Skip to main content

Table 2 Analysis of herd- and animal-level exposure factors for prevalence of sub-clinical mastitis among cattle in Africa from 2010 to 2020

From: Prevalence of subclinical mastitis, its associated bacterial isolates and risk factors among cattle in Africa: a systematic review and meta-analysis

Variable

Level

No. of datasets

Cattle tested by CMT

Heterogeneity

Univariate meta-regression (test for moderator association with sub-clinical mastitis)

   

No. tested

No. positive

% (95% CI)

χ2

p-value

I2 (%)

p-value

Ï„2, H2

Coefficient QM

R2 (%)

Age

        

< 0.0001

0.045, 27.2

26.2 (df = 2)

24.3

 

2 to 5 years

31

4524

1587

33.9 (26.8, 41.6)

557.1

< 0.01

96.5

    
 

6 to 9 years

32

5962

2779

51.4 (43.8, 58.9)

991.7

< 0.01

97.2

    
 

> 9 years

17

1161

754

67.6 (56.9, 77.5)

208.8

< 0.01

96.8

    
 

Total

    

2191.3

< 0.0001

96.3

    

Breed

        

0.0002

0.033, 20.5

17.3 (df = 2)

21.5

 

Crossbreed

26

4824

2349

50.2 (42.9, 57.5)

519.4

< 0.01

96.1

    
 

Exotic

13

2268

1223

59.3 (49.1, 69.1)

280.8

< 0.01

95.8

    
 

Local

24

2447

823

33.5 (26.1, 41.3)

361.7

< 0.01

95.2

    
 

Total

    

1407.8

< 0.01

95.1

    

Lactation stage

        

0.019

0.04, 19.6

7.8 (df = 2)

5.9

 

Early

36

4236

1978

48.4 (41.5, 55.4)

663.6

< 0.01

95.2

    
 

Mid

33

4096

1813

46.8 (39.6, 53.9)

643.1

< 0.01

95.1

    
 

Late

35

3380

1988

59.9 (52.8, 66.7)

324.1

< 0.01

94.9

    
 

Total

    

1831.2

< 0.01

94.9

    

Milk yield (litres)

        

0.38

0.06, 27.4

1.93 (df = 2)

0.0

 

< 7

6

654

189

38.7 (20.7, 58.4)

78.7

< 0.01

96.2

    
 

7 to 15

7

1199

537

48.5 (31.0, 66.2)

307.7

< 0.01

96.6

    
 

> 15

5

365

197

59.6 (37.7, 79.6)

24.7

< 0.01

96.4

    
 

Total

    

488.2

< 0.01

96.3

    

Parity

        

0.0008

0.058, 31.9

14.2 (df = 2)

13.3

 

1 to 3

36

6838

2745

39.5 (31.8, 47.5)

1040.4

< 0.01

97.2

    
 

4 to 6

35

4114

2362

58.3 (50.0, 66.3)

827.4

< 0.01

97.1

    
 

≥ 7

17

762

520

63.9 (50.2, 76.6)

195.4

< 0.01

96.8

    
 

Total

    

2539.7

< 0.0001

96.8

    

Production system

        

0.79

0.058, 28.8

0.47 (df = 2)

0.0

 

Extensive

8

430

269

52.0 (33.8, 70.0)

100.9

< 0.01

96.5

    
 

Semi-intensive

10

1189

657

57.7 (42.3, 72.5)

117.8

< 0.01

96.4

    
 

Intensive

12

2151

1245

59.9 (45.8, 73.2)

237.5

< 0.01

96.4

    
 

Total

    

468.1

< 0.01

96.4

    
  1. CI: Confidence intervals. 95% CIs were calculated as described by Higgins and Thompson [85]
  2. I2 (%): Residual heterogeneity (unaccounted heterogeneity)
  3. R2: Proportion of between-study variance explained
  4. QM: Coefficient of test for heterogeneity between subgroups; df = degrees of freedom
  5. τ2 (tau squared) = between-study variance - estimated variance of the distribution of true prevalence in the population of sub-clinical mastitis studies
  6. H2 = unaccounted variability (sampling variability) – the ratio of the standard deviation of the estimated overall prevalence from the random-effects model compared to the standard deviation from the fixed-effects model
  7. CMT = California mastitis test
Back to article page

BMC Veterinary Research

ISSN: 1746-6148

Contact us