Prevalence Of Footrot Research Articles

A review of foot-related lameness in feedlot cattle

Lameness is the second most prevalent morbidity in North American feedlot cattle and is both an animal welfare and economic concern. Lameness accounts for 30%–40% of all feedlot treatments with greater than 70% being foot-related lameness (FRL). This review focused on foot rot (FR), digital dermatitis (DD), and toe tip necrosis syndrome (TTNS). While there are significant study-to-study differences regarding the prevalence of FR, DD, and TTNS, it is unequivocal that FR is the most prevalent. Poor pen conditions are risk factors for both FR and DD, but the epidemiology of the two diseases is quite different. Whereas FR is diagnosed throughout the feeding period, DD typically occurs after 80 days on feed (DOF). TTNS is the least prevalent of the three FRL, but has the greatest negative effect on animal welfare and production performance. Most TTNS cases occur within 50 DOF with treatment failure leading to a significant loss in production performance and even death. This review provides an overview of the epidemiology of lameness in feedlot cattle with emphasis on the prevalence and risk factors associated with FR, DD, and TTNS.

Field Study on the Prevalence of Ovine Footrot, Contagious Ovine Digital Dermatitis, and Their Associated Bacterial Species in Swedish Sheep Flocks.

Ovine footrot and contagious ovine digital dermatitis (CODD) cause lameness in sheep, affecting welfare and economics. Previous Swedish studies focused on individual slaughter lambs, leaving flock-wide prevalence less explored. This study examined the prevalence of footrot and CODD in Swedish sheep flocks, focusing on adult sheep. From 99 flocks, 297 swabs were analysed using real-time PCR for Dichelobacter nodosus, Fusobacterium necrophorum, and Treponema spp. Sampled feet were photographed and assessed using scoring systems for footrot and CODD. Results indicated footrot prevalences (footrot score ≥ 2) of 0.7% and 2.0% at the individual and flock levels, respectively, whereas there were no signs of CODD. The individual footrot prevalence was lower than that from a 2009 study but aligned with a 2020 study, both conducted on slaughter lambs. Dichelobacter nodosus, F. necrophorum, and Treponema spp. were found in 5.7%, 1.3%, and 65.0% of sheep, and in 9.1%, 3.0%, and 82.8% of flocks, respectively. Compared to the 2020 study, there was a notable decrease in F. necrophorum and Treponema spp., while D. nodosus was consistent. In conclusion, the findings show a low prevalence of footrot, CODD, D. nodosus, and F. necrophorum in Swedish sheep flocks. Continuous surveillance and owner education are important to maintain this favourable status.

Prevalence of bacterial species associated with ovine footrot and contagious ovine digital dermatitis in Swedish slaughter lambs

BackgroundOvine footrot and contagious ovine digital dermatitis (CODD) are contagious mixed bacterial infections with major impacts on animal health and production. In Sweden, ovine footrot and CODD were first detected in 2004 and 2019, respectively. In 2009, a voluntary control programme for footrot was established, and a prevalence study in slaughter lambs was conducted, however, the distribution of footrot and CODD-associated bacteria is still unknown. This study examined the prevalence of Dichelobacter nodosus, Fusobacterium necrophorum and Treponema spp., as well as the current prevalence of footrot and CODD, in Swedish slaughter lambs.ResultsA total of 2048 feet, from 512 slaughter lambs, were collected from eight slaughterhouses throughout Sweden in autumn 2020. All feet were visually examined for lesions of footrot and CODD and sampled for subsequent real-time polymerase chain reaction (PCR) analysis. Nine lambs (1.8%) had at least one foot affected with footrot (footrot score ≥ 2). A CODD grade 1 lesion was detected in a single lamb (0.2%). The prevalence of D. nodosus, F. necrophorum and Treponema spp. was 6.1%, 7.6% and 90.6%, respectively. The D. nodosus detected were benign strains.ConclusionsThe prevalence of footrot in Swedish slaughter lambs has been significantly reduced, from 5.8 to 1.8%, during the past 11 years. This indicates that preventive measures, such as the national control programme and elimination of footrot from affected flocks, have been effective. A single lamb (0.2%) was found with a CODD lesion (grade 1). In Sweden, benign rather than virulent strains of D. nodosus seem to be the most common. Neither D. nodosus nor F. necrophorum were widespread among Swedish slaughter lambs, but both were more likely to be found in lambs with footrot. Treponema spp. was very commonly found in lambs with and without footrot, but there is a lack of information on the individual Treponema spp. present in Swedish slaughter lambs and their potential pathogenicity.

