Experimental in vitro transmission of Babesia sp. (EU1) by Ixodes ricinus

Babesia sp. (EU1), first characterized in 2003, has been implicated in human cases of babesiosis in Italy, Austria and Germany. It has been identified in roe deer and in its suspected tick vector, Ixodes ricinus, in several European countries. The aim of the present study was to validate the competence of I. ricinus as a vector of Babesia sp. (EU1) via experimental infections. For this purpose, a parasite strain isolated from roe deer was cloned in sheep erythrocytes. After experimental infections, parasite DNA was successfully amplified by PCR in both eggs and larvae originating from infected I. ricinus females and in the salivary glands of females exposed to Babesia sp. (EU1) as nymphs. We also demonstrate that infected females were able to transmit parasite DNA during a new blood meal. Together with previous epidemiological studies, these results validate I. ricinus as a competent vector for Babesia sp. (EU1)

Gastrointestinal nematode and lungworm infections in organic dairy calves reared with nurse cows during their first grazing season in western France

The rearing system of dairy calves with nurse cows has been developing since 2010 in organic farms in western France. This system allows cow-calf contact until a weaning age close to the natural weaning for cattle and is characterized by an early turnout for calves at around one month of age with their nurse cows and a first grazing season with mixed grazing of calves and adults at a ratio of 2–4 calves per nurse cow. The objectives of this study were to assess the gastrointestinal (GIN) and lungworm infections in such reared calves and their variability during the first grazing season. Faecal egg count (FEC), pepsinogen (PEP) concentration and Ostertagia ELISA optical density ratio (ODR) were determined in calves (n =497) at housing in 33 groups from 24 farms in 2018, and in calves (n =405) and nurse cows (n =199) throughout the 2019 grazing season in 41 groups from 20 farms. For lungworm infection, information was obtained during 2019 through the recording of coughing epi-sodes along the grazing season and the Dictyocaulus ELISA ODR determination at housing both in calves and nurses. Results indicated that the level of GIN infection was overall low for calves during the first grazing season with PEP and Ostertagia ODR group-average values ranging from 0.97 to 1.6 U Tyr and 0.23 to 0.71 ODR respectively. No anthelmintic treatment being given in any group of calves. Ostertagia ODR values increased with the duration of the grazing season (>240 d) and with the ratio calves/nurse (>2). GIN parameters for nurses remained fairly stable during the grazing season with mean FEC, PEP and Ostertagia ODR group-average values of 13 epg, 2.28 U Tyr and 0.81 ODR, respectively. Antibodies against lungworms were detected in 3–62 % of calves depending on the duration of grazing, but only 6% of calves showed a coughing episode. The dilution effect due to the mixed grazing of resistant (nurse cows) and susceptible (calves) animals associated with predominant milk diet of calves during the first months of grazing in combination with protective grazing management allow calves to be turned out at an early age without using anthelmintic treatments. Further studies are needed to assess the GIN infection dynamics during the second grazing season in weaned heifers

Suckling Dairy Calves/Nurse Cows System And Risk Of Gastrointestinal Nematodes Infection During The First Grazing Season In Organic Farms

In dairy farms, new rearing practices of calves with nurse cows have been developed by farmers but still remain poorly documented. The objective was to assess the impact of rearing suckling calves with nurse cows on the same pastures on the risk of gastrointestinal nematode (GIN) infection in calves. The grazing management has been recorded for each group. Serum pepsinogen level and GIN egg excretion per gram of faeces (epg) were determined in 438 calves belonging to 38 groups from 30 farms in the western part of France at housing (October 2018 to January 2019). The maximum number of infective larval generations met by the animals (LG) in each pasture plot was modelled by Parasit’Sim expert system. The data were analyzed using logistic regression (univariate and multivariate). Mean parasiticological parameters per group were low. On average, the serum pepsinogen level was 1.1 units of tyrosine (U Tyr) and the GIN egg output was 130 epg. Pasture infectivity was above LG4 for 2/3 of the groups. These results suggest that rearing suckling dairy calves with nurse cows decreases the level of GIN infection in calves at the end of the 1st grazing season compared with putting out to pasture weaned heifers alone. This can be explained by i) the fact that cows were immune and have a cleansing effect on the pastures when eating a lot of larvae while excreting few eggs and ii) Because not weaned calves had a slow larval intake when drinking milk from nurse cows

Performance and health status of dairy calves reared with nurse cows, a 2-year study involving 3 cohorts

