Didier Raboisson

Diseases, reproductive performance, and changes in milk production associated with subclinical ketosis in dairy cows: A meta-analysis and review

Many studies have shown that subclinical ketosis (SCK) is associated with an increased risk of developing various diseases, reproductive disorders, and changes in milk production. The present work aims at producing an overview between this disorder and theses outcomes. A meta-analysis of the literature, including 131 different models from 23 papers, or a review when the literature was scarce was conducted. For each outcome, the odds ratio (OR), relative risk, or hazard ratio was presented for various moderators to reduce heterogeneity among the studies. The raw change in milk production associated with SCK was estimated and adjusted, taking into consideration the outcomes known to interact with milk production during the peripartum period. The results showed that 2 main categories of moderators had a significant effect on the adjusted risk. First, the adjustment made by defining SCK as (1) β-hydroxybutyrate concentration >1.4 mM, (2) nonesterified fatty acid (NEFA) concentration >0.4 mM prepartum, or (3) NEFA concentration >1.0 mM postpartum corrected the underestimated risk (despite low significance). This is because several trials reported the relevant risks using lower thresholds for the β-hydroxybutyrate or NEFA values. Using a low threshold leads to lower risk of disease compared with using a high threshold. Second, the correction produced using the polyfactorial terms corrected the overestimation of risk because many trials reported only univariable models. The relative risk or OR (95% confidence interval) related to abomasal displacement, clinical ketosis, early culling and death, metritis, placental retention, clinical mastitis, lameness, and a doubling of the SCC in cases with SCK were 3.33 (2.60-4.25), 5.38 (3.27-8.83), 1.92 (1.60-2.30), 1.75 (1.54-2.01), 1.52 (1.20-1.93), 1.61 (1.24-2.09), 2.01(1.64-2.44), and 1.42 (1.26-1.60), respectively. The precision level of the estimate depended on the outcome. The direct mean ± standard deviation of the 305-d milk losses associated with SCK were 251 ± 73 kg after adjusting for abomasal displacement, clinical ketosis, metritis, and placental retention. The OR (95% confidence interval) for first service calving risk in cases of SCK was 0.67 (0.53-0.83). The calving-to-first-service interval was 8 d longer and the calving-to-conception interval was 16 to 22 d longer in cows with SCK. The relationships among the different reproductive indicators were quantified in only 1 or 2 trials. The present work highlights the need to conduct further studies on the associations between SCK and the risks of diseases, changes in milk production, and reproductive parameters.

Perinatal, neonatal, and rearing period mortality of dairy calves and replacement heifers in France

Dairy calf and replacement heifer mortality in France was assessed by calculating mortality rates at 0 to 2d (calves), 3d to 1 mo (calves and heifers), 1 to 6 mo of age, and 6 mo of age to first calving (heifers) using the national identification database. Between birth and 2-d-old, 261,000 and 251,000 of the 3.56 and 3.43 million calves born in 2005 and 2006, respectively, died. The overall 0- to 2-d-old calf mortality rate was around 6.7%, which is similar to the low range of values reported in the literature. Among the 2.38 and 2.39 million calf-month, 139,000 and 133,000 died between 3d and 1 mo of age in 2005 and 2006, respectively. Among the 3d to 1 m of age group, dairy calf mortality rate was around 5.7%. Such a rate has not been reported previously because of the great differences in age classes between studies. For the 0- to 2-d-old and 3-d- to 1-mo-old calves, annual mortality was zero on 26 and 44% of the farms, respectively. Calf mortality during the first month of life increased in winter (to 12-17%) and decreased in summer (to 8-12%), with a small peak in June or July. Mortality during the first month of life is higher in males than in females, with a mortality odds ratio of 1.20 (and 95% confidence interval of 1.19-1.21). Such a difference is also found within the noncrossed or beef-crossed calf subpopulations. Disregarding the sex, the mortality of beef-crossed calves is slightly less than that of noncrossed dairy calves, with a mortality odds ratio of 0.98 (and 95% confidence interval of 0.98-0.99) before 1 mo of age. In heifers, around 51,000, 35,000, and 40,900 out of the 1.2 million 3-d- to 1-mo-old, 1.1 million 1- to 6-mo-old, and 950,000 6-mo-old to first calving heifers died, respectively. The respective mortality rates were 4.5, 3.1, and 4.1%; these rates are similar to the low range of values previously published. The proportions of farms with no heifer mortality during a year were higher than for calves, between 60 and 70%. The mortality probability for heifers was very high for the first day of life (95% survival between 2-30 d of age), then decreased during the first year of life and became constant up to around 3 yr of age (88% survival at 36 mo of age). The risk of mortality is higher in Montbéliarde and Normande heifers compared with Holstein. In conclusion, and beyond the average mortality rates, farmers and farm advisors should keep in mind the broad range of mortality values, which shows that very low mortality (1-2%) can be achieved, even in animals with a known high risk of mortality, such as beef-crossed dairy calves.

