Tannins - a dietary problem for hand-reared grey partridge Perdix perdix after release?

A 4-week feeding trial on 22 grey partridges Perdix perdix was conducted in this study. Seven birds were fed commercial poultry food, seven natural fo od and eight commercial poultry food containing 6% of quebracho-tannin. Our results suggest that 6% dietary tannin, when added to a commercial food wi th high protein content, effects the grey partridge only slightly. No diffe rence was seen in food consumption and body mass remained stable. However, birds fed tannin had longer small intestines, which most probably indicate gastrointestinal detoxication. They also excreted a high amount of tannin i n their faeces. In addition, no between-group variation was seen in cytochr ome P450 enzymes. Birds fed natural food had high concentration of nitrogen in intestinal excreta and high plasma alanine concentrations. They also su ffered a rapid decrease in body mass after the change in diet and their bod y mass remained low. This may indicate increased protein excretion and/or c atabolism of endogenous nutrient reserves. Potential short-term effects of the change in diet were seen in plasma. These findings coincide with the hi gh mortality period of birds released into the wild. (C) 2001 Elsevier Scie nce Inc. All rights reserved.