS to S3 and from 97 to 94, respectively (P < .05). Inclusion of HT instead of LT hulls decreased apparent and true ileal CP digestibil- ity from 83 to 74 and 94 to 90 (P < .05) and increased the excretion of endogenous CP from 22 to 32 and from 13 to 23 g/kg of DM intake at the ileal and fecal level, respectively (P < .05). It is concluded that condensed tannins in faba beans interact with both dietary and endogenous proteins in the digestive tract of pigs. This reduces the true digestibility of dietary protein and increases the excretion of endogenously secreted proteins. Tannins from faba beans show some prefer- ence to interact with proteins with a high content of proline and histidine. Key Words: Pigs, Tannins, Faba Beans, Digestibility, Endogenous Protein, 15N Dilution Technique Introduction Faba beans ( Vicia faba L.) contain antinutritional factors zyxwvutsr (M) such as condensed tannins that are found in particular in the hulls of colored-flowering varieties (Bos and Jetten, 1989). Tannins are water- soluble polyphenolic compounds that are able to 'The authors wish to thank P. van Leeuwen and D. J. van Kleef for surgery on the experimental pigs and H. Schulze and T. Zandstra for their assistance during the experiment. 'To whom correspondence should be addressed. Received August 24, 1993. Accepted August 15, 1994. J. Anim. Sci. 1995. 73:118-127 precipitate proteins from aqueous solutions (Butler, 1989). In vivo, tannins may cause a number of different antinutritional effects such as reduced feed intake, decreased nutrient digestibility, and reduced animal performance (Jansman, 1993). In the gas- trointestinal tract, they can interact with both dietary and endogenous proteins. Condensed tannins from faba beans reduced the activity of trypsin in digesta obtained from the small intestine of pigs (Jansman et al., 1994). This suggests that tannins interact with digestive enzymes. Information on the effects of condensed tannins from faba beans on the apparent ileal digestibility of protein and amino acids in pigs is scarce. The origin of 118 Published December 11, 2014