Impact of diet and management on rumen pH and acidosis in feedlot cattle

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Impact of diet and management on rumen pH and
acidosis in feedlot cattle Galen Erickson,
Terry Klopfenstein Rick Stock, and Rob Cooper
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When Nebraska students are asked a question and
they dont know the answer, they are instructed
to answer acidosis.
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Grain Feeding
Whole corn
Energy
Dry rolled corn
Rumen
High moisture corn
VFA
CH3CO OH
VFA
Starch
CH3CH2CO OH
VFA
CH3CH2CH2CO OH
Small Intestine
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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.

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Acute Versus Subacute Acidosis
Ruminal pH
Acute Acidosis
lt5.0
Subacute Acidosis
lt5.6
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Acute Acidosis

• Most often recognized
• Diet transition period
• Intake regulation
• Forages rumen fill
• Grain chemical mechanisms
• Sudden Death Syndrome
• Liver Abscesses
• Bloat

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Sub-Acute Acidosis

• 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

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Symptoms of Subacute Acidosis
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Acidosis and Intake Variation
Over consumption
Low ruminal pH
High ruminal pH
Reduced intake
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Intake Variance Individually Fed Cattle
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Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers
Burrin et al., 1988
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Correlation between intake variance and
gain/feed All r .30 All concentrate r .49
Burrin et al., 1988
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Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers But,
averaged similar to a "pen"
Burrin et al., 1988
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Managing Acidosis

• Rate of starch digestion
• Amt of starch adaptation
• Grain type processing
• Byproducts
• Roughage
• Feed additives
• Bunk management

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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.

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Acidosis Research At Nebraska

• Submersible pH probes fitted through rumen
  cannula
• Data collected via PC

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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!!!

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Acidosis Research At Nebraska
Typical Feed Intake And Ruminal pH
Lbs./ day
pH
Cooper et al., 1998
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Acidosis Research At Nebraska
Average Daily Ruminal pH
566
330
Cooper et al., 1998
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Acidosis Research At Nebraska
Subacute Acidosis Feed Intake And Ruminal pH
Lbs./ day
pH
Cooper et al., 1998
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Acidosis Research At Nebraska
Feed intake and ruminal pH of same steer as in
previous figure, first and second day of step 2
(65 concentrate).
Cooper et al., 1998
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Acidosis Research At Nebraska
DMI of Three Steers During Step-up
Cooper et al., 1998
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Acidosis Research At Nebraska
Average Daily Ruminal pH
Cooper et al., 1998
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Roughage
Crawford et al., 2006
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Roughage

• 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 lt 5.6, min 1015 853 778 0.02 0.56
• Area lt 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
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Dietary Buffers
Item Control Acidbuf Acidbuf Bicarb
F-test 0.75 1.25 1.25

• 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 lt 5.6, min 406 268 237 156 0.06
• a,b,c Means differ (P 0.15).

Farran et al., 2003
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Feeding Rumensin
Treatment
Item Control Rumensin
DMI, lb/d 28.3 27.6 Rate of intake, of daily
intake/min .61 .55 Ruminal pHa 5.59 5.73 Area
below 5.6bc 216.1 98.2 pH DIFFd 1.10 1.07 pH
VARe .063 .055
aMeans differ (P 0.11). bArea ruminal pH units
below 5.6 by minute. cMeans differ (P lt
0.10). dMagnitude of daily ruminal pH
change. eVariance of daily ruminal pH.
Cooper et al., 1997
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Feeding Rumensin
Treatment
Item Control Rumensin Rumensin 33 g/ton 44 g/ton
DMI, lb/d pre challenge, d 15-21 22.0 21.6 21.6
challenge, d 23 32.8 32.5 32.1 post challenge,
d 24-28 18.6 21.6 20.2 Ruminal pH pre
challenge 5.75 5.64 5.67 challenge1 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)
Blackford et al., 2000
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Feeding Rumensin
c
d
a
a
d
b
Blackford et al., 2002
a,b Means differ (P lt 0.05) c,d Means differ (P
lt 0.10)
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Feeding Rumensin
Treatment
Item Control Rumensin Rumensin 33 g/ton 44 g/ton
DMI, lb/d pre challenge 24.9a 20.6b 19.4b chall
enge 34.3a 30.5b 29.4b post challenge 21.6a 19.1b
18.2b Ruminal pH pre challenge 5.57 5.57 5.65
challenge1 5.68 5.71 5.77 post
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)
Patterson et al., 2002
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Krehbiel et al., 1995
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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
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Conclusions

• Link of DMI and pH
• Inducing experimentally to study!
• Acidosis in individuals versus pens
• Individual intakes in pens?
• Subacute acidosis/bloat gt acute acidosis
• or 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

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Beef Extension Page http//beef.unl.edu
Beef Reports
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CONTACT Galen Erickson 402 472-6402
geericks_at_unlnotes.unl.edu http//beef.unl.edu