Nine steers were fed finishing diets in a replicated 3x3 Latin square design to determine if dietary manipulation would alter total and acid resistant E. coli populations. Manipulating diet by limit-feeding of finishing diets did not affect total or acid-resistant E. coli populations. Altering dietary ingredients did not affect total E. coli populations; however, steers fed diets containing dry-rolled or high-moisture corn had lower acid-resistant E. coli populations. Following completion of the Latin Square, all animals were fed alfalfa hay ad libitum for five days. Switching steers to alfalfa hay lowered both total and acid-resistant E. coli populations

Bailey, Doreen

Gray, Jeff

Hungerford, Laura

Klopfenstein, Terry J.

Milton, Todd

Moxley, Rodney A.

Scott, Tony

Smith, David R.

Wilson, Casey

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2000 Influence of Diet on Total and Acid Resistant E. coli and Colonic pH Tony Scott University of Nebraska-Lincoln Casey Wilson University of Nebraska-Lincoln Doreen Bailey University of Nebraska-Lincoln, dbailey2@unl.edu Terry J. Klopfenstein University of Nebraska-Lincoln, tklopfenstein1@unl.edu Todd Milton University of Nebraska-Lincoln See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Scott, Tony; Wilson, Casey; Bailey, Doreen; Klopfenstein, Terry J.; Milton, Todd; Moxley, Rodney A.; Smith, David R.; Gray, Jeff; and Hungerford, Laura, "Influence of Diet on Total and Acid Resistant E. coli and Colonic pH" (2000). Nebraska Beef Cattle Reports. 389. https://digitalcommons.unl.edu/animalscinbcr/389 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Tony Scott, Casey Wilson, Doreen Bailey, Terry J. Klopfenstein, Todd Milton, Rodney A. Moxley, David R. Smith, Jeff Gray, and Laura Hungerford This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/animalscinbcr/389 Page 39 — 2000 Nebraska Beef ReportInfluence of Diet on Total and Acid ResistantE. coli and Colonic pHTony ScottCasey WilsonDoreen BaileyTerry KlopfensteinTodd MiltonRod MoxleyDave SmithJeff GrayLaura Hungerford1Manipulation of finishing dietsdoes not reduce shedding of acid-resistant Escherichia coli in feces;however, short duration hay feed-ing reduces acid-resistant E. colishedding in the feces.SummaryNine steers were fed finishing dietsin a replicated 3x3 Latin square designto determine if dietary manipulationwould alter total and acid resistant E.coli populations. Manipulating diet bylimit-feeding of finishing diets did notaffect total or acid-resistant E. colipopulations. Altering dietary ingredi-ents did not affect total E. coli popu-lations; however, steers fed dietscontaining dry-rolled or high-moisturecorn had lower acid-resistant E. colipopulations. Following completion ofthe Latin Square, all animals were fedalfalfa hay ad libitum for five days.Switching steers to alfalfa hay loweredboth total and acid-resistant E. colipopulations.IntroductionThe bacterium Escherichia coli is anormal inhabitant of the intestinal tractsof human beings and animals. However,some strains of E. coli — for example,serotype O157:H7 — are capable ofcausing disease in humans. In cattle, E.coli O157:H7 is carried in the gastrointes-tinal tract and is shed in the feces whilethe animal shows no signs of disease.The organism is thought to enter thefood chain through fecal contaminationof the hide during slaughter. Two impor-tant features of E. coli O157:H7 are itslow infective dose and acid resistance.The low infective dose for humans,coupled with the fact that complete pre-vention of microbial contamination atslaughter is not feasible, has lead to thedevelopment of the concept that food-borne illness might best be prevented byreducing pathogen prevalence in live-stock, a concept also known as pre-harvest food safety.Recently, short-duration hay feedingwas suggested as a viable pre-harvestfood safety technique (Diez-Gonzalez,et al., 1998, Science, 281:1578). Whenanimals that had been consuming grainwere fed hay for four days, the preva-lence of both generic and acid-resistantE. coli was reduced. High grain dietsallow undigested starch to accumulate