Distribution and repeatability of nematode faecal egg counts in dairy goats: a farm survey and implications for worm control

doi:10.1053/rvsc.2002.0546

Research in Veterinary Science

Volume 72, Issue 3, June 2002, Pages 211-215

https://doi.org/10.1053/rvsc.2002.0546 Get rights and content

Abstract

The aims of this study were to characterise trichostrongyle egg excretion in dairy goat flocks under various epidemiological conditions, and to assess the relative importance of animals in their first lactation and goats with high levels of milk production on the total egg output of the flock. The repeatability of egg excretion was estimated on 4 different dates in 14 dairy goat farms in France. Egg outputs were positively skewed on most farms suggesting an aggregated distribution of parasites. Within-year repeatability coefficients ranged from 0·29 to 0·82 suggesting that, on most farms, animals with high egg excretion on one occasion are likely to show high rates of excretion on other occasions. Comparisons of egg outputs from the selected subgroups showed that the high producing goats contributed prominently to egg excretion, particularly at times of peak parasitism. Results from goats in their first lactation were more equivocal. These results provide a rationale for anthelmintic strategies in dairy goats based on phenotypic characters.

References (24)

I.A. Barger et al.
Repeatability of ovine faecal egg counts and blood packed cell volumes in Haemonchus contortus infections
International Journal for Parasitology
(1987)
C. Chartier et al.
Response to challenge infection with Haemonchus contortus and Trichostrongylus colubriformis in dairy goats: differences between high- and low-producers
Veterinary Parasitology
(1997)
C. Chartier et al.
Effects of the initial level of milk production and of the dietary protein intake on the course of natural nematode infection in dairy goats
Veterinary Parasitology
(2000)
L. Gruner et al.
Worm population characteristics and pathological changes in lambs after a single or trickle infection withTeladorsagia circumcincta
International Journal for Parasitology
(1994)
H. Hoste et al.
Distribution and repeatability of faecal egg counts and blood parameters in dairy goats naturally infected with gastrointestinal nematodes
Research in Veterinary Science
(2001)
S. Richard et al.
Genetic and environment factors associated with nematode infection of dairy goats in North Western France
Veterinary Parasitology
(1990)
T. Sreter et al.
The distribution of nematode egg counts and larval counts in grazing sheep and their implications for parasite control
International Journal for Parasitology
(1994)
M.J. Stear et al.
The repeatability of ovine faecal egg counts, peripheral eosinophil counts and plasma pepsinogen concentrations during deliberate infections with Ostertagia circumcincta
International Journal for Parasitology
(1995)
A.F. Vatta et al.
Testing for clinical anemia caused by Haemonchus spp. in goats farmed under resource-poor conditions in South Africa using an eye colour chart developed for sheep
Veterinary Parasitology
(2001)
J. Cabaret
Anthelmintic resistance in goats: from fiction to facts
(2000)

C. Chartier et al.

Repeated infections with Haemonchus contortus and Trichostrongylus colubriformis in dairy goats: comparison of resistant and susceptible animals

Parasitology Research

(1998)

E. Etter et al.

Parasitisme par les nématodes du tube digestif et utilisation du pâturage: Epidémiologie de l'infestation dans les troupeaux caprins laitiers en France

Epidémiologie et Santé Animale

(2000)

Cited by (31)

