Klövform och klövsjukdomar hos intensivt uppfödda köttrastjurar

Abstract: The top selection of Swedish beef bulls are evaluated yearly by Svensk Köttrasprövning AB at Gismestad. The bulls are selected from six different breeds; Angus, Blonde d´Aquitaine, Charolais, Hereford, Limousin and Simmental, and are kept on straw bedding apart from a concrete alley in front of the feeding area during the six months of evaluation period. The bulls are evaluated according to their fertility scores, growth, exterior and temperament and the exterior, body posture and claw conformation reflect important qualities for their longevity. In spite of good values for fertility, it has been noticed in the last years that the fertility results and longevity have been unsatisfactory and claw and/or bone disorders have been suspected as a contributory cause. Persson et al. (2007) studied breeding bulls from Gismestad and other places, which had been slaughtered due to poor fertility (no pregnancies in the herd during their last year in service). In a post mortem examination, 27 out of 34 experimental bulls had severe bilateral joint lesions (osteochondrosis dissecans) in their hind legs. None of 11 fertile control bulls had severe joint lesions. It was believed that the infertility was caused by leg pain, which decreased their libido and mounting ability, even if no signs of lameness were observed by the owners. The main purpose of the present work, performed at Gismestad, was to study claw growth, claw conformation and claw diseases, with special emphasis on laminitis-related lesions such as sole hemorrhages, their prevalence and associations. Moreover, the influence of breed and weight gain was assessed as well. At the end of the evaluating period and before the annual auction of the bulls, the left hind claw of all present bulls (n=122) were measured and photographed before and after claw trimming. On the same occasion all claw lesions were recorded in claw health reports. No significant differences in claw measurements between breeds were found. The most frequent claw disorder was sole haemorrhage which was noticed in 63% of the bulls. Charolais was the breed that suffered most from sole haemorrhages. The prevalence was 75%, which differed significantly (p=0,013) from that of Angus, the breed with the lowest prevalence (11 %). Furthermore, a correlation between increasing weight gain and sole hemorrhage was found (p=0,056). On good reasons, we can presume that a great deal of these lesions have a metabolic explanation and are caused by intensive feeding rather than from abnormal claw shape. A well-managed deep straw bedding can be considered as a very comfortable and forgiving lying surface and will probably prevent the development of sole lesions. On the other hand, straw bedding may result in overgrown claws and promote undesirable claw conformation if not a satisfactory wear is achieved by hard abrasive flooring, which is preferably placed in connection to the feeding area.