Use of a Mycoplasma hyopneumoniae bacterin for the manufacture of a vaccine for treating or preventing a disease or disorder in an animal caused by infection with Mycoplasma hyopneumoniae whereby the vaccine is suitable for a single administration of an effective dose to the animal at from 3 to 10 days of age.Use of a Mycoplasma hyopneumoniae bacterin for the manufacture of a vaccine for treating or preventing a disease or disorder in an animal caused by infection with Mycoplasma hyopneumoniae whereby the vaccine is suitable for a single administration of an effective dose to the animal at from 3 to 10 days of age.