A dataset for sustainability assessment of agroecological practices in a crop-livestock farming system.

This article presents data designed by European researchers who performed a literature review and interpreted the results to determine impact factors of many agroecological practices on a wide variety of sustainability indicators. The impact factors are represented in a matrix that connects practices to indicators. The indicators are related to environmental, economic and social sustainability of a typical European integrated crop-livestock farm. The data are included in the serious game SEGAE to learn agroecology, as described in "SEGAE: a serious game to learn agroecology" [1]. The data can be modified to adapt the game to other agricultural systems. Finally, the data can be re-used in research projects as a basis to assess impacts of agroecological practices.

Risk of seropositivity to Coxiella burnetii in humans living in areas with endemically infected cattle: No way for specific prevention.

Q fever, a zoonotic disease caused by Coxiella burnetii, is endemic among cattle in Western France. However, studies assessing the risk of human infection in such areas are lacking to date, while they may provide information about key specific preventive actions which could be advised to the human populations living with or close to cattle. Therefore, we conducted a cross-sectional study in two departments of Western France during the 2017/18 winter in order to explore possible risk factors for seropositivity among two distinct populations, i) an occupational risk group, that is, the cattle farmers, and ii) the general adult population (approached by blood donors). Sera were collected in 176 cattle farmers and 347 blood donors respectively, and tested for phase I and II antibodies using an indirect immunofluorescence antibody assay. Each participant was asked to fill in a questionnaire containing socio-demographic characteristics, occupational and non-occupational risk exposure. Identified risk factors were: in the general population, working in contact with ruminants, comparatively to any other activity (OR = 4.41; 95% CI: [1.59-6.55]); among farmers, managing an itself infected cattle herd (OR = 3.20; 95% CI: [1.59-6.55]). No other controllable risk factor (lifestyle, outdoor activities, proximity to pets and livestock animals, occupational practices) was here evidenced. In areas with endemically infected cattle, human exposure to Coxiella burnetii is to some extent unavoidable. This strengthens the need for physicians' awareness of the symptoms of Q fever and the appropriateness of general biosecurity measures, especially among at-risk groups living there.

To what extent does the composition of batches formed at the sorting facility influence the subsequent growth performance of young beef bulls? A French observational study.

To meet the demands of the beef cattle sector in France, weaned beef calves are transported to sorting facilities and sorted into batches composed of animals of similar body weight (BW) before the beginning of the fattening period. This procedure aims to facilitate animal management. However, it leads to practices that affect animal welfare, health and performance, such as transporting weaned beef calves over long distances and mixing animals originating from different cow/calf farms. In contrast, other potentially beneficial practices, such as pre-weaning vaccination against bovine respiratory diseases (BRD), are seldom taken into consideration when batches are formed. This observational study, based on field data from 15,735 Charolais bulls, aimed to investigate which criteria should be favored for batch constitution by quantifying the effect of batch characteristics on the growth performance of young bulls during the fattening period. Clustering analysis was used to group young bulls exhibiting similar batch characteristics and define batch types. Associations between batch characteristics/batch types and individual growth performance/homogeneity of growth performance (mean and standard deviation (SD) of average daily gain (ADG) and fattening period duration) were studied using linear mixed models. The mean BW and the percentage of animals vaccinated against BRD before weaning were positively associated with ADG (+35 g/d for each additional 50 kg and +28 g/d for a high percentage of vaccinated animals, P < 0.05). In contrast, transportation distance was negatively associated with ADG (-12 g/d for each additional 120 km travelled). Mixing animals and BW homogeneity did not affect growth performance (P > 0.05). Only the mean BW and mixing animals negatively influenced the homogeneity of ADG (P < 0.01). The clustering analysis revealed that batches with the most BW heterogeneity, the least mixing, the shortest transportation distance and a high percentage of pre-weaning animals vaccinated against BRD had better growth performance compared to batches with the opposite characteristics (+61 g/d, P < 0.001). Our results suggest that major improvements of growth performance of fattening young bulls could be obtained by minimizing transportation distance, providing vaccination programs against BRD before weaning, and maintaining groups from the same cow/calf farm instead of constituting groups of animals with similar BW at the beginning of fattening.

