Norwegian Reds are known for their genetically superior udder health com- pared with Holstein–Friesians, and for this reason they have been imported into Ireland for use in dairy herds. Having established that their udder health superiority persists under Irish conditions (Walsh et al., 2007), their potential suitability for crossbreeding with Holstein–Friesians has been evaluated in the dairy industry (Begley et al., 2007). Feed costs account for about 80% of total variable costs in milk production (Shalloo et al., 2004).