Disorders of performance-age bucking bulls.

OBJECTIVE To describe disorders of performance-age bucking bulls. DESIGN Retrospective case-control study. ANIMALS 78 bucking (cases) and 236 nonbucking (controls) beef bulls. PROCEDURES The medical record database of a referral hospital was reviewed to identify beef bulls > 1 year old that were examined for a medical or musculoskeletal disorder between January 1, 2000, and April 1, 2014. Bucking bulls were designated as cases, and nonbucking bulls were designated as controls. For each bull, the signalment, history, physical examination and diagnostic test results, and clinical diagnosis were recorded. The frequency of each disorder was compared between cases and controls. RESULTS Fifteen of 78 (19%) cases and 132 of 236 (56%) controls had medical disorders; however, the frequency did not differ between the 2 groups for any medical disorder. Musculoskeletal disorders were identified in 55 (70.5%) cases and 109 (46%) controls. Cases were 10.55 times as likely as controls to have horn and sinus disorders. Of the 43 (55%) cases examined because of lameness, the thoracic limb was affected in 19 (44%). Compared with controls, cases were 13.37 and 3.31 times as likely to have a musculoskeletal disorder of the vertebral region and pelvic limb, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated bucking bulls were more likely than nonbucking bulls to develop horn and sinus disorders and musculoskeletal disorders of the vertebral region and pelvic limbs. The limb distribution of lameness for bucking bulls may differ from that for nonbucking bulls.

SNP-based association mapping of the polled gene in divergent cattle breeds.

Naturally, hornless cattle are called polled. Although the POLL locus could be assigned to a c. 1.36-Mb interval in the centromeric region of BTA1, the underlying genetic basis for the polled trait is still unknown. Here, an association mapping design was set up to refine the candidate region of the polled trait for subsequent high-throughput sequencing. The case group comprised 101 homozygous polled animals from nine divergent cattle breeds, the majority represented by Galloway, Angus, Fleckvieh and Holstein Friesian. Additionally, this group included some polled individuals of Blonde d'Aquitaine, Charolais, Hereford, Jersey and Limousin breeds. The control group comprised horned Belgian Blue, Fleckvieh, Holstein Friesian and Illyrian Busa cattle. A genome-wide scan using 49,163 SNPs was performed, which revealed one shared homozygous haplotype block consisting of nine neighbouring SNPs in all polled animals. This segment defines a 381-kb interval on BTA1 that we consider to be the most likely location of the POLL mutation. Our results further demonstrate that the polled-associated haplotype is also frequent in horned animals included in this study, and thus the haplotype as such cannot be used for population-wide genetic testing. The actual trait-associated haplotype may be revealed by using higher-density SNP arrays. For the final identification of the causal mutation, we suggest high-throughput sequencing of the entire candidate region, because the identification of functional candidate genes is difficult owing to the lack of a comparable model.

Further studies on horn aberrations in Dall's sheep (Ovis dalli dalli) from Yukon Territory, Canada.

The prevalence of horn aberrations in Dall's sheep from the Kluane Lake area of Yukon Territory observed during July 1982 represented 1% of the total population and 7% of rams 6 yr or older. Ewes were not considered in these percentages because they were too difficult to inspect by aerial survey. When these data were combined with other data collected from 1977 through 1981, the prevalence equalled 2.4% of the total population and slightly exceeded 16% in mature rams (greater than or equal to 6 yr). The anomaly followed necrosis of the terminal region of the horn core and the sequestering of portions of the core within the sheath as the sheath continued to grow. Sheath that was produced after the core was anatomically altered resulted in abnormal growth patterns of the horn. Rams with aberrant horns could not maintain homeostatic temperatures within horn cores when horns were experimentally exposed to -80 C for 30 min. Histologic examination of superficial and cornual vascular systems did not reveal any structural alterations that would restrict blood flow within cores of affected horns. Examination of museum specimens consisting of 130 skulls from rams and 81 from ewes collected from Alaska, USA, Yukon Territory, Canada, and Northwest Territories, Canada, established only one ewe and no rams with the horn aberration. The skull was from a ewe and had both horns affected and was collected from the Joe River Drainage, Yukon Territory in 1912.