Effects on milk quantity and composition associated with extruded linseed supplementation to dairy cow diets.

Enhanced milk composition can improve human health. The composition of milk determines its nutritional and market value. Therefore, in almost all pricing schemes the economic benefits obtained from raw milk sales are influenced by the milk yield and composition. The objective of this retrospective study was to quantify the average effects of supplementing extruded linseed, rich in α-linolenic acid, to dairy cows on milk yield and milk fat and protein content under field conditions. The study included test day records performed on cows from 1294 dairy herds during the period from 2008 to 2015 that were supplied at least 4 times with extruded linseed deliveries. Exposure statuses were defined according to the time sequence and the amount of extruded linseed distributed in the herd. The unexposed population was composed of cows being in a herd period when extruded linseed was not offered. In a linear dose-response relationship, every 100 g increase in exposure to EL was associated with an increased milk yield from 0.11 to 0.14 kg/day, decreased milk fat from 0.06 to 0.13 g/kg and decreased milk protein from 0 to 0.02 g/kg, according to the cow parity. This study provides information on the associations between estimated intakes of EL and milk production and composition using a large database obtained from commercial dairy herds.

Use of sexed semen and female genotyping affects genetic and economic outcomes of Montbéliarde dairy herds depending on the farming system considered.

Genomic evaluation of cows and the use of sexed semen have recently provided opportunities for commercial dairy farmers to accelerate genetic progress at the herd level by increasing both selection accuracy and selection intensity. Because implementing genomic tests or using sexed semen generate extra costs, a higher investment capacity of the farm is required. In this study, we compared the effect of female genotyping alone or combined with the use of sexed semen on genetic and economic performance of the herds. Three typical Montbéliarde herds with different farming systems were considered: a 77-cow herd producing milk at a high price sold to make cheese with a protected designation of origin, a 60-cow herd producing organic milk at a medium price sold for dairy, and a 120-cow herd producing standard milk at a lower price sold for dairy. Eight alternative scenarios were simulated over a 10-yr period for each herd, with combinations of the following: use (or not) of dairy sexed semen, use (or not) of beef breed semen, use (or not) of female genotyping at 15 d of age. A mechanistic, stochastic, and dynamic model was used to mimic the farmer's daily decisions and the individual cow's biology. Heifers (80%) and first-lactation cows (30%) that ranked highest on the French total merit index (France's national dairy index) were inseminated with sexed semen to ensure replacement and to maximize genetic gain, when sexed semen was used. During the 10 yr of simulation, scenarios that included sexed semen (whether female genotyping was used or not) gained, on average, one extra year of overall genetic gain over scenarios that did not include sexed semen. During the same period, scenarios that used female genotyping (whether sexed semen was used or not) gained, on average, 5 mo of overall genetic gain over scenarios using parent average only. The highest gains in net margin were always obtained when combining use of sexed semen with terminal crossbreeding. Maximum genotyping prices under which routine female genotyping is economically valuable (breakeven prices of genotyping) were under €37. Maximum genotyping prices, such that the female genotyping costs are refunded within 10 yr of investment (investor genotyping price), were under €26. However, they would be higher over a longer period of use because genetic gain is cumulative. Because genotyping price is expected to decrease in the future, female genotyping will be worthwhile if combined with the use of sexed semen and beef breed semen.

Significance of anti-CarLA salivary IgA antibody in first grazing season cattle naturally infected with gastrointestinal nematodes.