Determination of prevalence, serological diversity, and virulence of Dichelobacter nodosus in ovine footrot with identification of its predominant serotype as a potential vaccine candidate in J&K, India.

The aim of this study was to determine the prevalence, serological diversity, and virulence of Dichelobacter nodosus in footrot lesions of sheep and identification of its predominant serotype as a potential vaccine candidate. The overall prevalence of footrot in sheep was 16.19%, and ranged from 13.69 to 19.71%, respectively. A total of 759 flocks with 22,698 sheep were investigated for footrot and 2374 clinical samples were collected from naturally infected sheep exhibiting footrot lesions. Of the 2374 samples collected, 1446 (60.90%) were positive for D. nodosus by polymerase chain reaction (PCR). These positive samples when subjected to serogroup-specific multiplex PCR, 1337 (92.46%) samples carried serogroup B, 247 (17.08%) possessed serogroup E, 86 (5.94%) serogroup I, and one (0.069%) serogroup G of D. nodosus. While mixed infection of serogroups B and E was detected in 127 (8.78%), B and I in 46 (3.18%) and B, E, and I in 26 (1.79%) samples, respectively. The serogroup B of D. nodosus was the predominant (92.47%) serogroup affecting sheep population with footrot followed by serogroup E (19.91%) and serogroup I (4.57%), respectively. Virulent status of D. nodosus strains were confirmed by presence of virulence-specific integrase A (intA) gene and the production of thermostable proteases. The intA gene was detected in 709 (72.79%) samples while gelatin gel test carried out on 246 representative isolates all positive for intA gene produced thermostable proteases, confirming their virulence nature. The PCR-restriction fragment length polymorphism (PCR-RFLP) of whole fimA gene of serogroup B revealed the predominance of serotype B5 (82.97%) of serogroup B. This information suggests that serotype B5 is the predominant serotype of D. nodosus associated with severe footrot lesions in sheep in Jammu & Kashmir (J&K), India. Hence, this serotype can be a potential vaccine candidate for the effective control and treatment of ovine footrot.

Sheep and farm level factors associated with footrot: a longitudinal repeated cross-sectional study of sheep on six farms in the UK

Footrot is an ovine foot disease of infectious origin and a cause of serious welfare and economic compromise in affected animals and flocks. The development of footrot in sheep is...

Epidemiological and Economic Evaluation of Alternative On-Farm Management Scenarios for Ovine Footrot in Switzerland.

Footrot is a multifactorial infectious disease mostly affecting sheep, caused by the bacteria Dichelobacter nodosus. It causes painful feet lesions resulting in animal welfare issues, weight loss, and reduced wool production, which leads to a considerable economic burden in animal production. In Switzerland, the disease is endemic and mandatory coordinated control programs exist only in some parts of the country. This study aimed to compare two nationwide control strategies and a no intervention scenario with the current situation, and to quantify their net economic effect. This was done by sequential application of a maximum entropy model (MEM), epidemiological simulation, and calculation of net economic effect using the net present value method. Building upon data from a questionnaire, the MEM revealed a nationwide footrot prevalence of 40.2%. Regional prevalence values were used as inputs for the epidemiological model. Under the application of the nationwide coordinated control program without (scenario B) and with (scenario C) improved diagnostics [polymerase chain reaction (PCR) test], the Swiss-wide prevalence decreased within 10 years to 14 and 5%, respectively. Contrary, an increase to 48% prevalence was observed when terminating the current control strategies (scenario D). Management costs included labor and material costs. Management benefits included reduction of fattening time and improved animal welfare, which is valued by Swiss consumers and therefore reduces societal costs. The net economic effect of the alternative scenarios B and C was positive, the one of scenario D was negative and over a period of 17 years quantified at CHF 422.3, 538.3, and −172.3 million (1 CHF = 1.040 US$), respectively. This implies that a systematic Swiss-wide management program under the application of the PCR diagnostic test is the most recommendable strategy for a cost-effective control of footrot in Switzerland.

Whole-flock, metaphylactic tilmicosin failed to eliminate contagious ovine digital dermatitis and footrot in sheep: a cluster randomised trial

The aim of this study was to evaluate the clinical success of whole-flock systemic tilmicosin and enhanced biosecurity in eliminating active contagious ovine digital dermatitis (CODD) from sheep flocks. Thirty...