inthe colon. Accumulated starch is subse-quently fermented resulting in volatilefatty acid production, an acidic pH, andfacilitated growth of acid-resistant E.coli. The resulting hypothesis is thatreducing the starch load in the colon willsignificantly reduce the numbers of E.coli O157:H7.Regardless of the potential benefitsof hay feeding, it is not a practical ap-proach for cattle feeders. However, ifthe amount of starch being fermented inthe colon is the key to reducing theprevalence of E. coli, there may be alter-native means to achieve the same results.Wet corn gluten feed and high-moisturecorn are two common dietary ingredi-ents that offer opportunities to achievesimilar results as observed with hay feed-ing. Wet corn gluten feed contains littleor no starch and is 80% digestible in therumen. Therefore, feeding wet corn glu-ten feed should reduce the starch load inthe colon since material bypassing di-gestion in the rumen would be fibrouscorn bran as opposed to starch. High-moisture corn is more extensively de-graded in the rumen than dry-rolled corn.Therefore, comparatively less starchbypasses digestion in the rumen whenfeeding high-moisture corn. The net ef-fect of replacing dry-rolled corn withwet corn gluten feed or high-moisturecorn would be reduced starch load in thecolon.Therefore, our hypothesis for thisstudy was by manipulating the finishingdiet, the amount of starch being fer-mented in the colon would decrease,thereby increasing colonic pH anddecreasing the number of acid-resistantE. coli. Also, it was hypothesized thatlimit-feeding of finishing diets may offeran alternative means of reducing acid-resistant E. coli. Limit-feeding of fin-ishing diets should result in lessfermentation in the colon (increasedcolonic pH) because of more completedigestion in the rumen due to slower rateof passage, increased retention time andincreased extent of digestion.ProcedureExperiment 1Nine steers were fed finishing diets ina replicated 3 x 3 Latin square design.Treatments were finishing diets (Table1) based on dry-rolled corn (DRC), high-moisture corn (HMC), or wet corn glu-ten feed (WCGF). Diets were formulatedto contain a minimum of 12.5% CP, .7%Ca, .35% P, .6% K, and included 25 g/ton Rumensin and 10 g/ton Tylan.Each period was 21 days in duration.During days 1-9 of each period, steerswere fed at 1.8% of body weight (DMbasis). Intake for each subsequentperiod was adjusted based on weightstaken at the end of each 21-day period.Steers were allowed to consume feed adlibitum during days 10-21 of eachperiod. Samples of colonic digesta wereobtained on days 9, 20 and 21 and ana-lyzed for volatile fatty acid concentra-tion (analyses not completed; therefore,data not shown), pH and numbers oftotal and acid-resistant E. coli.(Continued on next page)2000 Nebraska Beef Report — Page 40Experiment 2Upon completion of the final periodof the 3 x 3 Latin Square, the nine steerswere fed alfalfa hay ad libitum, allowingthree steers each previously being feddry-rolled corn, wet corn gluten feed, orhigh-moisture corn to be observed aftershort duration hay feeding. Samples ofcolonic digesta were obtained on twoconsecutive days following five days ofhay feeding and analyzed for volatilefatty acid concentration (analyses notcompleted; therefore, data not shown),pH, and numbers of total and acid-resis-tant E. coli.ResultsExperiment 1The effects of diet on DMI, mostprobable number (MPN) of total andacid-resistant E. coli, and colonic pHare shown in Table 2. During the periodwhen steers were being limit-fed, neithertotal nor acid-resistant E. coli countswere statistically different among thethree treatments; however, colonic pHwas higher (P < .10) in steers fed WCGFthan in steers fed DRC or HMC. Therewas no treatment effect on DMI whensteers were switched to ad libitum feed-ing. Total E. coli numbers were similaramong treatments. Steers consumingDRC or HMC had significantly lower (P< .10) acid-resistant E. coli numbersthan steers consuming WCGF. ColonicpH was higher in steers fed WCGF orHMC (P < .10) than in steers fed DRC.Our interpretation is that acid-resistantE. coli numbers