Five trials investigated the feeding value of wet and dried corn distillers byproducts as a source of protein and energy for growing and finishing cattle and investigated the effect of heat damage on the feeding value of dried distillers byproducts. In a calf growth trial, no differences in rate of gain or protein efficiency were observed among calves fed wet distillers byproducts (wet distillers grains + thin stillage; WDB) or one of three composites of dried distillers grain + solubles (DDGS) having a low, medium, or high concentration of ADIN. A finishing trial compared the energy value of dry-rolled corn (DRC) with WDB or the three DDGS composites, fed at 40% of the diet DM replacing DRC. Cattle consuming WDB or DDGS gained faster (P < .05) and more efficiently (P < .05) than cattle fed DRC. Although gains were similar, cattle fed WDB consumed less feed (P < .10) and were more efficient (P < .10) than cattle fed DDGS. Level of ADIN in DDGS did not affect efficiency of gain (P > .10). In a lamb finishing trial, the addition of 5 or 10% ethanol did not affect (P > .10) daily gain, DMI, or feed efficiency. In two metabolism trials with steers, grain byproducts (wet distillers grains, dry distillers grains plus solubles, wet corn gluten feed, dry corn gluten feed, hominy feed) and DRC had similar effects on ruminal pH and total VFA. Feeding thin stillage or condensed solubles reduced (P < .10) ruminal pH and tended to reduce acetate:propionate. Wet corn distillers byproducts, fed at 40% of the diet DM, contain more NEg than did DRC and drying WDB reduces its NEg content. Acid detergent insoluble N is a poor indicator of protein and energy value in distillers grains.

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.

Modulation of somatotrophic and homeorhetic hormones, along with changes in visceral mass and metabolic activity, were measured in growing lambs restricted in energy (ER) or metabolizable protein (PR) to maintain BW for 7 wk and then repleted for 2 wk. Control lambs were fed an adequate diet for 9 wk. Serum IGF-I decreased more rapidly in PR, but both ER and PR were 70% of controls by wk 7 of restriction (P < .05) and increased above controls by d 14 of repletion. Somatotropin, increased by PR, returned to control levels upon repletion (P < .05). Insulin was decreased by PR (P < .02) but was transiently elevated above controls by repletion in ER and PR at d 2 (P < .01). Serum triiodothyronine, reduced to 70% of controls by PR and ER, returned to control levels after d 6 of repletion (P < .05). Thyroxine declined gradually to 65% of controls in ER and PR (P < .07) but did not respond to repletion. By wk 7 of restriction, liver mass in ER and PR was decreased to 50% of controls (P < .05). Return of liver mass, on an empty body weight basis, occurred by d 2 of repletion (P < .01). In vitro O2 consumption per gram of liver tissue was increased to 125% of controls by ER and PR (P < .05). Calculated whole liver O2 consumption in ER and PR was 68% of controls at wk 7 of restriction (P < .10). Protein restriction had a more immediate impact on hormones but not on visceral mass or activity compared with energy restriction. Elevated IGF-I levels, as observed in previously restricted lambs, may mediate compensatory growth in ruminants.

One growing and two finishing trials evaluated the feeding value of corn gluten feed for cattle. In the growth trial, calves were fed (DM basis) one of two control diets (44% dry-rolled corn [DRC], 50% alfalfa hay, 5% molasses, 1% supplement or 33% DRC, 33% alfalfa hay, 33% corn silage, 1% supplement), diets containing 49 or 65% wet corn gluten feed (WCGF) with alfalfa hay and supplement, or a diet containing 61% WCGF with cornstalks and supplement. Calves fed diets containing 49 or 65% WCGF with alfalfa hay gained faster (P < .10) and more efficiently (P < .10) than calves fed the two control diets. In finishing trial 1, yearling steers were fed 92.5% concentrate diets containing (DM basis) 79% DRC, a combination of DRC and 35 or 70% WCGF, a combination of DRC and 70% dry corn gluten feed (DCGF) with or without added water, or a combination of high-moisture corn (HMC) and 70% WCGF. Steers fed 35 or 70% WCGF in combination with either DRC or HMC had gains and efficiencies similar (P > .10) to those of steers fed DRC. Inclusion of water in the 70% DCGF diet reduced DMI (P < .10) and daily gain (P < .10) but did not affect (P > .10) feed efficiency. In Trial 2, WCGF replaced either 20, 40, 60, 80, or 100% of the DRC and molasses (DM basis). Feed efficiency was not different (P > .10) among diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Five experiments were conducted to determine the effect of fat addition to dry-rolled corn (DRC) finishing diets on subacute acidosis. In Exp. 1, five ruminally fistulated steers (410 +/- 12 kg BW) were used in a 5 x 5 Latin square design. Treatments consisted of 0, 2, 4, 6, or 8% tallow added to a 50% fine-ground corn: 50% dry-rolled wheat basal challenge diet and dosed intraruminally as an acidosis challenge. Area below pH 6 was determined to quantify the total decrease in ruminal pH over a 24-h period. Area below pH 6 responded quadratically (P < .05); greatest time below pH 6 occurred with diets containing 2, 4, and 6% tallow. In Exp. 2, six ruminally fistulated steers (527 +/- 47 kg BW) were used in a 6 x 6 Latin square design and intraruminally dosed with 0, 4, 6, or 8% tallow or 4 or 8% yellow grease added to a 50% fine-ground corn:50% dry-rolled wheat basal challenge diet. Area below pH 6 responded quadratically for both tallow (P = .10) and yellow grease (P < .05) and was greatest for steers dosed with 4% tallow or yellow grease and decreased as tallow or yellow grease increased from 4 to 8%. Experiment 3 was a metabolism study using six ruminally fistulated steers (469 +/- 68 kg BW) in a 6 x 6 Latin square design. Cattle were fed a DRC finishing diet containing 0, 4, 6, or 8% tallow or 4 or 8% yellow grease.(ABSTRACT TRUNCATED AT 250 WORDS)