Herd-level and contextual factors influencing dairy cow mortality in France in 2005 and 2006

Dairy cow mortality causes financial loss and is increasing over time; it indicates suboptimal herd health or welfare. To describe the herd-level and contextual factors affecting cow mortality, the French National Bovine Dataset Identification was used to create dairy, beef, or fattening units within farms, for 2005 and 2006. Mortality rate (MO-RA, outcome variable) and most variables were calculated at the unit level, whereas contextual variables were defined at the municipality level [cattle density, inhabitant density, agricultural land always with grass on overall agricultural land (ALWG/OAL)]. The localization (11 dairy production areas, representative of the farming systems) was also included. The statistical analysis was performed with a probit regression model (MO-RA=0 or>0) and with a linear model corrected by the Heckman method for bias sample selection. For 2005 and 2006, 3.8 and 3.7 million dairy cow-years, 101,445 and 96,954 dairy units, and 141,677 and 143,424 deaths were recorded, respectively. Over one-third of the units had no dairy cow mortality in 2005 or 2006. Overall MO-RA was 3.7 and 3.8% for 2005 and 2006, respectively. Restricted MO-RA (farms without death excluded) was 5.8% for 2005 and 2006. The correlation of MO-RA among units between the 2 yr was 0.25. The same effects and close estimate values were reported for 2005 and 2006 with both models. Mortality rate was positively associated with the number of cow-years, having a beef unit in addition to a dairy unit, the proportion of purchased cows, the proportion of first-calving cows, the average calving interval, being a Milk Control Program member, inhabitant density, not being in dairy production area Grand-Ouest, and ALWG/OAL. Negative associations were reported for breed other than Holstein, being a Good Breeding Practices member, having a calving peak in autumn, culling rate, and municipal cattle density. This study reports an average mortality rate for the French dairy cows. It suggests that the farmers management style highly influences mortality. In addition, farming system has an effect on the mortality. A possible association between municipal intensification of production and decreased mortality was also reported.

Addressing Antimicrobial Resistance: An Overview of Priority Actions to Prevent Suboptimal Antimicrobial Use in Food-Animal Production

The growing concern regarding emergence of bacteria resistant to antimicrobials and their potential for transmission to humans via animal production has led various authorities worldwide to implement measures to decrease antimicrobial use (AMU) in livestock production. These measures are influenced by those implemented in human medicine, and emphasize the importance of antimicrobial stewardship, surveillance, infection prevention and control and research. In food producing animals, unlike human medicine, antimicrobials are used to control diseases which cause economic losses. This major difference may explain the failure of the public policies implemented to control antimicrobial usage. Here we first review the specific factors influencing AMU across the farm animal sector and highlighting the farmers’ decision-making process of AMU. We then discuss the efficiency of existing regulations implemented by policy makers, and assess the need for alternative strategies, such as substitution between antimicrobials and other measures for infectious disease control. We also discuss the interests of regulating antimicrobial prices. Finally, we emphasize the value of optimizing antimicrobial regimens, and developing veterinary precision medicine to achieve clinical efficacy in animals while limiting negative impacts on public health. The fight against antimicrobial resistance requires both a reduction and an optimization of antimicrobial consumption. The set of actions currently implemented by policy makers does not adequately address the economic interests of farmers’ use of antimicrobials.

