Transcript GPVEC acidosis 2008 - University of Nebraska–Lincoln

Impact of diet and management
on rumen pH and acidosis in
feedlot cattle
Galen Erickson, Terry Klopfenstein
Rick Stock, and Rob Cooper
When Nebraska students are
asked a question and they
don’t know the answer, they
are instructed to answer
“acidosis”.
Grain Feeding
Energy
CH3C=O
OH
CH3CH2C=O
OH
CH3CH2CH2C=O
OH
Rumen
Whole corn
Dry rolled corn
High moisture corn
VFA
VFA
Starch
VFA
Small Intestine
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
<5.0
Subacute Acidosis
<5.6
Acute Acidosis
• Most often recognized
• Diet transition period
• Intake regulation:
• Forages = rumen fill
• Grain = chemical mechanisms
• “Sudden Death Syndrome”
• Liver Abscesses
• Bloat
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
Symptoms of Subacute Acidosis
Acidosis and Intake Variation
Over consumption
High ruminal pH
Low ruminal pH
Reduced intake
Intake Variance
Individually Fed Cattle
Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers
VARIANCE
20
18
16
14
12
10
8
6
4
2
0
1- 2
DAYS
% CONC 50
P<.001
CONTROL
RUMENSIN
P<.01
P<.01
3-7
65
8 - 12
85
13 - 28
57- 70
97 - 110
100
Burrin et al., 1988
Correlation between intake
variance and gain/feed
All: r = .30
All concentrate: r = .49
Burrin et al., 1988
Variance in Feed Intake Among Days Within
Feeding Period for Individually Fed Steers
VARIANCE
20
18
16
14
12
10
8
6
4
2
0
DAYS 1 - 2
% CONC 50
But, averaged similar to a "pen"
CONTROL
RUMENSIN 25 G/ton
3-7
65
8 - 12
80
13 - 28
100
57 - 70
97-110
Burrin et al., 1988
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.
Acidosis Research At Nebraska
•
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
Typical Feed Intake And Ruminal pH
50
6.5
Ruminal pH
40
Lbs./ 30
day 20
5.5
pH
Feed Intake
10
4.5
8:00
0:00
16:00
8:00
0:00
16:00
3.5
8:00
0
Time of day
Cooper et al., 1998
Acidosis Research At Nebraska
Average Daily Ruminal pH
6.0
566
5.5
330
5.0
Time of day
8:00
0:00
16:00
8:00
0:00
16:00
4.5
8:00
Ruminal pH
6.5
Cooper et al., 1998
Acidosis Research At Nebraska
Subacute Acidosis Feed Intake And Ruminal pH
50
6.5
Ruminal pH
40
Lbs./ 30
day 20
5.5
pH
4.5
Feed Intake
10
8:00
0:00
16:00
8:00
0:00
16:00
3.5
8:00
0
Time of day
Cooper et al., 1998
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
Acidosis Research At Nebraska
DMI of Three Steers During Step-up
30
DMI, lb
25
steer 1
steer 2
steer 3
20
15
10
0
5
10
15
20
Days On Feed
25
30
Cooper et al., 1998
Acidosis Research At Nebraska
Average Daily Ruminal pH
Ruminal pH
7.0
steer 1
steer 2
steer 3
6.5
6.0
5.5
5.0
0
5
10
15
Days On Feed
20
25
30
Cooper et al., 1998
Roughage
Crawford et al., 2006
Roughage
P-valuea
Alfalfa level, %
Item
4.5
9.0
13.5
DMI
14.5
14.7
15.0
Average pH
Maximum pH
Minimum pH
5.41
6.25
4.92
Time < 5.6, min 1015
Area < 5.6
361
aNo
5.52
6.39
4.95
853
276
5.58
6.41
5.02
778
252
L
Q
0.01
0.09
0.05
0.70
0.43
0.56
0.02
0.05
0.56
0.48
alfalfa level x CaMg(CO3)2 interactions were observed (P ≥ 0.15).
Crawford et al., 2006
Dietary Buffers
Item
Control Acidbuf Acidbuf
Bicarb
0.75
1.25
1.25
20.0b
22.0bc
0.02
6.25c
5.63c
6.88c
0.01
23.5c
DMI
Average pH
Minimum pH
Maximum pH
5.95a
5.34a
6.65a
Time < 5.6, min 406
a,b,c Means
21.2ab
6.13bc
5.51b
6.79bc
268
6.11b
5.53bc
6.75ab
237
156
F-test
0.02
0.01
0.06
differ (P ≥ 0.15).
Farran et al., 2003
Feeding Rumensin
Treatment
Item
Control
DMI, lb/d
Rate of intake, % of daily intake/min
Ruminal pHa
Area below 5.6bc
pH DIFFd
pH VARe
28.3
.61
5.59
216.1
1.10
.063
Rumensin
27.6
.55
5.73
98.2
1.07
.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.
Cooper et al., 1997
Feeding Rumensin
Treatment
Item
DMI, lb/d
pre challenge, d 15-21
challenge, d 23
post challenge, d 24-28
Ruminal pH
pre challenge
challenge1
post challenge2
pHVAR3
Control
22.0
32.8
18.6
Rumensin
33 g/ton
21.6
32.5
21.6
Rumensin
44 g/ton
21.6
32.1
20.2
5.75
5.53a
5.56
5.64
5.63ab
5.54
5.67
5.76b
5.71
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
Feeding Rumensin
600
Control
Rumensin, 33 g/ton
Rumensin, 44 g/ton
c
pH < 5.6 * minute (Area < 5.6)
500
d
400
d
a
a
300
200
b
100
0
prechallenge
a,b
challenge day
Means differ (P < 0.05); c,d Means differ (P < 0.10)
post challenge
Blackford et al., 2002
Feeding Rumensin
Treatment
Item
DMI, lb/d
pre challenge
challenge
post challenge
Ruminal pH
pre challenge
challenge1
post challenge2
Max pH (initial)3
Control
Rumensin
33 g/ton
Rumensin
44 g/ton
24.9a
34.3a
21.6a
20.6b
30.5b
19.1b
19.4b
29.4b
18.2b
5.57
5.68
5.41
5.57
5.71
5.50
5.65
5.77
5.45
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
Krehbiel et al., 1995
Managing Acidosis
CLEAR
 Rate of starch digestion
 Amt of starch: adaptation
 Grain type & processing
CLEAR
 Byproducts
 WCGF effective, WDGS not as effective
CLEAR
 Roughage
CLEAR
 Feed additives
 Rumensin
 Buffers variable
Conclusions
• Link of DMI and pH
• Inducing experimentally to study!
• Acidosis in individuals versus pens
• Individual intakes in pens?
• Subacute acidosis/bloat > 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
Beef Extension Page
http://beef.unl.edu
Beef Reports
CONTACT:
Galen Erickson
402 472-6402; [email protected]
http://beef.unl.edu