Multiple model triangulation to identify factors associated with lameness in British sheep flocks.

Identification of factors associated with an outcome can be challenging when the number of explanatory variables is large in relation to the number of observations. Multiple model triangulation, where results from several model types are combined, improves the likelihood of identifying true predictor variables. The aim of this study was to use triangulation to identify covariates likely to be truly associated with the prevalence of lameness in sheep flocks in Great Britain. Data were collected using a questionnaire sent to 3200 sheep farmers in Great Britain in 2018. The useable response rate was 14.1 %. The geometric mean prevalence of lameness was 1.4 % (95 % CI 1.2-1.7) for ewes, and 0.6 % (95 % CI 0.5-0.9) for lambs, however, approximately 60 % flocks had >2% prevalence of lameness in ewes. Four model types were investigated, two generalised linear models (negative binomial and quasi-Poisson) built using stepwise selection, and two elastic net models (Poisson and Gaussian distributions) refined with selection stability estimation. Triangulated covariates were those selected in three or all four models - 10 for ewes and 12 for lambs. Higher prevalence of lameness in ewes was associated with 5-100% feet bleeding during routine foot trimming compared with not foot trimming, footbathing the flock to treat severe footrot (SFR) and always using formalin in footbaths, both compared with not footbathing, using FootVax™ for <1 year compared with not using FootVax™, and never quarantining new or returning sheep to the farm for >3 weeks compared with always. Lower prevalence of lameness in ewes was associated with vaccinating with FootVax™ for >5 years compared with not vaccinating, peat soil compared with no peat soil, and having no lame ewes to treat. Higher prevalence of lameness in lambs was associated with 5-100% feet bleeding during routine foot trimming, always foot trimming ewes with SFR, not knowingly selecting replacement ewes from ewes that were never lame compared with always, replacement sheep purchased and homebred compared with only homebred, treating lambs >3 days after recognition of lameness compared with 0-3 days and footbathing the flock to treat interdigital dermatitis compared with not footbathing at all. Lower prevalence of lameness in lambs was associated with peat soil, flocks in Scotland versus England, an altitude of >230-500 m compared with ≤230 m, never using antibiotic injection to treat lambs with SFR compared with always, and having no lame lambs to treat. We conclude triangulation identified reliable management practices for farmers to implement to minimise lameness in sheep.

Footbathing, formalin and foot trimming: The 3Fs associated with granulomas and shelly hoof in sheep.

Granulomas and shelly hoof (SH), are lesions of sheep feet. Our objective was to use data from four questionnaires on lameness sent to English sheep farmers in 2004, 2013, 2014 and 2015 to further understanding of the risks and aetiologies of both lesions. Granulomas were more likely in flocks where routine foot trimming (odds ratio [OR]=3.17; 95% confidence intervals [CI] 1.11-11.47) and routine footbathing (OR=2.38; 95% CI 1.19-4.83) were practised than where these management protocols were not. SH was more likely in flocks that were footbathed in formalin compared with not footbathing (OR=1.65; 95% CI 1.19-2.30), and was less common in flocks that stocked ewes at more than eight vs. four per acre (OR=0.34; 95% CI 0.17-0.68). There were weak associations between SH and foot trimming. In 2004 only, SH was more likely in flocks where therapeutic foot trimming was practised than not practised (OR=2.24; 95% CI 1.12-4.68). In 2014 only, SH was marginally less likely in flocks where no feet bled during trimming, compared with flocks not routinely trimmed (OR=0.55; CI 0.30-1.00); SH was not related to foot trimming once severe footrot was included. We propose that flocks with granulomas and SH would decrease if farmers stopped footbathing in general, in particular with formalin, and avoided foot trimming whether as a therapeutic or routine practice. Further work is needed to understand the role of stocking density.

Heritability of phenotypic udder traits to improve resilience to mastitis in Texel ewes.

