Table 5.

Multivariable logistic regression analysis of the association of cow-level mastitis with different risk factors

Variable	Category	OR	SE	z	p	95% CI for OR
Herd size
	≤10 cows	Ref
	>10 cows	3.1	1.0	3.74	<0.001	1.7 – 5.7
Breed
	Local	Ref
	Cross	16.4	8.3	5.55	<0.001	6.1 – 44.1
Milking mastitic cow last
	Yes	Ref
	No	2.0	0.6	2.53	0.011	1.2 – 3.5
Bedding material
	Yes	Ref
	No	2.8	0.9	3.24	0.001	1.5 – 5.3
Parity
	1	Ref
	2	1.2	0.5	0.48	0.629	0.5 – 2.9
	3	3.2	1.5	2.46	0.014	1.3 – 8.1
	≥4	24.8	12.2	6.50	<0.001	9.4 – 65.2
Stage of lactation
	Early (1 – 2 months)	Ref
	Mid (3 – 6 months)	0.3	0.1	−4.17	<0.001	0.1 – 0.5
	Late (≥7 months)	0.7	0.2	−0.99	0.323	0.4 – 1.4
Udder & leg hygiene
	Slightly dirty	Ref
	Moderately dirty	2.6	0.8	3.27	0.001	1.5 – 4.7
	Very dirty	8.7	4.0	4.73	<0.001	3.5 – 21.3
Teat end shape
	Pointed	Ref
	Round	3.2	1.0	3.72	<0.001	1.7 – 5.9
	Flat	7.6	2.8	5.57	<0.001	3.7 – 15.7
Constant				−7.44	<0.001