The Effect of Different Dietary Protein Sources and Tannins on the Fattening Performance and Carcass Characteristics of Finishing Holstein–Friesian Bulls

The aim of this study was to evaluate the effect of different protein sources on the fattening performance and carcass characteristics of finishing bulls. Thirty HF bulls in three feeding groups were fed diets with different protein sources: rapeseed meal (RSM), Vicia faba seeds (VFB), and lupine seeds (LP). The proportions (g/kg DM) of feed ingredients in the diets were as follows: group RSM-MS (maize silage) 620, TG (Triticale grain) 210, and RSM 150; group VFB-MS 620, TG 170, and VFB 190; group LP-MS 620, TG 190, and LP 170. Bulls fed RSM were characterized by the highest ADG and feed intake, and the most desirable FCR (p < 0.05). Carcass conformation and fatness scores were higher in group RSM than in groups VFB and LP. Tannins contained in V. faba seeds did not exert a positive influence on feed intake, average daily gain (ADG) or the feed conversion ratio (FCR). The value of WBSF was lowest in group VFB, indicating superior meat tenderness (p < 0.05). The inclusion of feed component containing tannins resulted in lower (p < 0.05) redness and higher pH stability of their meat during storage.