Effects of wet corn gluten feed and yellow grease on digestive function of cattle fed steam-flaked corn-based finishing diets

Twelve ruminally cannulated, English-crossbred steers (436 ± 16 kg) were used in a completely random experiment to evaluate the influence of dietary wet corn gluten feed (WCGF) and yellow grease (fat) in steam-flaked corn-based finishing diets on diet intake, digestibility, and rumen fermentation characteristics. Treatments consisted of steam-flaked corn-based diets containing the following WCGF/fat combinations: (1) 0 g/kg WCGF/30 g/kg added fat (STD3), (2) 250 g/kg WCGF/0 g/kg added fat (WCGF0), and (3) 250 g/kg WCGF/30 g/kg added fat (WCGF3). Steers fed WCGF3 consumed more (P=0.01) dry matter (DM) than did those fed STD3 or WCGF0 (23.5 > 18.4 = 18.8 ± 0.9 g/kg of body weight (BW) daily, respectively). Organic matter intake was also greater (P≤0.02) for WCGF3-fed steers than steers fed STD3 and WCGF0 (22.1 > 17.7 = 17.8 ± 0.8 g/kg BW, respectively). Total tract digestibilities of DM, organic matter (OM), neutral detergent fiber (aNDF), acid detergent fiber (ADF), and crude protein (CP) were not different (P≥0.15) in the 3 groups. Digestion of aNDF was greater in cattle fed WCGF3 and WCGF0 than in those fed STD3 (1.6 = 1.3 > 0.8 ± 0.1 g/kg BW, respectively). Ruminal fluid dilution rate (0.075 > 0.057 = 0.052 ± 0.4/h for WCGF3, WCGF0, and STD3, respectively) and particulate passage rate (0.059 > 0.042 = 0.036 ± 0.4/h, for WCGF3, WCGF0, and STD3, respectively) increased (P<0.03) in steers fed WCGF3 compared with those fed WCGF0 and STD3. Ruminal pH was greater (P<0.05) in steers fed WCGF0 than in those fed WCGF3 and STD3 (5.9 > 5.4 = 5.3 ± 0.1, respectively). Total ruminal volatile fatty acids (VFA) in WCGF0-fed steers tended to be less (P<0.09) than in steers fed WCGF3 or STD3 (97.8 < 119.4 = 122.6 ± 6.8 mM, respectively). Ruminal propionate concentration (mol/100 mol) tended to be greater (P≤0.06) in steers fed WCGF3 (43.4 ± 2.1) than in those consuming WCGF0 (35.0 ± 2.1) or STD3 (34.0 ± 2.1). The acetate:propionate ration tended to be greater (P<0.09) in steers fed STD3 and WCGF0 than in those fed WCGF3 (1.3 = 1.3 > 0.9 ± 0.1, respectively). Supplementing 30 g/kg fat to a finishing diet containing 250 g/kg WCGF increased DM intake due to faster liquid and particle passage rates, and to increased total tract nutrient digested.