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Impact of diet and management on rumen pH and acidosis in
feedlot cattle
Galen Erickson, Terry KlopfensteinRick Stock, and Rob Cooper
When Nebraska students are
asked a question and they
don’t know the answer, they
are instructed to answer
“acidosis”.
Starch
VFA
Whole corn
High moisture cornDry rolled corn
VFA
VFA
CH3C=OOH
CH3CH2C=OOH
CH3CH2CH2C=OOH
Energy
Small Intestine
Rumen
Grain Feeding
Acidosis As A Continuum
• The severity of the acidosis insult determines the symptoms
observed. However, for simplicity it is often divided into acute and subacute acidosis.
Acute Versus Subacute Acidosis
Ruminal pH
Acute Acidosis
Subacute Acidosis
<5.0
<5.6
Acute Acidosis
• Most often recognized
• Diet transition period
• Intake regulation:
• Forages = rumen fill
• Grain = chemical mechanisms
• “Sudden Death Syndrome”
• Liver Abscesses
• Bloat
• Occurs more frequently
• Difficult to observe or identify
• Major response = Reduced feed intake!
• Pen feeding conditions
• Individual reductions in feed intake masked by pen average
• Erratic feed intake patterns
Sub-Acute Acidosis
Symptoms of Subacute Acidosis
Acidosis and Intake Variation
Low ruminal pH
Reduced intake
High ruminal pH
Over consumption
Intake Variance
Individually Fed Cattle
Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers
Burrin et al., 1988
1- 2 3 - 7 8 - 12 13 - 28 57- 70 97 - 1100
2
4
6
8
10
12
14
16
18
20
1- 2 3 - 7 8 - 12 13 - 28 57- 70 97 - 110DAYS
CONTROLRUMENSIN
% CONC 50 65 85 100
VARIANCE
P<.001
P<.01
P<.01
Correlation between intakevariance and gain/feed
All: r = .30All concentrate: r = .49
Burrin et al., 1988
Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers
But, averaged similar to a "pen"
Burrin et al., 1988
1 - 2 3 - 7 8 - 12 13 - 28 57 - 70 97-11002468
101214161820
1 - 2 3 - 7 8 - 12 13 - 28 57 - 70 97-110
CONTROLRUMENSIN 25 G/ton
% CONC 50 65 80 100DAYS
VARIANCE
Managing Acidosis Rate of starch digestion
Amt of starch: adaptation Grain type & processing
Byproducts
Roughage
Feed additives
Bunk management
Acidosis Research At Nebraska
• Continuous data acquisition system developed for individual
measurements• Individual feed bunks suspended
from load cells• Actually measuring feed
“disappearance”
• Can get intake rate over time, meal size, meal frequency, etc.
• Submersible pH probes fitted through rumen cannula
• Data collected via PC
Acidosis Research At Nebraska
• Typical research study:• Computer takes readings of feed
bunks and pH probes every 5 seconds
• Computer records average values for feed bunks and pH probes every minute to data file
• 60 minutes/hour * 24 hours/day = • 1480 DATA POINTS PER DAY!!!
Acidosis Research At Nebraska
0
10
20
30
40
50
8:00
16:0
0
0:00
8:00
16:0
0
0:00
8:00
Time of day
3.5
4.5
5.5
6.5Ruminal pH
Feed Intake
Lbs./day pH
Typical Feed Intake And Ruminal pH
Acidosis Research At Nebraska
Cooper et al., 1998
Average Daily Ruminal pH
4.5
5.0
5.5
6.0
6.58:
00
16:0
0
0:00
8:00
16:0
0
0:00
8:00
Time of day
Rum
inal
pH
566 330
Acidosis Research At Nebraska
Cooper et al., 1998
0
10
20
30
40
50
8:00
16:0
0
0:00
8:00
16:0
0
0:00
8:00
Time of day
3.5
4.5
5.5
6.5Ruminal pH
Feed Intake
Lbs./day pH
Subacute Acidosis Feed Intake And Ruminal pH
Acidosis Research At Nebraska
Cooper et al., 1998
Feed intake and ruminal pH of same steer as in previous figure, first and second day of step 2 (65% concentrate).
