View Full Table | Close Full ViewTable 1.

Composition of the basal diet

 
Item Percent DM
Ingredient
    Barley silage1 8.0
    Barley grain, dry rolled2 85.2
    Supplement3,4 6.8
        Barley grain, ground 3.34
        Canola meal 1.52
        Urea 0.23
        Limestone 0.76
        Mineralized salt 0.53
        Molasses 0.28
        Canola oil 0.12
        Vitamins A, D, and E 0.01
Chemical composition5
    DM, % 81.9 ± 1.76
    OM, % of DM 95.9 ± 0.26
    CP, % of DM 13.4 ± 0.69
    NDF, % of DM 17.3 ± 1.03
    ADF, % of DM 5.25 ± 0.53
1Composition (% of DM; mean ± SD): 38.5 ± 2.25 DM (% as fed), 93.3 ± 0.12 OM, 11.7 ± 0.66 CP, 42.3 ± 0.75 NDF, and 22.2 ± 0.57 ADF.
2Composition (% of DM; mean ± SD): 91.1 ± 1.19 DM (% as fed), 97.8 ± 0.18 OM, 14.0 ± 0.65 CP, 17.8 ± 0.82 NDF, and 4.5 ± 0.51 ADF.
3Composition (% of DM; mean ± SD): 93.6 ± 0.49 DM (% as fed), 66.3 ± 1.44 OM, 9.6 ± 0.31 CP, 10.4 ± 0.55 NDF, and 3.17 ± 0.12 ADF.
4Supplied per kilogram of dietary DM: 51 mg of Zn, 24 mg of Mn, 13 mg of Cu, 0.25 mg of Se, 0.17 mg of Co, 8,600 IU of vitamin A, 850 IU of vitamin D, and 90 IU vitamin E.
5Based on 5 composite period samples.



View Full Table | Close Full ViewTable 2.

Rumen evacuation measurements and calculation of molarity of organic acid treatments

 
Rumen evacuation Mean SD Minimum Maximum
Total contents, kg1 40.0 8.19 34.3 50.3
    DM content, % 17.3 1.86 15.2 19.2
    Total DM, kg 6.87 1.43 5.64 8.31
    Total fluid, kg 33.1 7.02 28.2 41.9
Dose2
    Low fumaric acid, mM 6.27 0.84 5.21 7.75
    High fumaric acid, mM 12.89 1.71 10.67 15.89
    Low malic acid, mM 5.28 0.76 4.36 6.79
    High malic acid, mM 11.93 1.59 9.90 14.74
1Calculated values are average of the data observed during rumen evacuations performed before the start of Period 1 and after the end of Period 5.
2Values presented are the estimated plateau concentrations of organic acids calculated based on total intake of 61 or 125 g/d of fumaric acid and 59 or 134 g/d of malic acid for the low and high doses, respectively, and assuming hourly liquid ruminal turnover rate of 11% and constant influx of the respective organic acid. The molecular weights are 116.07 and 134.09 g/mol for fumaric acid and malic acid, respectively.



View Full Table | Close Full ViewTable 3.

Feed intake and ruminal pH in beef cattle fed high-grain diets supplemented with different levels of fumaric or malic acid

