. 2020 Mar 12;62:15. doi: 10.1186/s13028-020-0513-x

Table 1.

Descriptive statistics and unconditional associations of variables selected as candidates for multivariable model for within-herd calf (aged 21–90 days) mortality rate in years 2017–2018 in 212 Estonian dairy herds estimated in negative binomial regression model

Variable	Continuous	Categorical	n	Within-herd MR^a	p-value^b
Variable	Median (Q1; Q3)	Categories	n	Within-herd MR^a	p-value^b
Herd size (number of cows)	129.7 (53.7; 459.7)		212		0.015
Herd average milk yield per cow per year (kg)	8787 (6950; 9758)		212		0.132
Herd proportion of stillbirths (%)	7.5 (5.6; 9.5)		212		0.018
Herd proportion of abortions (%)	0.8 (0; 1.6)		212		< 0.001
Herd type^c		Dairy herd	199	0.26	0.035
Herd type^c		Mixed herd	13	0.09
Proportion of Holstein breed cows		< 90%	89	0.20	0.160
		> 90%	119	0.28
		Missing	4	0.35
Region^d		Northeast	59	0.29	0.402
		Southeast	44	0.19
		Southwest	71	0.26
		Northwest	38	0.22
Farmer attending trainings within the last 4 years		Once	49	0.15	0.002
		2–3 times	108	0.33
		More than 3 times	31	0.22
		No	24	0.14
Place of calving		Group pen	69	0.32	0.024
		Individual pen	41	0.26
		Tiestall	84	0.21
		Combined or other^f	16	0.07
		Missing	2	NE^e
Time of feeding the first colostrum (hours after birth)		0.5	22	0.19	0.149
		1	87	0.23
		2	69	0.33
		3	17	0.19
		≥ 4	12	0.14
		Calf drinks by itself	3	NE^e
		As soon as possible	2	NE^e
Disinfecting navel cord		No	68	0.21	0.070
		Sometimes	51	0.17
		Always (in more than 95% of calves)	93	0.32
Prophylactic administration of vitamins to calves		No	64	0.22	0.101
		Sometimes	70	0.21
		Yes (in more than 95% of calves)	78	0.31
Housing of preweaned calves > 2 weeks of age		Group pen	170	0.27	0.007
		Single pen	18	0.18
		Single and group pen	23	0.11
		Missing	1	NE^e
Disinfection of pens of calves aged < 1 month		No	39	0.09	0.002
		Wet disinfectants	54	0.32
		Dry disinfectants	77	0.27
		Wet and dry desinfectants	41	0.28
		Missing	3	0.29
Frequency of milk feeding per day during first month of life		Two times	175	0.24	0.141
		Three times	22	0.21
		Automatic milk feeder and other	15	0.42
Antibiotics administered to calves with diarrhoea		No	87	0.17	0.019
Antibiotics administered to calves with diarrhoea		Yes	125	0.30
Way of responding to questionnaire		Postal	127	0.24	0.667
Way of responding to questionnaire		Phone	85	0.26

^aWithin-herd mortality rate of calves in years 2017 to 2018 (per 100 calf-months)

^bEstimated in bivariable negative binomial regression models including herd number of cows

^cDairy herd—at least 75% of cattle were of dairy breed; mixed herd – more than 25% of cattle were of beef breed

^dNortheast Estonia: Ida-Viru, Lääne-Viru, Jõgeva, Järva county; Southeast Estonia: Tartu, Valga, Võru, Põlva county; Southwest Estonia: Pärnu, Viljandi, Saare county; Northwest Estonia: Harju, Rapla, Lääne, Hiiu county

^eNot estimated due to small number of farms belonging to that category

^fOther: calving on pasture and its combinations between other systems