Building a combined targeted selective treatment scheme against gastrointestinal nematodes in tropical goats
2014, Small Ruminant Research
Citation Excerpt :
Furthermore, ∼70% shed less than 1000 EPG in most age groups (except for age group 3) and less than 3% of the individuals had an EPG counts above 5000. Previous epidemiological surveys described over dispersion of FEC in goats under temperate conditions in France (Hoste et al., 2001, 2002) and tropical conditions in Kenya (Keyyu and Kassuku, 1999). The present survey, performed in 103 small-scale goat flocks during the rainy season, confirmed that natural GIN infections in goats of Yucatán show over-dispersion.
The design and validation of a combined targeted selective treatment (C-TST) scheme to control gastrointestinal nematodes (GIN) of goats under tropical conditions is described. A survey performed on 1585 goats (older than 4 months) from 103 smallholder subsistence farms from tropical México (Yucatán), showed the classical over-dispersion distribution of the GIN fecal egg excretions (FEC) indicating that most goats had a low excretion of eggs and only a few had high FEC. A second stage of the survey (20 farms) tested the association between FAMACHA© and packed cell volume (PCV) (n = 638) as well as FAMACHA© and FEC (n = 627). The survey showed that FAMACHA© was a good tool to identify anemic animals but no association was found with their FEC. As a result, we proposed to combine FAMACHA© with body condition score (BCS) to identify adult animals at risk of high GIN infections. The FEC was used to identify goats needing anthelmintic (AH) treatment. The C-TST scheme was surveyed in a goat farm (mean 138 adult goats/year) in Yucatán for 6 years (8292 events recorded). In that period, the mean number of goats left without AH treatment was 57.4%. Meanwhile, nearly 30% of the goats needed only one treatment per year. Less than 15% of the goats required 2 or more treatments per year. Besides, the AH doses were distributed amongst small number of animals every month throughout the year. Thus, under the browsing conditions of Yucatán, México, the combination of BCS and FAMACHA© can be used as a screening procedure to identify animals at risk of severe GIN infections and the FEC help to reduce the number of goats treated per year with no apparent negative consequences on the goats.
Effects of gastrointestinal infections caused by nematodes on milk production in goats in a mountain ecosystem: Comparison between a cosmopolite and a local breed
2014, Small Ruminant Research
Alpine goats, a cosmopolite breed, and Nera di Verzasca, an autochthonous breed, reared in a mountain ecosystem of Lombardy, northern Italy, were tested for the effect of gastrointestinal nematode-sustained natural infections on both yield and quality of their milk. The survey was based on to the hypothesis that high levels of gastrointestinal nematode infection might affect milk yield, milk quality and lactation period length, and that the animal breed might influence such an effects. Seventy-one adult goats reared in the same farm were used in the study. From February to September 2010, 37 Alpine and 34 Nera di Verzasca goats were sampled for milk and feces monthly. Milk quantity, fat and protein contents, and somatic cell counts (SCC) were determined. The gastrointestinal parasitic infections were evaluated by fecal egg count (EPG) and animals were ranked into five classes according to their mean EPG: Le0 (Level0): <100 EPG; Le1 (Level1): 101–200 EPG; Le2 (Level2): 201–600 EPG; Le3 (Level3): 601–1500 EPG; Le4 (Level4): >1500 EPG. EPG counts and infection prevalence showed a high variability in both breeds, however the mean EPG values in Alpine goats were higher more than twice in comparison with Nera di Verzasca. Milk yield decreased in both breeds as the infection level increased. It occurred when Alpine goats reached level 3 of EPG counts while no decrease was found in Nera di Verzasca goats before reaching EPG level 4. Protein and fat contents were influenced by breed, level of EPG and milking days. Nematode infection was found to affect SCC values only at greatest levels of EPG counts. The results supported a different host–parasite relationship in the two goat breeds. In fact, though a reduction in milk yield, protein and fat contents was observed in both breeds, Alpine goats were found to be weaker in contrasting the effects of gastrointestinal nematodes than the more resilient Nera di Verzasca. The results of this survey can contribute to develop proper strategies in controlling goat parasitism by exploiting resilient breeds and improving sustainable rearing of local breeds.
Novel insights in the faecal egg count reduction test for monitoring drug efficacy against gastrointestinal nematodes of veterinary importance
2012, Veterinary Parasitology
The faecal egg count reduction test (FECRT) is the method of choice to monitor anthelmintic efficacy against gastro-intestinal nematodes in livestock. Guidelines on how to conduct a FECRT are made available by the World Association for the Advancement of Veterinary Parasitology (WAAVP). Since the publication of these guidelines in the early 1990s, some limitations have been noted, including (i) the ignorance of host–parasite interactions that depend on animal and parasite species, (ii) their feasibility under field conditions, (iii) appropriateness of study design, and (iv) the high detection limit of the recommended faecal egg count (FEC) method. Therefore, the objective of the present study was to empirically assess the impact of the level of excretion and aggregation of FEC, sample size and detection limit of the FEC method on the sensitivity and specificity of the FECRT to detect reduced efficacy (<90% or <95%) and to develop recommendations for surveys on anthelmintic resistance. A simulation study was performed in which the FECRT (based on the arithmetic mean of grouped FEC of the same animals before and after drug administration) was conducted under varying conditions of mean FEC, aggregation of FEC (inversely correlated with k), sample size, detection limit and ‘true’ drug efficacies. Classification trees were built to explore the impact of the above factors on the sensitivity and specificity of detecting a truly reduced efficacy. For a reduced-efficacy threshold of 90%, most combinations resulted in a reliable detection of reduced and normal efficacy. For the reduced-efficacy threshold of 95% however, unreliable FECRT results were found when sample sizes <15 were combined with highly aggregated FEC (k = 0.25) and detection limits ≥5 EPG or when combined with detection limits ≥15 EPG. Overall, an increase in sample size and mean preDA FEC, and a decrease in detection limit improved the diagnostic accuracy. FECRT remained inconclusive under any evaluated condition for drug efficacies ranging from 87.5% to 92.5% for a reduced-efficacy-threshold of 90% and from 92.5% to 97.5% for a threshold of 95%. The results highlight that (i) the interpretation of this FECRT is affected by a complex interplay of factors, including the level of excretion and aggregation of FEC and (ii) the diagnostic value of FECRT to detect small reductions in efficacy is limited. This study, therefore, provides a framework allowing researchers to adapt their study design according to a wide range of field conditions, while ensuring a good diagnostic performance of the FECRT.
