Effects of tannic acid on growth performance, carcass characteristics, digestibility, nitrogen volatilization, and meat lipid oxidation of steers fed steam-flaked corn-based finishing diets

Effects of a tannic acid blend (ByPro; Silvateam USA, Ontario, CA) added to steam-flaked corn–based fishing diets on beef cattle growth performance, carcass characteristics, nutrient digestibility, fecal N volatilization, and meat lipid oxidation were evaluated. Steers (n = 144; 349 ± 25 kg initial BW) were blocked by initial BW and assigned randomly to 1 of 3 treatments with 12 pens/treatment and 4 steers/ pen and fed ad libitum. Treatments included a control (CON; no ByPro) and ByPro fed at 30 or 60 g DM/ steer daily (30-ByPro and 60-ByPro, respectively). Pen fecal samples were collected 7 d after cattle were shipped to slaughter for estimation of N volatilization. Strip loins were aged for 21 d for evaluation of color and antioxidant activity. Intake quadrati-cally increased (P = 0.05) from d 0 to 35, whereas linear trends were observed for increased DMI from d 0 to 105 and d 0 to slaughter (P = 0.07 and P = 0.06, respectively), resulting in a 3.7% greater overall DMI for 60-ByPro than for CON. No differences were detected for carcass-adjusted ADG (P = 0.65) or G:F (P = 0.17). Carcass characteristics including HCW (P = 0.52), fat thickness (P = 0.32), LM area (P = 0.57), quality grade (P = 0.44), yield grade (P = 0.29), and percentage of condemned livers (P = 0.13) were not affected by treatments. Apparent total tract digestibility of starch linearly decreased tendency (P = 0.03) with increasing ByPro dose, whereas tends for a linear decrease (P = 0.09) in CP and a quadratic increase (P = 0.09) in OM digestibility were observed. No effects of treatment (P ≥ 0.39) were noted for fecal N volatilization. An increase (P < 0.01) in metmyoglobin in strip loin steaks was observed with ByPro inclusion. Oxymyoglobin decreased (P < 0.01) as display day progressed, except on d 5, at which time CON and 30-ByPro steaks had lower proportions than 60-ByPro steaks. Only subtle changes in discoloration ratio and deoxymyoglobin were observed, whereas no effects (P ≥ 0.43) for pH or thiobarbituric acid reactive substances were noted. Feeding ByPro increased DMI during the first half of the feeding period without negatively affecting gain efficiency; however, fecal N retention was not altered by ByPro. ByPro did not negatively affect meat quality or carcass characteristics, and it did not seem to affect retail meat antioxidant activity.