Effects of degraded intake protein concentration in diets containing wet sorghum distiller's grains plus solubles on performance and carcass characteristics of finishing beef steers fed steam-flaked corn based diets
Shaw, Landon M.
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Two hundred crossbred steers (initial body weight [BW] = 359.4 kg) were used to determine the effects of degraded intake protein (DIP) concentration in diets containing 10% of the dry matter (DM) as sorghum wet distiller’s grains plus solubles (SWDG) on performance and carcass characteristics of finishing beef cattle fed steam-flaked corn-based (SFC) diets. Treatments consisted of a SFC-based control diet (without SWDG; Control; formulated to contain 13.5% CP) and three diets with 10% SWDG. Among the three SWDG diets, one diet (0 DIP) was formulated to have the same CP concentration as the Control diet (and therefore be potentially deficient in DIP), one diet had urea added to restore 50% of the difference in the DIP concentration between the 0 DIP diet and the Control diet (50 DIP), and one diet had urea added to restore 100% of the difference in the DIP concentration between the 0DIP diet and the Control diet (100 DIP). A completely randomized block design was used with pen as the experimental unit (10 pens/treatment). The average final BW was 605.3, 596.2, 586.7, and 582.6 kg for the Control, 0DIP, 50DIP, and 100DIP diets, respectively, with the BW of steers fed the Control diet being greater than that of all SWDG diets (P = 0.03). Cattle fed the Control diet also were greater than all SWDG diets in dry matter intake (DMI) for d 0 to 35, d 0 to 70, and d 0 to 105 (P = 0.01, 0.04, and 0.09, respectively). There was a linear decrease in DMI as level of DIP restored was increased for d 0 to 105 (P = 0.03) and d 0 to end (P = 0.02). During the entire study, ADG was superior for cattle fed the Control diet compared with the mean of all three SWDG diets (P = 0.04), whether based on live BW or carcass-adjusted BW (P = 0.04). As with DMI, there was a linear decrease in overall ADG as level of DIP restored increased (P = 0.08). For gain:feed ratio, the Control diet was greater (superior efficiency) than the average of all SWDG diets throughout the whole trial, both on a live BW basis (P = 0.05) and on a carcass-adjusted basis (P = 0.07). Not surprisingly, hot carcass weight was greater for cattle fed the Control diet compared with all SWDG diets (P = 0.03). The carcasses of steers fed the Control diet had greater values for both fat thickness at the ¾ measure opposite the split lean surface between the 12th and 13th ribs (P = 0.02) and USDA yield grade (P = 0.01). The percentage of carcasses that graded USDA choice did not differ (P >0.42) among treatments. Because of conflicting data with other research involving wet distiller’s grain, it is recommended that further studies are needed to determine the cause for the poorer performance when feeding SWDG under the conditions of this experiment and the negative response to increasing DIP level.