A system of continual data acquisition of feed intake and ruminal pH has been developed for studying subacute acidosis in finishing steers. Feed intake is monitored with feedbunks which are suspended from weigh cells. Ruminal pH is monitored with submersible pH electrodes suspended in the rumen. Numerous anecdotal observations of subacute acidosis have been made throughout the feeding periods of several steers, providing information unlikely to be recognized during a planned trial. Therefore, this model for studying subacute acidosis offers many unique opportunities for enhancing our understanding of the interactions between feed intake and acidosis

Cooper, Rob

Klopfenstein, Terry J.

Stock, Rick

Parrott, Cal

English

Stadtarchiv Düsseldorf, "Tagebuch Willy Spatz" 1914-1919. 0-1-23-42.0000 Alle Scans zum Tagebucheintrag vom 26. November 1914 Willy Spatz (1861-1931) war Professor an der Kunstakademie Düsseldorf. Donnerstag, d. 26. November.   Heut begeht mein liebes Else-Kind ihren 18. Geburtstag. Dankerfüllt zu Gott, daß der furchtbare Krieg nicht in unsere Heimat getragen worden ist; beglückwünschten wir unser Geburtstagskind u. führten es dann zu seinem kleinem Geschenktisch, auf dem sich nützliche Mädch..

Stadtarchiv Düsseldorf

OpenEdition

26. November 1914

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University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 1998 
Observations on Acidosis Through Continual Feed Intake and 
Ruminal pH Monitoring 
Rob Cooper 
University of Nebraska-Lincoln 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
Rick Stock 
University of Nebraska-Lincoln 
Cal Parrott 
Elanco Animal Health, Greenfield, IN 
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Cooper, Rob; Klopfenstein, Terry J.; Stock, Rick; and Parrott, Cal, "Observations on Acidosis Through 
Continual Feed Intake and Ruminal pH Monitoring" (1998). Nebraska Beef Cattle Reports. 329. 
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Page 75 — 1998 Nebraska Beef Report
Table 5. Effects of imposed intake variation on performance of steers fed at ad libitum levels in
Finishing Trial 1
Treatment
Item Ad libituma Intake variationb SEM
Daily DMI, lbc 23.7 24.1 .1
Daily gain, lb 3.75 3.84 .06
Gain/DMI .159 .159 .003
aAd libitum feed offered with no imposed intake variation.
bDaily intake variation of 4 lb/day from days 35 through slaughter.
cMeans differ (P<.05).
Table 6. Effects of imposed intake variation on performance of steers fed at ad libitum levels in
Finishing Trial 2
Treatment
Item Ad libituma Intake variationb SEM
Daily DMI, lb 24.5 24.3 .2
Daily gain, lb 4.06 3.96 .05
Gain/DMI .165 .163 .003
aAd libitum feed offered with no imposed intake variation.
bDaily intake variation of 4 lb/day from days 35 through slaughter.
adapted to the routine of imposed
changes and therefore were less
affected. On the other hand, random
occurrences of intake variation, such
as a weather change or mill break-
down, may increase the incidence of
acidosis. These data suggest that fin-
ishing cattle can naturally vary their
intake (up to 4 lb/day and maybe
more) without creating acidosis or
reduced performance.
1Rob Cooper, research technician, Animal
Science, Lincoln; Terry Klopfenstein, Professor,
Animal Science, Lincoln; Rick Stock, Former
Professor, Animal Science, Lincoln; Cal Parrott,
Elanco Animal Health, Greenfield, IN.; Dan Herold,
research technician, Animal Science, Lincoln.
Observations on Acidosis Through Continual Feed
Intake and Ruminal pH Monitoring
Rob Cooper
Terry Klopfenstein
Rick Stock
Cal Parrott1
A system of continually moni-
toring feed intake and ruminal pH
of finishing steers has provided
many opportunities for making
anecdotal observations of subacute
acidosis during the finishing period.
Summary
A system of continual data acquisi-
tion of feed intake and ruminal pH has
been developed for studying subacute
acidosis in finishing steers. Feed in-
take is monitored with feedbunks which
are suspended from weigh cells. Rumi-
nal pH is monitored with submersible
pH electrodes suspended in the rumen.
Numerous anecdotal observations of
subacute acidosis have been made
throughout the feeding periods of sev-
eral steers, providing information
unlikely to be recognized during a
planned trial. Therefore, this model for
studying subacute acidosis offers many
unique opportunities for enhancing our
understanding of the interactions
between feed intake and acidosis.
Introduction
The cattle feeding business in the
United States has evolved into an inten-
sively managed, production-oriented
industry. Due to costs associated with