On the treatment, control and elimination of ovine footrot: a comparative review.

Abstract Ovine footrot is detrimental to sheep health, welfare and production worldwide. Strategies for management of footrot have varied between countries and regions due to differences in climate, production systems and proportion of positive flocks. Recent research from Great Britain, where >90% flocks have footrot has highlighted that treatment of individual lame sheep within 3 days with parenteral and topical antibiotics, and without foot trimming, results in rapid recovery. This benefits both animal welfare and productivity. Recent evidence indicates that foot trimming into sensitive tissue during routine foot trimming is associated with higher prevalence of lameness, and careful routine foot trimming is not associated with lower prevalence of lameness, rendering this practice void for control of footrot. Fifty percent of farmers in England are now no longer practising routine foot trimming. The lowest prevalence of footrot without elimination is achieved by treatment of sheep with footrot within 3 days of onset of lameness, separation of lame sheep until recovered and rapid footbathing of a flock when an outbreak of interdigital dermatitis occurs. Vaccination and selection of breeding replacements from non-lame ewes contribute to further reducing the prevalence of lameness. Improving control of footrot has occurred between 2004 and 2013: the global mean prevalence of lameness in sheep has halved from 10 to 5%. Flock elimination of footrot has been successful in flocks across the world through treatment of diseased sheep, culling all non-respondents and persistently lame sheep, targeted vaccination (including mono and bivalent vaccines) and regular footbathing of healthy sheep in periods of non-transmission until no further disease is detected, even in a period of disease transmission. This has been most successful when initiated when climatic conditions are regularly unfavourable to transmission of footrot and where the percentage of flocks with footrot is low and flock level biosecurity can be maintained to prevent re-introduction of footrot to a naïve flock. Both control and elimination strategies are successful to reduce the global burden of footrot. Success is dependent on choosing the correct strategy for the flock given climate, biosecurity and force of infection and commitment to the programme.

Dynamics and impact of footrot and climate on hoof horn length in 50 ewes from one farm over a period of 10 months

Footrot, including interdigital dermatitis, is caused by Dichelobacter nodosus cause the majority of lameness in sheep in the UK. Lame sheep often have overgrown hoof horn but recent evidence has indicated that trimming overgrown hoof horn increases recovery time, and that routine foot trimming of the flock does not reduce the prevalence or incidence of lameness. The objectives of this study were to investigate the temporal associations between hoof horn length, footrot and climate. Fifty multiparous ewes were monitored for 10 months. On eight occasions hoof horn length, foot lesions and body condition were recorded. At the first examination, ewes were assigned to one of two treatment groups. All ewes that became lame with footrot were treated at one time point per week, either by trimming hoof horn and applying a topical antibiotic spray or with parenteral antibiotic and topical antibiotic spray.Hoof horn length in ewes at pasture varied over the year and was associated with temperature and rainfall. New cases of footrot occurred all year round and were associated with prior prevalence of footrot in the flock and prior temperature and rainfall. Overgrown hoof horn did not precede lameness but occurred once the sheep were lame. One year of prompt treatment of footrot reduced the range in hoof horn length in the sheep in both treatment groups. At the end of the study the hoof lengths of ewes in both groups were not significantly different. On this farm, hoof horn length was self-regulating in both non-lame and treated lame sheep whether trimming was part of the treatment or not and there would have been no benefit from routine foot trimming of this flock.

Selenium Supplementation Alters Gene Expression Profiles Associated with Innate Immunity in Whole-Blood Neutrophils of Sheep

Footrot (FR) is a common, contagious bacterial disease of sheep that results in lameness and significant economic losses for producers. We previously reported that sheep affected with FR have lower whole-blood (WB) selenium (Se) concentrations and that Se supplementation in conjunction with routine control practices accelerates recovery from FR. To determine whether oral Se-yeast administered at supranutritional levels (>4.9 mg Se/week) alters the ability of sheep to resist or recover from FR infection, 60 ewes with and 60 ewes without FR were drenched once weekly for 62.5 weeks with 0, 4.9, 14.7, or 24.5 mg organic Se-yeast (30 ewes per treatment group). Footrot prevalence and severity were measured at 0, 20, 28, 40, and 60 weeks of Se supplementation. Genomic expression of eight WB-neutrophil genes for selenoproteins and seven WB-neutrophil genes for proteins involved in innate immunity was determined at the end of the treatment period using SYBR Green and quantitative polymerase chain reaction methodology. Supranutritional Se-yeast supplementation successfully increased Se status in sheep but did not prevent FR. Supranutritional Se-yeast supplementation increased WB-neutrophil expression of genes involved in innate immunity: L-selectin, interleukin-8 receptor, and toll-like receptor 4, which were or tended to be lower in ewes affected with FR. Furthermore, supranutritional Se-yeast supplementation altered the expression of selenoprotein genes involved in innate immunity, increasing selenoprotein S and glutathione peroxidase 4 and decreasing iodothyronine deiodinases 2 and 3. In conclusion, supranutritional Se-yeast supplementation does not prevent FR, but does alter WB-neutrophil gene expression profiles associated with innate immunity, including reversing those impacted by FR.

