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<p>Five months is a relatively long recording period for a cross-sectional study and might have biased our results. However, because of considerable climate differences between the three regions it was impossible to avoid trimming in different months with this study design. It was important for us to include three regions to achieve the largest possible study population.</p> <p>Average herd sizes in our study were larger than the Norwegian average, but are probably representative for future beef-cow herd sizes in Norway. The study was part of a project where the main aim was to study claw health in dairy herds, and systematic errors caused by differences in claw-trimming practices and diagnosing of claw lesions are discussed by <em>Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>]. All claw trimmers in our study also participated in the study of dairy herds where a lack of cluster effect within claw trimmer (except for heel-horn erosions in front and hind claws and white-line fissures in front claws) indicated that agreement between trimmers was satisfactory. The recording protocol in this study was identical to the protocol in the dairy-herd study and results from our beef and dairy-cattle studies are compared below. <em>Manske </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B22">22</a>] found differences in recording among claw trimmers, and underreporting of mild and common lesions were marked. Underreporting might have biased our results, but we expect the most-important lesions to be recorded. There is probably an underestimation of lameness in the present study. It was difficult to observe lameness when the cows were moved to the trimming chute. Consequently the sensitivity for detection of lameness was low and the recorded prevalence should be considered as an assessment of moderate or rather severe lameness.</p> <p>Herdsmen, who did not want to participate in the study, might have been less interested in maintaining good claw health. Consequently, bad claw health in their herds might have led to underestimation of the prevalence. On the other hand, bad claw health might have been an incentive for participation. Because of many drop-outs and exclusions the study population is small and cows are also separated on breeds. Nevertheless, prevalence of claw and limb disorders in beef-cow herds has hardly been presented before and if interpreted with care, the results should be useful.</p> <h4>Lameness</h4> <p>The 1.1% prevalence of hind-limb lameness in this study was approximately the same as in our dairy-cattle study where hind-limb lameness was recorded in 1.2% of the animals <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B23">23</a>]. In a Swedish study of dairy cows the prevalence of lameness was 5.1% <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>]. <em>Roeber et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B25">25</a>] found that the incidence of lameness of cattle was 26.6% for beef cows and 30.2% for dairy cows. Arthritic stifle joints were one of the most important causes of lameness in both beef and dairy herds. He also found that economic losses had increased since 1994 <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B2">2</a>]). <em>Hird et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B26">26</a>] reported that the highest costs of veterinary services in 57 Californian beef herds were related to dystocia, lameness and ocular carcinoma. Foot rot was the costliest disease causing lameness. <em>Stokka </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B9">9</a>] claimed that traumatic injuries are important causes of feedlot morbidity and mortality that often is not recognized until the animal has deteriorated substantially.</p> <p>The low prevalence of lameness in our study might partly be explained by no foot rot, no infectious arthritis and no traumatic injuries. Compared to most other countries beef-cow herds in Norway are small and this might imply management which has positive influence on animal health. Foot rot and traumatic injuries also occur occasionally in Norwegian beef-cow herds, but our experience from practice and the present study indicate that the problem is small compared to in feedlot cattle where these disorders have a major influence on claws and limbs <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B27">27</a>]. On the other hand, our material was small and such diseases might easily have been missed in the prevalence study.</p> <h4>Infectious claw lesions</h4> <p>The low prevalence of dermatitis in this study might partly be explained by the fact that digital dermatitis is not established in Norway <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B28">28</a>]. The prevalence of dermatitis was also lower than in the dairy-herd study <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>] which shows that even interdigital dermatitis was not a problem in these beef-cow herds. The prevalence of heel-horn erosions was low compared to Norwegian free-stall dairy herds (39.6%), but more lesions were score 2.