Acidosis Research At Nebraska
Cooper et al., 1998
10
15
20
25
30
0 5 10 15 20 25 30Days On Feed
DM
I, lb steer 1
steer 2steer 3
DMI of Three Steers During Step-up
Acidosis Research At Nebraska
Cooper et al., 1998
5.0
5.5
6.0
6.5
7.0
0 5 10 15 20 25 30
Days On Feed
Rum
inal
pH
steer 1
steer 2
steer 3
Average Daily Ruminal pH
Acidosis Research At Nebraska
Cooper et al., 1998
Roughage
Crawford et al., 2006
Alfalfa level, % P-valuea
Item 4.5 9.0 13.5 L Q
DMI 14.5 14.7 15.0
Average pH 5.41 5.52 5.58 0.01 0.70
Maximum pH 6.25 6.39 6.41 0.09 0.43
Minimum pH 4.92 4.95 5.02 0.05 0.56
Time < 5.6, min 1015 853 778 0.02 0.56
Area < 5.6 361 276 252 0.05 0.48
aNo alfalfa level x CaMg(CO3)2 interactions were observed (P ≥ 0.15).
Crawford et al., 2006
Roughage
DMI 23.5c 21.2ab 20.0b 22.0bc 0.02
Average pH 5.95a 6.13bc 6.11b 6.25c 0.01
Minimum pH 5.34a 5.51b 5.53bc 5.63c 0.02
Maximum pH 6.65a 6.79bc 6.75ab 6.88c 0.01
Time < 5.6, min 406 268 237 156 0.06
a,b,c Means differ (P ≥ 0.15).
Farran et al., 2003
Dietary Buffers
Item Control Acidbuf Acidbuf Bicarb F-test0.75 1.25 1.25
DMI, lb/d 28.3 27.6Rate of intake, % of daily intake/min .61 .55Ruminal pHa 5.59 5.73Area below 5.6bc 216.1 98.2pH DIFFd 1.10 1.07pH VARe .063 .055
aMeans differ (P= 0.11).bArea = ruminal pH units below 5.6 by minute.cMeans differ (P < 0.10).dMagnitude of daily ruminal pH change.eVariance of daily ruminal pH.
Item Control Rumensin
Treatment
Feeding Rumensin
Cooper et al., 1997
DMI, lb/dpre challenge, d 15-21 22.0 21.6 21.6challenge, d 23 32.8 32.5 32.1post challenge, d 24-28 18.6 21.6 20.2
Ruminal pHpre challenge 5.75 5.64 5.67challenge1 5.53a 5.63ab 5.76b
post challenge2 5.56 5.54 5.71
pHVAR3 0.57 0.49 0.48
9 X 2 Incomplete Latin rectangle; (6 reps/diet)Fed 50% of "normal" DMI on d 22, then 175% on d 23 (4 hours late)1 (P = 0.06)2 (P = 0.11)3 challenge phase only (P = 0.10)
Item Control Rumensin Rumensin33 g/ton 44 g/ton
Treatment
Blackford et al., 2000
Feeding Rumensin
Feeding Rumensin
Blackford et al., 2002
0
100
200
300
400
500
600
prechallenge challenge day post challenge
pH
< 5
.6 *
min
ute
(A
rea
< 5
.6)
Control
Rumensin, 33 g/ton
Rumensin, 44 g/ton
c
d
d a a
b
a,b Means differ (P < 0.05); c,d Means differ (P < 0.10)
DMI, lb/dpre challenge 24.9a 20.6b 19.4b
challenge 34.3a 30.5b 29.4b
post challenge 21.6a 19.1b 18.2b
Ruminal pHpre challenge 5.57 5.57 5.65challenge1 5.68 5.71 5.77post challenge2 5.41 5.50 5.45
Max pH (initial)3 7.02 7.11 7.12
18 fistulated steers (9 measured per period); (6 reps/diet, but different steers)Fed 50% of "normal" DMI on d 22, then 175% on d 23 (4 hours late)1 (P = 0.06)2 (P = 0.11)3 challenge phase only (P = 0.10)
Item Control Rumensin Rumensin33 g/ton 44 g/ton
Treatment
Patterson et al., 2002
Feeding Rumensin
Krehbiel et al., 1995
Managing Acidosis Rate of starch digestion
Amt of starch: adaptation Grain type & processing
Byproducts WCGF effective, WDGS not as effective
Roughage
Feed additives Rumensin Buffers variable
CLEAR
CLEAR
CLEAR
CLEAR
Conclusions• Link of DMI and pH
• Inducing experimentally to study!
• Acidosis in individuals versus pens• Individual intakes in pens?
• Subacute acidosis/bloat > acute acidosisor “sudden death”
• Multiple factors influence rumen function• Diet: grain, roughage, byproduct, additives• Amount/rate of starch digestion• Rumen stasis and bloat• Metabolic acidosis and death may occur• Decrease in DMI, liver abscesses, founder, etc
