Beef finishing and dairy lactation experiments were conducted to evaluate the nutritional value of distillers grains (DG) from sorghum or corn fermentation, in both wet (35.4% DM) and dry (92.2% DM) form (dairy trial only). In the finishing experiment, 60 yearling steers were used in a completely randomized design with three diets that were fed for 127 d: 1) control diet with 86% (DM basis) dry-rolled corn and no DG; 2) 30% of ration DM as wet corn DG in place of dry-rolled corn; and 3) 30% of ration DM as wet sorghum DG in place of dry-rolled corn. All diets contained a minimum of 6.8% degradable intake protein and 13.0% CP. Steers fed DG had 10% greater ADG (< 0.01) and 8% greater efficiency of gain (P < 0.01) than steers fed the control diet. Wet corn and sorghum DG resulted in similar ADG and efficiency of gain. Hot carcass weights, fat thickness, and yield grades were greater for steers fed DG than for controls (P < 0.07). Improvements in ADG and feed efficiency observed when DG replaced dry-rolled corn indicated that the NEg content of wet DG is approximately 29% greater than that of dry-rolled corn. In the dairy lactation experiment, 16 lactating Holstein cows (eight multiparous, including four fistulated) were used in a replicated 4 x 4 Latin square design with 4-wk periods. Corn and sorghum DG were fed at 15% of the ration DM in either wet or dry form. Diets were fed as total mixed rations that contained 50% of a 1:1 mixture of alfalfa and corn silages, 24.3% ground corn, and 9.1% soybean meal (DM basis). There was no effect of source or form of DG on DMI, ruminal pH and VFA, or in situ digestion kinetics of NDF from DG. Efficiency of milk production was unaffected by diet. Corn and sorghum DG resulted in relatively similar performance when fed to beef or dairy cattle in this study.

The processing of grains to produce human foods, beverages, or fuel ethanol has resulted in a wide variety of associated feed by-products. Hominy feed and distillers by-products are feed by-products associated with two distinctly different drymilling industries. Hominy feed contains approximately 57% starch, 11% CP, and 5% fat (DM basis). When fed to finishing cattle, hominy feed has approximately 87% the net energy value of corn. Distillers by-products contain 25 to 32% CP and 13 to 16% fat (DM basis). Wet distillers by-products have approximately 97 to 147% the net energy value of corn. The energy value of wet distillers by-products may be affected by the type of grain used in the fermentation process (corn vs grain sorghum) and the amount of solubles added to the distillers grains. Drying distillers by-products reduces their net energy value but does not seem to affect their protein value. Corn gluten feed (CGF) and corn gluten meal (CGM) are feed by-products of the wet milling industry. Corn gluten feed is composed primarily of bran and steep. Corn gluten feed is lower in both CP (14 to 24%, DM basis) and escape protein (20 to 30%, % of CP) than CGM, but it is high in net energy for gain (90 to 114% of corn; DM basis). As the proportion of steep increases and bran decreases in CGF, the CP and net energy for gain content increases. When fed to finishing cattle, dried CGF has a lower net energy value than wet CGF. Wet distillers by-products and wet CGF seem to reduce the incidence of subacute acidosis. Because feed by-products have a high nutritional content and are often economically priced, they are excellent sources of energy and protein for feedlot cattle.

In Exp. 1, 88 yearling steers (332 kg) were fed dry-rolled corn finishing diets to evaluate effects of dietary urea level on performance and carcass characteristics. Diets contained 0, .5, 1.0, or 1.5% urea (DM basis), which supplied all supplemental N, and 10% chopped prairie hay. Gains (P = .10) and gain efficiency (G/F; P < .05) were increased by .5% urea, with little improvement by additional urea. Regression analysis estimated optimal dietary urea at .9% of DM for ADG and G/F. Fat thickness (P < .05) and yield grade (P < .10) increased linearly with dietary urea level. In Exp. 2, four ruminally and duodenally cannulated steers (557 kg) were fed the diets used in Exp. 1 to evaluate effects of dietary urea on site and extent of digestion. True ruminal OM and starch digestion were increased 25 and 37%, respectively, by .5% urea, but higher urea levels did not differ from .5%. Flows of total N and microbial N to the duodenum were not affected by urea level. In Exp. 3, 100 yearling steers (347 kg) were fed dry-rolled corn finishing diets that contained 10% alfalfa hay as the dietary roughage to evaluate effects of dietary urea level on performance and carcass characteristics. Urea levels were 0, .35, .70, 1.05, or 1.40% urea (DM basis), with no other supplemental N provided. Dry matter intake (P = .10), ADG (P < .05), and G/F (P < .05) increased with intermediate concentrations of urea but decreased with the highest concentration. Regression analysis indicated that the optimal dietary urea level was .5% of DM for ADG and G/F. Urea increased dietary energy utilization but not metabolizable protein supply.

ABSTRACT:Four metabolism and two finishing trials were conducted to determine the effects of imposed feed intake variation on acidosis and performance of finishing steers. In Metabolism Trial 1, four ruminally fistulated steers were limit-fed and subjected to either a constant amount of feed per day ( C ) or low intake variation of .7 kg/d (LV). No treatment differences were found for intake or measures of acidosis. Metabolism Trial 2 was conducted similarly to Metabolism Trial 1 with treatments of C and high intake variation of 1.4 kg/d (HV). Treatment HV increased ( P < .05) acidosis, as indicated by the area of ruminal pH below 5.6. In Metabolism Trial 3, four steers were fed at ad libitum levels of intake and subjected to three levels of intake variation: ad libitum intake with no imposed intake variation (AL), LV of .7 kg/d, and HV of 1.4 kg/d. No treatment differences were found. In Metabolism Trial 4, six ruminally fistulated steers were fed at ad libitum levels and subjected to three levels of intake variation: AL, LV of .9 kg/d, and HV of 1.8 kg/d. Average ruminal pH increased ( P < .05) and area of ruminal pH below 5.6 decreased ( P < .05) as level of intake variation was increased. In Finishing Trial 1, 75 steers were assigned to eight pens and two treatments: AL or HV of 1.8 kg/d. Dry matter intake increased ( P < .05) from AL to HV. Daily gain and gain/feed were not affected by treatment. In Finishing Trial 2, 94 steers were assigned to 12 pens and two treatments: AL or HV of 1.8 kg/d. No treatment differences were noted in DMI, daily gain, or gain/ feed. Therefore, results of these trials indicate that intake variation of up to 1.8 kg/d does not increase acidosis or decrease performance of finishing steers fed at ad libitum levels of intake.