can not be reducedthrough either limit-feeding or this typeof dietary manipulation. However, feed-ing WCGF did increase colonic pH insteers during both the limit-feedingperiod and the ad libitum feeding period.Wet corn gluten feed is very low instarch concentration, but it does notappear that lowering the amount of starchreaching the colon will reduce acid-resistant E. coli numbers. Likewise,even though HMC is more extensivelydegraded in the rumen and colonic pHincreased during ad libitum feeding com-pared to DRC, there was no reduction inTable 1. Composition of finishing diets.TreatmentaIngredient (% of DM) DRC HMC WCGFDry-rolled corn 84.707 33.773 40.832High-moisture corn —— 50.866 ——Wet corn gluten feed —— —— 45.000Alfalfa hay 7.500 7.500 7.500Molasses 5.000 5.000 5.000Limestone 1.338 1.337 1.304Urea .952 1.019 ——Salt .300 .300 .300Dicalcium phosphate .107 .108 ——Potassium chloride .032 .033 ——Trace mineral .020 .020 .020Rumensin premix .016 .016 .016Vitamin premix .015 .015 .015Tylan premix .013 .013 .013aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.Table 2. Effect of diet on DMI and MPN of total and acid-resistant E. coli.TreatmentaItem DRC HMC WCGF SEMLimit-fed periodbTotal E. coli, log10c 7.87 8.54 8.50 .28Acid-resistant E. coli, log10d 2.61 4.52 4.24 .77Colonic pH 6.42e 6.61e 6.85f .12Ad libitum periodgDMI, lb/day 18.69 18.03 18.88 .62Total E. coli, log10c 8.25 8.45 8.46 .21Acid-resistant E. coli, log10d 3.04e 3.24e 3.71f .47Colonic pH 6.21e 6.55f 6.68f .14aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.bLimit-fed period = days 1-9.cMPN = most probable number of total E. coli is expressed in log10 units.dMPN = most probable number of acid-resistant E. coli is expressed in log10 units.efMeans within a row with unlike superscripts differ (P < .10).gAd libitum period = days 10-21.Table 3. Effect of hay feeding on MPN of total and acid-resistant E. coli.TreatmentaItem DRC HMC WCGF SEMTotal E. coli, log10b 7.13 6.89 6.89 .34Acid-resistant E. coli, log10c 1.70 1.00 1.33 .29Colonic pH 8.00 7.86 7.96 .06aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.bMPN = most probable number of total E. coli is expressed in log10 units.cMPN = most probable number of acid-resistant E. coli is expressed in log10 units.Table 4. Effect of feeding alfalfa hay versus a finishing diet on MPN of total and acid-resistantE. coli.TreatmentaItem ALF FIN SEMTotal E. coli, log10b 6.97c 7.95d .20Acid-resistant E. coli, log10e 1.34c 3.99d .33Colonic pH 7.94c 6.52d .14aALF = alfalfa hay; FIN = finishing diet.bMPN = most probable number of total E. coli is expressed in log10 units.cdMeans within a row with unlike superscripts differ (P < .01).eMPN = most probable number of acid-resistant E. coli is expressed in log10 units.Page 41 — 2000 Nebraska Beef ReportDRC, HMC, and WCGF, respectively.These numbers indicate irrespective ofdiet, acid-resistant E. coli numberswere reduced when steers were fedalfalfa hay ad libitum for a period of fivedays.Since there were no significant dif-ferences among DRC, HMC, or WCGFfinishing diets when switched to alfalfahay feeding, data were pooled to illus-trate the effect of feeding alfalfa hayversus feeding finishing diets on the MPNof total and acid-resistant E. coli andcolonic pH (Table 4). Switching steersto alfalfa hay lowered (P < .01) both totaland acid-resistant E. coli. Total E. colinumbers were lowered by about 1 log10unit while acid-resistant E. coli numberswere lowered by about 2.5 log10 units.Colonic pH was increased (P < .01) byover 1 pH unit in response to hay feed-ing. These data indicate short-durationhay feeding reduced acid-resistant E.coli populations in the feces by over99%.acid-resistant E. coli counts. Similarly,limit-feeding of the finishing diets didnot alter acid-resistant E. coli numbersin comparison to ad libitum feeding.Potentially, one could limit intake moreand possibly reduce acid-resistant E.coli; however, the reduced intakewould impact daily gain and potentiallycarcass merit.Experiment 2The effect of switching steers toalfalfa hay for five days is shown inTable 3. Total E. coli counts weresimilar