Quantifying the sources of variability in equine faecal egg counts: Implications for improving the utility of the method
2012, Veterinary Parasitology
The faecal egg count (FEC) is the most widely used means of quantifying the nematode burden of horses, and is frequently used in clinical practice to inform treatment and prevention. The statistical process underlying the FEC is complex, comprising a Poisson counting error process for each sample, compounded with an underlying continuous distribution of means between samples. Being able to quantify the sources of variability contributing to this distribution of means is a necessary step towards providing estimates of statistical power for future FEC and FECRT studies, and may help to improve the usefulness of the FEC technique by identifying and minimising unwanted sources of variability. Obtaining such estimates require a hierarchical statistical model coupled with repeated FEC observations from a single animal over a short period of time. Here, we use this approach to provide the first comparative estimate of multiple sources of within-horse FEC variability. The results demonstrate that a substantial proportion of the observed variation in FEC between horses occurs as a result of variation in FEC within an animal, with the major sources being aggregation of eggs within faeces and variation in egg concentration between faecal piles. The McMaster procedure itself is associated with a comparatively small coefficient of variation, and is therefore highly repeatable when a sufficiently large number of eggs are observed to reduce the error associated with the counting process. We conclude that the variation between samples taken from the same animal is substantial, but can be reduced through the use of larger homogenised faecal samples. Estimates are provided for the coefficient of variation (cv) associated with each within animal source of variability in observed FEC, allowing the usefulness of individual FEC to be quantified, and providing a basis for future FEC and FECRT studies.
Effects of gastrointestinal nematodes on milk productivity in three dairy goat breeds
2012, Small Ruminant Research
Citation Excerpt :
However, substantial differences among goats can be noticed in relation to GIN infection response, a diversity probably due to a complex set of factors. For example, epidemiological studies in dairy goat flocks showed that both animals in their first lactation and high milk-producing multiparous animals have the highest FECs (Hoste et al., 2002). Moreover, both production level and production stage of the animals are relevant; in fact, previous surveys underlined a strong interaction between lactation and parasite challenge, where lactation can be depressed by a parasite infection (Chartier and Hoste, 1997).
Resistance and resilience against gastrointestinal nematodes (GIN) in sheep and to a lesser extent in goats have been more and more supported by evidence, recently. Such phenomena can be noted among different breeds as well as within a single breed. This study was performed to test the effect of GIN on qualitative and quantitative productivity of milk, and was prompted by the hypothesis that such effect might be different among goat breeds and their lactations. Thus, fecal samples from goats of three distinct breeds (216 Alpine, 130 Saanen and 33 Nera di Verzasca) were collected; their main GIN eggs were counted using a modified McMaster method. As to milk production, related data were collected monthly; using the routine infrared method they were accounted for milk quantity, fat, protein and lactose contents. Our research highlighted that the emission of parasite eggs was influenced by the goat breed and by the number of lactations. In particular, Verzasca showed the highest quantity of eggs per gram (EPG), while Saanen had the lowest values; in each breed, the number of lactations led to an increase of EPG. On one hand, milk composition showed a reduced variability among breeds, but no effect due to the parasites was observed. On the other hand, daily milk yield was strongly related to parasite burden, breed and number of lactations. In fact during first lactation, parasites had a negative effect on milk production in Alpine breed, caused a slight reduction in Saanen, while they did not affect the production in Verzasca; then, during following lactations the negative effect of parasites showed to be decreasing.
Parasitological and pathophysiological methods for selective application of anthelmintic treatments in goats
2012, Small Ruminant Research
Citation Excerpt :
Parasitological (faecal egg count – FEC), pathophysiological and performance indicators of GI strongyle infection in small ruminants has been recently proposed (Kenyon et al., 2009). For example, the FAMACHA© system (Van Wyk and Bath, 2002) can be used to identify goats suffering from anaemia (likely caused by Haemonchus contortus); a diarrhoea index can be a good indicator of actual nematode infection during the summer and autumn in a temperate climate (Cabaret, 2004); in addition, body condition scoring (Van Wyk and Bath, 2002), liveweight gain and milk production (Hoste et al., 2002a,b) are also potential methods for identifying animals requiring anthelmintic treatments. The present paper reviews the parasitological and pathophysiological/performance indicators most commonly used in goats with new insights for selective application of anthelmintic treatments.
The global problem of anthelmintic resistance in small ruminants, and in particular in goats, ensures that attention also needs to be given to the sustainability of anthelmintic treatment regimes as well as to their immediate economic benefit. There is currently a general agreement to replace the practice of treating the whole flock with targeted selective treatments on specific animals in the farm. Indeed, the potential problem associated with whole flock strategic treatment is that they do not provide populations in refugia and thus can, in some circumstances, select for anthelmintic resistance. The challenge is to choose the best criterion to select animals, which depends on the epidemiology of parasites and the management system. The present paper reviews the parasitological (faecal egg count) and pathophysiological/performance (e.g. FAMACHA© and milk production) indicators most commonly used in goats with new insights for selective application of anthelmintic treatments.

