Biomedical subjects

R A Stock

Publications and source records attributed to R A Stock.

At least 37 records · Page 2Linked to original sources

PubMed1995

Influence of grain type, tallow level, and tallow feeding system on feedlot cattle performance.

Two experiments were conducted to evaluate the effects of grain type, tallow level, and tallow feeding system on finishing steer performance. Experiment 1 involved 256 yearling steers (359 kg) in a 4 x 2 factorial arrangement of treatments. Steers were assigned randomly to one of four tallow feeding systems: 1) 0% tallow fed throughout the experiment; 2) 4% tallow fed throughout the experiment; 3) 0% tallow fed d 1 through 33 and then 4% tallow fed until slaughter; and 4) 4% tallow fed d 1 through 33 and then 0% tallow fed until slaughter. Tallow treatments were applied to diets containing either dry-rolled corn (DRC) of high-moisture corn (HMC). No fat treatment x grain type interaction (P > .10) was observed. Steers fed 4% tallow throughout the experiment, only during d 1 through 33, or only during d 34 until slaughter were more (P < .10) efficient than steers fed 0% tallow. No differences in DMI or ADG were observed (P > .10). In Exp. 2, 120 large-framed steer calves (286 kg) were blocked by weight and allotted randomly within block to one of three treatments consisting of the addition fo 0, 2, or 4% tallow added d 1 and fed for 197 d. Feed efficiency of calves increased linearly (P < .05) with increasing tallow level. Daily gain was not different (P > .10), but DMI decreased linearly (P < .05) with increasing tallow level. This research indicates that tallow added during or after grain adaptation to DRC- or HMC-based diets fed to yearling steers will result in similar improvement in feed efficiency, and that including up to 4% tallow to diets fed to large-framed calves can significantly improve feed efficiency.

Animal Feed↗

PubMed1995

Feeding wet corn gluten feed to reduce subacute acidosis in cattle.

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.

Acidosis↗

PubMed1995

The effects of ruminal acidosis on volatile fatty acid absorption and plasma activities of pancreatic enzymes in lambs.

Twenty crossbred wethers (41.9 +/- 4.0 kg BW), each fitted with a ruminal cannula and a jugular catheter, were used in a completely randomized design to examine the effects of ruminal acidosis on plasma activities of pancreatic enzymes and fractional rates of VFA absorption. Lambs had ad libitum access to a 50% concentrate diet. Acidosis was induced by an intraruminal dose of glucose at 0, 6, 12, or 18 g/kg BW via the ruminal cannula. Ruminal fluid and plasma were collected 0, 4, 8, 12, 18, 24, 36, 48, and 72 h after dosing. Ruminal fluid pH was reduced (linear, P < .001) with increasing ruminal glucose. Total ruminal VFA concentration decreased (linear, P < .01) and D(-)-lactate (linear, P < .01) and L(+)- lactate (linear, P = .07) concentrations increased with increasing ruminal glucose. Activities of amylase and lipase in plasma were not affected by ruminal glucose (P > .10). Ten days after the acidosis insult, rumens were evacuated and contents were replaced with an isotonic Cr:VFA solution to measure ruminal VFA absorption. Ruminal fluid was collected hourly from 0 to 6 h. Fractional rate of acetate absorption was 13% lower for lambs receiving 18 g/kg BW glucose than for control lambs. In addition, fractional liquid passage rate was lower (P < .05) in lambs receiving 18 g/kg BW glucose 6 mo after the insult of acidosis. These data suggest that a short-term, severe insult of acute acidosis does not result in pancreatic tissue damage but may result in reduced ruminal VFA absorption for an extended period of time.

Absorption↗

PubMed1995

Efficacy of laidlomycin propionate to reduce ruminal acidosis in cattle.