among treatments; however,counts were reduced from previouslyobserved counts in Period 3 by .5, 1.27,and 1.16 log10 units for DRC, HMC, andWCGF, respectively. Similarly, therewere no differences in acid-resistantE. coli counts among the treatments;however, counts were reduced fromthose previously observed in Period 3by 2.35, 2.58, and 3.01 log10 units forDietary manipulation of finishingdiets either by substituting ingredientsor limit-feeding successfully increasedcolonic pH, indicating substrate changesat the level of the colon; however,increased colonic pH was not asso-ciated with reduced populations ofacid-resistant E. coli. Feeding alfalfahay both increased colonic pH anddecreased acid-resistant E. coli. Thisstudy confirms Diez-Gonzalez (1998)report that feeding hay for a short dura-tion can reduce acid-resistant E. colipopulations.1Tony Scott, Casey Wilson, researchtechnicians, Animal Science, Lincoln; DoreenBailey, research technician, Veterinary andBiomedical Sciences, Lincoln; Terry Klopfenstein,Professor, Todd Milton, Assistant Professor,Animal Science, Lincoln. Rod Moxley, Professor,Dave Smith, Jeff Gray, Assistant Professors,Veterinary and Biomedical Sciences, Lincoln;Laura Hungerford, Associate Professor, GreatPlains Veterinary Educational Center, Clay Center.Effects of Programmed Gain Feeding Strategies onPerformance and Carcass Characteristics ofYearling SteersTony ScottTodd MiltonTerry MaderTerry KlopfensteinSimone Holt1Programming gain for the first21 or 42 days of the feeding periodreduced the total amount of feedconsumed but did not improvecumulative performance comparedwith ad libitum feeding.SummaryTwo hundred forty-five crossbredyearling steers were used in a random-ized complete block design to deter-mine effects of including a programmedgain phase in the feeding period onperformance and carcass characteris-tics. Including a programmed gainphase in the finishing period resulted insimilar cumulative daily gains and feedconversions when compared with steersallowed to consume feed ad libitum.Programming gain reduced the totalamount of feed consumed per animal;however, the lack of an improvement infeed conversion coupled with slightnumerical differences in hot carcassweights resulted in net profits favoringad libitum feeding.IntroductionPrevious research regarding control-ling intake during the finishing periodhas focused on maintaining a static in-take relative to ad libitum fed controlpens. Improvements in efficiency havebeen demonstrated; however, daily gainmay decrease, resulting in increased dayson feed. Recent studies (Knoblich, et al.,1997, J. Anim. Sci., 75:3094; Loerchand Fluharty, 1998, J. Anim. Sci., 76:371)have shown similar daily gains, hot car-cass weights and days on feed. At thesame time, reductions in the amount offeed consumed result in improvementsin efficiency.Currently research on controlling in-take during the finishing period hasshifted toward programmed gain sys-tems. Programmed gain systems arebased on the net energy equations in theNRC (1996). Based on the diet beingfed, a programmed rate of gain is se-lected and the amount of feed required toachieve the programmed rate of gain canbe calculated.In a previous study (1999 NebraskaBeef Report, pp 46-48), programmed(Continued on next page)

Influence of Diet on Total and Acid Resistant \u3ci\u3eE. coli\u3c/i\u3e and Colonic pH

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 2000 
Influence of Diet on Total and Acid Resistant E. coli and Colonic 
pH 
Tony Scott 
University of Nebraska-Lincoln 
Casey Wilson 
University of Nebraska-Lincoln 
Doreen Bailey 
University of Nebraska-Lincoln, dbailey2@unl.edu 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
Todd Milton 
University of Nebraska-Lincoln 
See next page for additional authors 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Scott, Tony; Wilson, Casey; Bailey, Doreen; Klopfenstein, Terry J.; Milton, Todd; Moxley, Rodney A.; Smith, 
David R.; Gray, Jeff; and Hungerford, Laura, "Influence of Diet on Total and Acid Resistant E. coli and 
Colonic pH" (2000). Nebraska Beef Cattle Reports. 389. 
