14 research outputs found
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 2â4 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 3â62 % 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 ParasitâSim 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 âbottom upâ 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 0â4). The risk of excretion (score 0 versus 1â4) 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 premiÚre saison de pùturage dans des fermes en Agriculture Biologique
Dans les exploitations laitiĂšres, de nouvelles pratiques d'Ă©levage des veaux avec des vaches nourrices ont Ă©tĂ© dĂ©veloppĂ©es par les agriculteurs mais restent encore mal documentĂ©es, notamment sur le plan sanitaire. Ces pratiques impliquent un pĂąturage commun des veaux avec des vaches nourrices adultes. L'objectif de notre Ă©tude Ă©tait d'Ă©valuer l'impact de cette conduite sur l'infestation des veaux par les strongles gastro-intestinaux (SGI). La gestion des pĂąturages a Ă©tĂ© enregistrĂ©e pour chaque lot. Le taux de pepsinogĂšne sĂ©rique et l'excrĂ©tion d'Ćufs de SGi par gramme de fĂšces (opg) ont Ă©tĂ© dĂ©terminĂ©s chez 438 veaux appartenant Ă 38 lots de 30 exploitations de l'ouest de la France lors de la rentrĂ©e en bĂątiment (octobre 2018 Ă janvier 2019). Le nombre maximum de gĂ©nĂ©rations larvaires(GL) rencontrĂ©es par les animaux a Ă©tĂ© modĂ©lisĂ© par le systĂšme expert Parasit'Sim.
Les indicateurs parasitaires moyens par lot montraient un faible niveau dâinfestation par les SGI. En moyenne, le niveau de pepsinogĂšne sĂ©rique Ă©tait de 1,1 unitĂ© de tyrosine (U Tyr) et lâexcrĂ©tion d'Ćufs de SGI Ă©tait de 130 opg. Le nombre de gĂ©nĂ©rations larvaires sur les parcelles Ă©tait supĂ©rieure ou Ă©gal Ă 4 pour 2/3 des lots. Ces rĂ©sultats suggĂšrent quâen dĂ©pit dâune saison de pĂąturage longue, l'Ă©levage de veaux laitiers avec des vaches nourrices permet un faible niveau d'infestation par les SGI chez les veaux Ă la fin de la premiĂšre saison de pĂąturage par rapport Ă l'Ă©levage de gĂ©nisses conduites seules au pĂąturage. Cela peut s'expliquer par le fait que les vaches sont immunisĂ©es et ont un effet assainissant sur les pĂąturages en ingĂ©rant beaucoup de larves tout en excrĂ©tant peu d'Ćufs et par le fait que les veaux non sevrĂ©s ont une ingestion larvaire faible en raison de lâallaitement 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 rĂ©pandue, notamment en Agriculture Biologique, mais reste peu documentĂ©e : les descriptions zootechniques et lâimpact de ce systĂšme sur la croissance et la santĂ© des veaux sont peu connus. Les objectifs de cette Ă©tude Ă©taient donc de dĂ©crire cette conduite et dâĂ©valuer chez les veaux Ă©levĂ©s sous nourrice les performances zootechniques ainsi que les risques parasitaires liĂ©s Ă la cryptosporidiose et aux strongyloses digestives, deux maladies majeures des jeunes ruminants.
Cette Ă©tude a Ă©tĂ© rĂ©alisĂ©e dans 20 fermes biologiques pratiquant cette conduite. Les veaux restaient sous la mĂšre durant 4,5 jours en moyenne, puis passaient, pour 57% dâentre eux, par une phase dâallaitement artificiel. Lâadoption par une nourrice Ă©tait rĂ©alisĂ©e en moyenne Ă 8 jours. Les fĂšces de 611 veaux ĂągĂ©s de 5 Ă 21 jours ont Ă©tĂ© prĂ©levĂ©s de janvier Ă septembre 2019 pour dĂ©tecter les oocystes de Cryptosporidium. La prĂ©valence dâexcrĂ©tion de 40,2% Ă©tait similaire Ă celle trouvĂ©e chez des veaux Ă©levĂ©s classiquement mais lâintensitĂ© dâexcrĂ©tion et la prĂ©valence de diarrhĂ©e semblaient infĂ©rieures. Les facteurs de risque dâexcrĂ©tion identifiĂ©s Ă©taient soit non spĂ©cifiques de cette conduite sous nourrices (ex : naissance en milieu ou fin de saison de vĂȘlage vs dĂ©but de saison), soit en lien avec cette conduite (ex : phase dâallaitement ou dâadoption vs phase uniquement avec sa mĂšre). Concernant la croissance et les strongyloses digestives, des pesĂ©es et des prĂ©lĂšvements de fĂšces et de sang ont Ă©tĂ© rĂ©alisĂ©s Ă 4 reprises sur les 416 veaux gardĂ©s pour le renouvellement et leurs 197 nourrices au cours de la saison de pĂąturage. Les veaux avaient un GMQ Ă©levĂ© (en moyenne 783 grammes par jour) durant cette premiĂšre saison de pĂąturage. Lâensemble des indicateurs concernant les strongles gastro-intestinaux (excrĂ©tion fĂ©cale, pepsinogĂšne sanguin, sĂ©rologie Ostertagia, ParasitâSim) ont montrĂ© une faible exposition parasitaire malgrĂ© une durĂ©e de pĂąturage longue (191 jours en moyenne). Ces rĂ©sultats suggĂšrent que le pĂąturage mixte vaches nourrices/veaux protĂšgent ces derniers vis-Ă -vis des strongles gastro-intestinaux. Globalement sur la premiĂšre annĂ©e de vie, la conduite de veaux laitiers avec des nourrices semble avoir un effet bĂ©nĂ©fique sur la santĂ© et la croissance des veaux
Evolution of the treated cowsâ milk production over time in comparison with control cows (G<sub>i</sub>s) according to the pre-treatment production level (corrected for parity and days in milk).
<p>Week<sub>0</sub> = week of treatment, the first day of week<sub>0</sub> is the day of treatment. Black dots on the curve indicate that the corresponding negative G<sub>i</sub> 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 cowsâ milk production over time in comparison with control cows (G<sub>i</sub>s) according to the history of anthelmintic treatment (treated <i>versus</i> not treated during the previous housing period).
<p>Week<sub>0</sub> = week of treatment, the first day of week<sub>0</sub> is the day of treatment. Black dots on the curve indicate that the corresponding negative G<sub>i</sub> are significantly different from zero, adjusted p-value<0.05: the drop in milk production for treated cows is significant during these weeks).âSee <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