interest on cattle, yardage in the feedlot
and the price and inconvenience of
roughages, economics usually favor
rapidly increasing the grain portion of
the diet to put the cattle on a high
concentrate diet as soon as possible.
However, both the rapid increase in
concentrate and low roughage levels in
the finishing diet increase the potential
for subacute acidosis.
Subacute acidosis is generally char-
acterized as ruminal pH between 5.6
and 5.2. Ruminal pH below 5.2 is in-
dicative of acute acidosis. The major
response seen with subacute acidosis is
reduced intake; therefore subacute aci-
dosis is more subtle and more difficult
to access than acute acidosis. Even in
metabolism studies it is difficult to
measure all the effects of subacute aci-
dosis, because as ruminal pH declines
cattle adjust by decreasing feed intake
and alter their eating patterns. How-
ever, subacute acidosis continues to be
a major factor limiting feedlot cattle
performance. Several models have been
used to study subacute acidosis. One
model, the evaluation of intake varia-
tion of individually fed cattle (1991
Nebraska Beef Report, pp. 55), is
based on the premise that intake varia-
tion is caused by subacute acidosis.
Therefore, subacute acidosis can be
evaluated by monitoring the magnitude
of feed intake variation. The second
model is a steer metabolism model
(1993 Nebraska Beef Report, pp. 60).
Fistulated cattle are challenged with
sufficient grain to create subacute aci-
dosis. The challenge, usually half-corn
and half-wheat, is placed directly in the
rumen, and the ruminal pH determined
(Continued on next page)
1998 Nebraska Beef Report — Page 76
at 3-hour intervals over a 24-hour
period. These two models have been
very useful in the study of acidosis;
however, each has limitations. The
challenge used in the steer metabolism
model may not be appropriate for the
study of subacute acidosis as it may
overwhelm the system. While erratic
day-to-day intake variation is indica-
tive of subacute acidosis, within-day
intake patterns have not been evaluated
directly in the intake variance model.
Therefore, it was desirable to develop a
more complete subacute acidosis model.
A system of continual acquisition of
feed intake and ruminal pH was devel-
oped so a more complete under-
standing of the interactions between
ruminal pH and feed intake would be
possible.
Procedure
Continuous data acquisition of feed
intake and ruminal pH has been col-
lected on many steers throughout sev-
eral different trials. In some of these
trials, subacute acidosis has been mon-
itored during the grain adaptation
period. Feed intake and ruminal pH
data also have been gathered on num-
erous steers during periods of subacute
acidosis induced by varying dry matter
intake of steers fed a high concentrate
diet, directly placing grain in the rumen
and late feeding. The results from these
trials have been previously reported.
However, in this report, observations
and comments will be made concerning
interesting situations and anecdotal
events which have occurred throughout
the large amount of data collected.
During all trials in which these data
were collected, steers were tethered in
individual metabolism stalls. Feed in-
takes were monitored with individual
feedbunks suspended from weigh cells.
Ruminal pH was monitored with sub-
mersible pH electrodes suspended
through the plug of the rumen cannula
of each steer. Each pH electrode was
encased in a weighted, four wire metal
shroud to keep the electrode in a sta-
tionary position 5 inches above the ven-
tral floor of the rumen while allowing
rumen contents to flow freely through
it. Weigh cells and pH electrodes were
linked directly to a computer allowing
data acquisition software to record both
a feed weight and a ruminal pH every
minute for each steer during collection
periods.
Although steers were tethered in
metabolism stalls, both intake and ani-
mal performance have been favorable
in all trials. It was not uncommon for
the yearling steers used in these trials to
consume over 25 lb of dry matter and to
gain approximately 4 lb per day.
Results
Examples of feed weight and rumi-
nal pH data collected are shown in
Figure 1, which depicts the two-day
intake and ruminal pH of a steer in the
middle of the finishing period. This
steer was fed a 92.5% concentrate, dry-
rolled corn-based diet once daily at
0800. Figure 1 also shows the typical
cyclic pattern of ruminal pH, which is
usually highest at feeding and declines
to its lowest point 5-10 hours later. The
graph for feed weight in Figure 1 actu-
ally shows feed disappearance from the
