Cross-sectional serological survey on gastrointestinal and lung nematode infections in first and second-year replacement stock in the netherlands: relation with management practices and use of anthelmintics

Behavioural response to gastrointestinal parasites of yearling dairy calves at pasture

AIMS

To investigate the association between gastrointestinal parasites (GIP) and animal behaviour in dairy calves under New Zealand pastoral conditions, using animal-mounted, accelerometer-based sensors.

METHODS

Thirty-six, 5-6-month-old, Friesian-Jersey, heifer calves fitted with animal activity sensors to track behaviour were randomly allocated to one of two treatment groups. Half the animals were challenged with an oral dose of 20,000 larvae of Ostertagia ostertagi and Cooperia oncophera once a week for 3 weeks and half were unchallenged. Five weeks after the last dose, seven infected and nine uninfected animals were treated with an oral anthelmintic (AHC) and data collected for a further week. Accelerometer data were classified into minutes per day eating, ruminating, in moderate-high activity or in low activity. Live weight and faecal egg counts (FEC) were recorded weekly over the study period. All animals co-grazed a newly sown pasture not previously grazed by ruminants and were moved every week to fresh grazing. Treatment status was blinded to those managing the animals which were otherwise treated identically.

RESULTS

Complete behavioural records were available from 30/36 calves, (13 challenged and 17 unchallenged). Before treatment with AHC, FEC increased in infected and un-treated calves over the study, while uninfected animals maintained a near zero FEC. There was no difference in live weight gain between the two groups over the study period. Bayesian, multinomial regression predicted differences in animal behaviour between infected and uninfected animals that were not treated with AHC over the 7 weeks following initial infection. Parasitised calves not treated with AHC were less active and spent up to 6 (95% highest density interval (HDI) = 1-11) minutes/day less in low level activity and up to 15 (95% HDI = 7-20) minutes/day less in moderate to high level activity. They ruminated up to 9 (95% HDI = 2-15) minutes/day more and ate up to 10 (95% HDI = 2-19) minutes/day more than control calves that were not treated with AHC. The effect of AHC on time spent in each behaviour differed between infected and uninfected calves and increased the coefficient of dispersion of the behavioural data.

CONCLUSIONS AND CLINICAL RELEVANCE

Small differences in animal behaviour can be measured in calves with GIP. However, to use this to target treatment, further validation studies are required to confirm the accuracy of behavioural classification and understand the complex drivers of animal behaviour in a dynamic and variable pasture-parasite-host environment.

Spatiotemporal trends in cattle lungworm disease (Dictyocaulus viviparus) in Great Britain from 1975 to 2014

Background

Clinical disease caused by the bovine lungworm (Dictyocaulus viviparus) causes significant welfare and economic problems for the livestock industry. Anecdotal reports suggest that the number of clinical cases has increased, particularly in Northern England and Scotland. However, these spatiotemporal changes have not been quantified and the current impact that the disease is having across Great Britain remains unclear.

Methods

Here, we report a retrospective analysis of the spatial distribution, seasonality and age of lungworm cases reported by the Veterinary Investigation Diagnosis Analysis database from 1975 to 2014.

Results

A sharp overall increase in the dictyocaulosis diagnostic rate (DR, cases / 1000 submissions) was observed, with, for example, median 2010–2014 DR 3.5 times as high as 1980–1984 DR. Such increases were most pronounced for Scotland, which became the region with the highest proportion of cases by 2009. Cases were increasingly diagnosed during the winter months (December–February).

Conclusion

The apparent spatiotemporal changes in lungworm epidemiology pose new challenges to cattle farmers in Great Britain. Farmers and veterinarians need to remain vigilant for this disease and consider it as a possible cause for milk production losses at any time of the year. Awareness levels may have to be raised particularly in northern England and Scotland.

