Jacques Barnouin

Risk factors for stillbirth in holstein heifers under field conditions in france: A prospective survey

Risk factors for stillbirth, defined as birth of a dead calf or a calf dead within 24 h after parturition, were studied in Holstein heifers. Data came from an overall 4-yr prospective survey conducted in French dairy herds. Only heifers that delivered a single calf were included in the study. The stillbirth incidence was 6.9%. The predictive indicators of stillbirth risk were: gestation length, prepartum body condition and dirtiness scores, biochemical and hematological blood parameters measured during the last 2 mo of gestation, and calving conditions. Multiple logistic regressions were run using herd, calving year, calving season, blood sampling-to-parturition interval, and body scoring-to-parturition interval as the fixed effects. The results, expressed as the ratio of the odds of disease occurrence in the exposed and non-exposed subgroups (OR), indicated that dystocia and a body condition score (BCS) higher than 4 before calving were significant risk factors for stillbirth (OR=14.6, P<0.0001 and OR=2.98, P<0.05, respectively). Prepartum circulating neutrophil counts higher than 1950/mm3 (OR=0.50, P<0.05) were associated with a lower risk of stillbirth. A higher occurrence of placental retention, lower fertility and a lower 305-d milk yield were significant consequences of stillbirth.

Ecological Factors Characterizing the Prevalence of Bacterial Tick-Borne Pathogens in Ixodes ricinus Ticks in Pastures and Woodlands

ABSTRACT Ecological changes are recognized as an important driver behind the emergence of infectious diseases. The prevalence of infection in ticks depends upon ecological factors that are rarely taken into account simultaneously. Our objective was to investigate the influences of forest fragmentation, vegetation, adult tick hosts, and habitat on the infection prevalence of three tick-borne bacteria, Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, and Rickettsia sp. of the spotted fever group, in questing Ixodes ricinus ticks, taking into account tick characteristics. Samples of questing nymphs and adults were taken from 61 pastures and neighboring woodlands in central France. The ticks were tested by PCR of pools of nymphs and individual adults. The individual infection prevalence was modeled using multivariate regression. The highest infection prevalences were found in adult females collected in woodland sites for B. burgdorferi sensu lato and A. phagocytophilum (16.1% and 10.7%, respectively) and in pasture sites for Rickettsia sp. (8.7%). The infection prevalence in nymphs was lower than 6%. B. burgdorferi sensu lato was more prevalent in woodlands than in pastures. Forest fragmentation favored B. burgdorferi sensu lato and A. phagocytophilum prevalence in woodlands, and in pastures, the B. burgdorferi sensu lato prevalence was favored by shrubby vegetation. Both results are probably because large amounts of edges or shrubs increase the abundance of small vertebrates as reservoir hosts. The Rickettsia sp. prevalence was maximal on pasture with medium forest fragmentation. Female ticks were more infected by B. burgdorferi sensu lato than males and nymphs in woodland sites, which suggests an interaction between the ticks and the bacteria. This study confirms the complexity of the tick-borne pathogen ecology. The findings support the importance of small vertebrates as reservoir hosts and make a case for further studies in Europe on the link between the composition of the reservoir host community and the infection prevalence in ticks.

Detecting emerging diseases in farm animals through clinical observations.

Clinical observations will allow early detection of emerging diseases in animal to enhance response time and capabilities.

The relationships between Ixodes ricinus and small mammal species at the woodland–pasture interface

