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.

Two experiments were conducted to evaluate the effects of feeding wet corn gluten feed (WCGF) on subacute acidosis in cattle. In Exp. 1, 60 individually fed yearling steers (270 +/- 22 kg BW) were used in a 5 x 2 factorial arrangement of treatments. Steers were assigned to one of five dietary treatments: 1) dry-rolled corn (DRC), 2) 35% WCGF fed d 1 to 132, 3) 86.5% WCGF fed d 1 reduced to 35% WCGF by d 19 and increasing the proportion of DRC, 4) 86.5% WCGF fed d 1 to 132, or 5) 94.5% WCGF fed d 1 to 132. Final diets for Treatments 1 through 4 contained 92% concentrate and 8% alfalfa hay (DM basis). Treatment 5 was a 100% concentrate diet. All diets were fed with or without the addition of escape protein. During d 19 to 24, steers fed WCGF had less (P < .05) DMI variation than steers fed the control diet. Steers fed 86.5 and 94.5% WCGF had lower (P < .05) DMI and ADG than steers fed TReatments 1 through 3, although gain/feed was mot different (P > .10) In Exp. 2, three ruminally fistulated steers (615 +/- 36 kg BW) were used in a repeated 3 x 3 Latin square design. On d 14 of each period, 7.9 kg (DM) of 100% DRC, 50% DRC:50% WCGF, of 100% WCGF was intraruminally dosed as an acidosis challenge. Area within the curve below ruminal pH 6.0 was greater (P < .05) over a 24-h period for steers dosed with 100% DRC than for steers dosed with 50% DRC: 50% WCGF or 100% WCGF. In addition, more (P < .05) ruminal VFA accumulated over 24 h for steers dosed with 100% DRC. These data suggest that feeding WCGF does nor eliminate ruminal acidosis but may reduce the length of time cattle are exposed to the insult.

Two trials were conducted to determine the feeding value of sorghum distillers byproducts. Trial 1, a finishing trial, used 160 yearling steers (327 kg). Treatments consisted of dry-rolled corn (DRC) control, sorghum wet distillers grains (SWDG), sorghum wet distillers grains plus solubles (SWDGS), and sorghum dried distillers grain plus solubles (SDDGS). Distillers byproducts were fed at 40% of the diet DM. Cattle fed diets containing SWDG, SWDGS, or DRC were similar in efficiency of gain (P > .10); cattle fed SDDGS were less efficient (P < .10) than all other treatments. Sorghum wet distillers grains, SWDGS, and SDDGS contained 96, 102, and 80% relative NEg of corn, respectively. In Trial 2, 16 crossbred lambs (55 kg) were used to determine the digestibility of sorghum and corn distillers byproducts. Byproducts were fed at 80% of the diet DM and treatments consisted of corn wet distillers grains (CWDG), corn dried distillers grains plus solubles (CDDGS), SWDG, and SDDGS. Neutral detergent fiber digestibility was not different among treatments (P > .10). Corn wet distillers grains were higher in true nitrogen (P < .001), apparent nitrogen (P < .01), and organic matter digestibility (P < .05) than SWDG. Wet distillers byproducts were higher (P < .01) in apparent organic matter and nitrogen digestibility than dried distillers byproducts. Digestibility of distillers byproducts and subsequent energy values are influenced by type of grain used in the fermentation process and drying of the finished byproduct.

ABSTRACT:Two finishing trials and a metabolism trial were conducted to evaluate the effect of forage source and particle size in dry-rolled corn finishing diets. In Exp. 1, 224 crossbred yearling steers (BW = 342 ± 11 kg) were used in a randomized complete block design consisting of seven treatments. Treatments were an all-concentrate diet or diets containing equal NDF levels provided by alfalfa hay or wheat straw (three treatments each) with each forage source ground to pass through a .95-, 7.6-, or 12.7-cm screen. Steers fed diets containing forage had greater ( P < .05) DMI than steers fed an allconcentrate diet. Steers fed alfalfa diets gained faster ( P < .05) with a greater ( P < .05) concentrate efficiency than steers fed either all-concentrate or straw diets. In Exp. 2, 120 crossbred yearling steers (BW = 307 ± 2 kg) were used in a completely randomized design and fed dry-rolled corn diets containing 10% alfalfa ground to pass through either a .95-or 7.6-cm screen. Alfalfa particle size had no effect on performance or carcass measurements. In Exp. 3, six ruminally fistulated steers (BW = 508 ± 34 kg) were used in a 6 × 6 Latin square design and fed an all-concentrate diet or diets containing equal NDF levels provided by alfalfa hay, wheat straw, or ground corncobs with alfalfa and straw ground to pass through either a 2.54-or 12.7-cm screen. Steers fed straw diets spent more time ( P < .10) chewing than those receiving the other diets. In conclusion, forage particle size had no effect on finishing cattle performance or ruminal metabolism data. However, cattle consuming different forage sources in dry-rolled corn finishing diets may not respond similarly in animal performance.