In addition we estimated pig:sheep susceptibility ratio and pig infectivity, assuming all parameters constant through time. We found that cattle:sheep susceptibility ratio is 6. Table 1 shows parameter estimates for cattle and sheep are largely unaffected by ignoring the pig population, with none of the estimates from the two analyses being significantly different. We conclude that including pigs would not change the conclusions presented in Table 1 regarding cattle and sheep (given the very small number of IPs which had pigs) but it would decrease the power of the analysis and increase model complexity.