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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 don’t know the answer, they are instructed to answer “acidosis”.
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Starch VFA Whole corn High moisture corn Dry rolled corn VFA CH 3 C=O OH CH 3 CH 2 C=O OH CH 3 CH 2 CH 2 C=O OH Energy Small Intestine Rumen Grain Feeding
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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 Subacute Acidosis <5.0 <5.6
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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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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
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Symptoms of Subacute Acidosis
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Acidosis and Intake Variation Low ruminal pH Reduced intake High ruminal pH Over consumption
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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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Submersible pH probes fitted through rumen cannula Data collected via PC Acidosis Research At Nebraska
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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
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Lbs./ day pH Typical Feed Intake And Ruminal pH Acidosis Research At Nebraska Cooper et al., 1998
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Average Daily Ruminal pH 566330 Acidosis Research At Nebraska Cooper et al., 1998
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Lbs./ day pH Subacute Acidosis Feed Intake And Ruminal pH Acidosis Research At Nebraska Cooper et al., 1998
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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
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DMI of Three Steers During Step-up Acidosis Research At Nebraska Cooper et al., 1998
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Average Daily Ruminal pH Acidosis Research At Nebraska Cooper et al., 1998
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Roughage Crawford et al., 2006
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Alfalfa level, %P-value a Item4.59.013.5LQ DMI14.514.715.0 Average pH 5.415.52 5.58 0.010.70 Maximum pH 6.256.39 6.41 0.090.43 Minimum pH 4.924.955.02 0.050.56 Time < 5.6, min 1015853778 0.020.56 Area < 5.6 361276252 0.050.48 a No alfalfa level x CaMg(CO 3 ) 2 interactions were observed (P ≥ 0.15). Crawford et al., 2006 Roughage
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DMI 23.5 c 21.2 ab 20.0 b 22.0 bc 0.02 Average pH 5.95 a 6.13 bc 6.11 b 6.25 c 0.01 Minimum pH 5.34 a 5.51 b 5.53 bc 5.63 c 0.02 Maximum pH 6.65 a 6.79 bc 6.75 ab 6.88 c 0.01 Time < 5.6, min 406268237156 0.06 a,b,c Means differ (P ≥ 0.15). Farran et al., 2003 Dietary Buffers ItemControlAcidbufAcidbufBicarb F-test 0.751.251.25
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DMI, lb/d28.327.6 Rate of intake, % of daily intake/min.61.55 Ruminal pH a 5.595.73 Area below 5.6 bc 216.198.2 pH DIFF d 1.101.07 pH VAR e.063.055 a Means differ (P= 0.11). b Area = ruminal pH units below 5.6 by minute. c Means differ (P < 0.10). d Magnitude of daily ruminal pH change. e Variance of daily ruminal pH. ItemControlRumensin Treatment Feeding Rumensin Cooper et al., 1997
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DMI, lb/d pre challenge, d 15-2122.021.621.6 challenge, d 2332.832.532.1 post challenge, d 24-2818.621.620.2 Ruminal pH pre challenge5.755.645.67 challenge 1 5.53 a 5.63 ab 5.76 b post challenge 2 5.565.545.71 pHVAR 3 0.570.490.48 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) ItemControlRumensinRumensin 33 g/ton44 g/ton Treatment Blackford et al., 2000 Feeding Rumensin
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Blackford et al., 2002 c d d a a b a,b Means differ (P < 0.05); c,d Means differ (P < 0.10)
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DMI, lb/d pre challenge24.9 a 20.6 b 19.4 b challenge34.3 a 30.5 b 29.4 b post challenge21.6 a 19.1 b 18.2 b Ruminal pH pre challenge5.575.575.65 challenge 1 5.685.715.77 post challenge 2 5.415.505.45 Max pH (initial) 3 7.027.117.12 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) ItemControlRumensinRumensin 33 g/ton44 g/ton Treatment Patterson et al., 2002 Feeding Rumensin
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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
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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 > 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@unlnotes.unl.edugeericks@unlnotes.unl.edu http://beef.unl.edu
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