Adverse effects of Influenza A(H1N1)pdm09 virus infection on growth performance of Norwegian pigs - a longitudinal study at a boar testing station

Table 7 Multilevel regression for overall feed intake of pig infected with influenza A(H1N1)pdm09 virus

Overall feed intake of pig growing from 33 kg to 100 kg (OFI)
Predictors	Coefficients	SE	P values	95% CI
Breed
Landrace	Reference
Duroc	5.89	1.6	<0.001	2.8	9.0
Birthdate	−0.02	0.0009	<0.001	−0.020	−0.016
Average daily feed intake	11.74	1.6	<0.001	8.5	14.9
Infection group
SERONEG	Reference
SEROPOS	2.3	0.6	<0.001	1.1	3.5
VIR1	8.0	1.2	<0.001	5.7	10.3
VIR2	5.9	2.1	0.005	1.8	10.0
VIR3	7.2	2.0	<0.001	3.3	11.2
Constant (β ₀ )	445.0	16.5	<0.001	412.7	477.2

Abbreviations: SERONEG Seronegative pigs, SEROPOS Seropositive pigs (not tested for virus), VIR1 pigs viral positive between bodyweight 33 kg and 60 kg, VIR2 pigs viral positive between bodyweight 61 kg and 80 kg, VIR3 pigs viral positive between bodyweight 81 kg and 100 kg.
Growth phase was from 33 kg to 100 kg bodyweight. The model is hierarchical with two levels; pig (n = 1955) and herd (n = 43).