Mid-season targeted selective anthelmintic treatment based on flexible weight gain threshold for nematode infection control in dairy calves

The suitability of a single mid-season targeted selective treatment (TST) for gastrointestinal nematodes control, based on flexible average daily weight gain (ADWG) thresholds, was investigated in 23 groups of first grazing season calves. In each group, animals were weighed three times: before turnout, at mid-season and at housing. Just after the first weighing, each group was divided in two homogenous sub-groups in terms of age, breed and weight, and randomly allocated to one of two sub-groups intented for two different mid-season anthelmintic treatment strategies: (1) a treatment of all calves composing the sub-group (whole-group treatment (WT)) or (2) a targeted selective weight gain-based treatment (TST) of the animals showing an individual pre-treatment ADWG inferior to the mean pre-treatment ADWG of the corresponding WT sub-group. Anthelmintic treatment (levamisole 7.5 mg/kg BW) was performed 3 to 4 months after turnout. At housing, two parasitological parameters (the anti-Ostertagia ostertagi antibody level-Ostertagia optical density ratio (ODR) and the pepsinogen level) and a clinical parameter (the breech soiling score) were assessed at individual level in each group. Then, the high exposed groups to gastrointestinal nematode (GIN) were defined as groups for which untreated animals exhibited a mean Ostertagia ODR ⩾0.7 and among these groups, the ones characterized by high abomasal damage due to Ostertagia for which untreated animals exhibited a mean pepsinogen level ⩾2.5 U Tyr were also identified. Among TST sub-groups, the treatment ADWG thresholds varied from 338 to 941 g/day and the percentage of treated animals from 28% to 75%. Pre- and post-treatment ADWG as well as parasitological and clinical parameters measured at housing were similar between TST and WT sub-groups including the 17 high exposed groups to GIN. Within these 17 groups, the treatment allowed to significantly improve post-treatment ADWG compared with untreated animals. In the six high exposed groups showing mean pepsinogen level ⩾2.5 U Tyr, the average effect of treatment on post-treatment ADWG was the highest and estimated up to 14 kg after a grazing duration of 4 months. In contrast, in six other groups showing mean Ostertagia ODR<0.7 in untreated animals, no effect of treatment was seen suggesting an absence of production losses related to a low level of GIN infection. This study highlighted the suitability of a convenient mid-season TST strategy for first grazing season calves, based on the use of flexible thresholds of ADWG, allowing similar growth compared with a whole-group treatment while keeping a GIN population in refugia.

Parasitism level by helminths and weight gain of calves kept in organic and conventional grazing

Sustainable production is a principle in which we must meet the needs of the present without compromising the capacity of future generations. Despite the successful development of pesticides against endo and ectoparasites found in domestic ruminants, these parasites are still the major problem of the herbivore production system. The purpose of this study was to know the population of gastrintestinal parasites and their influence on weight gain of calves kept in organic and conventional grazing. Thus, organic and conventional calves were randomly selected in 2008 and 2009. The fecal egg count (FEC) indentified the following genders of helminths: Haemonchus, Trichostrongylus, Oesophagostomum, Cooperia, Strongyloides, Trichuris and oocysts of Eimeria. There was no significant difference (p>0.05) between FEC in organic and conventional animals. Calves younger than 6 months showed significant higher infection (p<0.05) than calves between 7 and 12 months of age. The weight gain observed during the study was of 327g/day and 280g/day for conventional and organic systems animals, respectively. Consequently, the combination of sustainable practices of grazing associated with the selective application of anthelmintics may be a feasible alternative for nematode control in a conventional system and in transition to an organic one.

Optimization of in-house ELISA based on recombinant major sperm protein (rMSP) of Dictyocaulus viviparus for the detection of lungworm infection in cattle