 
Item Treatments
P-value
Fumaric acid2
Malic acid3
Control vs. organic acid Control vs. fumaric acid Control vs. malic acid Fumaric acid vs. malic acid
Control1 LF HF LM HM SEM
DMI, kg/d 10.0 10.1 10.3 9.80 9.40 0.39 0.77 0.63 0.31 0.07
Ruminal pH
    Mean 5.68 5.68 5.64 5.74 5.76 0.06 0.74 0.71 0.33 0.11
    Minimum 5.09 5.07 5.02 5.08 5.11 0.05 0.64 0.39 0.98 0.28
    Maximum 6.37 6.39 6.39 6.44 6.53 0.06 0.27 0.71 0.11 0.12
Ruminal pH < 6.2
    AUC,4 pH × h 12.3 12.4 13.3 11.7 11.4 1.2 0.97 0.65 0.61 0.24
    Duration, h/d 20.3 20.5 20.2 18.4 17.1 2.0 0.20 0.95 0.02 <0.01
Ruminal pH < 5.8
    AUC, pH × h 5.28 5.45 6.22 5.49 5.45 0.76 0.66 0.54 0.84 0.62
    Duration, h/d 14.1 14.2 14.8 13.1 12.4 1.36 0.73 0.75 0.35 0.13
Ruminal pH < 5.5
    AUC, pH × h 1.95 1.93 2.57 2.17 2.28 0.42 0.55 0.57 0.61 0.95
    Duration, h/d 7.99 9.12 9.53 8.80 8.51 1.26 0.43 0.35 0.64 0.56
Ruminal pH < 5.2
    AUC, pH × h 0.40 0.21 0.58 0.33 0.45 0.14 0.93 0.96 0.92 0.95
    Duration, h/d 2.32 2.32 4.18 3.50 3.55 0.82 0.28 0.29 0.17 0.69
1Control = no supplementation.
2Treatments provided a low level (low fumaric acid [LF]; 61 g/d) and a high level (high fumaric acid [HF]; 125 g/d) of fumaric acid mixed with the diets.
3Treatments provided a low level (low malic acid [LM]; 59 g/d) and a high level (high malic acid [HM]; 134 g/d) of malic acid mixed with the diets.
4AUC = area under the curve.



View Full Table | Close Full ViewTable 4.

Ruminal volatile fatty acids and microbial populations in beef cattle fed high-grain diets supplemented with different levels of fumaric or malic acid

 
Item Treatments
Fumaric acid2
Malic acid3
P-value
Control1 LF HF LM HM SEM Control vs. organic acid Control vs. fumaric acid Control vs. malic acid Fumaric acid vs. malic acid
Total VFA, mM 135.6 138.4 138.6 134.5 128.8 3.83 0.98 0.30 0.32 0.02
Individual VFA, mol/100 mol
    Acetate 51.1 49.3 49.1 50.2 50.2 1.20 0.15 0.08 0.38 0.26
    Propionate 34.7 35.2 34.9 34.3 34.4 2.33 0.98 0.91 0.89 0.78
    Butyrate 9.11 9.90 10.2 10.0 10.3 0.98 0.53 0.59 0.54 0.92
    Isobutyrate 0.91 0.84 0.91 0.97 0.88 0.05 0.76 0.42 0.80 0.20
    Valerate 2.04 2.49 2.68 2.31 1.98 0.35 0.40 0.21 0.82 0.20
    Isovalerate 1.60 1.74 1.79 1.75 1.80 0.33 0.60 0.64 0.62 0.98
    Caproate 0.45 0.51 0.48 0.47 0.35 0.09 0.95 0.58 0.66 0.23
Lactate, mM 0.09 0.21 0.50 0.13 0.15 0.14 0.32 0.13 0.78 0.13
Succinate, mM 0.11 0.97 0.09 0.08 0.12 0.40 0.64 0.38 0.99 0.28
Acetate:propionate 1.59 1.61 1.54 1.60 1.68 0.21 0.95 0.94 0.85 0.73
T otal culturable bacteria (× 109), cfu/mL 5.64 5.00 4.76 4.60 3.86 0.66 0.13 0.63 0.03 0.03
L actate utilizers (× 109), cfu/mL 4.74 4.78 4.16 4.18 4.91 0.74 0.59 0.91 0.38 0.35
1Control = no supplementation.
2Treatments provided a low level (low fumaric acid [LF]; 61 g/d) and a high level (high fumaric acid [HF]; 125 g/d) of fumaric acid mixed with the diets.
3Treatments provided a low level (low malic acid [LM]; 59 g/d) and a high level (high malic acid [HM]; 134 g/d) of malic acid mixed with the diets.