A carbohydrate larval surface antigen (CarLA) present on infective larvae of all trichostrongylid nematodes is a target antigen for host immunoglobulins (Ig). Levels of anti-CarLA salivary IgA antibody (CarLA-IgA) have been shown to be correlated to the level of protective immunity to GIN in sheep and deer but no information is available in cattle. The first objective of this study was to assess the pattern of CarLA-IgA response in 7 groups (G1-G7) of first grazing season cattle (FGSC) naturally infected with gastrointestinal nematodes. The second objective was to assess the phenotypic correlations between CarLA-IgA level, 3 parasitological indicators (faecal egg count-FEC, pepsinogen level, serum anti-O. ostertagi IgG antibody level-OstertagiaIgG), a clinical indicator (diarrhea score) and average daily weight gain (ADWG). Overall, CarLA-IgA response gradually increased over grazing season and showed large variations in speed and magnitude both between and within groups. Based on the mean group CarLA-IgA response pattern, the 7 groups could be allocated to 3 different classes: (i) 'Late High' class characterized by a high response at housing (G1 and G2); (ii) 'Low' class with a low response over time (G3, G4 and G5); and (iii) 'Early' class with an high initial then stable response (G6 and G7). This classification was consistent with the grazing management practices. In the 'Late High' class, the mean CarLA-IgA at housing was 6.05units/mL and negatively correlated with FEC while no correlation was seen with the other indicators nor ADWG. In the 'Low' class, CarLA response at housing was low (1.95units/mL) and mainly positively correlated with OstertagiaIgG. In the 'Early' class, mean CarLA-IgA ranged from 1.32 to 1.86units/mL during the grazing season and positive correlations were seen with parasitological and clinical indicators. These results suggest that, according to the intensity of larval challenge occurring during the first grazing season, CarLA-IgA response in cattle could be either an indicator of the early manifestation of immunity (FEC decreases) or the reflection of exposure to GIN.

Effectiveness of collective treatments in the prevention and treatment of bovine digital dermatitis lesions: A systematic review.

The collective treatment (CT) of an affected herd is commonly advised to control bovine digital dermatitis (DD). Several CT are commercialized, frequently without major evidence supporting their effectiveness. The objective of this systematic review was to evaluate the published evidence that supports CT in the treatment and prevention of DD lesions in dairy herds. Across the evidence, the main limitations in the studies design were identified and the possible sources of inconsistency were investigated. An extensive literature search of publications through electronic databases and gray literature was conducted between July 2015 and January 2016. Studies that did not include an untreated or placebo control group were excluded from the review. The literature search and screening process identified 13 publications with 24 treatment trial comparisons and 18 prevention trial comparisons. The published evidence included studies mostly considered to have a low or unclear risk of bias. Descriptive analyses were performed according to the prevention and treatment outcomes, and case and success definitions were identified for each study and summarized in odds ratios (OR). Pairwise meta-analyses were conducted according to the prevention and treatment outcomes, comparing directly the intervention used in each study, and ignoring any other differences in the intervention characteristics. The results of the meta-analyses indicated a low degree of heterogeneity across the evidence for the prevention outcome [I2 = 0%, 95% CI: 0 to 37.2%, 95% prediction interval (PI): 0.72 to 1.74)] and a moderate degree for the treatment outcome (I2 = 25.3%, 95% CI: 0 to 63%, 95% PI: 0.39 to 3.73). Similarly, appraisal of the graphical L'Abbé plot suggested a considerable degree of heterogeneity across the evidence for the treatment outcome. For both outcomes, the frequent small sample sizes of the trials indicate imprecision across the included studies. Additionally, for the treatment and prevention outcomes, an asymmetric funnel plot suggested possible publication bias. The overall quality of the evidence, for both outcomes (prevention and treatment), was therefore considered to be low, indicating that the true effect of CT may be substantially different from that estimated across the included studies. Consequently, this review and meta-analysis does not support an association between the CT considered in the review and a beneficial effect in the prevention and treatment of DD lesions. The effectiveness of CT therefore remains uncertain, and the epidemiological circumstances in which it can be useful must be investigated. These findings highlight the importance of developing high quality, controlled trials to evaluate the effectiveness of CT for DD control.

Design and evaluation of multi-indicator profiles for targeted-selective treatment against gastrointestinal nematodes at housing in adult dairy cows.