https://digitalcommons.unl.edu/animalscinbcr/389 
This Article is brought to you for free and open access by the Animal Science Department at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle 
Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
Authors 
Tony Scott, Casey Wilson, Doreen Bailey, Terry J. Klopfenstein, Todd Milton, Rodney A. Moxley, David R. 
Smith, Jeff Gray, and Laura Hungerford 
This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/
animalscinbcr/389 
Page 39 — 2000 Nebraska Beef Report
Influence of Diet on Total and Acid Resistant
E. coli and Colonic pH
Tony Scott
Casey Wilson
Doreen Bailey
Terry Klopfenstein
Todd Milton
Rod Moxley
Dave Smith
Jeff Gray
Laura Hungerford1
Manipulation of finishing diets
does not reduce shedding of acid-
resistant Escherichia coli in feces;
however, short duration hay feed-
ing reduces acid-resistant E. coli
shedding in the feces.
Summary
Nine steers were fed finishing diets
in a replicated 3x3 Latin square design
to determine if dietary manipulation
would alter total and acid resistant E.
coli populations. Manipulating diet by
limit-feeding of finishing diets did not
affect total or acid-resistant E. coli
populations. Altering dietary ingredi-
ents did not affect total E. coli popu-
lations; however, steers fed diets
containing dry-rolled or high-moisture
corn had lower acid-resistant E. coli
populations. Following completion of
the Latin Square, all animals were fed
alfalfa hay ad libitum for five days.
Switching steers to alfalfa hay lowered
both total and acid-resistant E. coli
populations.
Introduction
The bacterium Escherichia coli is a
normal inhabitant of the intestinal tracts
of human beings and animals. However,
some strains of E. coli — for example,
serotype O157:H7 — are capable of
causing disease in humans. In cattle, E.
coli O157:H7 is carried in the gastrointes-
tinal tract and is shed in the feces while
the animal shows no signs of disease.
The organism is thought to enter the
food chain through fecal contamination
of the hide during slaughter. Two impor-
tant features of E. coli O157:H7 are its
low infective dose and acid resistance.
The low infective dose for humans,
coupled with the fact that complete pre-
vention of microbial contamination at
slaughter is not feasible, has lead to the
development of the concept that food-
borne illness might best be prevented by
reducing pathogen prevalence in live-
stock, a concept also known as pre-
harvest food safety.
Recently, short-duration hay feeding
was suggested as a viable pre-harvest
food safety technique (Diez-Gonzalez,
et al., 1998, Science, 281:1578). When
animals that had been consuming grain
were fed hay for four days, the preva-
lence of both generic and acid-resistant
E. coli was reduced. High grain diets
allow undigested starch to accumulate in
the colon. Accumulated starch is subse-
quently fermented resulting in volatile
fatty acid production, an acidic pH, and
facilitated growth of acid-resistant E.
coli. The resulting hypothesis is that
reducing the starch load in the colon will
significantly reduce the numbers of E.
coli O157:H7.
Regardless of the potential benefits
of hay feeding, it is not a practical ap-
proach for cattle feeders. However, if
the amount of starch being fermented in
the colon is the key to reducing the
prevalence of E. coli, there may be alter-
native means to achieve the same results.