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^f1: Corresponding author: H. Hoste. Fax: (33) 0561193944; E-mail:[email protected]

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Research in Veterinary Science

Abstract

References (24)

Repeatability of ovine faecal egg counts and blood packed cell volumes in Haemonchus contortus infections

International Journal for Parasitology

Response to challenge infection with Haemonchus contortus and Trichostrongylus colubriformis in dairy goats: differences between high- and low-producers

Veterinary Parasitology

Effects of the initial level of milk production and of the dietary protein intake on the course of natural nematode infection in dairy goats

Veterinary Parasitology

Worm population characteristics and pathological changes in lambs after a single or trickle infection withTeladorsagia circumcincta

International Journal for Parasitology

Distribution and repeatability of faecal egg counts and blood parameters in dairy goats naturally infected with gastrointestinal nematodes

Research in Veterinary Science

Genetic and environment factors associated with nematode infection of dairy goats in North Western France

Veterinary Parasitology

The distribution of nematode egg counts and larval counts in grazing sheep and their implications for parasite control

International Journal for Parasitology

The repeatability of ovine faecal egg counts, peripheral eosinophil counts and plasma pepsinogen concentrations during deliberate infections with Ostertagia circumcincta

International Journal for Parasitology

Testing for clinical anemia caused by Haemonchus spp. in goats farmed under resource-poor conditions in South Africa using an eye colour chart developed for sheep

Veterinary Parasitology

Anthelmintic resistance in goats: from fiction to facts

Repeated infections with Haemonchus contortus and Trichostrongylus colubriformis in dairy goats: comparison of resistant and susceptible animals

Parasitology Research

Parasitisme par les nématodes du tube digestif et utilisation du pâturage: Epidémiologie de l'infestation dans les troupeaux caprins laitiers en France

Epidémiologie et Santé Animale

Cited by (31)

Building a combined targeted selective treatment scheme against gastrointestinal nematodes in tropical goats

Effects of gastrointestinal infections caused by nematodes on milk production in goats in a mountain ecosystem: Comparison between a cosmopolite and a local breed

Novel insights in the faecal egg count reduction test for monitoring drug efficacy against gastrointestinal nematodes of veterinary importance

Quantifying the sources of variability in equine faecal egg counts: Implications for improving the utility of the method

Effects of gastrointestinal nematodes on milk productivity in three dairy goat breeds

Parasitological and pathophysiological methods for selective application of anthelmintic treatments in goats

Regular ArticleDistribution and repeatability of nematode faecal egg counts in dairy goats: a farm survey and implications for worm control

Abstract

International Journal for Parasitology

Veterinary Parasitology

Veterinary Parasitology

International Journal for Parasitology

Research in Veterinary Science

Veterinary Parasitology

International Journal for Parasitology

International Journal for Parasitology

Veterinary Parasitology

Anthelmintic resistance in goats: from fiction to facts

Repeated infections with Haemonchus contortus and Trichostrongylus colubriformis in dairy goats: comparison of resistant and susceptible animals

Parasitology Research

Parasitisme par les nématodes du tube digestif et utilisation du pâturage: Epidémiologie de l'infestation dans les troupeaux caprins laitiers en France

Epidémiologie et Santé Animale

Regular Article
Distribution and repeatability of nematode faecal egg counts in dairy goats: a farm survey and implications for worm control