Targeted-selective treatments against gastrointestinal nematode (GIN) in adult dairy cows require the identification of "cows to treat", i.e. cows whose milk production (MP) would increase after treatment. This study aimed at quantifying the ability of multi-indicator profiles to identify such cows. A randomized controlled clinical trial was conducted at housing in 25 French pasturing dairy herds. In each herd, treated cows received fenbendazole orally, control cows remained untreated. Daily MP was recorded and the MP variation between the pre- and post-visit periods was calculated (ΔMP) for each cow. ΔMP was modelled with control cows data (n=412) (piecewise linear mixed model). Estimated parameters were applied to treated cows data (n=414) to predict the expected ΔMP in treated cows if they had not been treated. Treated cows with an observed ΔMP (with treatment) higher than the expected ΔMP (without treatment) were labelled as "cows to treat". Herds where at least 50% of the young cows were "cows to treat" were qualified as "herds to target". To characterize such cows and herds, the available candidate indicators were (i) at the cow-level: parity, stage of lactation and production level, faecal egg count (FEC), serum pepsinogen level and anti-Ostertagia antibody level (expressed as ODR); (ii) at the herd-level: bulk tank milk (BTM) Ostertagia ODR, Time of Effective Contact (TEC, in months) with GIN infective larvae before the first calving, and percentage of positive FEC. These indicators were tested one-by-one or in combination to assess their ability to characterize "herds to target" and "cows to treat" (Chi-square tests). 115 out of 414 treated cows (27.8%) were considered as "cows to treat", and 9 out of 22 herds were qualified as "herds to target". The indicators retained to profile such cows and herds were the parity, the production level, the BTM Ostertagia ODR and the TEC. Multi-indicator profiles were much more specific than single indicator profiles, induced lower treatment rates, thereby minimizing the selection pressure on parasite populations. Particularly, to target a herd, the specificity was better with the profile "high BTM Ostertagia ODR and low-TEC" than with the BTM ODR value taken into account alone. The targeted-selective treatment of "young cows, belonging to herds with a high BTM ODR at housing and a low TEC" appeared as a pertinent solution, enabling a global approach for the control of GIN infection in which GIN control in heifers is connected to GIN control in adult cows.

End-season daily weight gains as rationale for targeted selective treatment against gastrointestinal nematodes in highly exposed first-grazing season cattle.

A two-year study was carried out to assess the feasibility of a targeted selective treatment to control gastrointestinal nematodes (GIN) in 24 groups of first grazing season (FGS) cattle. A two-step procedure aiming at defining exposure risk at group level and at identifying the most infected individuals within groups through measurement of the average daily weight gain (ADWG) at housing was used. The first step was to define retrospectively, by grazing management practices (GMP) indicators, two levels of groups' exposure to GIN determined by anti O. ostertagi antibody ODR level (cut-off 0.7). For the low level of exposure, no relationship between parasitological parameters and heifer growth was seen, whereas for the high level ADWG was negatively correlated with increasing Ostertagia ODR values. The best classification was obtained with an expert system modelling the number of Ostertagia L3 generations on plots. GMP input for the expert system included standard data (turnout/housing data and supplementary feeding amount) combined with paddock rotation planning and monthly temperatures. The threshold of 3 successive generations of L3 or more on plots allowed identifying the groups according to low or high infection exposure level, except two groups that were misidentified as being highly exposed. In the second step, individual ADWG was found to be negatively associated with Ostertagia ODR in heifers from groups classified as highly exposed (≥3 generations of L3). In these groups, sensitivity and specificity of ADWG thresholds were calculated for several individual Ostertagia ODR thresholds. The best compromise between sensitivity (i.e., correctly treating the heifers that need to be treated) and specificity (i.e., not treating animals that should not be treated) was equivalent respectively to 76% and 56% (AUC≈0.7) and was reached using an end-season ADWG threshold of 683g/day to detect animals exhibiting an Ostertagia ODR cut-off at 0.93. Other ADWG thresholds were proposed taking into account the farmers' or the veterinarians' objectives: either maximizing the production through both an increase of the ADWG threshold and the sensitivity or keeping a significant nematode population in refugia with a corresponding limitation of anthelmintic treatments through a decrease of ADWG threshold and an increase of the specificity. Finally, a targeted selective treatment for FGS cattle based on GMP and flexible ADWG thresholds seems feasible at housing without laboratory analysis, accepting that some resilient animals with high Ostertagia ODR will not be treated due to their ability to perform under parasitic challenge.