Polymorphism of the MHC-DQA2 gene in the Chios dairy sheep population and its association with footrot

The objectives of this study were to assess (i) the nature and frequency of polymorphism of the DQA2 gene in Chios dairy sheep and (ii) if it is associated with footrot prevalence in the population. A total of 20 DQA2 alleles/haplotypes and 78 genotypes were detected. Allele 0301was the most common, followed by haplotype 0603–1101, alleles 0501 and 0602. Furthermore, it was found that a single copy of 1101 was associated with 9.0% higher susceptibility to footrot. Regarding genotypes, 0301/0301 was the most common (12.0%), followed by 0301/0603–1101 (7.0%) and the overall effect of genotype on prevalence of footrot was statistically significant. Moreover, remarkable differences were observed, regarding frequencies of alleles/haplotypes and genotypes in Chios sheep population, when comparisons were made with breeds utilized for meat and wool production. A high diversity at the ovine DQA2 gene locus was revealed in the Chios dairy breed, suggesting that genetic selection against allele 1101 may be successful in rendering the breed less susceptible to footrot.

Prevalence of ovine footrot in the tropical climate of southern India and isolation and characterisation of Dichelobacter nodosus.

The present communication records the first determination of the prevalence of footrot in the unexpected situation of the tropical climate of Andhra Pradesh and Tamil Nadu, two states in southern India where the maximum temperature rises to 42 degrees C. In total, 73 outbreaks of footrot in Nellore brown sheep were investigated in 11 districts of Andhra Pradesh and one district of Tamil Nadu during the period March 2009 to March 2011.The overall prevalence of ovine footrot was 15%, with severity scores of 2 to 4 (lesion severity scale 0 to 4). The outbreaks occurred mostly during the rainy season, which is usually from June to December. From a total of 1,050 samples of lesions in naturally infected sheep, 478 (45.5%) were positive for Dichelobacter nodosus. Serogrouping of the isolates revealed six serogroups: A, B, C, E, F and I. Among the positive samples, 448 (93.7%) were a single serogroup and 30 (6.3%) carried a mixed infection with two serogroups. Taking single and mixed infections together, serogroup B was most frequent at 50.4% and was found in all districts, followed by serogroup I in 29.3% of samples, A in 14%, F in 6.7% and C in 5.6%. Serogroup E was detected in only one sample. Serogroups A and F were detected for the first time in India. All of 58 D. nodosus isolates in a sub-sample representing different serogroups were found to be virulent, based on the production of thermostable proteases and the presence of the integrase A gene intA. Thus, the present paper reporting isolation and characterisation of D. nodosus confirms the occurrence of virulent footrot in the tropical climate of southern India.

The interaction of host genetics and disease processes in chronic livestock disease: A simulation model of ovine footrot

A stochastic, individual-based, simulation model of footrot in a flock of 200 ewes was developed that included flock demography, disease processes, host genetic variation for traits influencing infection and disease processes, and bacterial contamination of the environment. Sensitivity analyses were performed using ANOVA to examine the contribution of unknown parameters to outcome variation. The infection rate and bacterial death rate were the most significant factors determining the observed prevalence of footrot, as well as the heritability of resistance. The dominance of infection parameters in determining outcomes implies that observational data cannot be used to accurately estimate the strength of genetic control of underlying traits describing the infection process, i.e. resistance. Further work will allow us to address the potential for genetic selection to control ovine footrot.

