Should performance at different race lengths be treated as genetically distinct traits in Coldblooded trotters?

Speed, in the form of racing time per kilometre (km), is a performance trait of the Swedish-Norwegian Coldblooded trotter included in the joint Swedish-Norwegian genetic evaluation. A few popular stallions have dominated Coldblooded trotter breeding, which has led to an increasing average relationship between individuals in the population. This study investigated the scope for broadening the breeding goal by selecting for racing time per km over different race lengths (short: 1640 m, medium: 2140 m and long: 2640 m), as this could encourage the use of breeding sires that are less related to the population.