Henri Seegers

Effect of disease on reproduction in the dairy cow: a meta-analysis.

Effects on reproduction of dystocia, stillbirth, abortion, milk fever, retained placenta, metritis, cystic ovaries, anestrus, ketosis, displaced abomasum, locomotor disorders, and mastitis were reviewed. Papers were considered if they provided quantitative estimates of diseases on days to first estrus, days to first service, conception rate at first service, days from first service to conception, days to conception or days open, calving interval, conception rates at various days post partum (dpp), and number of services per conception or per cow. Only papers in English in peer-reviewed journals were selected for analysis of post 1960 data from intensive dairy regions. Seventy papers fulfilled the selection criteria. Summary estimates of disease effects were calculated according to meta-analysis methods, and study designs were described in detail to identify possible heterogeneity of the results. Stillbirth, milk fever, displaced abomasum and mastitis had no effect on reproduction. Clinical ketosis, dystocia and retained placenta were associated with 2 to 3 more days to first service and with a 4 to 10% lower conception rate at first service, resulting in 6 to 12 more days to conception. Locomotor disorders were associated with an average increase of 12 d to conception, with wide variation depending on lesions and stage of occurrence. Metritis was associated with 7 more days to first service, 20% lower conception rate at first service, resulting in 19 more days to conception. Cystic ovaries were associated with 6 to 11 more days to first service and with 20 to 30 more days to conception. Anestrus was associated with 26 more days to first service and with an 18% lower conception rate at first service, resulting in 41 more days to conception. Abortion was associated with 70 to 80 more days to conception.

EFFECTS OF DISEASE ON MILK PRODUCTION IN THE DAIRY COW : A REVIEW

Estimates of milk losses consequent to dystocia, stillbirth, milk fever, retained placenta, metritis, cystic ovaries, ketosis, displaced abomasum and locomotor disorders were reviewed. Papers were selected if they provided quantitative estimates of losses based on data collected after 1965, with a sample size resulting in a minimum number of disease cases of 25. Thirty-five papers fulfilled the selection criteria. Milk losses were expressed in kg/day over the period under study to allow comparison of results. Milk fever and cystic ovaries were not associated with yield losses (six studies for each disease). Less than half of the studies found losses associated with dystocia, retained placenta, and metritis, with, respectively, five studies out of 13 (0.3-2.3 kg/day across the lactation), five studies out of 13 (0.8 kg/day across the lactation to 2.5 kg/day across 100 days in milk), and two studies out of 10 (0.4 kg/day across the lactation, and 2.3 kg/day across 119 days in milk). More than half of the studies found losses associated with stillbirth, clinical ketosis, ketosis evidenced by a diagnostic test, and locomotor disorders, with, respectively, three studies out of five (0.7-1.3 kg/day across the lactation), seven studies out of 11 (2.6-5.7 kg/day short-term, and 1.2 kg/day across the lactation), five studies out of seven (1-7 kg/day on the day of diagnosis, and around 1 kg/day across 200 days in milk), and six studies out of 11 (0.3-3.3 kg/day across the lactation). All the five studies, investigating effects of displaced abomasum, found losses (3.5-10.9 kg/day across 80 days in milk, or 0.8-2.5 kg/day across the lactation).

Prevalence of Coxiella burnetii infection in domestic ruminants: A critical review

Reliable detection of Coxiella burnetii is a critical point for the control of the spread of this zoonotic disease (Q fever), ruminants being considered as the main source for human infection as confirmed by the recent human outbreak in the Netherlands since 2007. Considering both public and animal health, providing consolidated prevalence data could be relevant within the decision process of public policy makers or producers organizations. The objective of this study was to conduct a critical review of the literature focused on the prevalence of C. burnetii infection at animal, herd and within-herd levels in cattle, goat and sheep. A qualitative assessment of the 69 selected publications, based on the analysis of the sampling frame and testing procedures, was also performed. While the number of publications increased recently, major methodological issues were still evidenced. These critical issues were related to (i) the absence of description of the sampling strategy and (ii) the lack of sensitivity of the testing procedure. The lack of well designed studies makes not possible to estimate accurately the current prevalence of the infection. Nevertheless, the literature review reported the detection of C. burnetii infection in the all 5 continents with a wide range whatever the species. The apparent prevalence was slightly higher in cattle (20.0% and 37.7% of mean apparent prevalence at animal and herd level respectively) than in small ruminants (around 15.0% and 25% respectively for animal and herd level in sheep and goat). The present conclusions and the current situation support the persistent need of conducting well designed studies, aiming at estimating the true prevalence of C. burnetii infection in the three main domestic ruminant species.

