Figure 1From: Transmission of border disease virus from a persistently infected calf to seronegative heifers in early pregnancy Relative optical density from day 0 to day 60 of the infection phase. Relative optical density (OD) expressed as percentage of the optical density of a standard serum in six heifers in early pregnancy from day 0 to day 60 of the infection phase. Relative OD values >30% (black line) are defined as positive.Back to article page