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Effect of induced ruminal acidosis on blood variables in heifers.

Marchesini G, De Nardi R, Gianesella M, Stefani AL, Morgante M, Barberio A, Andrighetto I, Segato S - BMC Vet. Res. (2013)

Bottom Line: Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis.The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040).Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, (PD) 35020, Italy.

ABSTRACT

Background: Ruminal acidosis is responsible for the onset of different pathologies in dairy and feedlot cattle, but there are major difficulties in the diagnosis. This study modelled the data obtained from various blood variables to identify those that could indicate the severity of ruminal acidosis. Six heifers were fed three experimental rations throughout three periods. The diets were characterised by different starch levels: high starch (HS), medium starch (MS) and low starch, as the control diet (CT). Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis. Blood samples were analysed for complete blood count, biochemical profile, venous blood gas, blood lipopolysaccharide (LPS) and LPS-binding proteins (LBP).

Results: The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040). Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001). A canonical discriminant analysis (CDA) was used to classify the animals into four ruminal pH classes (normal, risk of acidosis, subacute ruminal acidosis and acute ruminal acidosis) using haemoglobin, mean platelet volume, β-hydroxybutyrate, glucose and reduced haemoglobin.

Conclusions: Although additional studies are necessary to confirm the reliability of these discriminant functions, the use of plasma variables in a multifactorial model appeared to be useful for the evaluation of ruminal acidosis severity.

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Mean amount of time per day below the three ruminal pH thresholds. Thresholds (pH < 5.0; 5.0 ≤ pH < 5.5 and 5.5 ≤ pH < 5.8) on d1 through d3, separated by the dietary treatment (CT = control, MS = medium starch, HS = high starch) and period (P1, P2, P3). Data are presented as averages and the associated P values are given by using the non parametric Kruskal-Wallis test. A, B Means of the amount of time per day below pH 5.0 with different superscripts are different (P < 0.05); a, b Means of the amount of time per day between pH 5.0 and 5.5 with different superscripts are different (P < 0.05); α, β Means of the amount of time between pH 5.5 and 5.8 with different superscripts are different (P < 0.05). The superscript letters refer to the interaction between the treatment and the period.
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Figure 3: Mean amount of time per day below the three ruminal pH thresholds. Thresholds (pH < 5.0; 5.0 ≤ pH < 5.5 and 5.5 ≤ pH < 5.8) on d1 through d3, separated by the dietary treatment (CT = control, MS = medium starch, HS = high starch) and period (P1, P2, P3). Data are presented as averages and the associated P values are given by using the non parametric Kruskal-Wallis test. A, B Means of the amount of time per day below pH 5.0 with different superscripts are different (P < 0.05); a, b Means of the amount of time per day between pH 5.0 and 5.5 with different superscripts are different (P < 0.05); α, β Means of the amount of time between pH 5.5 and 5.8 with different superscripts are different (P < 0.05). The superscript letters refer to the interaction between the treatment and the period.

Mentions: The dry matter intake (DMI) was significantly affected by the treatment, the day, the interactions period x day and treatment x period x day (Table 1). The interactions were significant because the challenge diets were provided only on the challenge day (d1) as specified in the protocol to induce acidosis. The lowest DMI was observed following the high starch (HS) treatment as a result of the ruminal pH drop (Figure 1) on the day after the d1 (d2) and it could be explained as an attempt to avoid the effects of the very low ruminal pH. Moreover, in the second period, the heifers that had experienced a pH below 5.0 after ingesting the MS diet in the first period dramatically reduced their intake with the HS diet (Figure 2). The reluctance to consume diets rich in starch after experiencing ruminal acidosis could be explained as a memory effect due to previously experienced ruminal acidosis despite the two-week recovery period. This result depends not only on the memory effect but also on individual sensitivity to ruminal acidosis. Heifers that consumed MS feed in the second period had less severe acidosis than the heifers that had fed on the same diet in the first period (Figure 3) and showed a lower reduction in the intake of HS feed in the third period (Figure 2).