Foot rot and other foot diseases of goat and sheep in the semiarid region of northeastern Brazil

This paper reports the occurrence and epidemiology of outbreaks of foot rot and other foot diseases in goats and sheep in the semiarid region of Paraíba, northeastern Brazil. Four farms were inspected for the presence of foot lesion in sheep and goats and for environmental conditions, general hygiene, pastures, and disease control measures. The prevalence of foot lesions was 19.41% (170/876) in sheep and 17.99% (52/289) in goats, ranging between 5.77% and 33.85% in different farms. Foot rot was the most common disease, affecting 12.1% of the animals examined (141/1165), but with significantly higher (p<0.05) prevalence in sheep (13.69%) than in goats (7.27%). The frequency of malignant foot rot was also significantly lower (p<0.05) in goats (9.53%) than in the sheep (40.83%). On one farm, Dorper sheep showed significantly higher (p<0.05) prevalence of foot rot (17.5%) than Santa Inês sheep (6.79%), and the number of digits affected was also higher in the former. Dichelobacter nodosus and Fusobacterium necrophorum were isolated from cases of foot rot. White line disease was found in 3.95% of the animals, sole ulcers in 1.29%, foot abscess in 1.03% and hoof overgrowth in 0.5%. The high rainfall at the time of occurrence, grazing in wetlands, clay soils with poor drainage, presence of numerous stony grounds, closure of the flocks in pens at night, and introduction of affected animals were considered predisposing factors for the occurrence of foot diseases.

Prevalence of footrot in Swedish slaughter lambs

BackgroundFootrot is a world-wide contagious disease in sheep and goats. It is an infection of the epidermis of the interdigital skin, and the germinal layers of the horn tissue of the feet. The first case of footrot in Swedish sheep was diagnosed in 2004. Due to difficulties in distinguishing benign footrot from early cases of virulent footrot and because there is no possibility for virulence testing of strains of Dichelobacter nodosus in Sweden, the diagnosis is based of the presence or absence of clinical signs of footrot in sheep flocks. Ever since the first diagnosed case the Swedish Animal Health Service has worked intensively to stop the spread of infection and control the disease at flock level. However, to continue this work effectively it is important to have knowledge about the distribution of the disease both nationally and regionally. Therefore, the aims of this study were to estimate the prevalence of footrot in Swedish lambs at abattoirs and to assess the geographical distribution of the disease.MethodsA prevalence study on footrot in Swedish lambs was performed by visual examination of 2000 feet from 500 lambs submitted from six slaughter houses. Each foot was scored according to a 0 to 5 scoring system, where feet with score ≥2 were defined as having footrot. Moreover, samples from feet with footrot were examined for Dichelobacter nodosus by culture and PCR.ResultsThe prevalence of footrot at the individual sheep level was 5.8%, and Dichelobacter nodosus was found by culture and PCR in 83% and 97% of the samples from feet with footrot, respectively. Some minor differences in geographical distribution of footrot were found in this study.ConclusionsIn a national context, the findings indicate that footrot is fairly common in Swedish slaughter lambs, and should be regarded seriously.

Determination of prevalence and economic impact of ovine footrot in central Kashmir India with isolation and molecular characterization of Dichelobacter nodosus

The present study determines the prevalence, economic impact of virulent footrot in central Kashmir, India, along with isolation and molecular characterization of Dichelobacter nodosus ( D. nodosus) where so far no such work has been carried out. Over all 12.54% prevalence of footrot was recorded in central Kashmir with highest (15.84%) in district Srinagar, and least (10.89%) in district Budgam, while it was 13.28% in district Ganderbal. Overall economic impact of footrot was estimated to the tune of Rs 15.82 million annually to the sheep farming in central Kashmir. Out of 370 samples collected from footrot lesions of naturally infected sheep, 200 (54.05%) detected D. nodosus positive by polymerase chain reaction (PCR). Out of these, 132 (66.00%) samples carried serogroup B of D. nodosus, five (2.50%) serogroup E, one (0.50%) serogroup I, while, 53 (26.50%) had mixed infection of serogroups B and E, four (2.00%) of serogroups B and I, two (1.00%) of serogroups B and G and the remaining three (1.50%) samples harboured the mixed infection of serogroups B, E and I. Serogroup G was detected for the first time in India. Over all serogroup B was most frequent (97.0%) followed by E (30.5%), while serogoups I (4.0%) and G (1.0%) were least prevalent. A total of 265 D.nodosus strains were isolated out of which 194 (73.20%) were typed as serogroup B, 61 (23.01%) as serogroup E, eight (3.01%) as serogroup I and remaining two (0.75%) belonged to serogroup G. Out of 265 D. nodosus isolates, 164 (61.88%) possessed intA (integrase) gene, thus were considered as virulent strains. Serogroup wise intA gene was found in 121(62.37%) isolates of serogroup B, 36 (59.01%) of E, two (100%) of G and five (62.50%) of I. Out of 20 randomly selected isolates subjected to gelatin gel test, 16 isolates with intA gene produced thermostable protease while four isolates without intA gene revealed the production of thermolabile protease. This indicated a good co-relation between presence of intA gene and gelatin gel test in determination of the D. nodosus virulence. Thus the present investigation suggests the incorporation of serogroups B and E, based on their predominant prevalence, in the formulation of an effective bivalent vaccine to combat footrot in central Kashmir.