There are no estimates of the heritability of phenotypic udder traits in suckler sheep, which produce meat lambs, and whether these are associated with resilience to mastitis. Mastitis is a common disease which damages the mammary gland and reduces productivity. The aims of this study were to investigate the feasibility of collecting udder phenotypes, their heritability and their association with mastitis in suckler ewes. Udder and teat conformation, teat lesions, intramammary masses (IMM) and litter size were recorded from 10 Texel flocks in Great Britain between 2012 and 2014; 968 records were collected. Pedigree data were obtained from an online pedigree recording system. Univariate quantitative genetic parameters were estimated using animal and sire models. Linear mixed models were used to analyse continuous traits and generalised linear mixed models were used to analyse binary traits. Continuous traits had higher heritabilities than binary with teat placement and teat length heritability (h 2) highest at 0.35 (SD 0.04) and 0.42 (SD 0.04), respectively. Udder width, drop and separation heritabilities were lower and varied with udder volume. The heritabilities of IMM and teat lesions (sire model) were 0.18 (SD 0.12) and 0.17 (SD 0.11), respectively. All heritabilities were sufficiently high to be in a selection programme to increase resilience to mastitis in the population of Texel sheep. Further studies are required to investigate genetic relationships between traits and to determine whether udder traits predict IMM, and the potential benefits from including traits in a selection programme to increase resilience to chronic mastitis.

Quantifying the beliefs of key players in the UK sheep industry on the efficacy of two treatments for footrot.

Clinical trials have demonstrated that sheep with footrot treated with parenteral and topical antibiotics without foot trimming (treatment A), cure faster than sheep treated with foot trimming and topical antibiotics (treatment B). We investigated how key players in the UK sheep industry recommended treating footrot, and tested whether reviewing the evidence surrounding treatment of footrot changed their beliefs. Eight key players attended a workshop to investigate their current practices, and their perceived efficacy of treatments, using probabilistic elicitation. At the start of the study, all participants recommended use of antibiotic injection but only four recommended not foot trimming feet with footrot. Initial beliefs in the difference in cure rate within five days of treatment ranged from 30 to 97% in favour of treatment A (true difference 60%); this heterogeneity reduced after reviewing the evidence. Participants who believed the cure rate differed by >60% over-estimated the cure rate of treatment A whilst participants who believed the difference was <60% over-estimated the efficacy of treatment B. During discussions, participants stated that parenteral antibiotics had always been recommended as a treatment for footrot but that the new research clarified when to use them. In contrast, it was highly novel to hear that foot trimming was detrimental to recovery, and key players and farmers are taking longer to accept this evidence. Three months after the workshop, two participants stated that they now placed greater emphasis on rapid individual antibiotic treatment of lame sheep and one was no longer recommending trimming feet.

The contribution of previous lameness events and body condition score to the occurrence of lameness in dairy herds: A study of 2 herds.

It has been demonstrated that low body condition and previous occurrence of lameness increase the risk of future lameness in dairy cows. To date the population attributable fraction (PAF), which provides an estimate of the contribution that a risk factor makes toward the total number of disease events in a population, has not been explored for lameness using longitudinal data with repeated measures. Estimation of PAF helps to identify control measures that could lead to the largest improvements on-farm. The aim of this study was to use longitudinal data to evaluate the proportion of lameness that could be avoided in 2 separate herds (2 populations) through (1) reduced recurrence of previous lameness events, (2) and moving body condition score (BCS) into more optimal ranges. Data were obtained from 2 UK dairy herds: herd A, a 200-cow herd with 8 yr of data from a total of 724 cows where lameness events were based on weekly locomotion scores (LS; 1 to 5 scale), and herd B, a 600-cow herd with data recorded over 44 mo from a total of 1,040 cows where treatment of clinical cases was used to identify lameness events. The PAF for categories of BCS were estimated using a closed equation appropriate for multiple exposure categories. Simulation models were used to explore theoretical scenarios to reflect changes in BCS and recurrence of previous lameness events in each herd. For herd A, 21.5% of the total risk periods (cow-weeks) contained a lameness event (LS 3, 4, or 5), 96% of which were repeat events and 19% were recorded with BCS <2 (3 wk previously; 0 to 5 scale). When lameness events were based on 2 consecutive weeks of LS 4 or 5, 4% of risk periods were recorded as lame, of which 89.5% were repeat events. For herd B, 16.3% of the total risk periods (consecutive 30 d) contained a lameness event (72.6% were repeat events) and 20% were recorded with BCS ≤2 (0 to 120 d previously). The median PAF for all previous lameness was between 79 and 83% in the 2 herds. Between 9 and 21% of lameness events could be attributed to previous lameness occurring >16 wk before a risk period. The median PAF estimated for changes in BCS were in the region of 4 to 11%, depending on severity of lameness. Repeated bouts of lameness made a very large contribution to the total number of lameness events. This could either be because certain cows are initially susceptible and remain susceptible, due to the increased risk associated with previous lameness events, or due to interactions with environmental factors. This area requires further research.