bunk. Therefore a meal is depicted when
the feed weight line declines. As Figure
1 shows, this steer ate at a more rapid
rate and consumed larger meals on day
1 than on day 2. The effects of these
intake patterns are reflected in the
ruminal pH, which dropped lower and
stayed lower longer during the first day
than compared to the second. This fig-
ure shows the truly cyclic nature of
ruminal pH and its relationship to feed
intake. Ruminal pH was relatively high
at the beginning of the first day which
probably promoted (or at least did not
Figure 1. Feed intake and ruminal pH of a steer over a two-day period on a finishing diet (92.5%
concentrate).
Figure 2. Feed intake and ruminal pH of a steer during the first and second day on feed (55%
concentrate).
35
30
25
20
15
10
5
0
Fe
ed
 W
ei
gh
t, 
lb
7.0
6.5
6.0
5.5
5.0
4.5
R
um
inal pH
Ruminal pH
Feed Weight
9:
00
13
:0
0
17
:0
0
21
:0
0
1:
00
5:
00
9:
00
13
:0
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:0
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21
:0
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1:
00
5:
00
9:
00
Time of Day
35
30
25
20
15
10
5
0
Fe
ed
 W
ei
gh
t, 
lb
6.5
6.0
5.5
5.0
R
um
inal pH
Ruminal pH
Feed weight
8:
00
12
:0
0
16
:0
0
20
:0
0
0:
00
4:
00
8:
00
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:0
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:0
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4:
00
8:
00
Time of Day
Page 77 — 1998 Nebraska Beef Report
hinder) the rapid rate of intake. As a
result of the rapid intake during day
one, ruminal pH dropped to a level
indicative of subacute acidosis. Rate of
intake was not as rapid during the sec-
ond day. This is likely due to both the
low ruminal pH experienced during day
1 and to a lower initial ruminal pH at
feeding time during day 2. During day
2, it appears the steer consumed feed at
a rate which prevented ruminal pH from
dropping to the first day’s level. It is
important to note the steer consumed
approximately the same amount of feed
on both days. However, the intake pat-
terns had significant effects on ruminal
pH and acidosis.
Figure 2 shows the feed intake and
ruminal pH of a steer which experi-
enced acidosis during the first day of
step 1 of the grain adaptation period.
Previously, this steer had been offered
alfalfa hay ad libitum. Figure 2 shows
the first and second day of step 1, a 55%
concentrate dry-rolled corn-based diet.
This steer consumed the diet very rap-
idly on day 1, eating approximately 30
lb (as-fed) in only two meals. Conse-
quently, ruminal pH dropped to ap-
proximately 5.0 and did not increase
until the next morning. The following
day, the steer was offered the same
amount of feed but did not consume a
meal until about midnight and then
only ate approximately 7 lb (as-fed) in
several small meals. Even on only a
55% concentrate diet, a steer can be-
come acidotic if the diet is consumed
too rapidly. This figure clearly shows
the relationship between feed intake
and ruminal pH and how an acidotic
steer will adjust intake to return rumi-
nal pH to a normal level. It is likely this
steer learned from this experience and
was consequently less aggressive at the
feedbunk later in the feeding period to
avoid acidosis. Figure 3 shows the feed
intake and ruminal pH of the same steer
on day 1 and day 2 of step 2, a 65%
concentrate diet (days 5 and 6 on feed).
During these days, the steer ate at a
slower rate, consuming small meals
throughout the day. As a result, ruminal
pH stayed relatively high and constant
compared to the two days in Figure 2.
Both figures show how a steer learns to
adjust intake pattern during grain adap-
tation in order to avoid acidosis.
Figure 4 shows the dry matter intake
of three steers during the grain adapta-
tion period. Steers were fed a dry-rolled,
corn-based diet once daily at ad libitum
levels. Step-up diets consisted of 45%
(d 1-5), 35% (d 6-10), 25% (d 11-15),
15% (d 26-20) and 7.5% alfalfa hay
(day 21-30) in place of dry-rolled corn.
Figure 5 shows the average daily rumi-
nal pH (average of 1,440 observations
per steer per day) of the same three
steers during the grain adaptation pe-
riod. In Figure 4, notice the steer repre-
sented by triangles steadily climbed in
intake during step 1, but dramatically
dropped in intake the first and second
days of step 2. Figure 5 shows that as the
steer was building intake during step 1,
its average ruminal pH was steadily
decreasing, reaching approximately 5.3
on the last day of step 1. Even if this
steer had not been moved to the next
step-up diet the next day, he likely