Explaining variability in first grazing season heifer growth combining individually measured parasitological and clinical indicators with exposure to gastrointestinal nematode infection based on grazing management practice.

The objective of our study was to explain the variability of average daily weight gain (ADWG) due to gastrointestinal nematode (GIN) infection for 291 non treated first grazing season (FGS) heifers, from 12 independent groups in the western part of France, by combining parasitological and clinical indicators at individual level and grazing management indicators at group level. Parasitological indicators were faecal egg count (FEC), anti Ostertagia ostertagi antibody level (Ostertagia ODR), and pepsinogen level. Clinical indicators were diarrhea score (DISCO) and breech soiling score (BSS). At group level, grazing management practice (GMP), based on three variables (supplementation, month of turnout, grazing season duration), was clustered into three categories reflecting low, medium or high exposure (EXP) to GIN. Depending on the groups, turnout was from mid-March to early July and housing was from mid-October to late November, with a FGS duration ranging from 4 to 8.4 months. At turnout, the mean age of heifers was 8 months (range: 6-16 months) and they weighed between 175 and 268kg. In each GMP category, FEC significantly decreased between the mid-season and the housing, while Ostertagia ODR and pepsinogen level increased gradually throughout the grazing season. In contrast, clinical indicators did not show any seasonal variation. In a multivariate linear model, 22% of the ADWG variability was significantly explained by two individual indicators (Ostertagia ODR: 12.6%, DISCO: 4.8%) and by the group indicator (GMP category: 4.8%). ADWG losses due to GIN exposure (Ostertagia ODR) were estimated up to 39kg per heifer for the overall grazing season. For groups within the low EXP category the difference between animals with low (<697g/day) or high (>697g/day) ADWG was explained by the clinical indicator DISCO. In contrast, for groups within the medium and high EXP categories this difference was explained by a parasitological indicator (Ostertagia ODR). This study highlighted the value of combining both grazing management (group level) and parasitological (individual level) indicators to assess the impact of GIN on ADWG of FGS heifers. As a result, this combination might allow a better discrimination of animals or groups that may be in need of treatment in a targeting selective treatment approach.

Unexpected Decrease in Milk Production after Fenbendazole Treatment of Dairy Cows during Early Grazing Season.

Gastrointestinal nematodes (GIN) infection can impair milk production (MP) in dairy cows. To investigate whether MP would be optimized by spring targeted-selective anthelmintic treatment in grazing cows, we assessed (1) the effect on MP of an anthelmintic treatment applied 1.5 to 2 months after turn-out, and (2) herd and individual indicators associated with the post-treatment MP response. A randomized controlled clinical trial was conducted in 13 dairy farms (578 cows) in western France in spring 2012. In each herd, lactating cows of the treatment group received fenbendazole orally, control cows remained untreated. Daily cow MP was recorded from 2 weeks before until 15 weeks after treatment. Individual serum pepsinogen and anti-Ostertagia antibody levels (expressed as ODR), faecal egg count and bulk tank milk (BTM) Ostertagia ODR were measured at treatment time. Anthelmintic treatment applied during the previous housing period was recorded for each cow. In each herd, information regarding heifers' grazing and anthelmintic treatment history was collected to assess the Time of Effective Contact (TEC, in months) with GIN infective larvae before the first calving. The effect of treatment on weekly MP averages and its relationships with herd and individual indicators were studied using linear mixed models with two nested random effects (cow within herd). Unexpectedly, spring treatment had a significant detrimental effect on MP (-0.92 kg/cow/day on average). This negative MP response was particularly marked in high producing cows, in cows not treated during the previous housing period or with high pepsinogen levels, and in cows from herds with a high TEC or a high BTM ODR. This post-treatment decrease in MP may be associated with immuno-inflammatory mechanisms. Until further studies can assess whether this unexpected result can be generalized, non-persistent treatment of immunized adult dairy cows against GIN should not be recommended in early grazing season.