Effect of induced ruminal acidosis on blood variables in heifers.

Marchesini G, De Nardi R, Gianesella M, Stefani AL, Morgante M, Barberio A, Andrighetto I, Segato S - BMC Vet. Res. (2013)

Mean amount of time per day below the three ruminal pH thresholds. Thresholds (pH < 5.0; 5.0 ≤ pH < 5.5 and 5.5 ≤ pH < 5.8) on d1 through d3, separated by the dietary treatment (CT = control, MS = medium starch, HS = high starch) and period (P1, P2, P3). Data are presented as averages and the associated P values are given by using the non parametric Kruskal-Wallis test. A, B Means of the amount of time per day below pH 5.0 with different superscripts are different (P < 0.05); a, b Means of the amount of time per day between pH 5.0 and 5.5 with different superscripts are different (P < 0.05); α, β Means of the amount of time between pH 5.5 and 5.8 with different superscripts are different (P < 0.05). The superscript letters refer to the interaction between the treatment and the period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3649929&req=5

Figure 3: Mean amount of time per day below the three ruminal pH thresholds. Thresholds (pH < 5.0; 5.0 ≤ pH < 5.5 and 5.5 ≤ pH < 5.8) on d1 through d3, separated by the dietary treatment (CT = control, MS = medium starch, HS = high starch) and period (P1, P2, P3). Data are presented as averages and the associated P values are given by using the non parametric Kruskal-Wallis test. A, B Means of the amount of time per day below pH 5.0 with different superscripts are different (P < 0.05); a, b Means of the amount of time per day between pH 5.0 and 5.5 with different superscripts are different (P < 0.05); α, β Means of the amount of time between pH 5.5 and 5.8 with different superscripts are different (P < 0.05). The superscript letters refer to the interaction between the treatment and the period.
Mentions: The dry matter intake (DMI) was significantly affected by the treatment, the day, the interactions period x day and treatment x period x day (Table 1). The interactions were significant because the challenge diets were provided only on the challenge day (d1) as specified in the protocol to induce acidosis. The lowest DMI was observed following the high starch (HS) treatment as a result of the ruminal pH drop (Figure 1) on the day after the d1 (d2) and it could be explained as an attempt to avoid the effects of the very low ruminal pH. Moreover, in the second period, the heifers that had experienced a pH below 5.0 after ingesting the MS diet in the first period dramatically reduced their intake with the HS diet (Figure 2). The reluctance to consume diets rich in starch after experiencing ruminal acidosis could be explained as a memory effect due to previously experienced ruminal acidosis despite the two-week recovery period. This result depends not only on the memory effect but also on individual sensitivity to ruminal acidosis. Heifers that consumed MS feed in the second period had less severe acidosis than the heifers that had fed on the same diet in the first period (Figure 3) and showed a lower reduction in the intake of HS feed in the third period (Figure 2).

Bottom Line: Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis.The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040).Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, (PD) 35020, Italy.

ABSTRACT

Background: Ruminal acidosis is responsible for the onset of different pathologies in dairy and feedlot cattle, but there are major difficulties in the diagnosis. This study modelled the data obtained from various blood variables to identify those that could indicate the severity of ruminal acidosis. Six heifers were fed three experimental rations throughout three periods. The diets were characterised by different starch levels: high starch (HS), medium starch (MS) and low starch, as the control diet (CT). Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis. Blood samples were analysed for complete blood count, biochemical profile, venous blood gas, blood lipopolysaccharide (LPS) and LPS-binding proteins (LBP).

Results: The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040). Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001). A canonical discriminant analysis (CDA) was used to classify the animals into four ruminal pH classes (normal, risk of acidosis, subacute ruminal acidosis and acute ruminal acidosis) using haemoglobin, mean platelet volume, β-hydroxybutyrate, glucose and reduced haemoglobin.

Conclusions: Although additional studies are necessary to confirm the reliability of these discriminant functions, the use of plasma variables in a multifactorial model appeared to be useful for the evaluation of ruminal acidosis severity.

Show MeSH
Related in: MedlinePlus