</p> <p>Dermatitis and heel-horn erosion are infectious in origin and moisture and dirt are considered to be important predisposing factors. Manure has detrimental effects on horn <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B29">29</a>]. Dairy cows in free stalls are at increased risk of getting dermatitis and heel-horn erosion relative to tied cows <a></a><a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>,<a href="http://www.actavetscand.com/content/49/1/24#B30">30</a>,<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>]. <em>Thysen </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B13">13</a>] found more heel-horn erosions both in free-stall dairy herds with slatted and full concrete alleys than in tie-stall herds, and more so when free stalls included concrete alleys. Most of the present herds were housed in free stalls, and the results indicate that interdigital dermatitis and heel-horn erosions are not widespread in Norwegian beef-cow herds. The results might partly be explained by low-intensity feeding, which usually results in drier manure, and a longer pasture period than in dairy herds. In agreement with <em>Somers et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B31">31</a>] who found that restricted grazing time was associated with increased odds of interdigital dermatitis and heel-horn erosion, it is our experience that these lesions usually are in-door diseases. More heel-erosions in hind claws than in front claws also agree with <em>Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>]. This is probably explained by hind claws being more exposed to manure than front claws in any housing system.</p> <h4>Laminitis-related claw lesions</h4> <p>The prevalence of recorded laminitis-related lesions including white-line and sole haemorrhages, sole ulcers, white-line fissures and double soles was low compared to Norwegian dairy herds. These lesions have a multifactorial aetiology and are influenced by nutrition, feeding routines, hormones around calving and external and internal mechanical forces <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B7">7</a>]. According to <em>Stokka </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B9">9</a>] laminitis may be the number-one cause of foot problems both in dairy and feedlot cattle. However, when comparing with feedlots, it must be kept in mind that most of those herds consist of bulls on high-energy feeding whereas our herds were cows fed much roughage and small amounts of concentrates. More laminitis-related lesions in hind claws than in front claws in our study are in agreement with studies of dairy cattle <a></a><a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B4">4</a>,<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>,<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>]. Differences in claw shape, limb conformation, movement and shifting of weight make the hind claws more disposed <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B19">19</a>], and hind claws are also more exposed to dirty environment.</p> <p>The prevalence of haemorrhages of the white line and the sole was low compared to many studies of dairy cattle <a></a><a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B32">32</a>,<a href="http://www.actavetscand.com/content/49/1/24#B33">33</a>,<a href="http://www.actavetscand.com/content/49/1/24#B30">30</a>]<em>. Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>] found that 13.6% of hind feet in free-stall herds were affected by haemorrhages of the white line and 20% by haemorrhages of the sole. Lower prevalence of haemorrhages in beef-cow herds might be the result of low-intensity feeding. <em>Greenough et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B34">34</a>] found that high-energy feed increased the prevalence of toe and heel haemorrhages in feedlot calves and heel haemorrhages in feedlot yearlings. External mechanical forces is also considered to cause claw-horn disruption and haemorrhages <a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B16">16</a>,<a href="http://www.actavetscand.com/content/49/1/24#B35">35</a>], but our material is too small and there is too much variation in housing and conformation systems for any conclusions on the influence of environment.</p> <p>The prevalence of sole ulcers was also low compared to what has been found in most studies of dairy cattle <a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B36">36</a>,<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>] but approximately the same as in the Norwegian dairy cattle study. Sole ulcers are the result of haemorrhages and contusions in the corium leading to claw-horn disruption and possible infection <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B8">8</a>]<em>. Thysen </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B13">13</a>] found that the prevalence of sole ulcers observed at claw trimming was not affected by the housing system, which is in agreement with <em>Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B15">15</a>]. This suggests that metabolic and hormonal factors are important in the pathogenesis of sole ulcers both in beef and dairy cattle.