Three trials were conducted to evaluate the efficacy of laidlomycin propionate (LP) to reduce the incidence and severity of ruminal acidosis in cattle fed high-grain finishing diets. In each trial, LP was fed at 0, 6, or 12 mg/kg of diet DM. In two acidosis-challenge trials, ruminally fistulated steers were fed (DM basis) a 50% concentrate diet and then fed a 95% concentrate diet at a specific intake (2.75% BW) or steers were dosed intraruminally with a 100% concentrate diet. Laidlomycin propionate did not alter ruminal pH or total acid concentrations, but in Trial 1 the 6 mg/kg level altered (P < .10) the molar proportions of the acids, increasing total ruminal VFA and decreasing ruminal lactate. In Trial 3, a finishing trial, LP reduced (P < .10) intake day-to-day variation of individually fed steers during a 13-d adaptation period from a 65 to a 100% concentrate diet, suggesting reduced incidence of subacute acidosis. Feed intake was lower (P < .05) during the first 13 d of the trial due to LP but was not affected over the entire trial. Laidlomycin propionate improved feed efficiency (gain/feed) when calculated on a live weight basis (linear, P = .05) or carcass weight basis (linear, P = .20). Laidlomycin propionate does not prevent ruminal acidosis, but it may reduce the severity of ruminal acidosis during adaptation to a 100% concentrate diet.

Acidosis↗

PubMed1995

High-lysine corn as a source of protein and energy for finishing calves.

Three trials evaluated the protein and energy value of high-lysine corn for finishing calves. In Trial 1, 60 finishing steer calves were used to evaluate corn source (high-lysine vs control) and protein source (urea, blood meal [BM], corn gluten meal [CGM]) and level (BM and CGM addition; low, medium, high). Calves were individually fed using Calan gates for 102 d, and then were pen-fed (two pens per corn treatment) the remaining 83 d. During the initial 102 d, calves fed high-lysine corn had similar gains but were 6% more efficient (P < .10) compared with calves fed control corn. Performance did not differ (P > .10) among sources or levels of protein supplementation. Over the entire feeding period (185 d), calves fed high-lysine corn were 10% more efficient (P < .10) than calves fed control corn. In the second study, in situ starch disappearance was faster (P < .10) and the proportion of CP degraded by 12 h was 27% greater (P < .10) for high-lysine corn than for control corn. In a metabolism trial, five steers fitted with ruminal, duodenal, and ileal cannulas were used in a randomized block design to evaluate the effect of corn source on site and extent of digestion. Intake and ruminal and total tract digestibility of OM and N did not differ (P > .10) between corn sources. Steers fed high-lysine corn tended to have greater ruminal (P = .23) and postruminal (P = .18) starch digestion, resulting in greater (P < .10) total tract starch digestibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1995

Effect of monensin and monensin and tylosin combination on feed intake variation of feedlot steers.

A trial involving four commercial feedlots and an individual feeding trial evaluated the effect of monensin and monensin/tylosin on intake variation and deaths from digestive disorders. Four commercial feedlots in Texas and Colorado fed 2,904 yearling crossbred steers (340 kg) high-grain diets containing approximately 82% grain, 8% silage and alfalfa hay, 4% fat, and 6% supplement (DM basis). Steers were allotted randomly to one of three monensin/tylosin levels: 1) no monensin or tylosin (control); 2) 22 mg/kg of monensin and 11 mg/kg of tylosin; or 3) 33 mg/kg of monensin and 11 mg/kg of tylosin. Monensin/tylosin reduced DMI (P < .05) and improved ADG (P < .05) and feed efficiency (P < .01). Intake variation associated with dry matter offered per pen was not different among treatments. In the individual feeding trial, feeding 27 mg/kg of monensin reduced (P < .10) DMI variation during grain adaptation and during d 57 to 70 and d 97 to 110 compared with the control (no monensin) diet. The magnitude of intake variance was 5 to 10 times greater with individually fed steers than with steers fed in the commercial feedlot pens. When the DMI of the individually fed steers were averaged and treated as a pen of steers, DMI variance was reduced drastically and was not different between treatments. We interpret these data to indicate that monensin and monensin/tylosin reduce feed intake variation among individual steers within a pen of steers. Pen means mask individual animal variation to the point that it is difficult to detect treatment differences.