Lameness in dairy heifers; impacts of hoof lesions present around first calving on future lameness, milk yield and culling risk.

The importance of lameness in primiparous dairy heifers is increasingly recognised. Although it is accepted that clinical lameness in any lactation increases the risk of future lameness, the impact of foot lesions during the first lactation on long-term lameness risk is less clear. This retrospective cohort study aimed to investigate the impacts of foot lesions occurring around the time of first calving in heifers on future lameness risk, daily milk yield and survival within a dairy herd. Records were obtained for 158 heifers from one UK dairy herd. Heifers were examined in 2 month blocks from 2 months pre-calving through to 4 months post-calving. Sole lesions and white line lesions were scored on a zero to 10 scale and digital dermatitis on a zero to 3 scale. Outcomes investigated were; lameness risk based on weekly locomotion scores, average daily milk yield and culling risk. Mixed effect models were used to investigate associations between maximum lesion scores and outcomes. Lesion scores in the highest score categories for claw horn lesions (sole lesions and white line lesions) in the 2 to 4 month post-calving period were associated with an increased risk of future lameness; heifers with white line lesion scores ≥3 compared with scores zero to 1 and heifers with sole lesion scores ≥4 compared with score 2, at this time point, had a predicted increased risk of future lameness of 1.6 and 2.6 respectively. Sole lesions ≥4 were also associated with a reduction in average daily milk yield of 2.68kg. Managing heifers to reduce claw horn lesions during this time period post-calving may provide health, welfare and production benefits for the long-term future of those animals. A novel finding from the study was that mild lesion scores compared with scores zero to 1, were associated with a reduced risk of future lameness for white line lesions and sole lesions occurring in the pre-calving or 2 to 4 months post-calving periods respectively. Mild sole lesions in the pre-calving period were also associated with a reduced risk of premature culling. One hypothesis for this result is that a mild insult may result in adaptive changes to the foot leading to greater biomechanical resilience and so increased longevity.

A cross-sectional study of 329 farms in England to identify risk factors for ovine clinical mastitis.

The aims of this study were to estimate the incidence rate of clinical mastitis (IRCM) and identify risk factors for clinical mastitis in suckler ewes to generate hypotheses for future study. A postal questionnaire was sent to 999 randomly selected English sheep farmers in 2010 to gather data on farmer reported IRCM and flock management practices for the calendar year 2009, of which 329 provided usable information. The mean IRCM per flock was 1.2/100 ewes/year (CI:1.10:1.35). The IRCM was 2.0, 0.9 and 1.3/100 ewes/year for flocks that lambed indoors, outdoors and a combination of both, respectively. Farmers ran a variety of managements before, during and after lambing that were not comparable within one model, therefore six mixed effects over-dispersed Poisson regression models were developed. Factors significantly associated with increased IRCM were increasing percentage of the flock with poor udder conformation, increasing mean number of lambs reared/ewe and when some or all ewes lambed in barns compared with outdoors (Model 1). For ewes housed in barns before lambing (Model 2), concrete, earth and other materials were associated with an increase in IRCM compared with hardcore floors (an aggregate of broken bricks and stones). For ewes in barns during lambing (Model 3), an increase in IRCM was associated with concrete compared with hardcore flooring and where bedding was stored covered outdoors or in a building compared with bedding stored outdoors uncovered. For ewes in barns after lambing (Model 4), increased IRCM was associated with earth compared with hardcore floors, and when fresh bedding was added once per week compared with at a frequency of ≤2 days or twice/week. The IRCM was lower for flocks where some or all ewes remained in the same fields before, during and after lambing compared with flocks that did not (Model 5). Where ewes and lambs were turned outdoors after lambing (Model 6), the IRCM increased as the age of the oldest lambs at turnout increased. We conclude that the reported IRCM is low but highly variable and that the complexity of management of sheep around lambing limits the insight into generating hypotheses at flock level for risks for clinical mastitis across the whole industry. Whilst indoor production was generally associated with an increased IRCM, for ewes with large litter size indoor lambing was protective, we hypothesise that this is possibly because of better nutrition or reduced exposure to poor weather and factors associated with hygiene.