Does milk yield reflect the level of welfare in dairy herds?

Under the assumption that milk yield may be reduced in herds with impaired welfare, the present study aimed at investigating whether milk yield could be used as a reliable indicator of welfare. In 125 commercial French dairy herds, the association between the welfare of the herd (evaluated using the Welfare Quality assessment protocol) and cow milk yield was investigated using linear mixed models. Positive associations were identified between milk yield and low aggressions between cows and good emotional state of the herd but there was a negative association with good health assessed through the occurrence of diseases and injuries. These opposite associations resulted in no association with the overall welfare of the herd. Milk yield should not therefore be used as an indicator of overall welfare.

A reliable severity scoring system for radiographic findings in the limbs of young horses.

The validity of methods used to score the severity of radiographic findings (RFs) in horses is uncertain since only one or two joints are usually studied, classification criteria are heterogeneous and the internal validity is not assessed. The aim of this study was to assess the internal validity of a severity scoring system (SSS) of RFs by repeated scoring of a sample of radiographs. This SSS of RFs is based on four criteria that can be applied to every type of RF observed in limb joints. It consists of five weighted severity indexes (0, 1, 2, 4, 8) and was used to assess RFs found on the limbs of 392 young horses. The internal validity of the SSS was assessed using Kappa coefficients calculated on a subsample of 137 horses whose radiographs were interpreted twice. The final RF severity indices from these radiographs were obtained after three experienced veterinarians had reached a consensus, similar to the procedure used at foal and yearling sales. The majority of RFs from the 392 horses were scored either 1 or 2, while scores of 8 were only observed in the stifle and tarsus. Among the subsample, the overall agreement on the presence or absence of RFs was good (κ=0.63; 95% Confidence Interval [CI], 0.56-0.69), and was excellent for the severity of RFs (weighted κ=0.82; 95% CI, 0.75-0.87). Most disagreements involved RFs that scored 1. The fore fetlock and the carpus experienced the lowest agreement. The SSS was a stable and reliable procedure applicable to any RF on any limb joint of the horse. It will be of potential interest in clinical practice and in the pre-purchase evaluation of young horses and could also be used in additional studies on the evolution or risk factors of RFs.

Association of growth, feeding practices and exercise conditions with the severity of the osteoarticular status of limbs in French foals.

The aim of this study was to identify the risk factors for the severity of Juvenile OsteoChondral Conditions (JOCC) in limbs of French foals. Twenty-one farms in Normandy, France, were sampled and enrolled in a cohort study including 378 foals from three breeds, followed from the 8th month of pregnancy of the mares until the foals were approximately 6months old. Data on growth, feeding practices and exercise conditions were regularly collected. The carpus, the front and hind digits, the hock and the stifle of the foals were radiographed at the end of follow-up. JOCC severity in each foal was described using a global appraisal of its osteoarticular status (OAS) depending on the number and the severity of radiographic findings. Of the 378 foals, 53% had a good OAS, 34% had an intermediate OAS and 13% had a poor OAS. The breed (Selle Français and French Trotter Standardbred vs. Thoroughbred), a high girth perimeter at early age and an irregular exercise were significantly associated with a poor OAS. This study contributes to the understanding of the development of JOCC. An increased growth and reduced or irregular physical activity during the first weeks of life would be responsible for more severe lesions. Growth and exercise conditions should be carefully monitored to reduce the prevalence of severe JOCC in foals.

