Impact of metabolizable protein source on performance and carcass quality in finishing cattle fed dry-rolled corn-based diets

Abstract Text: Previous reports have indicated that finishing cattle performance is linearly increased among cattle consuming corn-based diets with increasing amounts of MP. We evaluated effects of added MP from either dried distillers’ grains or porcine blood meal and corn gluten meal to finishing cattle fed dry-rolled corn-based diets designed to meet CP requirements. Two hundred and sixteen cross bred steers (362.3 ± 3.4 kg BW) were blocked by BW and randomly assigned to 18 pens. Subsequently, cattle were adapted to 1 of 3 dry-rolled corn-based diets formulated to meet or exceed cattle CP requirements. Treatments were a dry-rolled corn-based diet with added urea designed to meet CP requirements (Control), a diet designed to provide 200 g/d of additional MP from distillers’ grains (DGS), and a diet designed to provide 100 g/d additional MP from blood meal and 100 g/d of additional MP in from corn gluten meal (BMCGM). Samples of each feed ingredient, diet and refusals were collected weekly and composited prior to analyses for DM, OM, and N. Pen weight was measured each 28 d and initial and final body weight were determined by 2 sequential daily measures of individual steer BW. Overall DMI (9.6 ± 0.11 kg/d) was not different (P ≤ 0.18) between Control, DGS and BMCGM. However, feed efficiency was increased (P = 0.02) by additions of MP, but overall feed efficiency did not differ (P = 0.85) among source of added MP. Nonetheless, feed efficiency was greater (P = 0.05) from d 1 to 56 when additions of MP were from BMCGM compared to DGS. Similarly, ADG was greater (P < 0.01) for cattle fed additional MP, but did not differ (P = 0.22) between BMCGM and DGS. Metabolizable protein source had no effect (P ≥ 0.16) on USDA calculated yield grade (3.04 ± 0.05), marbling score (423.5 ± 4.9) or ribeye area (12.48 ± 0.1). However, there was a numerical tendency (P = 0.16) for cattle fed BMCGM to have greater back fat depth compared to Control.

Keywords: Cattle, Metabolizable Protein, Performance