Table 3.

The results of the cumulative first-week mortality in the study of 2267 flocks in 104 farms with 253 houses (Spain, 2015–2018) for the differences between each pair of categories of every significant variable (differences were measured in terms of OR).

Factor	Category a	Category b	p-Value	OR 1 (CI 2)
Type of broiler house	One floor	Multiple floor	0.0129	1.09 (1.02–1.15)
Drip cup	No	Yes	<0.0001	1.17 (1.10–1.25)
Season	Winter	Autumn	0.0027	1.01 (1.00–1.02)
	Winter	Spring	<0.0001	1.10 (1.09–1.10)
	Winter	Summer	<0.0001	1.05 (1.04–1.05)
	Autumn	Spring	<0.0001	1.08 (1.08–1.09)
	Autumn	Summer	<0.0001	1.03 (1.03–1.04)
	Summer	Spring	<0.0001	1.05 (1.04–1.05)
Study year	2015	2016	<0.0001	1.09 (1.08–1.09)
	2015	2017	<0.0001	1.06 (1.06–1.07)
	2015	2018	<0.0001	1.10 (1.09–1.10)
	2017	2016	<0.0001	1.02 (1.01–1.03)
	2016	2018	0.0107	1.01 (1.00–1.02)
	2017	2018	<0.0001	1.03 (1.02–1.04
Egg storage days	<7	7–10	<0.0001	1.07 (1.06–1.07)
	7–10	>10	<0.0001	1.03 (1.02–1.04)
	<7	>10	<0.0001	1.10 (1.09–1.11)
Breeder age (weeks)	34–50	25–33	<0.0001	1.04 (1.03–1.05)
	51–68	25–33	<0.0001	1.26 (1.25–1.26)
	51–68	34–50	<0.0001	1.22 (1.20–1.22)
Chick gender	Males	Females	<0.0001	1.11 (1.11–1.12)
	Mixed	Females	<0.0001	1.17 (1.17–1.18)
	Mixed	Males	<0.0001	1.05 (1.04–1.05)
Breed	Ross	Cobb	<0.0001	1.08 (1.07–1.08)

¹ OR—Odds Ratio ² CI—95% Confidence Intervals.