A systematic review of animal based indicators of sheep welfare on farm, at market and during transport, and qualitative appraisal of their validity and feasibility for use in UK abattoirs.

In the UK, it has been suggested that abattoirs are ideal locations to assess the welfare of sheep as most are slaughtered at abattoirs either as finished lambs or cull ewes. Data from abattoirs could provide benchmarks for welfare indicators at a national level, as well as demonstrating how these change over time. Additionally, feedback could be provided to farmers and regulatory authorities to help improve welfare and identify high or low standards for quality assurance or risk-based inspections. A systematic review of the scientific literature was conducted, which identified 48 animal-based indicators of sheep welfare that were categorised by the Five Freedoms. Their validity as measures of welfare and feasibility for use in abattoirs were evaluated as potential measures of prior sheep welfare on the farm of origin, at market, or during transportation to the abattoir. A total of 19 indicators were considered valid, of which nine were considered theoretically feasible for assessing sheep welfare at abattoirs; these were body cleanliness, carcass bruising, diarrhoea, skin lesions, skin irritation, castration, ear notching, tail docking and animals recorded as 'obviously sick'. Further investigation of these indicators is required to test their reliability and repeatability in abattoirs. Novel welfare indicators are needed to assess short-term hunger and thirst, prior normal behaviour and long-term fear and distress.

Bacterial species and their associations with acute and chronic mastitis in suckler ewes.

Acute mastitis in suckler ewes is often detected because of systemic signs such as anorexia or lameness, whereas chronic mastitis, characterized by intramammary abscesses with no systemic disease, is typically detected when ewes are inspected before mating. The aims of the current study were to identify the species and strains of culturable bacteria associated with acutely diseased, chronically diseased, and unaffected mammary glands to investigate whether species and strains vary by state. To investigate acute mastitis, 28 milk samples were obtained from both glands of 14 ewes with acute mastitis in one gland only. To investigate chronic mastitis, 16 ovine udders were obtained from 2 abattoirs; milk was aspirated from the 32 glands where possible, and the udders were sectioned to expose intramammary abscesses, which were swab sampled. All milk and swab samples were cultured aerobically. In total, 37 bacterial species were identified, 4 from acute mastitis, 26 from chronic mastitis, and 8 from apparently healthy glands. In chronic mastitis, the overall coincidence index of overlap of species detected in intramammary abscesses and milk was 0.60, reducing to 0.36 within individual glands, indicating a high degree of species overlap in milk and abscesses overall, but less overlap within specific glands. Staphylococcus aureus was detected frequently in all sample types; it was isolated from 10/14 glands with acute mastitis. In 5 ewes, closely related strains were present in both affected and unaffected glands. In chronic mastitis, closely related Staphylococcus aureus strains were detected in milk and abscesses from the same gland.

Low body condition predisposes cattle to lameness: An 8-year study of one dairy herd.

Lameness in dairy cows is a multifactorial and progressive disease with complex interactions between risk factors contributing to its occurrence. Detailed records were obtained from one United Kingdom dairy herd over an 8-yr period. Weekly locomotion scores were used to classify cows as not lame (score 1 to 2), mildly lame (score 3) and severely lame (score 4 to 5). These outcomes were used to investigate the hypothesis that low body condition score (BCS) is associated with an increased risk of lameness in dairy cows. Mixed effect multinomial logistic regression models were used to investigate the association between prior BCS and repeat lameness events during the longitudinal period of the study. Discrete time survival models were used to explore the relationship between prior BCS and first lifetime lameness events. In total, 79,565 cow weeks at risk were obtained for 724 cows. The number of lameness events was 17,114, of which 8,799 were categorized as mildly lame and 8,315 as severely lame. The median BCS was 2.25 (range, 0.75 to 4.25) and the mean body weight (BW) and age at first calving were 619.5 kg (range, 355.6 to 956.4 kg) and 25.8 mo (range, 20.5 to 37.8 mo), respectively. Subsets of the data were used in the discrete time survival models: 333 mild and 211 severe first lifetime lameness events in heifers (first lactation cows), and 81 mild and 49 severe first lifetime lameness events in cows second lactation or greater. Low BCS 3 wk before a repeated lameness event was associated with a significantly increased risk of lameness. Cows with BCS<2 were at greatest risk of mild or severe lameness, and an increased BCS above 2 was associated with a reduced risk of mild or severe lameness. Low BCS 16 or 8 wk before a first mild or severe lifetime lameness event, respectively, also had a positive association with risk of lameness in cows second lactation or greater. This provides evidence to support targeting management toward maintaining BCS to minimize the risk of lameness. Low BW (independent of BCS) and increased age at first calving above 24 mo were also associated with increased long-term risk of repeated lameness events. Overall, the model explained 62 and 60% of the variability for mild and severe lameness, respectively, highlighting the importance of these variables as risk factors and hence where management could be targeted to significantly affect reducing the risk of lameness.

