Table 4.

Statistical output of multivariable linear regression analysis of total cost of rearing on 101 farms with age at first calving, time spent at grass, calving pattern, breed and herd size ¹

Variables	Coefficient	SEM	t	P	95% CI
Age at first calving (day)	2.87	0.53	5.40	<0.0001	1.82	3.93
Time spent grass (%)	−6.06	2.45	−2.47	0.016	−10.93	−1.18
Calving pattern
Baseline	All year round
Autumn	−273.20	88.04	−3.10	0.003	−448.22	−98.17
Multi-block	−22.39	95.58	−0.23	0.815	−212.39	167.61
Spring	−288.56	144.74	−1.99	0.049	−576.29	−0.83
Breed
Baseline	Holstein
Holstein-Friesian	66.71	66.50	1.00	0.319	−65.49	198.90
Holstein cross	170.39	90.97	1.87	0.064	−10.46	351.24
Friesian cross	−93.82	158.81	−0.59	0.556	−409.51	221.88
Other purebreds	52.78	114.04	0.46	0.645	−173.93	279.48
Jersey	−139.84	121.81	−1.15	0.254	−381.99	102.32
Herd size
Baseline	⩽99
100 to 199	−301.75	91.53	−3.30	0.001	−483.70	−119.81
200 to 299	−345.30	99.61	−3.47	0.001	−543.31	−147.28
300 to 399	−407.83	111.65	−3.65	<0.0001	−629.79	−184.87
⩾400	−318.53	146.37	−2.18	0.032	−609.51	−27.54
Constant (baseline)	171.91	459.06	0.37	0.709	−740.67	1084.48

CI=confidence interval.

¹ The final model had an R ² value of 0.616, P<0.0001.