A field trial to control ovine footrot via vaccination and genetic markers

Two sheep farms with clinical footrot for several years were selected to compare the efficacy of paucivalent-specific vaccines with a commercially available vaccine (Footvax ®). Furthermore, it was also investigated whether specific DQA 2-haplotypes may cause enhanced footrot-tolerance. Prior to the trial and vaccination of animals, Dichelobacter nodosus-strains isolated from both flocks were used to produce a pentavalent vaccine (containing serogroups A, B, G, H und I) for flock 1 and a quadrivalent vaccine (containing serogroups B, E, G and I) for flock 2. The trial included 695 ewes of German Mutton Merino ( n = 347), German Merino ( n = 115) and German Blackheaded Mutton ( n = 175). During the 16-week trial, the ewes were examined thrice, on weeks 1, 4 and 16. Vaccination was performed during the first and second examination. Prevalence of footrot (evaluated by the number of digits with underrun horn) decreased from 20.2 to 5.9%. Depending on the kind of vaccination, prevalence decreased from 12.3 to 2.5% within the Footvax ®-group, whereas sheep vaccinated with the autogenous vaccine showed a reduction of under-running footrot from 28.4 to 8.9%. Taking into account that vaccination with Footvax ® caused a significantly ( p < 0.001) greater number of local reactions, the autogenous vaccines containing milder adjuvants are recommended for reasons of animal welfare. The DQA 2-locus of 538 ewes was analysed to assess the genetic basis of footrot-tolerance. A total of 21 alleles and 96 genotypes were detected. The most common DQA 2-allele to be found was D ( n = 263), which was also part of the most frequent genotype B1/D ( n = 44). Of all confirmed alleles, 23.4% consisted of a DQA 2-allele accompanied by an additional DQA 2 -like sequence. The likelihood that animals carrying such a duplicated DQA 2-haplotype, had under-running footrot was significantly lower than the odds of ewes lacking the duplication (OR = 1.76 [95% confidence interval: 1.08–2.88], p = 0.02). Comparing single DQA 2-alleles with each other leads to the result that the likelihood of a footrot infection is smaller for ewes having one of the duplicated alleles G and J2 than for ewes carrying the unduplicated alleles E and L (OR L/J2 = 2.09 [95% confidence interval: 1.07–4.10], p = 0.03).

Effect of Parenteral Selenium Administration to Sheep on Prevalence and Recovery from Footrot

Insufficient intake of selenium (Se) is common in many regions, and can contribute to increased susceptibility to and prolonged recovery from infectious diseases. To determine the effect of Se administration in decreasing the severity and prevalence of footrot in sheep. Thirty-eight footrot-affected and 19 nonaffected sheep from a commercial flock of known high incidence of footrot. Placebo-controlled, prospective, 15-month clinical trial. Footrot-affected sheep were randomly assigned into 2 groups (n = 19) and injected with either 5 mg Se (footrot [FR]-Se) or saline (FR-Sal) at 1-month intervals for the duration of the study. Unaffected sheep (controls) received no treatment. Sheep feet were examined, trimmed, and scored for footrot with a scale of 0 (no footrot) to 4 (extensive) at 0, 3, 6, 9, and 15 months. Sheep were also bled at time 0 and then at 3, 6, and 15 months to assess whole blood Se concentrations. At time 0, control sheep (255 +/- 11 ng/mL) had higher (P < .05) whole blood Se concentrations compared with FR-Se (205 +/- 12 ng/mL) and FR-Sal (211 +/- 14 ng/mL) sheep. By 6 months, FR-Se sheep (317 +/- 9 ng/mL) had whole blood Se concentrations greater (P < .05) than both control (281 +/- 14 ng/mL) and FR-Sal (277 +/- 16 ng/mL) sheep. FR-Se ewes showed a faster decline in highest lesion score at 3 (P= .012) and 6 (P= .0036) months, and a greater decrease in the number of feet with foot score >0 at 6 (P= .020) months compared with FR-Sal ewes. Sheep with blood Se concentrations <300 ng/mL were at 3.5 times greater risk (1.1-12.1 confidence interval, odds ratio) for FR, although this relationship was only significant (P= .04) at 6 months of the study. In sheep with footrot, improved Se status in conjunction with routine control practices result in more rapid improvement of foot lesions.