Wet corn gluten feed and high-moisture
corn are two common dietary ingredi-
ents that offer opportunities to achieve
similar results as observed with hay feed-
ing. Wet corn gluten feed contains little
or no starch and is 80% digestible in the
rumen. Therefore, feeding wet corn glu-
ten feed should reduce the starch load in
the colon since material bypassing di-
gestion in the rumen would be fibrous
corn bran as opposed to starch. High-
moisture corn is more extensively de-
graded in the rumen than dry-rolled corn.
Therefore, comparatively less starch
bypasses digestion in the rumen when
feeding high-moisture corn. The net ef-
fect of replacing dry-rolled corn with
wet corn gluten feed or high-moisture
corn would be reduced starch load in the
colon.
Therefore, our hypothesis for this
study was by manipulating the finishing
diet, the amount of starch being fer-
mented in the colon would decrease,
thereby increasing colonic pH and
decreasing the number of acid-resistant
E. coli. Also, it was hypothesized that
limit-feeding of finishing diets may offer
an alternative means of reducing acid-
resistant E. coli. Limit-feeding of fin-
ishing diets should result in less
fermentation in the colon (increased
colonic pH) because of more complete
digestion in the rumen due to slower rate
of passage, increased retention time and
increased extent of digestion.
Procedure
Experiment 1
Nine steers were fed finishing diets in
a replicated 3 x 3 Latin square design.
Treatments were finishing diets (Table
1) based on dry-rolled corn (DRC), high-
moisture corn (HMC), or wet corn glu-
ten feed (WCGF). Diets were formulated
to contain a minimum of 12.5% CP, .7%
Ca, .35% P, .6% K, and included 25 g/
ton Rumensin and 10 g/ton Tylan.
Each period was 21 days in duration.
During days 1-9 of each period, steers
were fed at 1.8% of body weight (DM
basis). Intake for each subsequent
period was adjusted based on weights
taken at the end of each 21-day period.
Steers were allowed to consume feed ad
libitum during days 10-21 of each
period. Samples of colonic digesta were
obtained on days 9, 20 and 21 and ana-
lyzed for volatile fatty acid concentra-
tion (analyses not completed; therefore,
data not shown), pH and numbers of
total and acid-resistant E. coli.
(Continued on next page)
2000 Nebraska Beef Report — Page 40
Experiment 2
Upon completion of the final period
of the 3 x 3 Latin Square, the nine steers
were fed alfalfa hay ad libitum, allowing
three steers each previously being fed
dry-rolled corn, wet corn gluten feed, or
high-moisture corn to be observed after
short duration hay feeding. Samples of
colonic digesta were obtained on two
consecutive days following five days of
hay feeding and analyzed for volatile
fatty acid concentration (analyses not
completed; therefore, data not shown),
pH, and numbers of total and acid-resis-
tant E. coli.
Results
Experiment 1
The effects of diet on DMI, most
probable number (MPN) of total and
acid-resistant E. coli, and colonic pH
are shown in Table 2. During the period
when steers were being limit-fed, neither
total nor acid-resistant E. coli counts
were statistically different among the
three treatments; however, colonic pH
was higher (P < .10) in steers fed WCGF
than in steers fed DRC or HMC. There
was no treatment effect on DMI when
steers were switched to ad libitum feed-
ing. Total E. coli numbers were similar
among treatments. Steers consuming
DRC or HMC had significantly lower (P
< .10) acid-resistant E. coli numbers
than steers consuming WCGF. Colonic
pH was higher in steers fed WCGF or
HMC (P < .10) than in steers fed DRC.
Our interpretation is that acid-resistant
E. coli numbers can not be reduced
through either limit-feeding or this type
of dietary manipulation. However, feed-
ing WCGF did increase colonic pH in
steers during both the limit-feeding
period and the ad libitum feeding period.