Ixodes ricinus, as vector, and small mammals, as reservoirs, are implicated in pathogen transmission between wild fauna, domestic animals and humans at the woodland–pasture interface. The ecological relationship between ticks and small mammals was monitored in 2005 on four bocage (enclosed pastureland) sites in central France, where questing ticks were collected by dragging and small mammals were trapped. Questing I. ricinus tick and small mammal locations in the environment were assessed through correspondence analysis. I. ricinus larval burden on small mammals was modeled using a negative binomial law. The correspondence analyses underlined three landscape features: grassland, hedgerow, and woodland. Seven small mammal species were trapped, while questing ticks were all I. ricinus, with the highest abundance in woodland and the lowest in pasture. The small mammals were overall more abundant in hedgerow, less present in woodland and sparse in grassland. They carried mainly I. ricinus, and secondarily I. acuminatus and I. trianguliceps. The most likely profile for a tick-infested small mammal corresponded to a male wood mouse (Apodemus sylvaticus) in woodland or hedgerow during a dry day. A. sylvaticus, which was the only species captured in grassland, but was also present in hedgerow and woodland, may be a primary means of transfer of I. ricinus larvae from woodland to pasture.

Biological predictors for early clinical mastitis occurrence in Holstein cows under field conditions in France.

Individual risk factors for clinical mastitis within the first month of lactation (early clinical mastitis, ECM) were analyzed in 695 Holstein multiparous cows (561 ECM- and 134 ECM+) which were clinical mastitis-free during the previous lactation. They belonged to 44 herds from the French Brittany region and were surveyed for 4 years. Individual biological parameter levels during the last 2 months of gestation, production of the preceding lactation and calving conditions and health were the available explanatory variables. The construction and explanation model used multiple logistic regression run with herd as a fixed effect. High precalving plasma ceruloplasmin oxidase (p < 0.01) and low glutamate dehydrogenase (p < 0.05) activities, high 305-day previous-lactation milk yield (p < 0.001) and milk protein content at the last milk-test day before drying-off (p < 0.01) were the significant risk factors for ECM occurrence. Intensive production and unsatisfactory dietary conditions (energy and antioxidants) would increase ECM risk in the dairy cow. Further studies should be conducted to determine if metabolic and/or genetic factors could explain the relationship between ceruloplasmin and subsequent ECM occurrence.

A nation-wide epidemiological study of acute bovine respiratory disease in France.

Abstract Acute bovine respiratory disease (ABRD) is a respiratory syndrome caused by various infectious agents, and represents a major economic and health problem in cattle herds worldwide. The aim of the study was to present how we can describe the epidemiological characteristics of ABRD in France, including risk factor analysis and spatio-temporal pattern investigation. The data were collected by specialized surveyors during the 2001 animal survey conducted by the French Ministry for Agriculture and Fisheries, from a representative sample of cattle herds. The health questionnaire concerned farm characteristics, practice of BRD vaccination, presence of ABRD, time of occurrence and number of affected animals for the period November 2000–October 2001. After a descriptive analysis of the syndrome, a space–time scan statistic was performed to detect potential clusters, and a logistic regression model was used for analysis of risk factors. The study sample included 16,581 cattle herds as representative of the 260,000 French herds. The ABRD cumulative incidence at farm level was 9.8%, the cumulative incidence at animal level was 2.1%, the cumulative mortality 0.1% and the lethality proportion 6.5%. ABRD occurred mainly during cold months with an epidemic peak in December. Spatial repartition of the syndrome showed that the whole territory was affected, with a higher number of cases in the north-east region, the main bovine production area in France. Three space–time clusters were identified in the period November 2000–February 2001. ABRD was significantly associated with production type, herd size, and BRD vaccination. Beef herds were less affected than dairy herds, and increased herd size increased the risk of ABRD. The outbreak was clustered in space and time, suggesting a common infectious agent for the epidemic in the detected areas. The influence of production type and herd size on syndrome occurrence highlighted the importance of management practices, human movement and animal density.

Local environmental factors characterizing Ixodes ricinus nymph abundance in grazed permanent pastures for cattle

Although Ixodes ricinus ticks are mainly associated with woodland, they are also present in open habitat such as pastures. The distribution of nymphal I. ricinus was monitored by drag sampling the vegetation in May-June 2003 on 61 grazed permanent pastures for cattle located in central France. After selecting explanatory variables from among a set of 155, tick abundance was modelled on the perimeter of the pasture using a negative binomial model that took into account data overdispersion. An abundant tree layer at the perimeter of the pasture associated with a high humidity before sampling greatly enhanced the average number of captured I. ricinus nymphs. The presence of apple or cherry trees around the pasture perimeter, the presence of trees or bushes at the pasture edge, woodland around the pasture and a high number of I. ricinus nymphs in the nearest woodland to the pasture were also favourable to nymph abundance in the pasture. The study highlighted that woodland vegetation associated with humidity and the presence of attractive foraging areas for tick hosts around the pasture played a key role in the abundance of I. ricinus. Finally, the results raised the question of whether and how transfer of ticks between woodland and grazed pastures occurs.

