Polyethylene glycol inactivates red grape pomace condensed tannins for broiler chickens.

1. This study was conducted to investigate the effect of inactivating GP condensed tannins using graded levels of polyethylene glycol (PEG) on feed intake, physiological, carcase, and meat quality traits of male Cobb 500 broilers. 2. Three hundred, two-week old, male Cobb 500 broilers (334.6 ± 21.43 g live weight) were allocated to 30 pens carrying 10 birds each. Five isonitrogenous and isoenergetic diets were formulated for grower (14-35 d) and finisher (36-42 d) phases by diluting a commercial broiler diet with untreated GP (PEG0) at 6.5% (w/w) or with the same amount of GP but pre-treated with PEG at 2.5% (PEG1), 5% (PEG2), 10% (PEG3) or 15% (w/w) (PEG4) and randomly allocated to pens in a four-week feeding period. 3. Feed intake, weight gain, feed conversion efficiency (FCE), and blood, carcase and meat quality parameters were determined. Weekly weight gain and FCE linearly (P < 0.05) increased in week 4 and linearly (P < 0.05) decreased in week 6 in response to PEG treatment levels. 4. Mean corpuscular volume linearly (P < 0.05) decreased in response to PEG levels, whereas blood urea nitrogen/creatinine ratio, urea, total protein, globulin and cholesterol showed quadratic trends in response to PEG levels. Spleen and ileum weights tended (P < 0.1) to linearly decrease with PEG levels. Heart weight and meat redness tended (P < 0.1) to quadratically respond to increasing levels of PEG. 5. It was concluded that PEG treatment partially inactivated GP condensed tannins without compromising the health status of broiler chickens. An optimum PEG inclusion level could not be determined for feed intake, weight gain and FCE. However, the presence of other antinutrients such as fibre and low molecular weight phenolics in GP may be responsible for the linear decreases observed in this study.