A cross-sectional study on the prevalence and risk factors for foot and limb lesions in piglets on commercial farms in Ireland.

A cross-sectional survey of 68 integrated Irish pig farms was conducted to determine the prevalence and risk factors for foot and limb lesions in 2948 piglets from 272 litters. One litter was selected per age category; 3-7 days, 8-14 days, 15-21 days and 22-28 days per farm. All piglets were examined for sole bruising, sole erosion, coronary band injuries, limb abrasions, alopecia, swollen limbs and swollen feet and scored from 0 to 3 based on relative size. Environmental parameters were recorded for each litter examined. A questionnaire was completed on management, health and performance factors for each farm. The overall prevalence of each lesion was calculated and multilevel mixed effect logistic regression models were used to elucidate risk factors. The prevalence (farm range) of lesions were: sole bruising=61.5% (7-100%), sole erosion=34.1% (0-100%), coronary band injuries=11.3% (0-46%), limb abrasions=55.7% (11-98%), alopecia=24.8% (0-83%), swollen limbs=2.4% (0-11%) and swollen feet=4.4% (0-14%). Age was negatively associated with sole bruising (OR 0.42; CI 0.37, 0.50) and coronary band injury (OR 0.69; CI 0.60, 0.81) and positively associated with limb abrasions (OR 1.54; CI 1.12, 2.14). There was a reduced risk of sole bruising in piglets in pens with plastic slats with oval voids in the piglet area of the pen with a plastic solid area for piglets and metal slats under the crate (OR 0.32; CI 0.15, 0.70) compared with plastic stats throughout and a plastic solid area for piglets. There was an increased risk of sole erosion (OR 1.81; CI 1.07, 3.09) and foot and limb swellings (OR 1.90; CI 1.01, 3.57) in pigs in pens with metal slats only and a solid plastic area for piglets compared with plastic stats throughout and a solid plastic area for piglets. There was an increased risk of coronary band injury in pens with metal slats throughout and a metal solid area for piglets (OR 4.25; CI 1.96, 3.57) compared with plastic stats throughout and a plastic solid area for piglets. We conclude no single floor type was ideal for piglet foot and limb health with all floors influencing different lesions in different ways, however, the positive association between sole erosions, coronary band injury and foot and limb swellings and metal slats suggest that this floor type was most detrimental and most likely to be associated with joint infections that lead to severe health and welfare concerns.

Risks associated with preweaning mortality in 855 litters on 39 commercial outdoor pig farms in England.

A prospective longitudinal study was carried out on 39 outdoor breeding pig farms in England in 2003 and 2004 to investigate the risks associated with mortality in liveborn preweaning piglets. Researchers visited each farm and completed a questionnaire with the farmer and made observations of the paddocks, huts and pigs. The farmer recorded the number of piglets born alive and stillborn, fostered on and off and the number of piglets that died before weaning for 20 litters born after the visit. Data were analysed from a cohort of 9424 liveborn piglets from 855 litters. Overall 1274 liveborn piglets (13.5%) died before weaning. A mixed effect binomial model was used to investigate the associations between preweaning mortality and farm and litter level factors, controlling for litter size and number of piglets stillborn and fostered. Increased risk of mortality was associated with fostering piglets over 24h of age, organic certification or membership of an assurance scheme with higher welfare standards, farmer's perception that there was a problem with pest birds, use of medication to treat coccidiosis and presence of lame sows on the farm. Reduced mortality was associated with insulated farrowing huts and door flaps, women working on the farm and the farmer reporting a problem with foxes.