Transmission dynamics of Mycoplasma bovis in newly received beef bulls at fattening operations.

Mycoplasma bovis is an important cause of bovine respiratory disease (BRD) in newly received cattle at fattening operations. However, little information on its within-pen transmission dynamics during a BRD outbreak is available. Such information is nevertheless crucial to adapt control measures during M. bovis-associated BRD outbreaks. The objective of the current study was to determine whether single or multiple clones of M. bovis are present within a pen during a BRD outbreak that occurs early in the feeding period. Sixteen BRD outbreaks that naturally occurred in 12 pens of 8-12 bulls each (n = 112) newly received at 3 fattening operations were investigated. Two hundred and thirty-nine transtracheal aspirations (TTA) were performed during the outbreaks, and the M. bovis isolates obtained were characterized by pulsed-field gel electrophoresis (PFGE). Mycoplasma bovis isolates were recovered from TTA in 8 of the 16 BRD outbreaks that occurred. The within-pen prevalence of bulls positive for M. bovis during these outbreaks ranged from 8% to 100%. The PFGE analysis revealed that, even though bulls came from multiple origins, a single clone of M. bovis was present within a pen during BRD outbreaks with a high prevalence of M. bovis infection. The study therefore indicates that, even if M. bovis can recrudesce from carriers after stressful events such as transportation and commingling, the increased prevalence of M. bovis pulmonary infection observed during BRD outbreaks that are early occurring in the feeding period seems primarily due to the horizontal transmission of only 1 clone among cattle.

Early detection of bovine respiratory disease in young bulls using reticulo-rumen temperature boluses.

The use of reticulo-rumen temperature boluses to detect bovine respiratory disease (BRD) was investigated in young bulls following their entry into a fattening unit. Twenty-four bulls received a bolus at entry and were observed for 40 days. As soon as a reticulo-rumen hyperthermia (RH) episode was detected using the bolus, clinical examination was performed by a veterinarian and then repeated every 12-24h until the end of RH episode. Fifty-two RH episodes were detected in 22 animals. High rectal temperatures (40.1±0.6°C) were observed during these episodes. BRD was diagnosed on the basis of clinical examination during 38/52 RH episodes in 21 animals (positive predictive value 73%). The onset of BRD signs always occurred after the onset of RH episodes, with a time-lag from 12 to 136 h, depending on BRD signs. Monitoring reticulo-rumen temperature permits early detection of BRD; however, clinical examination is required to confirm BRD.

Management- and housing-related risk factors of respiratory disorders in non-weaned French Charolais calves.

Our aim was to determine at calf-batch level the management- and housing-related risk factors of respiratory disorders in non-weaned Charolais calves. Farmers recorded cases according to the definition provided i.e. the association of at least one respiratory sign and, in the same calf or another calf of the same batch, at least one general sign on the same day or the day before. During farm visits, quality of farmers' records was checked and questionnaires were applied to gather farm and herd characteristics and to describe farming practices and housing facilities. Data were suitable for analysis for 172 batches where no metaphylactic treatment was implemented. Batches had great disparity in incidence of respiratory disorders. In the 120 batches with at least one case, the quartiles of incidence rate were, respectively, 0.95, 2.15 and 3.59 cases per 1000 calf-days at-risk. For risk-factor analysis, the statistical unit was the calf-batch located in a given batch. We used a ZINB model because (i) there was significant overdispersion of incidence rates of respiratory disorders (overdispersion test statistic of O=1049 (P<0.001)), (ii) probability was high that a two-group modelling process existed (Vuong statistic of V=2.44 (P=0.0073)) and (iii) the ZINB model fit significantly better than the ZIP model (likelihood-ratio statistic of 340.14 (P<0.001)). The risk was higher in open-fronted barns or in open barns compared to closed ones (incidence-rate ratios (IRRs): 1.9 and 1.8), in barns where no annual disinfection was implemented (IRR: 1.5) and in part slope with straw/part scraped and in part straw-bedded/part scraped barns compared to completely straw-bedded barns (IRRs: 1.9 and 1.6). Larger calf-batches were more at-risk than smaller batches (OR for the effect of an increase of 10 calves on the probability of a 0 count: 0.5).