The aim of this study was to optimize an in-house ELISA based on a recombinant version of the major sperm protein (MSP) of Dictyocaulus viviparus for routine diagnosis of lungworm infection in cattle. A recombinant MSP (rMSP) was cloned into pGEX-6P-1 vector and expressed as a glutathione-S-transferase (GST) fusion protein in Escherichia coli BL21 (DE3) chemically competent cells. The product was then employed as capture antigen in an ELISA, and validated against 304 samples of known status (216 negative and 88 positive) in which the antibody levels in sera had also been measured earlier with a commercial ELISA kit (Ceditest® lungworm ELISA). The receiver operating characteristic (ROC) curve analysis of the ELISA results estimated the optimized diagnostic sensitivity and specificity as 97.7% (95% confidence interval [CI]: 91.9-99.7%) and 98.1% (CI: 95.3-99.5%), respectively. The results from the in-house rMSP-based ELISA were compared with results obtained on both fecal examination and the Ceditest® lungworm ELISA. Rising antibody levels in sera of experimentally infected calves were observed between 21 and 28 days post infection, when patency was also confirmed by the presence of larvae in feces. Notably, using the in-house rMSP-based ELISA infection was confirmed in calves shedding larvae approximately 3-4 weeks post inoculation, while using the Ceditest® lungworm ELISA those animals remained negative. Additionally, 251 sera samples from calves naturally exposed to the parasites on pasture were used to evaluate the test. In in-house rMSP-based ELISA no cross-reactions were observed with sera from calves infected with the gastrointestinal nematodes (Ostertagia ostertagi and Cooperia oncophora), even though the presence of eggs in the feces was confirmed. Overall, the in-house rMSP-based ELISA optimized in this study showed excellent diagnostic performance for detection of lungworm infection in cattle.

Ostertagia ostertagi in first-season grazing cattle in Belgium, Germany and Sweden: general levels of infection and related management practices

The objective of this study was to determine the prevailing levels of infection with Ostertagia ostertagi in first-season grazing calves and related management factors in three European countries (Belgium, Germany and Sweden). A cross-sectional survey was performed in first-season grazing dairy cattle during 2 consecutive years. Levels of infection with O. ostertagi were assessed by a standardized serum pepsinogen assay at the end of the grazing periods 2006 and 2007 and information on control measures against gastrointestinal nematodes were collected at the same time through a questionnaire. Information was collected from a total of 358 herds in 2006 and 726 herds in 2007. The general infection patterns were similar in the different countries and the 2 years with the majority of the herds having a low (<1 UTyr) or intermediate pepsinogen result (1-3 UTyr) and only 2-6% of the herds having levels of infection that are considered to induce significant production losses (>3 UTyr). The level of nematode control was high in each country, which is illustrated by the widespread use of anthelmintics (69-83% of herds) and the frequent combination of anthelmintic use and control through pasture management (>50% of herds combined two or more protective measures). However, the used control methods showed clear differences between the countries. After taking into account the effect of anthelmintic treatment, herd mean pepsinogen levels were significantly lower in large herds, in calves grazing on a small paddock (vs. pasture) and on mown (vs. non-mown) pastures and if turn out on pasture was postponed. The collected data may serve as a baseline from which we can monitor the methods and success of gastrointestinal nematode control in dairy cattle.

Effects of pastures' re-wetting on endoparasites in cattle in northern Germany

The influence of re-wetting of pastures on the occurrence of important endoparasites in cattle was monitored over the course of three years. The study was conducted on a peninsula at the German North-Sea Coast. The cattle were stabled from November to April. During summer season, they were kept on pastures included in a nature protection program differentiating between three states of re-wetting. Faecal samples from randomly selected animals were analysed with routine diagnostic methods for the occurrence of Eimeria spp., nematode and trematode eggs and lungworm larvae. Samples were taken three times per year: before turning out, in the middle of the grazing season and at the end. After a diagnostic and plausibility check, a total of 692 samples could be used for statistical analysis. The overall prevalence was 29.5% for Eimeria spp. and 42.2% for nematodes. Eggs of the liver fluke and lungworm larvae were only detected at very low levels. Statistical analyses were performed with a generalized linear model including the fixed effects wetting status, farm, year, and if it was the first summer on pasture for the animal. Significant influences on nematodes were detected for the stage of re-wetting, while Eimeria spp. were significantly affected by the grazing period. These findings indicate that the important parasites liver fluke and lungworm have not hitherto been affected at all by re-wetting measures. Furthermore, the prevalence of nematodes and Eimeria spp. did not increase. In conclusion, no clinical signs for parasitic diseases and no significantly elevated infection levels were shown after the third year of re-wetting, but even longer observations are essential to evaluate long-term consequences.