The economic impact of subclinical ketosis at the farm level: Tackling the challenge of over-estimation due to multiple interactions

Subclinical ketosis (SCK) is a major metabolic disorder that affects dairy cows, and its lactational prevalence in Europe is estimated to be at 25%. Nonetheless, few data are available on the economics of SCK, although its management clearly must be improved. With this in mind, this study develops a double-step stochastic approach to evaluate the total cost of SCK to dairy farming. First, all the production and reproduction changes and all the health disorders associated with SCK were quantified using the meta-analysis from a previous study. Second, the total cost of SCK was determined with a stochastic model using distribution laws as input parameters. The mean total cost of SCK was estimated to be Є257 per calving cow with SCK (95% prediction interval (PI): Є72-442). The margin over feeding costs slightly influenced the results. When the parameters of the model are not modified to account for the conclusions from the meta-analysis and for the prevalence of health disorders in the population without SCK, the mean cost of SCK was overestimated by 68%, reaching Є434 per calving cow (95%PI: Є192-676). This result indicates that the total cost of complex health disorders is likely to be substantially overestimated when calculations use raw results from the literature or-even worse-punctual data. Excluding labour costs in the estimation reduced the SCK total cost by 12%, whereas excluding contributors with scarce data and imprecise calibrations (for lameness and udder health) reduced costs by another 18-20% (Є210, 95%PI=30-390). The proposed method accounted for uncertainty and variability in inputs by using distributions instead of point estimates. The mean value and associated prediction intervals (PIs) yielded good insight into the economic consequences of this complex disease and can be easily and practically used by decision makers in the field while simultaneously accounting for biological variability. Moreover, PIs can help prevent the blind use of economic results in the field when only the mean value is considered.

Failure of Passive Immune Transfer in Calves: A Meta-Analysis on the Consequences and Assessment of the Economic Impact.

Low colostrum intake at birth results in the failure of passive transfer (FPT) due to the inadequate ingestion of colostral immunoglobulins (Ig). FPT is associated with an increased risk of mortality and decreased health and longevity. Despite the known management practices associated with low FPT, it remains an important issue in the field. Neither a quantitative analysis of FPT consequences nor an assessment of its total cost are available. To address this point, a meta-analysis on the adjusted associations between FPT and its outcomes was first performed. Then, the total costs of FPT in European systems were calculated using a stochastic method with adjusted values as the input parameters. The adjusted risks (and 95% confidence intervals) for mortality, bovine respiratory disease, diarrhoea and overall morbidity in the case of FPT were 2.12 (1.43–3.13), 1.75 (1.50–2.03), 1.51 (1.05–2.17) and 1.91 (1.63–2.24), respectively. The mean (and 95% prediction interval) total costs per calf with FPT were estimated to be €60 (€10–109) and €80 (€20–139) for dairy and beef, respectively. As a result of the double-step stochastic method, the proposed economic estimation constitutes the first estimate available for FPT. The results are presented in a way that facilitates their use in the field and, with limited effort, combines the cost of each contributor to increase the applicability of the economic assessment to the situations farm-advisors may face. The present economic estimates are also an important tool to evaluate the profitability of measures that aim to improve colostrum intake and FPT prevention.

Fetal protection against bovine viral diarrhoea type 1 virus infection after one administration of a live-attenuated vaccine.

A modified-live vaccine has been shown previously to prevent fetal infection with bovine viral diarrhoea virus (BVDV)-2 and, to some extent BVDV-1, when used in association with an inactivated vaccine in a two-step vaccination protocol. In this challenge study, the modified-live vaccine used alone was able to protect 13 heifers between 49 and 96 days of gestation at challenge from leucopenia and virus replication and, for a 4-month period, to prevent fetal infection. The efficacy of the BVDV-1f 22146/Han81 challenge was demonstrated by virus isolation from the fetuses of all nine non-vaccinated, control heifers. However, the small number of heifers tested meant that the vaccination failure rate could be as high as 10% in the field.