The agro-ecological transition is based on “bottom up” innovation processes developed by agricultural stakeholders. The role of researchers is now to accompany this process by working closely with them. Since the 90s, groups of dairy farmers have been set up in many developed countries to exchange information about intensive grazing management. Within these groups, organic dairy breeders have experimented new cow-calf rearing practices, in which a specific batch of lactating cows is constituted in order to nurse and raise 2-4 calves each (usually replacement heifers) for several months on pasture. The objective of our study was to assess effects of this innovative rearing system on growth and health of the calves, with a focus on the risk of grazing parasite (gastrointestinal nematodes). On an experimental organic farm located in East of France, we designed a cow-calf rearing system in collaboration with farmers experienced on this practice. A 2-year study of 3 cohorts of 9, 16 and 23 calves was conducted from 2016 to 2019. We weighed, recorded all health events and measured different parasitic indicators at key times of the grazing season. Calves showed a fast and steady growth during the 2 years of follow-up, allowing a calving at 24 months old. Parasitic risks were low, with nurse cows playing a protective role towards infection. In addition, early immunity against gastrointestinal nematodes was developed in calves. Throughout the study, the calves did not receive any antibiotic nor anti-parasitic treatments. Only one calf died due to ruminal tympany. Rearing calves with nurse cows seems to be of real interest for their growth and health, and in particular the management of parasitic risks. Further studies in other farms are needed to validate these results

Rearing system with nurse cows and risk factors for Cryptosporidium infection in Organic dairy calves

Rearing dairy calves with nurse cows has been increasingly adopted by French farmers especially in organic farming and is characterized by a fostering of two to four calves during the first month of life by an unmilked lactating cow. This type of rearing remains poorly documented regarding its impact on calf health, such as cryptosporidiosis. The objectives of our study were to describe practices related to rearing dairy calves with nurse cows and to evaluate the prevalence, intensity and risk factors for Cryptosporidium infection in calf neonates. Between January and September 2019, the rearing practices of calves were described in 20 organic French farms and faeces were sampled once from 611 animals aged between 5 and 21 days. Cryptosporidium oocyst shedding was identified by modified Ziehl-Neelsen technique and scored semi-quantitatively (score 0–4). The risk of excretion (score 0 versus 1–4) was analysed using multivariate logistic regression models.This cow-calf rearing system usually consisted of a first phase with the dam, followed by an optional phase of artificial milk feeding (calves being fed with whole milk of the farm) and a final phase of fostering by a nurse cow. Each nurse was suckled from one to five calves of close age with a fostering age of 8 days on average. The oocyst shedding prevalence was 40.2 % and similar to classically reared calves, but the intensity of shedding and the prevalence of diarrhoea appeared to be lower. The identified six risk factors for oocyst shedding were: born in the last two thirds of the birth order, born between January and July versus August and September, calf with its dam in the barn versus on pasture, having an artificial milk feeding phase versus being with the dam only, and contact between peer calves and notably the presence of an oocyst excretory calf fostered by the same nurse. These results emphasize the role of the environment for the direct and indirect contamination, particularly that related to the accumulation of oocysts from previous or peer calves facilitating the faecal-oral route of transmission. This highlights the crucial role of the premises used intensively during the winter and spring months with higher densities of calves in the barn compared to outdoor situations promoted by this rearing

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

Infestation par les strongles gastro-intestinaux chez les veaux laitiers élevés par des vaches nourrices pendant la première saison de pâturage dans des fermes en Agriculture Biologique

Dans les exploitations laitières, de nouvelles pratiques d'élevage des veaux avec des vaches nourrices ont été développées par les agriculteurs mais restent encore mal documentées, notamment sur le plan sanitaire. Ces pratiques impliquent un pâturage commun des veaux avec des vaches nourrices adultes. L'objectif de notre étude était d'évaluer l'impact de cette conduite sur l'infestation des veaux par les strongles gastro-intestinaux (SGI). La gestion des pâturages a été enregistrée pour chaque lot. Le taux de pepsinogène sérique et l'excrétion d'œufs de SGi par gramme de fèces (opg) ont été déterminés chez 438 veaux appartenant à 38 lots de 30 exploitations de l'ouest de la France lors de la rentrée en bâtiment (octobre 2018 à janvier 2019). Le nombre maximum de générations larvaires(GL) rencontrées par les animaux a été modélisé par le système expert Parasit'Sim. Les indicateurs parasitaires moyens par lot montraient un faible niveau d’infestation par les SGI. En moyenne, le niveau de pepsinogène sérique était de 1,1 unité de tyrosine (U Tyr) et l’excrétion d'œufs de SGI était de 130 opg. Le nombre de générations larvaires sur les parcelles était supérieure ou égal à 4 pour 2/3 des lots. Ces résultats suggèrent qu’en dépit d’une saison de pâturage longue, l'élevage de veaux laitiers avec des vaches nourrices permet un faible niveau d'infestation par les SGI chez les veaux à la fin de la première saison de pâturage par rapport à l'élevage de génisses conduites seules au pâturage. Cela peut s'expliquer par le fait que les vaches sont immunisées et ont un effet assainissant sur les pâturages en ingérant beaucoup de larves tout en excrétant peu d'œufs et par le fait que les veaux non sevrés ont une ingestion larvaire faible en raison de l’allaitement par les vaches nourrices