Effect of biological control through the daily application of spores of Duddingtonia flagrans in lambs kept under an evasive grazing system in the Netherlands

In 2004, an experiment was carried out to evaluate the effect of biological control through feeding spores of Duddingtonia flagrans on parasitic gastroenteritis in lambs, kept under an evasive grazing system. In total 66 lambs were used. Forty naturally infected 3-month old ram lambs were weaned in mid June, and divided into four groups of 10 lambs. On 21 June, G1-G4 were moved to four separate virtually clean plots, they were moved after 4 and 8 weeks to similar plots, and housed after 12 weeks to be necropsied 16 days later. The other 26 lambs had been raised helminth-free, and were used as pairs of tracer lambs. All but one of these pairs, were grazed during the last 2 weeks on each plot. The remaining pair (TA) was grazed during the last 2 weeks on pasture (30 August to 13 September) on the plot that had been grazed by G3 between 19 July and 16 August, to study inhibited development in Haemonchus contortus. All lambs were fed 200 g of concentrates daily throughout the whole period, and those of G1 and G2 were also fed 500,000 spores of D. flagrans/kg bodyweight daily. The faecal cultures demonstrated a high reduction in yield as a result of fungal application. However, no differences between groups were seen in weight gain, faecal egg counts, pasture larval counts, worm counts and tracer worm counts. H. contortus was the dominant species, and it is obvious that the moves at 4-week intervals prevented the development of severe haemonchosis. This is in particular demonstrated by the much higher worm counts in the two TA tracer lambs grazed. Nevertheless, increases to high faecal egg counts 3 weeks after the first and second moves, indicated acquisition of infection before these moves and at least subclinical haemonchosis. This was supported with the worm counts of lambs and tracer lambs. A higher proportion of inhibited early L4 than in other tracers and than in the permanent lambs were found in the pair of TA tracer lambs. This indicates that moves to new pastures in late summer and autumn delays the onset of inhibition.

Targeted selective treatment of lungworm infection in an organic dairy herd in Sweden

The effect of targeted selective anthelmintic treatment on the seroprevalence of the lungworm Dictyocaulus viviparus in cattle was investigated. The study was commenced on an organic dairy enterprise in Sweden in November 1998 after the observation of an outbreak dictyocaulosis in the herd, and then continued for almost 3 years. The first year sampling was conducted on a monthly basis and then biannually with the exception of between August and November 2000 when sampling was performed monthly following a second outbreak of dictyocaulosis. Throughout the study, blood samples were examined for specific IgG(1) levels from all animals in the herd that had been grazing for more than 3 months. At the first sampling occasion, 13% out of the 90 blood samples were seropositive. One month later, after targeted selective treatment with eprinomectin (Eprinex), Merial), the whole herd was seronegative. Seroprevalence then gradually increased and 1 year later it returned to levels similar to those observed at the start of the study. At turnout in April 2000, seroprevalence was 1.3% but it then rapidly increased to 28% and 30% in August and September, respectively. This increase was mainly due to an increase in FSG animals of which many were coughing. Consequently, all seropositive animals were injected with ivermectin (Ivomec), Merial) at 0.05 mg/kg body weight in late August 2000. Although all animals recovered, seroprevalence was only reduced to 12% 1 month later. The differences in seroprevalence after both of these anthelmintic treatments were probably attributed to the timing. The first deworming with eprinomectin was conducted in November when the infection already was transient, whereas ivermectin in connection with the second outbreak was injected in a more acute phase of the infection cycle. Infection levels in 2001 were low with seroprevalences of 2.3% and 5.6% in May and September, respectively. These results show that dictyocaulosis in Sweden can be effectively controlled by the use of macrocyclic lactones. However, the infection was not eradicated from the herd despite close monitoring of the seroprevalence and targeted selective treatment of every seropositive animal on two occasions.

