Table 2.

Overview of the fixed and random effects included in the four models

Model	Random effects
1	Genetic susceptibility focal individual	–	Farm*period
2	Genetic susceptibility focal individual	Genetic infectivity herd mates	Farm*period
3	Genetic susceptibility focal individual	–	–
4	Genetic susceptibility focal individual	Genetic infectivity herd mates	–

All models contained fixed effects for farm, period, parity, and months in milk; and a non-genetic random animal effect for the susceptible animal