Parasitisme et performances zootechniques des veaux laitiers conduits avec des vaches nourrices en Agriculture Biologique

La conduite des veaux laitiers avec des vaches nourrices est de plus en plus répandue, notamment en Agriculture Biologique, mais reste peu documentée : les descriptions zootechniques et l’impact de ce système sur la croissance et la santé des veaux sont peu connus. Les objectifs de cette étude étaient donc de décrire cette conduite et d’évaluer chez les veaux élevés sous nourrice les performances zootechniques ainsi que les risques parasitaires liés à la cryptosporidiose et aux strongyloses digestives, deux maladies majeures des jeunes ruminants. Cette étude a été réalisée dans 20 fermes biologiques pratiquant cette conduite. Les veaux restaient sous la mère durant 4,5 jours en moyenne, puis passaient, pour 57% d’entre eux, par une phase d’allaitement artificiel. L’adoption par une nourrice était réalisée en moyenne à 8 jours. Les fèces de 611 veaux âgés de 5 à 21 jours ont été prélevés de janvier à septembre 2019 pour détecter les oocystes de Cryptosporidium. La prévalence d’excrétion de 40,2% était similaire à celle trouvée chez des veaux élevés classiquement mais l’intensité d’excrétion et la prévalence de diarrhée semblaient inférieures. Les facteurs de risque d’excrétion identifiés étaient soit non spécifiques de cette conduite sous nourrices (ex : naissance en milieu ou fin de saison de vêlage vs début de saison), soit en lien avec cette conduite (ex : phase d’allaitement ou d’adoption vs phase uniquement avec sa mère). Concernant la croissance et les strongyloses digestives, des pesées et des prélèvements de fèces et de sang ont été réalisés à 4 reprises sur les 416 veaux gardés pour le renouvellement et leurs 197 nourrices au cours de la saison de pâturage. Les veaux avaient un GMQ élevé (en moyenne 783 grammes par jour) durant cette première saison de pâturage. L’ensemble des indicateurs concernant les strongles gastro-intestinaux (excrétion fécale, pepsinogène sanguin, sérologie Ostertagia, Parasit’Sim) ont montré une faible exposition parasitaire malgré une durée de pâturage longue (191 jours en moyenne). Ces résultats suggèrent que le pâturage mixte vaches nourrices/veaux protègent ces derniers vis-à-vis des strongles gastro-intestinaux. Globalement sur la première année de vie, la conduite de veaux laitiers avec des nourrices semble avoir un effet bénéfique sur la santé et la croissance des veaux

Evolution of the treated cows’ milk production over time in comparison with control cows (G_is) according to the pre-treatment production level (corrected for parity and days in milk).

<p>Week₀ = week of treatment, the first day of week₀ is the day of treatment. Black dots on the curve indicate that the corresponding negative G_i are significantly different from zero, adjusted p-value<0.05: the drop in milk production for treated cows is significant during these weeks). See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147835#pone.0147835.t002" target="_blank">Table 2</a> for the number of treated cows and control cows per category.</p

Evolution of the treated cows’ milk production over time in comparison with control cows (G_is) according to the history of anthelmintic treatment (treated <i>versus</i> not treated during the previous housing period).

<p>Week₀ = week of treatment, the first day of week₀ is the day of treatment. Black dots on the curve indicate that the corresponding negative G_i are significantly different from zero, adjusted p-value<0.05: the drop in milk production for treated cows is significant during these weeks).—See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147835#pone.0147835.t003" target="_blank">Table 3</a> for the number of treated cows and control cows per category.</p