Temporal associations between low body condition, lameness and milk yield in a UK dairy herd.

Previous work has hypothesised that cows in low body condition become lame. We tested this in a prospective longitudinal study. Body condition score (BCS), causes of lameness and milk yield were collected from a 600-cow herd over 44-months. Mixed effect binomial models and a continuous outcome model were used to investigate the associations between lameness, BCS and milk yield. In total, 14,320 risk periods were obtained from 1137 cows. There were 1510 lameness treatments: the most common causes of lameness were sole ulcer (SU) (39%), sole haemorrhage (SH) (13%), digital dermatitis (DD) (10%) and white line disease (WLD) (8%). These varied by year and year quarter. Body condition was scored at 60-day intervals. BCS ranged from 1 to 5 with a mean of 2.5, scores were higher in very early lactation but varied widely throughout lactation; approximately 45% of scores were <2.5. The key finding was that BCS<2.5 was associated with an increased risk of treatment for lameness in the following 0-2 months and >2-4 months for all causes of lameness and also specifically for SU/WLD lameness. BCS<2.5 was associated with an increased risk of treatment for SH in the following 0-2 months but not >2-4 months. There was no such association with DD. All lameness, SU/WLD, SH and DD were significantly more likely to occur in cows that had been lame previously, but the effect of BCS was present even when all repeat cases of lameness were excluded from the analysis. Milk yield was significantly higher and fell in the month before treatment in cows lame with SU/WLD but it was not significantly higher for cows that were treated for DD compared with non-lame cows. These findings support the hypothesis that low BCS contributes to the development of horn related claw lameness but not infectious claw diseases in dairy cows. One link between low BCS and lameness is a thin digital cushion which has been proposed as a trigger for claw horn disease. Cows with BCS 2 produced more milk than cows with BCS 2.5, however, this was only approximately 100 kg difference in yield over a 305-day lactation. Given the increased risk of lameness in cows with BCS 2, the direct costs of lameness and the small variability in milk yield by BCS, preventing cows from falling to BCS<2.5 would improve cow welfare and be economically beneficial.

Sheep farmer opinions on the current and future role of veterinarians in flock health management on sheep farms: a qualitative study.

A 2009 UK Government report on veterinary expertise in food animal production highlighted that there was insufficient herd health expertise among veterinarians and lack of appropriate business models to deliver veterinary services to the livestock sector. Approximately two thirds of sheep farmers only contact their veterinarian for emergencies and one fifth have all year round contact. The aim of the current study was to understand sheep farmers' perception, the current and future role of veterinarians in flock health management using qualitative methodology. The eligibility criteria were male farmers with a flock size of at least 200 adult sheep. Seven focus groups of farmers (n=45) stratified by three regions and two age groups (≤50 and >50) were conducted. Thematic analysis of the discussions indicated that most farmers considered and used their veterinarian as a fire-fighter, whilst other advice was gathered free of charge when the veterinarian was on the farm for other reasons (typically seeing cattle) or by telephone. A small group of farmers were using their veterinarian or a sheep consultant proactively with regular contact and found this financially beneficial. Farmers indicated that the key barriers to using a veterinarian proactively were inconsistent service, high turnover of veterinarians, lack of expertise of sheep farming among veterinarians and concern about independence of advice. Although economics was also mentioned as a key barrier to using veterinarians more proactively, most farmers did not know where they gained and lost income from their flock; there was heavy reliance on the single farm payment scheme (SPS) and very few farmers kept records from which they could investigate where there were inefficiencies in production. Overall sheep farmers considered sheep farming complex and that each farm was unique and that they themselves were the experts to manage their flock. We conclude that there is an impasse: veterinarians might need to provide consistency and wide expertise beyond knowledge of disease and a model of how flock planning would be financially beneficial but until sheep farmers keep production records flock health planning cannot be rigorous and the financial benefits cannot be evaluated. Given the reliance on SPS by farmers an alternative model would be to require farmers to keep production records to comply with SPS. This might lead to flock health planning being adopted at a faster rate and so develop the UK sheep industry and make it more environmentally sustainable by reducing waste from disease and low productivity.

Longitudinal study of the effect of rubber slat mats on locomotory ability, body, limb and claw lesions, and dirtiness of group housed sows.

