Effekt av relativ ålder på travhästars tävlingsprestation

Abstract: Harness racing in Sweden has evolved since the 18th century when it began as racing to the church or at frozen lakes. Since then Sweden has become one of the world's foremost harness racing nations with a world-class breeding. Mares show heat and are fertile during the bright season of the year, which in Sweden is from late February or early March until early autumn. This means that most foals are born in May and April. The breeding season can start earlier with a light program, which usually means less time outdoors for the mare when the program is most easily controlled by keeping the lighting in the stable on for a long time. The Standardbred trotter is expected to compete and perform at a high level at an early age. There are advantages and disadvantages for horses to be born early or late in the year. A disadvantage of late-born foals in addition to the relative age difference is that the foal often moves on large surfaces early, which can lead to skeletal damage. Contact with humans decreases as late-born foals often go out into large pastures shortly after birth. The advantage of late-born foals is that the foal can be offered movement at an early age without climate restrictions. The advantage of early-born foals is that the foal gets used to standing on stables and in human contact at an early age. In many cases, the mare has a good and controlled nutrient intake which gives a positive effect for the skeletal structure of the foal. The disadvantage is that the foal sometimes cannot be offered the outdoor space it needs. Early-born foals have been proposed to perform better on the racetrack. To get early foals breeding season for the mare need to be advanced which could affect the mare. The purpose of this study was to investigate whether the performances of Standardbred trotters is affected by month of birth. The material in this study was two- to four-year-old Standardbred trotters born in 2010-2012 and factors as earnings, speed, gender, birth period and numbers of starts were studied. The differences between the results were measured by p-value where the difference was significant at p-value <0.05 and tended to be significant if the p-value was <0.1. The results showed that it was most favorable for horses to be born early in the year. Horses born in February did most races per year and with a better earnings and speed then horses born later in the year. In conclusion the hypothesis that the month of birth would have an effect on the performance of two and three-year-old horses is true. The effect follows with the horses up to four years and possibly longer than that. Horses born in January-March perform best followed by horses born in April or late May and last horses born in June-August. The heat season can be advanced with an artificial light program. There are no studies that indicate that light programs would adversely affect the mare Keywords; horse, birth, age, artificial light program, race performance