Maternal antibody level	Primary vaccination	Booster vaccination	Blood sampling	Sample size
Mh high group	Mh: 200 or over				n = 11
Mh low group	Mh: under 200	the age of 1–3 weeks	4 weeks	3 weeks	n = 20
Pm high group	Pm: 100 or over		after primary vaccination	after booster vaccination	n = 18
Pm low group	Pm: under 100				n = 13

Primary – primary vaccination; booster – booster vaccination; BS – blood sampling; maternal antibody level – the titre at primary vaccination; Mh – M. haemolytica; Pm – P. multocida