Application of integrated production and economic models to estimate the impact of Schmallenberg virus for various beef suckler production systems in France and the United Kingdom

BackgroundSchmallenberg virus (SBV) was first detected in November 2011 in Germany and then rapidly spread throughout Europe. In beef suckler farms, clinical signs are mainly associated with reproductive disorders, particularly in late gestation, and intransient and non-specific symptoms, namely diarrhea, inappetence and fever. The objectives of this study were to develop models that simulate the production of different beef suckler systems in the United Kingdom (UK) and France and to use these models to estimate, through partial budget analyses, the farm-level economic cost of SBV under two disease impact scenarios, namely high and low impact. The probability for a farm to be in the high or low scenario depends, among other, on the high, low or nil vectorial activity for a given period and location and on the period(s) of sensitivity of the animals to the disease.ResultsUnder the high impact scenario, the estimated SBV impact ranged from 26€ to 43€ per cow per year in France and from 29€ to 36€ per cow per year in the UK. It was approximately half of this amount in the low impact scenario. These financial impacts represent 5 to 16% of the gross margin, depending on the country, impact scenario and livestock system considered. Most of the SBV impact originates from the costs of the steers and heifers not produced. Differences identified between the systems studied mainly stem from differences among the value of the steers or heifers sold: SBV impact is higher for British autumn calving systems compared to spring calving, and for French farms with calving and fattening activities compared to farms with only a single, annual calving activity.ConclusionsThis study shows the usefulness of integrated production and economic models to accurately evaluate the costs of diseases and understand which factors have major impacts in the different systems. The models stand as a useful basis for animal health professionals when considering alternative disease control measures. They are also a farm accounting tool for estimating disease impact on differing production practices, which creates the necessary basis for cost-effectiveness analysis of intervention strategies, such as vaccination.

The Impact of Farmers’ Strategic Behavior on the Spread of Animal Infectious Diseases

One of the main strategies to control the spread of infectious animal diseases is the implementation of movement restrictions. This paper shows a loss in efficiency of the movement restriction policy (MRP) when behavioral responses of farmers are taken into account. Incorporating the strategic behavior of farmers in an epidemiologic model reveals that the MRP can trigger premature animal sales by farms at high risk of becoming infected that significantly reduce the efficacy of the policy. The results are validated in a parameterized network via Monte Carlo simulations and measures to mitigate the loss of efficiency of the MRP are discussed. Financial aid to farmers can be justified by public health concerns, not only for equity. This paper contributes to developing an interdisciplinary analytical framework regarding the expansion of infectious diseases combining economic and epidemiologic dimensions.

Status Report on Education in the Economics of Animal Health: Results from a European Survey

Education on the use of economics applied to animal health (EAH) has been offered since the 1980s. However, it has never been institutionalized within veterinary curricula, and there is no systematic information on current teaching and education activities in Europe. Nevertheless, the need for economic skills in animal health has never been greater. Economics can add value to disease impact assessments; improve understanding of peoples incentives to participate in animal health measures; and help refine resource allocation for public animal health budgets. The use of economics should improve animal health decision making. An online questionnaire was conducted in European countries to assess current and future needs and expectations of people using EAH. The main conclusion from the survey is that education in economics appears to be offered inconsistently in Europe, and information about the availability of training opportunities in this field is scarce. There is a lack of harmonization of EAH education and significant gaps exist in the veterinary curricula of many countries. Depending on whether respondents belonged to educational institutions, public bodies, or private organizations, they expressed concerns regarding the limited education on decision making and impact assessment for animal diseases or on the use of economics for general management. Both public and private organizations recognized the increasing importance of EAH in the future. This should motivate the development of teaching methods and materials that aim at developing the understanding of animal health problems for the benefit of students and professional veterinarians.