Animals↗

PubMed1995

Determining the net energy value of wet and dry corn gluten feed in beef growing and finishing diets.

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)

Animal Feed↗

PubMed1995

Effect of corn hybrid and grain processing method on rate of starch disappearance and performance of finishing cattle.

Two trials evaluated the effects of different corn hybrids on in vitro rate of starch disappearance and finishing cattle performance. Hybrids were selected, based on in vitro rate of starch disappearance (A = fastest, B = intermediate, C = slowest). In Trial 1, hybrids A and B were fed as dry-rolled and early-harvested, high-moisture (28%) corn and hybrid C was fed as dry-rolled corn. Cattle fed dry-rolled hybrid A gained faster (P < .10) and more efficiently (P < .10) than cattle fed dry-rolled hybrids B and C. No differences were observed in DMI, quality grade, or fat thickness among hybrids fed dry-rolled. Dry matter intake was lower (P < .10) and feed efficiency was improved (P < .10) for cattle fed corn hybrids A and B as high-moisture corn compared with those same hybrids fed dry-rolled. In Trial 2, hybrids A, B, and C were fed as dry-rolled and early-harvested, high-moisture (29, 28, and 29% moisture, respectively) corn. Performance and carcass measurements were not affected by hybrid fed. Cattle fed high-moisture corn gained faster (P < .10), consumed less DM (P < .01), and were more efficient (P < .01) than cattle fed the same hybrids dry-rolled. Across trials, hybrids, and processing methods, in vitro rate of starch disappearance was correlated with feed efficiency (r2 = .58, P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1995

Effect of level and type of fat on subacute acidosis in cattle fed dry-rolled corn finishing diets.

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)

Acidosis↗

PubMed1994

Wet corn distillers byproducts compared with dried corn distillers grains with solubles as a source of protein and energy for ruminants.

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.

Animal Feed↗

PubMed1994

Effect of sequential implanting with Synovex on steer and heifer performance.

Studies were conducted using 72 (Exp. 1) and 248 (Exp. 2) steer and heifer calves from 1 to 2 mo of age through slaughter to determine whether preweaning implants affect postweaning feed conversion of cattle that are rapidly grown and(or) finished in the feedlot. In Exp. 1, treatments were three Synovex (S) implants administered 0, 70, and 140 d postweaning (NSSS) or Synovex-C (C) administered preweaning and three implants administered postweaning (CSSS). In Exp. 2, treatments were no implants (NNNN), implants administered 0, 74, and 148 d postweaning to calves that had either received no preweaning implant (NSSS), or C (CSSS), and CSSS plus trenbolone acetate (TBA) administered with the last S implant (CSSS-TBA). Synovex-S or -H implants were administered postweaning to steers and heifers, respectively. Steer and heifer calves implanted with C in the preweaning phase were 9.0 and 13.0 kg (Exp. 1) and 7.5 and 15.0 kg (Exp. 2) heavier (P < .10), respectively, at weaning than nonimplanted steer and heifer calves. In Exp. 1, preweaning implant had no affect on postweaning performance or quality grade. In Exp. 2, preweaning implants (NSSS vs CSSS) decreased (P < .10) steer postweaning gains, whereas postweaning implants (NSSS vs NNNN) increased (P < .10) DM intake; however, feed:gain ratio was not affected by implant strategy. Heifers in Exp. 2 that received implants had greater postweaning (P < .10) DM intakes and daily gains than heifers not receiving implants (NNNN); however, feed:gain ratios among treatment groups were unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Anabolic Agents↗

PubMed1993

Metabolizable protein and amino acid requirements of growing cattle.

