Table 2.

Parameters for the economic disease model. Where: H-S are healthy pigs with normal growth; PMWS-D are PMWS pigs that die due to the disease; PMWS-R are PMWS pigs that recover from the disease; Sub-D are PCV2 infected pigs with slow growth, no clear PMWS clinical sign and that die; and Sub-S are PCV2 infected pigs with slow growth, no clear PMWS clinical sign and that survive.

Parameters	Symbol	Value	Stochastic		Reference
			Distribution	Range
Post-weaning mortality
Overall post-weaning mortality	XT	1.29*exp(0.313*PMWS severity)	Normal	0.27–0.36	Fitted through non-linear regression of CS-2008 data (reg coef. p < 0.01, R2 = 0.88). The 95% confidence interval of the regression coefficient was used to define the stochastic range.
Post-weaning mortality non-PCV2 related (%)	X2+3	3.08	–	–	Post-weaning mortality at severity of 2.79 (see assumption 7 in Table 3)
Post-weaning mortality attributable to PMWS pigs	X5	ψ*FR	–	–	[Rule: Cannot be higher than the proportion of PCV2 infected pigs]
PMWS fatality rate (FR)	FR	1.0136*exp(−0.0382*ψ)	–	–	Fitted through non-linear regression of FO-2011 data (reg coef. p = 0.17, R2 = 0.82)
Post-weaning mortality attributable to PCV2 subclinical pigs	X4	XT − X2+3 − X5	–	–	[Rule: X4 cannot be less than zero]
PMWS morbidities and PCV2 prevalence			–	–
Proportion of PCV2 infected pigs	π	0.0982*exp(0.2244*PMWS severity)	Normal	0.18–0.27	Fitted through non-linear regression of CS-2008 data (p < 0.01, R2 = 0.87). The 95% confidence interval of the regression coefficient was used to define the stochastic range.
Percentage of PMWS pigs	ψ	0.1127*exp(2.8802*MF1)	Normal	2.61–0.15	Fitted through non-linear regression of CS-2008 data (p < 0.01, R2 = 0.82)). The 95% confidence interval of the regression coefficient was used to define the stochastic range.
Morbidity factor 1	MF1	See Eq. (1)	–	–
Proportion of PCV2 infected pigs that develop subclinical signs	Ω	0.73	Normal	0.27–0.48	Estimated from data of L-2001 (see assumption 3 in Table 3). The 95% confidence interval was used to define the stochastic range.
Growth rate parameters
Average weight at slaughter of a H-S pig (kg)	Wt1	102.6	–	–	T1*ADGH-S + Wt0
Average weight at weaning of a H-S pig (kg)	Wt0	8.1	–	–	Bench10
Average daily weight gain of a H-S pig (kg/day)	ADGH-S	0.675	–	–	Bench10
Percentage reduction in ADG of a Sub-S pig	ζSub	16	Normal	3–29	Estimated from data of L-2001 study. The 95% confidence interval was used to define the stochastic range.
Average daily weight gain of a Sub-S pig (kg/day)	ADGSub	0.567	–	–	ADGH-S*(1 − ζSub)
Percentage reduction in ADG of a PMWS-R pig	ζPMWS	26	Normal	16–36	Estimated from data of L-2001 study. The 95% confidence interval was used to define the stochastic range.
Average daily weight gain of a PMWS-R pig (kg/day)	ADGPMWS	0.500	–	–	ADGH-S*(1 − ζPMWS)
Average weight at death of a PMWS-D pig (kg)	WPMWSD	30.37	–	–	Wt0 + TPMWSD*ADGPMWS
Average weight at death of a Sub-D pig (kg)	WSubD	42.12	–	–	Wt0 + TSubD*ADGSub
Time parameters
Average days in feed of a H-S pig (days)	T1	140	–	–	Bench10
Average days in feed of a Sub-S pig (days)	T2	166.67	–	–	(Wt1 − Wt0)/ADGSub [161 days in the model as explained in assumption 8, Table 3)
Average days in feed of a PMWS-D pig (days)	TPMWSD	56	Beta pert	42–70	See assumption 6, Table 3
Average days in feed of a Sub-D pig (days)	TSubD	56	Uniform	50–80	See assumption 6, Table 3
Average days in feed of a PMWS-R pig (days)	T3	173.81	–	–	((TPMWSD) + ((WHS − WPMWSD)/ADGSub)
Breeding parameters
Litters per sow per year	LSY	2.2	–	–	Bench10
Pigs born alive per sow per litter	PBSL	11.20	–	–	Bench10
Mortality of pigs born alive (%)	X1	12.72	–	–	Bench10
Pigs weaned er sow per year	WSY	21.99	–	–	LSY*PBSY*(1 − (X1/100))
Sow year replacement rate (%)	SRR	49.25	–	–	Bench10
Average number of parities	AP	4.56	–	–	(100/SRR)*LSY
Cost of replacing a gilt (£)	CG	157.62	–	–	Bench09
Feed parameters
Sow feed consumption per year (kg)	FQS	1232	–	–	Bench10
Sow feed price/tonne (£)	FPS	162.87	–	–	Bench10
Grower feed price/tonne (£)	FPG	202.55	–	–	Bench10
Feed conversion of a H-S pig	FCRHS	2.39	–	–	Bench10
Feed consumed per H-S pig (kg)	FQHS	225.85	–	–	FCRHS*(Wt1 − Wt0)
Feed consumed per day per H-S pig (kg)	DFQHS	1.61	–	–	FQHS/T1
Appetite loss of a PMWS-D and PMWS-R pigs during the clinical stage (%)	ALPMWS	17	Linked to ζPMWS	Linked to ζPMWS	Estimated from data of L-2001 study trough the correlation observed between feed intake and average daily gain at pen level. See Appendix 1.
Reduction in feed consumption by subclinical pigs (%)	ALSub	10	Linked to ζSub	Linked to ζSub	Estimated from data of L-2001 study trough the correlation observed between feed intake and average daily gain at pen level. See Appendix 1.
Feed consumed per PMWS-D pig (kg)	FQPMWSD	79.37	–	–	DFQHS*(1 − (ALPMWS/100))*TPMWSD
Feed consumed per Sub-D pig (Kg)	FQSubD	104.86	–	–	DFQHS*TSubD
Feed consumed per PMWS-R pig (kg)	FQPMWSS	242.31	–	–	FQPMWSD + (DFQHS*(T3 − TPMWSD)
Feed consumed per Sub-S pig (kg)	FQSubS	259.72	–	–	DFQHS*T2
Other parameters
Veterinary multiplication factor	VMF	2.74	Beta pert	1–8.06	Average obtained from FO-2011 study. Minimum and maximum values obtained were used to define the stochastic range.
Cost of disposing a dead carcass (£)	DC	6	–	–	As reported by a farmer in the FO-2011 study.
Penalty on PMWS carcass (pp/kg)	PC	8.75	Beta pert	0–35	Average obtained from FO-2011 study. Minimum and maximum values obtained were used to define the stochastic range.
Deadweight average pig price (£/kg)	DAPP	1.39	–	–	Bench10