Prevalence of Anaplasma phagocytophilum, Rickettsia sp. and Borrelia burgdorferi sensu lato DNA in Questing Ixodes ricinus Ticks from France

Abstract:  A total of 4701 Ixodes ricinus, collected during the summer of 2003, were analyzed for three pathogens. DNA was detected from the three pathogens. Co‐detection of more than one pathogen was observed.

Dietary factors associated with milk somatic cell counts in dairy cows in Brittany, France

Abstract A survey (Enquete Ecopathologique Bretagne) was conducted in France for 4 years (1986–1990) in 48 commercial dairy herds (25–80 cows per herd) located in Brittany. Three groups of herd-years were made up to study peripartum dietary factors associated with milk somatic cell counts in the early lactation period (ECC). The first group included 20 herd-years with high ECC (over 400 000 cells ml −1 ). The second group included herdyears with medium ECC ( n = 20, median ECC 222 000) and the last group herd-years with low ECC ( n = 20, median ECC 95 000). Herd data (components of the diet, milk yield and reproduction parameters, clinical diseases, biochemical and hematological indicators, body and dirtiness scores) were analyzed using discrimination by barycentric analysis. Two separate analysis were conducted according to study period (LG period, last 60 days of gestation; EL period, first 60 days of lactation). The high ECC group had the following characteristics: (1) higher plasma gamma glutamyl transferase levels in the LG period; (2) higher quantities of cereal-based concentrates in the diet in the EL period; (3) shorter durations of feeding with Italian rye grass silage in the EL period. The relevance of the risk factors for high ECC are discussed with reference to dietary linolenic acid/linoleic acid ratio (through the synthesis of leukotrienes as chemotactic agents for the polymorphonuclear leukocytes), dietary energy supplies and liver fluke infestation in the herds. We speculate that nutritional factors could modulate the leukocyte activity in the milk and that supplementations with certain polyunsaturated fatty acids would be able to prevent the development of inflammation in the udder.

A nutritional risk factor for early metritis in dairy farms in France

Abstract A survey was conducted in dairy herds in France (79 herds were surveyed during 2–4 years in six regions). Two groups of herd-years (free of brucellosis) were constructed according to their early metritis cumulative incidence (EMEI) in order to detect nutritional risk factors for the disease. The first group included the 10% of herd-years with the highest EMEI (EME + group; n =24); the second group (EME − group) included the 24 herd-years with the lowest EMEI and with the same number of herd-years for each region and each annual period. Herd-years with both high EMEI and low EMEI/retained placenta incidence ratios were removed from the study in order to rule out herds in which EME was mainly connected with retained placenta. The herd data concerned EMEI and four other clinical disease incidences, Q-fever serology, herd size, breed, housing system, use of a calving pen, milk yield and composition, calving number, season of calving, duration of the dry period, number of feeding days for 14 major feedstuffs given to cows during the dry period and the presence in the diet of vitamins A, D and E. Data were analysed using barycentric analysis (a form of discriminant analysis) to find the variables discriminating EME − and EME + herd-years. EME + herd-years were characterised by longer durations of feeding dry cows with urea and by more winter calvings. These two variables explained 26.9% of the total variation in the barycentric analysis. None of the remaining 26 variables explained more than 10% of the variation. Dietary urea feeding might involve environmental changes in the uterus with subsequent easier bacterial growth and lowered local immune defence. Winter calvings might be associated with poor hygienic conditions which would favour uterine infections in the early postpartum period.