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences--but also due to structural-variation factors such as type of pathogen, animal and production level--estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.

Prevalence and Risk Factors for Bacterial Food‐Borne Zoonotic Hazards in Slaughter Pigs: A Review

The Hygiene Package and Regulation EC‐2160/2003 require information flow from farm to slaughterhouse to enhance European consumers protection in a ‘farm to fork’ approach. This obligation especially concerns food‐borne zoonotic hazards transmitted to humans through pork consumption, such as thermophilic Campylobacter spp., Listeria monocytogenes, Salmonella enterica and Yersinia enterocolitica. Prevalence estimates of these four hazards are affected by the sampling strategy and diagnostic procedure. Individual prevalence estimates for pig carriage (from digestive contents or lymph nodes collected at slaughterhouse) were higher than individual prevalence estimates for pig shedding (from faeces). Among risk factors described in the literature, poor pen cleaning and disinfection after pig departure to slaughterhouse and poor bio‐security measures are of major significance. Moreover, whereas wet feed increases the risk of pig infection by L. monocytogenes, dry feed is a risk factor for Salm. enterica. Mixing batches of pigs, notably in fattening herds, represents a risk for the transmission of Salm. enterica and Y. enterocolitica. Whereas small herds are more infected by thermophilic campylobacters and Y. enterocolitica, higher prevalence of Salmonella is observed in large herds due to a more frequent mixing of batches. Antibiotic treatment during the finishing period increases the risk of transmission of Salm. enterica. The forenamed elements should be taken into account to characterize farms in a risk assessment approach and to improve zoonotic hazard management in the pork food chain.

Reduction in milk yield associated with somatic cell counts up to 600 000 cells / ml in French Holstein cows without clinical mastitis

Abstract The reduction in milk yield (kg) on test day associated with individual somatic cell count (SCC) up to 600 000 cells/ml was assessed using monthly cow-records collected for a 1-year period in 105 Holstein herds located in western France. Monthly records with SCC over 600 000 cells/ml, and/or occurring after a clinical case of mastitis were excluded. The resulting dataset comprised 32 148 records from 4968 cows. A mixed autoregressive linear model was used to assess, on test day, the effects on the milk yield (dependent variable) of herd-season (random), SCC (after natural logarithmic transformation), days in milk on which SCC were recorded and an interaction term between SCC and days in milk. Regression coefficients associated with SCC were expressed as a polynomial of days in milk. The reduction in milk yield in kg associated with an increase in SCC was calculated in deviation from a reference SCC value set at 50 000 cells/ml as a function of SCC and days in milk on which SCC were recorded. In primiparous cows, the reduction in milk yield was 0.30 kg for an SCC of 100 000 cells/ml, 0.61 kg for an SCC of 200 000 cells/ml and 1.09 kg for an SCC of 600 000 cells/ml. In multiparous cows, the reduction in milk yield in kg increased with parity and with days in milk. For cows in parity 2 on day 50 pp, the reduction in milk yield was 0.32 kg for an SCC of 100 000 cells/ml, 0.63 kg for an SCC of 200 000 cells/ml and 1.13 kg for an SCC of 600 000 cells/ml. For cows in parity 2 with SCC of 200 000 cells/ml, the reduction in milk yield was 0.63 kg on day 50, 0.92 kg on day 150 and 1.77 kg on day 250 pp. For cows in parity ≥3 on day 50 pp, the reduction in milk yield was 0.30 kg for an SCC of 100 000 cells/ml, 0.60 kg for an SCC of 200 000 cells/ml and 1.07 kg for an SCC of 600 000 cells/ml. For cows in parity ≥3 with SCC of 200 000 cells/ml, the reduction in milk yield was 0.60 kg on day 50, 1.09 kg on day 150 and 1.85 kg on day 250 pp.