Wet corn gluten feed is very low in
starch concentration, but it does not
appear that lowering the amount of starch
reaching the colon will reduce acid-
resistant E. coli numbers. Likewise,
even though HMC is more extensively
degraded in the rumen and colonic pH
increased during ad libitum feeding com-
pared to DRC, there was no reduction in
Table 1. Composition of finishing diets.
Treatmenta
Ingredient (% of DM) DRC HMC WCGF
Dry-rolled corn 84.707 33.773 40.832
High-moisture corn —— 50.866 ——
Wet corn gluten feed —— —— 45.000
Alfalfa hay 7.500 7.500 7.500
Molasses 5.000 5.000 5.000
Limestone 1.338 1.337 1.304
Urea .952 1.019 ——
Salt .300 .300 .300
Dicalcium phosphate .107 .108 ——
Potassium chloride .032 .033 ——
Trace mineral .020 .020 .020
Rumensin premix .016 .016 .016
Vitamin premix .015 .015 .015
Tylan premix .013 .013 .013
aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.
Table 2. Effect of diet on DMI and MPN of total and acid-resistant E. coli.
Treatmenta
Item DRC HMC WCGF SEM
Limit-fed periodb
Total E. coli, log10
c 7.87 8.54 8.50 .28
Acid-resistant E. coli, log10
d 2.61 4.52 4.24 .77
Colonic pH 6.42e 6.61e 6.85f .12
Ad libitum periodg
DMI, lb/day 18.69 18.03 18.88 .62
Total E. coli, log10
c 8.25 8.45 8.46 .21
Acid-resistant E. coli, log10
d 3.04e 3.24e 3.71f .47
Colonic pH 6.21e 6.55f 6.68f .14
aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.
bLimit-fed period = days 1-9.
cMPN = most probable number of total E. coli is expressed in log10 units.
dMPN = most probable number of acid-resistant E. coli is expressed in log10 units.
efMeans within a row with unlike superscripts differ (P < .10).
gAd libitum period = days 10-21.
Table 3. Effect of hay feeding on MPN of total and acid-resistant E. coli.
Treatmenta
Item DRC HMC WCGF SEM
Total E. coli, log10
b 7.13 6.89 6.89 .34
Acid-resistant E. coli, log10
c 1.70 1.00 1.33 .29
Colonic pH 8.00 7.86 7.96 .06
aDRC = dry-rolled corn; HMC = high-moisture corn; WCGF = wet corn gluten feed.
bMPN = most probable number of total E. coli is expressed in log10 units.
cMPN = most probable number of acid-resistant E. coli is expressed in log10 units.
Table 4. Effect of feeding alfalfa hay versus a finishing diet on MPN of total and acid-resistant
E. coli.
Treatmenta
Item ALF FIN SEM
Total E. coli, log10
b 6.97c 7.95d .20
Acid-resistant E. coli, log10
e 1.34c 3.99d .33
Colonic pH 7.94c 6.52d .14
aALF = alfalfa hay; FIN = finishing diet.
bMPN = most probable number of total E. coli is expressed in log10 units.
cdMeans within a row with unlike superscripts differ (P < .01).
eMPN = most probable number of acid-resistant E. coli is expressed in log10 units.
Page 41 — 2000 Nebraska Beef Report
DRC, HMC, and WCGF, respectively.
These numbers indicate irrespective of
diet, acid-resistant E. coli numbers
were reduced when steers were fed
alfalfa hay ad libitum for a period of five
days.
Since there were no significant dif-
ferences among DRC, HMC, or WCGF
finishing diets when switched to alfalfa
hay feeding, data were pooled to illus-
trate the effect of feeding alfalfa hay
versus feeding finishing diets on the MPN
of total and acid-resistant E. coli and
colonic pH (Table 4). Switching steers
to alfalfa hay lowered (P < .01) both total
and acid-resistant E. coli. Total E. coli
numbers were lowered by about 1 log
10
unit while acid-resistant E. coli numbers
were lowered by about 2.5 log
10
 units.