would have decreased intake. To com-
pound the steer’s existing acidosis prob-
lem, step 2 (65% concentrate) was
offered on day 6, further reducing aver-
age ruminal pH and causing the steer to
dramatically reduce intake for several
days. In retrospect, there may be two
different ways to conduct the feed
calling for this steer: 1) either offer
enough feed during step 1, or extend
step 1, until this steer was “caught”
(leaving feed in the bunk) reducing its
aggression during step 2; or 2) prohibit
this steer from building so high an in-
take on step 1, so that the increase in
concentrate would not so drastically
impact ruminal pH. The latter method,
(Continued on next page)
Figure 3. Feed intake and ruminal pH of same steer as in Figure 2, first and second day of step 2
(65% concentrate).
9:
00
13
:0
0
17
:0
0
21
:0
0
1:
00
5:
00
9:
00
13
:0
0
17
:0
0
21
:0
0
1:
00
5:
00
9:
00
35
30
25
20
15
10
5
0
Fe
ed
 W
ei
gh
t, 
lb
7.0
6.5
6.0
5.5
5.0
4.5
Ruminal pH
Feed Weight
R
um
inal pH
Time of Day
Figure 4. Dry matter intake of three steers during grain adaptation.
30
25
20
15
10
D
ry
 m
at
te
r i
nt
ak
e,
 lb
0 5 10 15 20 25 30
Days on Feed
Days % Concentrate
1-5 55
6-10 65
11-15 75
16-20 85
21-30 92.5
1998 Nebraska Beef Report — Page 78
however would encourage more rapid
rates of intake, which can create acido-
sis even with diets relatively high in
roughage, as shown in Figure 2.
Figure 5 shows another interesting
anecdotal event which occurred during
these steers’ grain adaptation period.
The figure shows that on day 24, aver-
age ruminal pH consistently increased
for all three steers. On this day, a feed-
ing mistake occurred and the steers,
which were usually fed at 0800 each
day were not fed until 1200. When the
steers were fed, they were only given 5-
10 lb at a time about every two hours to
help keep them on feed. Day 24 is the
fourth day on the finishing diet (92.5%
concentrate), probably one of the most
critical days during the grain adaptation
period. It is important to note these
steers were at ad libitum levels of intake
and that all had some feed left in the
bunk on the morning of day 24. How-
ever, by 1200 all of the bunks were slick
and the steers were somewhat aggres-
sive. Average ruminal pH likely in-
creased on this day because the steers
were out of feed for about four hours,
after which they were offered feed
spread out over an extended period of
time. On day 25, steers were given their
feed as normal. Figure 5 shows the
dramatic decrease in average ruminal
pH on day 25 and thereafter. As indi-
cated by both the very low ruminal pH
and slightly reduced intakes, the steer
represented by circles in Figure 5 suf-
fered subacute acidosis for several days
following the feeding mistake. It is
important to note these values are aver-
age daily ruminal pH; minimum daily
ruminal pH reached below 5.0 for all
three steers during this period. It is
interesting to note that later in this trial
period there were unsuccessful attempts
to induce subacute acidosis by fluctuat-
ing dry matter intake by 4 lb per day.
Feeding four hours late had a much
more substantial effect on acidosis than
intake variation of 4 lb per day. This
suggests consistency and timing of
feeding are critical management com-
ponents in order to avoid acidosis.
These are just a few examples of
anecdotal events and observations made
with this system of continual feed intake
and ruminal pH monitoring. Often these
observations are as interesting and
informational as the results collected
from the respective trial. One important
point needs to be emphasized. Acidosis
affects individual cattle. Through con-
tinual monitoring of feed intake and
ruminal pH of individual steers, it is
evident that virtually all steers experi-
ence varying degrees of subacute aci-
dosis sometime during feeding. It is
unlikely, however, that these bouts
would ever be noticed in a feedlot pen.
Although a complete pen of cattle may
not be “off feed”, individual cattle are
likely experiencing bouts of subacute
acidosis. Many times, this acidosis goes
unnoticed because individuals with re-
duced intake are “averaged out” by the
other cattle in the pen not experiencing
acidosis.
1Rob Cooper, research technician, Animal
Science, Lincoln; Terry Klopfenstein, Professor,
Animal Science, Lincoln; Rick Stock, Former
Professor, Animal Science, Lincoln; Cal Parrott,
Elanco Animal Health, Greenfield, IN.
Figure 5. Average daily ruminal pH of three steers during grain adaptation.
7.0
6.5
6.0
5.5
5.0
R
um
in
al
 p
H
0 5 10 15 20 25 30
Days on Feed
Days % Concentrate
1-5 55
6-10 65
11-15 75
16-20 85
21-30 92.5