Reasons for culling in French Holstein cows

The study describes the profiles of culled cows in order to assess the possible contribution to economic losses due to health disorders. Data regarding dates of birth, final calving and culling, parity at culling, milk yield at the two first test-days of the final lactation and reason(s) for culling were collected in a 5-year survey, carried out from 1989 to 1994 in 84 commercial Holstein farms in western France. Polytomous logistic regression was used to assess the relationship between parity, calving-to-culling interval, milk yield and eight groups of primary culling reasons (i.e. udder disorders; infertility or reproductive disorders; lameness or foot/leg defects; emergency culling reasons; other health disorders; low milk yield; sales for dairy purpose; and other voluntary culling reasons). Out of a total of 5133 culled cows, the proportions of culls, for each of these groups of reasons, were 12.4, 28.4, 2.7, 3.9, 4.6, 16.7, 5.9, and 25.4%, respectively. Cows culled for udder disorders left the herd earlier in lactation and were more frequently at parities 4-6 than cows culled for voluntary reasons. In contrast, cows culled for infertility were younger and culled later within lactation. They were also higher yielding cows than those culled for other reasons. Cows culled for lameness were similar to those of the voluntarily culling group. Cows culled for emergency reasons were more frequently younger cows in early lactation. Cows culled for other health disorders left the herd early in lactation, but at a higher parity than the voluntarily culled cows. These results suggest that most of the culls related to health could be contributing to economic loss. However, special priority should be given to reduce culling for reproductive problems, which is the most costly exit reason.

Association of growth, feeding practices and exercise conditions with the prevalence of Developmental Orthopaedic Disease in limbs of French foals at weaning

Developmental Orthopaedic Disease (DOD) in limb joints of horses is frequent and is a common cause of pain and lameness. DOD is a multifactorial disease involving genetics, growth, feeding practices and exercise conditions leading to joint injuries. However, there is no clear understanding of the contribution of each factor. The aim of this cohort study was to assess the adjusted effects of breed and gender, growth, feeding practices and exercise conditions on the prevalence of DOD in the limbs of foals at weaning and on the prevalence restricted to osteochondrosis (OC). Twenty-one farms in Normandy, France, were convenience sampled and enrolled in a cohort study. The study sample consisted of 401 foals from 3 breeds, followed from the 8th month of pregnancy of the mares until weaning period at approximately 6 months of age of the foals. Stud farms were regularly visited to collect growth, feeding practices and exercise conditions data. The carpus, the front and hind digits, the hock and the stifle of the foals were X-rayed at the end of follow-up. Foals were categorised as affected or unaffected by DOD or by OC. Two mixed-effects logistic regression models were used to determine risk factors for DOD or OC, adjusting for clustering by farm. Of the 378 foals with complete data, 47% (95% CI: 42-52) were affected by DOD and 36% (95% CI: 31-41) by OC. Risk was significantly increased for DOD and for OC in Warmblood foals compared to Thoroughbreds (OR 2.8; 95% CI: 1.2-6.5 for DOD, OR 2.9; 95% CI: 1.1-7.5 for OC), in foals with a high wither height at 30 days of age, and in foals with a rapid increase of wither height (for DOD only). Exercise conditions such as large area of pasture, some irregular exercise, or some batch changes were also significant risk factors for DOD or OC. No association was found with quantitative feeding practices; it was likely due to the limited variability of horse regimens and to the partial inclusion of nutritional effects in other factors such as breed and growth. In order to reduce the prevalence of DOD or OC in foals, following the growth and reducing nutritional supply in subjects growing fast, limiting the pasture areas offered and providing a regular exercise to foals seems appropriate. To our knowledge, to date the assessment of adjusted effects of potential risk factors for DOD has never been proposed.