</p> <p>White-line fissures being the most frequent laminitis-related lesion in our study partly agrees with <em>Smith & Brodersen </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B37">37</a>] who found that separation of the wall from the sole at the white line was the most frequent external lesion in lame feedlot cattle. <em>Mülling </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B38">38</a>] considered separation of the white line to be the result of weakening of the suspensory apparatus of the claw, haemorrhages, accumulation of exudates and impaired horn production, which again predisposes to infection. He also suggests that haemorrhages of the white line predispose to white-line fissures, but also that fissures might be caused directly by mechanical influences in the environment. The Norwegian dairy cattle study also indicated that direct mechanical influences including uneven forces from slatted concrete floors, is important for the development of white-line fissures <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B35">35</a>]. Bad slats, narrow passageways, uncomfortable cubicles, overcrowding, increased competition and "bulling" activity have been suggested as negative factors in dairy free-stall herds <a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B39">39</a>,<a href="http://www.actavetscand.com/content/49/1/24#B40">40</a>]. Low prevalence of haemorrhages but relative high prevalence of white-line fissures in our study might indicate that direct mechanical influence is an important cause of the fissures. Some of these beef-cow herds were housed on slatted concrete floors while others were housed on solid concrete or deep litter, but the material was again too small to reveal associations between fissures and type of alley. <em>Smith & Brodersen </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B37">37</a>] found that there was a strong association between separation of the wall from the sole at the white line and internal claw lesions like osteomyelitis. The prevalence of white-line fissures was 36.4% in one herd in our study, indicating that this lesion can have serious consequences for meat production and animal welfare in some herds.</p> <p>The relative high prevalence of double soles in one herd confirms that laminitis is a problem in some Norwegian beef-cow herds. Only one animal recorded with a vertical fissure is in contrast to cross-sectional surveys reported by <em>Clark et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B41">41</a>] where the prevalence of vertical fissures in slaughtered beef cows in Western Canada was approximately 20%. Large lateral front claws were most prone to vertical fissures. The difference to <em>Clark et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B41">41</a>] might partly be the result of vertical fissures being easier to diagnose at slaughter than at the farm. However, our result agrees with experience from practice that vertical fissure is seldom seen in Norwegian beef cows.</p> <h4>Claw length and shape</h4> <p>Hind claws were on average longer than claws from Norwegian dairy cattle in free-stall housing <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B42">42</a>]. Claws were also approximately 10 mm longer than claws in dairy cows housed in tie stalls with concrete flooring. This might be explained by three of the herds being housed with deep litter both in the resting and walking area, and that routine trimming was performed in only one of the herds. There might also be a real difference in claw size between Norwegian Red breed and beef-cow breeds. The prevalence of corkscrewed claws was on average approximately the same as in Norwegian dairy herds, but 26% of the animals being affected in one herd indicate that corkscrewed claws might cause problems in some herds because secondary lesions like haemorrhages of the sole, pedal ostitis and arthrosis of the distal interdigital joint are frequent in corkscrew claws <a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B43">43</a>,<a href="http://www.actavetscand.com/content/49/1/24#B44">44</a>]. The breed distribution of asymmetric and corkscrewed claws should be interpreted with care because of the low number of animals.</p> <h4>Effect of age and breed on claw lesions</h4> <p>Both laminitis-related and infectious claw lesions were more prevalent with increasing age. This is partly in agreement with several studies which found more lameness with increasing age <a></a><a></a><a></a><a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B45">45-47</a>,<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>,<a href="http://www.actavetscand.com/content/49/1/24#B35">35</a>]. This might be the result of repeated scarring of the corium with irreversible and cumulative damage to claw tissue <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B8">8</a>]. More haemorrhages of the sole with increasing age are in contrast to many studies of dairy cattle which found highest odds for haemorrhages of the sole in primiparous cows <a></a><a></a><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B32">32</a>,<a href="http://www.actavetscand.com/content/49/1/24#B24">24</a>,<a href="http://www.actavetscand.com/content/49/1/24#B35">35</a>]. Dairy heifers are experiencing major changes in housing conditions, social environment, nutrition and physiologic demands which might lead to increased prevalence of haemorrhages in first lactation. Because beef-cattle heifers do not experience such dramatic changes around calving, fewer laminitic lesions including haemorrhages of the sole can be expected. <em>Stanek et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B10">10</a>] found that claw condition grew worse with an increase in body weight, and higher body weight with increasing age might partly explain the relation between more claw lesions and increasing age. <em>Townsend et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B48">48</a>] found that lameness in 326 young beef bulls was associated with weight. They predicted that the odds of lameness in the animal with the heaviest initial test weight was approximately seven times greater than in the animal with the lightest initial test weight. Foot rot, laminitis and minor traumatic injuries were evaluated to be the most important causes of lameness in their study.