Metabolizable protein and amino acid requirements for growing cattle were estimated using data from 11 research trials. A total of 543 steers were individually fed a high-roughage diet supplemented with protein at several levels above a urea supplement control. The mean weight for all animals was 253 kg, with a range in mean initial to final weights of 200 to 316 kg, respectively. Daily gain ranged from -.04 to .89 kg. Metabolizable protein for each treatment group was calculated at the point at which the protein requirement was met. The sum of dietary escape protein (basal and supplemental) and calculated microbial protein represented metabolizable protein supplied per test protein source analyzed in each trial. Daily gain was regressed against calculated metabolizable protein flow using weighted regression analysis (r2 = .69, n = 45) to determine the metabolizable protein requirements for maintenance (3.8 x BW.75 g/d, where BW is expressed in kilograms) and growth (305 g/kg of live weight gain). Calculated metabolizable amino acid requirements as a percentage of metabolizable protein for a 253-kg animal gaining .49 kg/d were as follows: methionine, 3.0%; total sulfur amino acids, 5.8%; lysine, 8.0%; tryptophan, 1.0%; threonine, 5.2%; valine, 5.7%; isoleucine, 5.6%; leucine, 6.9%; phenylalanine, 3.9%; and histidine, 1.6%. The proposed requirements were based on live animal gain and intake of metabolizable protein and should represent the needs of the growing beef animal.

Amino Acids↗

PubMed1993

Protein sources for finishing calves as affected by management system.

Two beef production systems were evaluated in conjunction with an evaluation of escape protein sources for finishing calves. Two hundred forty crossbred steers and 80 crossbred heifer calves (BW = 267 +/- 2 kg) were split into two groups: 1) control, finished (207 d) after a 3-wk feedlot adjustment period and 2) grazing cornstalks for 74 d after a 3-wk feedlot adjustment period, then finished (164 d). Finishing treatments were sources and proportions of supplemental CP: 1) urea 100%; 2) soybean meal (SBM) 100%; 3) blood meal (BM) 50%, urea 50%; 4) feather meal (FTH) 50%, urea 50%; 5) SBM 50%, FTH 25%, urea 25%; 6) SBM 25%, FTH 38%, urea 37%; 7) FTH 25%, BM 25%, urea 50%, and 8) FTH 38%, BM 13%, urea 50%. Treatments 1 to 8 were fed in dry-rolled corn (DRC)-based diets. Treatments 9 and 10 were supplement Treatments 1 and 7 fed in diets based on high-moisture corn. Calves finished after a 74-d period of grazing cornstalks consumed more feed (P < .01) and gained faster (P < .01) but were less efficient (P < .05) than calves finished directly after weaning. Although not statistically different, calves finished after grazing cornstalks and supplemented with natural protein in the feedlot were 7% more efficient than calves supplemented with urea alone. Efficiency of calves finished directly after weaning was similar for calves supplemented with natural protein or urea alone. Supplementing SBM/FTH/urea or BM/FTH/urea improved feed efficiency compared with supplementing FTH/urea alone. These data suggest that allowing calves to graze cornstalks before finishing is a possible management option, but this system may require more metabolizable protein in the finishing diet to maximize feed efficiency if the calves are expressing compensatory growth.

Animal Feed↗

PubMed1993

Effect of protein source and grain type on finishing calf performance and ruminal metabolism.