Incidence of health disorders in dairy farming systems in western France

Abstract Incidence of health disorders was described in 205 dairy farms in Pays de la Loire (France) in 1995/97 and compared between farming systems. Cases recorded by farmers with standard definitions were checked every month during 2 years. Incidences varied widely between herds. Median and mean values were, respectively, in cases per 100 cow-years, 40.2 and 44.1 for clinical mastitis (5.7 and 7.1 systemic mastitis), 7.6 and 10.9 for locomotor disorders, 3.3 and 5.1 for digestive disorders, and, in cases per 100 calvings, 8.1 and 8.8 for retained placenta, 5.2 and 6.6 for dystocia, 4.9 and 5.6 for milk fever, 1.9 and 5.1 for chronic metritis; somatic cell counts exceeded 200 000 cells/ml in 26.6% monthly test-days, d to first artificial insemination (AI) exceeded 90 days postpartum in 25.4% of first AI, and of total AI return rate was 50.4%. In 28% of the herds, health status was characterised by low incidences for all disorders, whereas 10% had high incidences for most disorders, 21% for several peripartum disorders or chronic metritis, 14% for retained placenta and locomotor disorders, 15% for milk fever only and 11% for mastitis only. Incidences varied widely within all farming systems. In each system, every category of herd-health status was present, and more than 20% of the farms had a low-incidence status. Little variation was associated with size of the dairy unit or dairy specialisation of the farm. Non-Holstein herds had less clinical mastitis, better reproductive performance and more dystocia than Holstein herds. Among Holstein systems, clinical mastitis were more frequent in farming systems with highest than with lowest intensification of the dairy production, whereas high somatic cell counts were less frequent. The most intensive group had the highest median incidence for nine out of 14 cow disorders. Variations were higher within than between farming systems.

Rapid identification and quantification of Campylobacter coli and Campylobacter jejuni by real-time PCR in pure cultures and in complex samples

BackgroundCampylobacter spp., especially Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli), are recognized as the leading human foodborne pathogens in developed countries. Livestock animals carrying Campylobacter pose an important risk for human contamination. Pigs are known to be frequently colonized with Campylobacter, especially C. coli, and to excrete high numbers of this pathogen in their faeces. Molecular tools, notably real-time PCR, provide an effective, rapid, and sensitive alternative to culture-based methods for the detection of C. coli and C. jejuni in various substrates. In order to serve as a diagnostic tool supporting Campylobacter epidemiology, we developed a quantitative real-time PCR method for species-specific detection and quantification of C. coli and C. jejuni directly in faecal, feed, and environmental samples.ResultsWith a sensitivity of 10 genome copies and a linear range of seven to eight orders of magnitude, the C. coli and C. jejuni real-time PCR assays allowed a precise quantification of purified DNA from C. coli and C. jejuni. The assays were highly specific and showed a 6-log-linear dynamic range of quantification with a quantitative detection limit of approximately 2.5 × 102 CFU/g of faeces, 1.3 × 102 CFU/g of feed, and 1.0 × 103 CFU/m2 for the environmental samples. Compared to the results obtained by culture, both C. coli and C. jejuni real-time PCR assays exhibited a specificity of 96.2% with a kappa of 0.94 and 0.89 respectively. For faecal samples of experimentally infected pigs, the coefficients of correlation between the C. coli or C. jejuni real-time PCR assay and culture enumeration were R2 = 0.90 and R2 = 0.93 respectively.ConclusionThe C. coli and C. jejuni real-time quantitative PCR assays developed in this study provide a method capable of directly detecting and quantifying C. coli and C. jejuni in faeces, feed, and environmental samples. These assays represent a new diagnostic tool for studying the epidemiology of Campylobacter by, for instance, investigating the carriage and excretion of C. coli and C. jejuni by pigs from conventional herds.