This study evaluated the influence of floor type on sow welfare with particular focus on lameness, claw lesions (CL), and injuries. The study used 164 gilts housed in groups of 8 from AI to 110 d of pregnancy in pens with concrete (n = 84) slatted floor left uncovered or covered by 10-mm rubber slat mats (n = 80) through 2 parities. Lameness (0 = normal to 5 = severe), limb (0 = normal to 6 = severe) and body (0 = normal to 5 = severe) lesions, and manure on the body (MOB; score 0 to 2) were recorded at AI, 24 to 72 h postmixing, between 50 and 70 d of pregnancy, and 2 wk before farrowing. Claw lesions (score 0 = normal to 3 = severe) were recorded at AI and between 50 and 70 d of pregnancy. The dirtiness and wetness of the floors was scored weekly (score 0 = clean to 4 = >75% of the pen soiled/wet). Data from the first and second parities were analyzed separately. Sows were categorized as nonlame (score ≤ 1) or lame (score ≥ 2). Median (M(e)) scores were calculated for CL and body and limb lesions and were classified as less than or equal to the median or greater than the median lesion scores. Sows on rubber slat mats had a reduced risk of lameness during both parities (P < 0.01) compared with sows on concrete. They also had an increased risk of scores greater than the median for toe overgrowth (M(e) = 2 and M(e) = 3 in the first and second parity, respectively) and heel sole crack (HSC; M(e) = 3) during both parities (P < 0.01) and for cracks in the wall (CW; M(e) = 4) and white line damage (WL; M(e) = 4; P < 0.01) in the first and second parity, respectively. There was a reduced risk of lameness in sows with scores greater than the median for HSC (P = 0.05) in the first parity and WL (M(e) = 3; P < 0.01) and CW (M(e) = 3; P < 0.05) in the second parity. Wounds (M(e) = 3) and severe lesions (M(e) = 0) on the limbs with scores greater than the median were associated with an increased risk of lameness (P < 0.01) in the first and second parity, respectively. Sows on rubber slat mats had a reduced risk of scores greater than the median for swellings (M(e) = 4) and wounds (P < 0.01) during both parities. Pens with rubber slat mats were dirtier than uncovered pens (P < 0.01); however, there was no association between MOB and flooring type. There was also no association between body lesion score and flooring type. In this study, CL were not associated with an increased risk of lameness. Therefore, even though rubber slat mats were associated with an increased risk of CL, they improved the welfare of group housed sows by reducing the risk of lameness and limb lesions.

Nociceptive threshold, blood constituents and physiological values in 213 cows with locomotion scores ranging from normal to severely lame.

The aim of this study was to investigate associations between mechanical nociceptive threshold, blood constituents, physiological measurements and locomotion score (LS) in dairy cattle with a range of LS from 1 (normal) to 5 (severely lame). The study used 213 Friesian/Friesian cross dairy cows from 12 farms. There were 40-50 cows each with LS 1-4 and 22 cows with LS 5. Each cow was restrained and her temperature and respiratory and cardiac rates were measured. Nociceptive threshold, plasma concentrations of haptoglobin, ß-hydroxybutyrate (ß-HB), cortisol, glucose, lactate, creatinine kinase activity, packed cell volume and white blood cell counts were determined. Mixed effect models were used to investigate associations between the variables measured and LS. Parity and stage of lactation were forced into all analyses and the model fit was checked by investigation of residuals. After accounting for parity and stage of lactation, nociceptive threshold was significantly lower in cattle with LS 3-5 compared with LS 1 in a dose response manner, indicating increasing hyperalgesia with increasing LS. Haptoglobin concentration was raised in all cattle with LS>1, demonstrating an inflammatory response with all levels of lameness. Cortisol and glucose concentrations were lower and ß-HB concentrations higher in cows with LS 2 compared with cows with other scores, possibly signifying metabolic challenge. Heart and respiratory rate and rectal temperature were significantly higher only in cows with LS 5, suggesting that these measurements were insensitive measures of pain or stress. It was concluded that hyperalgesia increases with increasing severity of lameness and that nociceptive pressure and haptoglobin were sensitive measures of pain from lameness.

A longitudinal study of risk factors for teat lesions in 67 suckler ewes in a single flock in England.