A finishing trial and a metabolism trial were conducted to evaluate sources of supplemental protein in dry-rolled corn (DRC) and dry-rolled grain sorghum (DRGS) diets fed to large-framed calves and to determine effects of grain and protein source on ruminal metabolism. In Exp. 1, 144 Charolais crossbred steer and heifer calves (BW = 269 +/- 3 kg) were used in a randomized complete block design and fed (199 d) DRC or DRGS diets supplemented with urea or urea plus a 60:40 combination (CP basis) of blood meal (BM) and feather meal (FTH). Calves supplemented with urea-BM/FTH were more efficient (P < .05) during the first 41 d of the trial than were calves supplemented with urea alone. After 41 d, daily gain and feed efficiency were not affected (P > .2) by source of protein. The NRC metabolizable protein (MP) requirements accurately predicted response to urea-BM/FTH. In Exp. 2, five ruminally cannulated steers (BW = 721 +/- 20 kg) were used in a 5 x 5 Latin square design and fed (on an ad libitum basis) diets similar to those used in Exp. 1. An additional treatment of DRC supplemented with soybean meal (SBM) was included. Rate (P < .01) and extent of 12-h (P = .14) and 18-h (P < .05) in situ N disappearance of SBM, BM, FTH, DRC, DRGS, and corn silage were greater when diets were supplemented with urea-BM/FTH or SBM. Estimates of escape N (percentage of total N) were 52.3, 93.3, 91.7, 65.7, 63.6, and 23.2% for SBM, BM, FTH, DRC, DRGS, and corn silage, respectively. Finishing calves supplemented with urea were deficient in MP during the early finishing period (0 to 41 d) but were adequate in MP from d 42 to slaughter. Supplementing urea-BM/FTH improved feed efficiency when MP was limiting but not when MP was adequate.

Animal Feed↗

PubMed1993

Energy value of hominy feed for finishing ruminants.

Three trials were conducted to evaluate the energy value of hominy feed in finishing diets for ruminants. Hominy feed contained 56.9% starch, 25.2% NDF, 11.1% CP, and 5.3% fat (DM basis). In all trials, hominy feed replaced dry-rolled corn. As the level of hominy feed or ground corn increased in a lamb digestion trial, DM digestibility decreased (P < .01); however, starch digestibility increased (P = .09). Hominy feed and ground corn interacted (linear, P = .08) with respect to NDF digestibility. As the level of ground corn increased, NDF digestibility decreased (linear, P = .10). In a finishing trial, yearling heifers were fed either hominy feed with or without fat added to hominy feed at 0, 13.3 (.67% added fat), 26.7 (1.33% added fat), and 40.0% (2.0% added fat) of diet DM. Fat addition did not interact with hominy feed level. Heifers fed 13.3 or 26.7% hominy feed or hominy feed + fat consumed more DM (P = .10) than heifers fed the 0 or 40.0% diets; however, gain and feed efficiency were similar. In a second finishing trial, steers fed 40% (diet DM) hominy feed consumed more (P = .05) DM, but daily gain and feed efficiency were similar to those of cattle fed dry-rolled corn. Steers fed all-concentrate diets were more efficient (P < .01) than cattle fed 7.5% forage. Results indicated that expeller-extracted hominy feed contained 1.35 Mcal of NEg/kg, or 87% of the energy of corn, when included at levels up to 40% of cattle finishing diets, despite its containing 20% less starch than corn.

Animal Feed↗

PubMed1993

Effect of a soybean hull:soy lecithin:soapstock mixture on ruminal digestion and performance of growing beef calves and lactating dairy cattle.

Four experiments were conducted to evaluate the effect of a soybean hull, soy lecithin, and soapstock mixture on ruminal fiber and protein digestion, growth efficiency of beef calves, and lactational performance of dairy cattle. An initial mixing experiment determined that a 4:1 ratio (DM basis) of soy lecithin:soapstock could be added to soybean hulls at 15% (wt/wt, DM basis); this mixture had acceptable mixing and handling characteristics. Dietary addition of a mixture of 85% soybean hulls, 12% soy lecithin, and 3% soapstock (DM basis; SLS) to provide 0, 3, 5, or 7% supplemental fat resulted in a linear (P < .01) decrease in in situ rate of ruminal NDF digestion with no effect on rate of CP digestion. Daily gain, DMI, and feed efficiency (kilograms of gain/kilogram of DMI) of growing beef calves were not affected (P > .10) as graded levels of SLS replaced corn grain. However, as graded levels of SLS replaced soybean hulls, daily gain and feed efficiency increased linearly (P < .01). Based on the results of these trials, Holstein dairy cattle were fed four isonitrogenous and isoenergetic diets that contained either high levels of nonfiber carbohydrates (43%) and no added fat, 1% ruminally inert fat, a 6% level of SLS, or a 12% SLS level (all on DM basis). Efficiency of 4% fat-corrected milk production (kilograms of milk/kilogram of DMI) was greatest for cows fed SLS at 6% of dietary DM. The SLS mixture was an excellent source of fiber and vegetable fat, comparable in feeding value to corn grain, for inclusion in the diets of beef calves and dairy cows.

