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

Table 5 Multilevel regression of average daily feed intake in pigs infected with influenza A(H1N1)pdm09 virus

Average daily feed intake (ADFI)
Predictors	Coefficients	SE	P values	95% CI
Breed
Landrace	Reference
Duroc	−0.10	0.0157	<0.001	−0.13	−0.07
Growth Phase
GF1(33_60 kg)	Reference
GF2(61_80 kg)	0.71	0.0136	<0.001	0.68	0.74
GF3(81_100 kg)	1.08	0.0136	<0.001	1.05	1.10
Birthdate	−0.00002	0.00002	0.257	−0.00005	0.00001
*Interaction term: INFGPGF**
SERONEG*GF(1–3)	Reference
SEROPOS*GF1	−0.003	0.016	0.851	−0.034	0.028
SEROPOS*GF2	0.022	0.016	0.166	−0.009	0.053
SEROPOS*GF3	0.017	0.016	0.278	−0.014	0.049
VIR1*GF1	−0.024	0.032	0.444	−0.086	0.038
VIR1*GF2	0.071	0.032	0.025	0.009	0.133
VIR1*GF3	0.104	0.032	0.001	0.042	0.166
VIR2*GF1	0.077	0.057	0.176	−0.035	0.190
VIR2*GF2	0.032	0.057	0.574	−0.080	0.144
VIR2*GF3	0.070	0.057	0.223	−0.042	0.182
VIR3*GF1	0.059	0.055	0.283	−0.049	0.167
VIR3*GF2	0.077	0.055	0.164	−0.031	0.184
VIR3*GF3	−0.085	0.055	0.122	−0.193	0.023
Constant (β ₀ )	1.897	0.3107	<0.001	1.288	2.506

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.
The model is hierarchical with three levels; observations (n = 5865); pig (n = 1955) and herd (n = 43). *denotes interaction term.

ISSN: 1746-6148