A longitudinal study of 67 suckler ewes on a commercial sheep farm near Wolverhampton, England was carried out from March to July 2010. Data on ewe teat lesions and udder and teat conformation were collected together with data on lamb health and weight at lambing and at 14-day intervals until lambs were 8-10 weeks old. Each ewe was examined on 4-5 occasions. Teat lesions were categorised as traumatic or non-traumatic based on appearance. Risk factors for the development of each type of teat lesion were investigated using mixed effect binomial regression models. The incidence of traumatic teat lesions was greatest 3-4 weeks after lambing with 27.9% new cases by udder half. There was an increased risk of traumatic teat lesions in 2 year old ewes (OR 3.5, CI 1.2, 10.5) compared with 6 year old ewes and in ewes with abnormal compared with normal teat placement, a wide or narrow udder width compared with a normal udder width, a heavy total litter weight, body condition score (BCS)<2.5, compared with BCS of 2.5 14-days previously, and in ewes with abnormal udder skin (waxy, dry or chapped) compared with normal udder skin. The incidence of non-traumatic teat lesions was greatest 7-10 weeks after lambing with 21.4% new cases. Non-traumatic lesions were more likely to occur in ewes with BCS=3 compared with BCS of 2.5. The risk factors for traumatic and non-traumatic teat lesions differ. Traumatic lesions are associated with teat and udder morphology, ewe age and BCS, and lamb growth rate, whereas non-traumatic lesions are associated with ewe BCS.

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.

The effects of early treatment for hindlimb lameness in dairy cows on four commercial UK farms.

An 'early threshold' protocol for treating cows within 48 h of being detected lame in one or more hind limbs at fortnightly mobility scoring was tested on a randomly selected group of cattle on four commercial dairy farms. The outcomes of the early threshold treatment for first cases of lameness were compared with those of the farmers' conventional approach to treatment. The early threshold schedule resulted in a much shorter time to treatment than the conventional approach, for which the median time from the cow first being scored lame to treatment was 65 days. The early threshold group presented with less severe foot lesions and cattle were less likely to be selected for further treatments by the farmer than conventionally treated cows. Early threshold treatment reduced the prevalence of lameness 4 weeks after treatment, compared with controls. A clear effect of the early treatment on milk yield was not detected.

Evaluation of milk yield losses associated with Salmonella antibodies in bulk tank milk in bovine dairy herds.

The effect of Salmonella on milk production is not well established in cattle. The objective of this study was to investigate whether introduction of Salmonella into dairy cattle herds was associated with reduced milk yield and determine the duration of any such effect. Longitudinal data from 2005 through 2009 were used, with data from 12 mo before until 18 mo after the estimated date of infection. Twenty-eight case herds were selected based on an increase in the level of Salmonella-specific antibodies in bulk-tank milk from <10 corrected optical density percentage (ODC%) to ≥70 ODC% between 2 consecutive three-monthly measurements in the Danish Salmonella surveillance program. All selected case herds were conventional Danish Holstein herds. Control herds (n=40) were selected randomly from Danish Holstein herds with Salmonella antibody levels consistently <10 ODC%. A date of herd infection was randomly allocated to the control herds. Hierarchical mixed effect models with the outcome test-day yield of energy-corrected milk (ECM)/cow were used to investigate daily milk yield before and after the estimated herd infection date for cows in parities 1, 2, and 3+. Control herds were used to evaluate whether the effects in the case herds could be reproduced in herds without Salmonella infection. Herd size, days in milk, somatic cell count, season, and year were included in the models. Yield in first-parity cows was reduced by a mean of 1.4 kg (95% confidence interval: 0.5 to 2.3) of ECM/cow per day from 7 to 15 mo after the estimated herd infection date, compared with that of first-parity cows in the same herds in the 12 mo before the estimated herd infection date. Yield for parity 3+ cows was reduced by a mean of 3.0 kg (95% confidence interval: 1.3 to 4.8) of ECM/cow per day from 7 to 15 mo after herd infection compared with that of parity 3+ cows in the 12 mo before the estimated herd infection. We observed minor differences in yield in second-parity cows before and after herd infection and observed no difference between cows in control herds before and after the simulated infection date. Milk yield decreased significantly in affected herds and the reduction was detectable several months after the increase in bulk tank milk Salmonella antibodies. It took more than 1 yr for milk yield to return to preinfection levels.