Animal Feed↗

PubMed1993

Influence of ruminal protozoa on site and extent of starch digestion and ruminal fermentation.

Eight ruminally, duodenally, and ileally fistulated sheep were used to study the effects of protozoa on ruminal fermentation and starch digestion in the rumen and intestines. The experimental diet (75% grain DM basis) was based on a mixture of 67% high-moisture corn (HMC) and 33% dry-rolled grain sorghum (DRGS). Protozoa were reduced from 51,286 to 13,987 organisms/mL of ruminal fluid by feeding a diet (13 d) containing 9% tallow and monensin at 27 mg/kg (DM basis). Three sheep were defaunated by intraruminal infusions of lactic acid (20 to 30 g/d) and one sheep by washing the rumen and heating ruminal contents (60 degrees C for 20 min). No differences were observed in DM or starch intake, ruminal fluid pH, lactate concentration, or total tract starch digestibility. Molar proportion of acetate was reduced (48.6 vs 58.3%; P < .01) and propionate was increased (32.2 vs 23.4%; P < .03) by defaunation. Total VFA tended (P = .20) to be lower in faunated sheep (118.5 vs 139.2 mM). In situ rate of starch digestion of HMC (22.3 vs 14.7 %/h; P < .02) and DRGS (5.1 vs 3.3 %/h; P < .009) was increased by defaunation. Starch digestibility (percentage of intake) in the rumen was increased (P < .001) by defaunation (84.2 vs 93.7%) and was reduced (P < .002) in the small intestine (5.2 vs 13.6%). Defaunation increased (P < .03) amylolytic activity (.40 vs .17 units/mg of protein; P < .03) and osmotic pressure (321 vs 245 mOsm/kg; P < .006).(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMed1993

Feeding value of wet distillers byproducts for finishing ruminants.

Yearling and calf finishing trials (replicated over 2 yr) evaluated the feeding value of wet distillers byproducts (wet distillers grains and thin stillage). An additional trial estimated the amount of thin stillage bypassing the rumen when consumed by drinking. Yearlings were 5, 10, and 20% more efficient (linear, P < .01; quadratic, P = .05), whereas calves were 2, 6, and 14% more efficient (linear, P < .01) when fed 5.2, 12.6, and 40.0% (DM basis) wet distillers byproducts, respectively, compared with cattle fed a 79% dry-rolled corn diet. Cattle fed 5.2 or 12.6% wet distillers byproducts, or the dry-rolled corn diet, received similar amounts of protein (crude or metabolizable), which exceeded the metabolizable protein requirement of all cattle. Therefore, differences in efficiency were attributed to differences in energy utilization of the diets. Wet distillers byproducts fed at 5.2, 12.6 and 40.0% contributed 80, 62, and 47% more net energy for gain than corn when fed to yearlings and 17, 33, and 29% more net energy for gain than corn when fed to calves, respectively. Wet distillers byproducts averaged 169% the energy value of corn (2.53 Mcal of NEg/kg) when fed to yearlings and 128% the energy value of corn (1.96 Mcal of NEg/kg) when fed to calves. The increased energy values cannot be explained by increased digestibility, but they may be due to a combination of factors (reduced acidosis, increased energy utilization, yeast end products, etc.) that increase the net energy content of distillers byproducts. Approximately 50% of the thin stillage consumed by drinking bypassed ruminal fermentation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