Associations between dairy herd management factors and bulk tank milk antibody levels against Ostertagia ostertagi

A cross-sectional questionnaire survey was performed on dairy herds in Flanders (Belgium) to detect management factors that are associated with an increased gastrointestinal parasite infection level of adult dairy cows. At the end of the grazing season, information concerning general herd factors, pasture management and anthelmintic treatment strategy was obtained from 956 herds. A bulk tank milk sample was obtained from 779 out of the 956 herds and the antibody levels (ODR) against Ostertagia ostertagi were determined. The associations between ODR and herd management factors were studied by two linear regression models. The first model evaluated the effect of general herd factors and the level of the cows' exposure to pasture. Large sized herds had significantly lower ODRs as compared to medium (P=0.001) or small sized herds (P=0.03). Herds with only dairy cows had lower ODRs than herds with both dairy and beef cows (P=0.02). An increased exposure to pasture of the cows was associated with higher ODRs (P<0.001). The second model was built to evaluate the effect of pasture management factors and anthelmintic treatment strategy. Later turn-out on pasture (P<0.001) and mowing (P=0.002) were both significantly associated with lower ODRs. Cows that had a restricted grazing time per day tended to have lower ODR than cows that grazed 24 h per day (P=0.07). An increased exposure to pasture of the heifers was significantly associated with higher ODRs (P=0.001). No associations were found between ODR and calf related management factors, anthelmintic treatment strategy, time of turn-in, rotational grazing type or stocking rate. Later turn-out on pasture, mowing and restricting the grazing time per day are factors that can be applied immediately on dairy farms to reduce economical losses due to gastrointestinal nematodes.

The possibilities and limitations of evasive grazing as a control measure for parasitic gastroenteritis in small ruminants in temperate climates

Between 1999 and 2003 studies were done at Utrecht University on the population dynamics of gastrointestinal nematodes and the potential to use evasive grazing for the control of nematode infections in small ruminants. On most pastures grazed in May and June it took at least 3 weeks before high pasture infectivity levels for Haemonchus contortus developed while it took at least 2 weeks on pastures grazed in July, August and September. Occasionally, larvae emerged earlier on pasture when high temperatures coincided with rain. Pasture infectivity levels for H. contortus subsequently increased and the highest levels were found between 5 and 9 weeks on pastures grazed in May-June and between 3 and 9 weeks on pastures grazed in July, August and September. Pasture infectivity usually had decreased again to low levels after approximately 3 months. Larvae of the other trichostrongylids emerged later on pasture. However, patterns of Teladorsagia circumcincta, Trichostrongylus spp. and Cooperia curticei were basically similar to H. contortus. Strongyloides papillosus larvae emerge within 2 weeks on pasture and survival is short. On the other hand Nematodirus larvae took a lot longer to emerge on pasture than the other trichostrongylids. The results imply that only on a small proportion of farms (mixed dairy cattle/sheep farms; some organic dairy goat farms) evasive grazing can be recommended as only control measure for parasitic gastroenteritis. However, the present data offer possibilities to combine evasive grazing with other methods in an integrated control scheme.

Seroprevalence of Dictyocaulus viviparus in first grazing season calves in Sweden

A serological survey was carried out to determine the prevalence and geographical distribution of Dictyocaulus viviparus in calves after their first grazing season in Sweden. A total of 754 animals from 76 randomly selected herds in seven geographical regions were examined between September 24 and December 19, 2001. To get an indication about the geographical distribution of the infection 41 herds with beef-suckler calves were investigated. On each farm, blood was collected from 8 to 10 animals after an average of 26 +/- 24 days post-housing to determine specific IgG1 levels against a possible lungworm sperm antigen that is highly specific against patent infections of D. viviparus. We also investigated the seroprevalence of lungworm infection in relation to cattle management. In one region additional samples were analysed from 35 herds either with: (a) beef-suckling calves that were dewormed at housing, (b) untreated organically raised dairy calves, and finally from conventionally raised dairy calves either, (c) with or, (d) without a prophylactic anthelmintic treatment programme against gastrointestinal parasites on pasture. A questionnaire was used to obtain information about herd size and management, including measures to control nematode parasites on the farm. A total of 86 (11.8%) out of 754 animals had antibodies against D. viviparus, and at least one infected individual was detected in 30 (39.5%) of the 76 herds examined. Lungworm infected animals were found throughout the country and there was no significant differences between regions, although in southern and southwestern Sweden 70.0% of the herds were infected. Furthermore, there were no major differences in the seroprevalence in relation to management. Between 40.0 and 44.4% of the herds were infected irrespective of management, with the exception of calves from organic herds where no seropositive samples were found (0%). This result is in contrast to previous findings of lungworms in Sweden, and indicates that the parasite status on organic farms is diverse.