A case-based learning approach for teaching undergraduate veterinary students about dairy herd health consultancy issues.

A case-based learning (CBL) format was implemented at the Veterinary School of Nantes, France, for veterinary students in their last year of the curriculum who had chosen to track toward a farm animal career. The focus of the CBL format was learning about dairy herd health consultancy. The goal was to emphasize teamwork among students, introduce professional communications and advisory relationships with clients, and work within the technical and economic limitations of participating farms. These farms volunteered to participate and had identified a problem. The learning objectives included gaining basic knowledge of herd-level diseases and the methods to control these within herds. The program focused on health audits of dairy farms performed by teams of four to five students, culminating in submission of a herd health management action plan specific for the farm visited by each team. The CBL program was comprised of defined learning objectives for each team. The learning process was supervised, from orientation through to validation, by a panel of experts from within the veterinary school and from local industry. Teams submitted written reports that listed recommendations and an action plan for implementation. This report was defended by each team in front of the farmers, their professional partners, and the panel of supervisors. Assessment of the program by students, participating farms, and industry professionals was positive.

Interdependence of udder quarters for new intramammary infection during the dry period in cows submitted to selective antibiotic therapy.

The aim was to investigate the interdependence of udder quarters within cow towards the incidence of intramammary infections during the dry period in herds under selective dry-cow antibiotic therapy. A total of 368 cows among 28 herds were included in a survey. Quarter milk samples collected at the last milking before drying-off and on day 3 after calving were submitted to microbiological procedures. An expected distribution of cows according to their number of newly infected quarters was calculated based on a binomial probability distribution from the overall quarter incidence (or from the quarter incidence in each herd) and compared with the observed distribution. Incidence of newly infected quarters ranged from 0.0 to 39.3%, depending on the herd (median: 17.7%). Interdependence of quarters towards new infection during the dry period was observed whatever the pathogen type, for both treated and untreated cows. Calculation of an expected distribution of cows according to their number of newly infected quarters using the quarter incidence in each herd (instead of the overall quarter incidence) reduced the distance to the observed distribution, but interdependence was still observed. Our results support the application of selective antibiotic therapy at the cow level rather than at the quarter level.

Incidence of intramammary infections during the dry period without or with antibiotic treatment in dairy cows--a quantitative analysis of published data.

The study was aimed at summarising the literature that compares the incidence levels of spontaneously occurring intramammary infections (IMI) during the dry period, without versus with antibiotic dry cow treatment (DCT). A meta-analytic relative risk (RR) calculation was implemented when a priori relevant. Two main categories of comparison were used in the 36 selected papers. In the first category, the udder quarters were randomly allocated (at quarter or cow level) to an untreated or a treated group. Quarter incidence averaged 12.8% (weighted mean) in untreated quarters, and depending on the DCT used, from 6.6 to 8.0% in treated quarters. The meta-analytic RR of new IMI for untreated versus treated quarters varied from 1.54 to 1.94, depending on the DCT used. DCT was mainly found effective against IMI due to streptococci and coagulase-positive staphylococci. Based on only a few papers, the application of an internal teat sealer was associated to a quite similar (or possibly better) protection against IMI than DCT, but only in a subpopulation of particular (selected) cows. In the second category of studies, a selective dry cow or quarter antibiotic-treatment (selective DCT or DQT), according to cow or quarter selection criteria, was compared to blanket DCT. The meta-analytic RR of new IMI was 1.71 for selective DCT versus blanket DCT. Selective DQT seemed to be more at risk than selective DCT, but consisted of treating a much lower proportion of quarters. The summary-results provided by our meta-analysis should only be used with caution, due to possibly low external validity. More research seems to be relevant on the risk factors of new IMI during the dry period to make the outcomes of omission of DCT in selected cows more predictable under field conditions.