</p> <p><em>Townsend et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B48">48</a>] found relation between lameness and breed and explained this by differences in claw shape, size, conformation and horn composition of the different beef-cattle breeds. Small groups in our study make comparison of different breeds difficult. There were 72 animals of the Hereford breed and 97 Charolais. The prevalence of laminitis-related lesions was 11% and 49%, respectively. The herd effect might be responsible for most of the difference, but the prevalence for the Charolais breed is still rather high. For infectious claw lesions, Simmental had the highest prevalence with 45%. However, this number refers to only 15 animals from one herd, and should be interpreted with care. Almost all dairy cattle in Norway are Norwegian Red, and the effect of breed must be kept in mind when these beef-cow herds are compared to the dairy-cattle herds.</p> <h4>Claw and limb disorders related to reproduction and carcass characteristics</h4> <p>Longer calving interval in animals with claw and limb disorders versus animals without is in agreement with <em>Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B23">23</a>] who found associations between moderate and severe heel-horn erosions and sole ulcers and increased calving interval in dairy cattle. Cows with tender feet are more reluctant to walk, show less estrual activity and likely eat less than other cows. <em>Barth & Waldner </em><a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B49">49</a>] found that lameness reduced the probability of satisfactory reproductive-soundness classification of beef bulls.</p> <p>Higher conformation class and increased carcass weight in animals with disorders versus those without can probably be explained by the breed differences. An unanswered question is why more cows of heavy than light breeds were slaughtered within two years of the claw inspection. <em>Sogstad et al</em>. <a></a>[<a href="http://www.actavetscand.com/content/49/1/24#B50">50</a>] found that lameness and lesions at the tarsus in dairy cattle were associated with lower conformation class and lower carcass weight, whereas sole ulcers were associated with higher conformation class. Our results might be a direct consequence of more claw and limb disorders in heavy breeds. However, the results might also be influenced by most lesions being mild.</p> <h4>Claw lesions related to environmental factors and management</h4> <p>The small power in the study makes association between claw lesions and environment and management hard to detect. The relation between increased time at pasture for both cows and heifers and laminitis-related claw lesions was not expected because pasture usually is positive for claw health. However, if the animals are at pasture in winter, as they were in some herds, and the soil gets frozen, this might lead to increased external pressure on the claws. Muddy and frozen feed might also cause digestive disorders. The associations between the presence of isolated room for staff and available hot and cold water and laminitis-related lesions might indicate that management and attention indirectly influence claw health. "Region" probably remained in the model because some variables influencing on laminitis-related lesions were different in the 3 regions (Table <a></a><a href="http://www.actavetscand.com/content/49/1/24/table/T3">3</a>). The distribution of both season for trimming and breed were skewed. It is not obvious how the recorded date for calving and age influenced our result. However, the herd with the highest prevalence of laminitis-related lesions, which was located in region II, also had a high mean age. Unfortunately the median date for calving in this herd was not reported and there might also be other unknown factors predisposing for laminitis-related lesions in this herd. Even though there was a lack of cluster effect within claw trimmer in our dairy-herd study we cannot exclude the possibility that different trimmers recording claw lesion might have biased the present result.</p> <p>The variable "frequency of change and supplementation of litter in calf pens" is an indicator for the general hygienic level in the herds. Frequent change and supplementation of litter might have a direct preventive effect on infectious claw lesions, however, the investigated herd groups, cows and heifers, did not use these pens at the time of recording.</p>
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