Colonic pH was increased (P < .01) by
over 1 pH unit in response to hay feed-
ing. These data indicate short-duration
hay feeding reduced acid-resistant E.
coli populations in the feces by over
99%.
acid-resistant E. coli counts. Similarly,
limit-feeding of the finishing diets did
not alter acid-resistant E. coli numbers
in comparison to ad libitum feeding.
Potentially, one could limit intake more
and possibly reduce acid-resistant E.
coli; however, the reduced intake
would impact daily gain and potentially
carcass merit.
Experiment 2
The effect of switching steers to
alfalfa hay for five days is shown in
Table 3. Total E. coli counts were
similar among treatments; however,
counts were reduced from previously
observed counts in Period 3 by .5, 1.27,
and 1.16 log
10
 units for DRC, HMC, and
WCGF, respectively. Similarly, there
were no differences in acid-resistant
E. coli counts among the treatments;
however, counts were reduced from
those previously observed in Period 3
by 2.35, 2.58, and 3.01 log
10
 units for
Dietary manipulation of finishing
diets either by substituting ingredients
or limit-feeding successfully increased
colonic pH, indicating substrate changes
at the level of the colon; however,
increased colonic pH was not asso-
ciated with reduced populations of
acid-resistant E. coli. Feeding alfalfa
hay both increased colonic pH and
decreased acid-resistant E. coli. This
study confirms Diez-Gonzalez (1998)
report that feeding hay for a short dura-
tion can reduce acid-resistant E. coli
populations.
1Tony Scott, Casey Wilson, research
technicians, Animal Science, Lincoln; Doreen
Bailey, research technician, Veterinary and
Biomedical Sciences, Lincoln; Terry Klopfenstein,
Professor, Todd Milton, Assistant Professor,
Animal Science, Lincoln. Rod Moxley, Professor,
Dave Smith, Jeff Gray, Assistant Professors,
Veterinary and Biomedical Sciences, Lincoln;
Laura Hungerford, Associate Professor, Great
Plains Veterinary Educational Center, Clay Center.
Effects of Programmed Gain Feeding Strategies on
Performance and Carcass Characteristics of
Yearling Steers
Tony Scott
Todd Milton
Terry Mader
Terry Klopfenstein
Simone Holt1
Programming gain for the first
21 or 42 days of the feeding period
reduced the total amount of feed
consumed but did not improve
cumulative performance compared
with ad libitum feeding.
Summary
Two hundred forty-five crossbred
yearling steers were used in a random-
ized complete block design to deter-
mine effects of including a programmed
gain phase in the feeding period on
performance and carcass characteris-
tics. Including a programmed gain
phase in the finishing period resulted in
similar cumulative daily gains and feed
conversions when compared with steers
allowed to consume feed ad libitum.
Programming gain reduced the total
amount of feed consumed per animal;
however, the lack of an improvement in
feed conversion coupled with slight
numerical differences in hot carcass
weights resulted in net profits favoring
ad libitum feeding.
Introduction
Previous research regarding control-
ling intake during the finishing period
has focused on maintaining a static in-
take relative to ad libitum fed control
pens. Improvements in efficiency have
been demonstrated; however, daily gain
may decrease, resulting in increased days
on feed. Recent studies (Knoblich, et al.,
1997, J. Anim. Sci., 75:3094; Loerch
and Fluharty, 1998, J. Anim. Sci., 76:371)
have shown similar daily gains, hot car-
cass weights and days on feed. At the
same time, reductions in the amount of
feed consumed result in improvements
in efficiency.
Currently research on controlling in-
take during the finishing period has
shifted toward programmed gain sys-
tems. Programmed gain systems are
based on the net energy equations in the
NRC (1996). Based on the diet being
fed, a programmed rate of gain is se-
lected and the amount of feed required to
achieve the programmed rate of gain can
be calculated.
In a previous study (1999 Nebraska
Beef Report, pp 46-48), programmed
(Continued on next page)


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Influence of Diet on Total and Acid Resistant \u3ci\u3eE. coli\u3c/i\u3e and Colonic pH

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