Performance and bunk attendance of cattle fed steam-rolled or ground corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin

British cross steer calves (n = 240; 332 ± 23 kg) in 16 pens were fed ground (G) or steam-rolled (SR) corn-based finishing diets medicated with 12 mg kg-1 laidlomycin propionate and 42.2 mg kg-1 chlortetracycline hydrochloride (LC) or with 30.4 mg kg-1 monensin sodium and 10.5 mg kg-1 tylosin phosphate (MT) in a 2 × 2 factorial experiment. Individual bunk attendance was monitored using radio frequency identification in one pen per diet. Finishing diets were fed for 125 d following a 27-d adaptation from 65 to 91% concentrate diet. In the first 56 d and overall, daily dry matter intake (DMI) was greater (P &lt; 0.05) with LC than with MT (8.8 vs. 8.3 kg), but did not differ (P = 0.97) between G and SR diets. There was a trend (P = 0.11) towards greater ADG for cattle fed LC than those fed MT (1.54 vs. 1.47 kg d-1), but gain:feed was similar (0.169; P = 0.80) between antibiotic supplements. Processing method did not (P = 0.29) affect rate of gain, but SR tended (P = 0.06) to improve gain:feed compared with G (0.171 vs. 0.165). Steers fed LC spent more (P &lt; 0.001) time at the bunk than those fed MT (125 vs. 120 min d-1). On G diets, cattle fed LC made fewer daily visits (9.3 vs. 9.5 visits d-1; P = 0.03), but spent more time at the bunk (135.9 vs. 124.0 min d-1; P &lt; 0.001) resulting in greater duration per meal (15.4 vs. 13.7 min meal-1; P &lt; 0.001). These cattle also had the greatest deviation in daily duration at the bunk (37.3 vs. 33.7 min; P &lt; 0.001). The prevalence of liver abscesses was 13.2% with LC and 6.5% with MT (P = 0.09). However, the prevalence of severely abscessed livers (2.9%) was unaffected (P = 0.45) by treatment. The prevalence of foot rot was greater (P = 0.02) for cattle fed MT (7.5%) than for cattle fed LC (0.8%). Compared with feeding MT, feeding LC may enhance ADG, possibly due to greater DMI. Key words: Beef, chlortetracycline, corn processing, laidlomycin, monensin, tylosin

Distribution and prevalence of footrot in Bhutan

The first cases of footrot in Bhutan were reported in sheep in 1990 at the National Sheep Breeding Centre (NSBC), which supplies breeding animals to village sheep flocks throughout Bhutan. Despite the presence of footrot at the Centre the distribution of apparently disease-free sheep continued. Cases of footrot were reported in village flocks soon after the disease was diagnosed at NSBC. A national survey was designed to establish the distribution and prevalence of footrot in Bhutan. This detected footrot in 19/94 village sheep flocks surveyed. The 19 affected flocks were distributed among nine different administrative districts whereas the villages selected were in 13 of a total of 16 sheep growing districts. The highest within-flock prevalences were among the seven flocks sampled in Bumthang district (mean 20.4%). The prevalence of the disease within flocks was generally much lower in other affected districts and in three districts a single affected animal was identified in the sample of 14 sheep examined in each village. Nationally, footrot prevalence was estimated to be 3.1% (95% CI 2.16–4.04%). There was a positive association between the receipt of animals from NSBC and the presence of footrot. The prevalence of the disease was higher in flocks with a migratory system of management than in those using a sedentary system. The relative risk of there being footrot in a migratory flock was nine-times higher than in a non-migratory flock. Only one strain of Dichelobacter nodosus (serogroup B) was identified among the 234 isolates obtained from the 19 affected flocks. Sheep with footrot healed quickly when treated with a vaccine made from this strain.