Individual variation and effect of priming dose level on establishment, growth and fecundity ofCooperia oncophorain re-infected calves

We investigated the effect of bovine anamnestic immunity on a range of parasitological variables. To this end, calves were primed with a single oral dose of 30 000 or 100 000 infective larvae (L3) ofCooperia oncophora, drenched with anthelmintic, maintained worm free in the following 2·5 months and subsequently re-infected with 100 000 L3. Parasitological profiles of low, intermediate, and high responders were compared. The reduction in establishment of the worms was shown by a lower worm burden and increased percentage of fourth-stage (L4) larvae. Worm length and fecundity were similarly reduced by both priming doses but, the speed by which the effect occurred differed between animals primed with 30 000 or 100 000 L3. The difference in establishment between the responder types demonstrates that the ability of intermediate responders to mount a more effective and faster immune response compared to low responders is sustained after secondary infection.

The effect of treatment with eprinomectin on lungworms at early patency on the development of immunity in young cattle

An experiment was carried out to study the effect of topical application of eprinomectin at early patency on the build up of infection and development of protection against Dictyocaulus viviparus in young cattle. Three groups of six calves were used and parasitological and blood variables were monitored at weekly intervals throughout the trial. At the start of the experiment calves in groups A and B were experimentally inoculated with 100 D. viviparus infective third-stage larvae (L3) for five consecutive days, whereas calves in group C served as uninfected controls. The calves in group A were each treated with eprinomectin (0.5mg/kg bodyweight) in a pour-on formulation at early patency at day 24 post the first inoculation, whereas the calves in groups B and C were left untreated. Seven weeks following anthelmintic treatment all groups were challenged with 1500 L3. Another 4 weeks later the animals were sacrificed and established worms in the lungs were counted. Moderate transient signs of lungworm disease occurred both in groups A and B. However, group B calves were found to be about 8 times more resistant than those in group A, whereas the naive infection controls in Group C was found to be about 35 times more susceptible to infection. Also the ELISA values showed that the course of infection was different between experimental groups. The eosinophil counts prior to and at the time of slaughter indicate that immunity was involved in the protection and the response was correlated with previous exposure and worm load. Weight gains differed significantly, but only between groups A and C and between groups B and C that on an average were approximately 13kg heavier at the termination of the experiment. It was concluded that eprinomectin was effective against established adult lungworms. However, the untreated calves (group B) developed a more marked resistance to lungworms compared to those that were subjected to anthelmintic treatment at early patency (group A). On the other hand, the cumulative number of excreted larvae was on an average 43 times higher in group B as compared to group A. Consequently, infected calves that remain out on pasture should be treated. This will restrain transmission of the parasite despite the fact that immunity is deteriorated.

Treatment vs non-treatment of helminth infections in cattle: defining the threshold

Helminth infections are an important cause of lost productivity in livestock world-wide, often necessitating anthelmintic treatment. However, a large part of the anthelmintics are used indiscriminately because the parasite levels are too low to justify treatment or because the treatments are not correctly programmed, resulting in undertreatment or overtreatment. The objective of this paper is to discuss possible thresholds for anthelmintic treatment of some of the more important helminth infections in livestock, i.e. gastrointestinal nematodes, lungworms and liver fluke, to promote a more appropriate use of anthelmintics. When possible, a distinction is made between therapeutic thresholds, production-based thresholds and preventive thresholds. A "therapeutic threshold" is intended to identify (an) animal(s) with parasite levels that necessitate immediate treatment. The therapeutic threshold is basically the diagnosis of clinical disease, and can be determined relatively easily for the parasites discussed in this paper. A "production-based threshold" is intended to measure the effects of sub-clinical parasitism on productivity parameters, such as weight gain and milk yield, before clinical disease occurs. Finally, a "preventive threshold" is meant to predict future infection levels, to enable the application of appropriate control measures.