Christophe Chartier

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

The level of dietary protein is known to alter the establishment and the pathophysiology of gastrointestinal nematodes in sheep. On the other hand, high-producing dairy goats are less resistant and/or resilient than low-producing ones to experimental nematode infection. During a 2-year study, we have investigated the course of a natural nematode infection (mainly T. colubriformis) in a high-producing dairy goat flock. In year 1, 50 grazing goats divided in high (HP) or low producer (LP) were compared from April to October for parasitological and milk parameters. In year 2, the 25 HP goats were only considered and were allocated to two levels of dietary protein, high level (HPr) with a protein coverage of 125% or normal level (NPr) with a protein coverage of 106%. They were monitored as above. In year 1, HP goats showed a greater nematode egg output (1856 vs. 1000epg) associated with higher values in T. colubriformis IgG in autumn than LP ones whereas the decrease in serum phosphate concentration was similar in both groups. In year 2, HPr goats exhibited lower egg output in autumn (2219 vs. 2817) vs. NPr ones. Moreover, milk yield and fat content were significantly higher in HPr vs. NPr in the 2nd part of the study. HP goats are less resistant to nematode infection in natural conditions. Resistance and resilience of HP goats may partially be improved by a protein supplementation in the diet.

Efficacy of copper oxide needles for the control of nematode parasites in dairy goats.

The spread of benzimidazole-resistant nematodes in dairy goat farms is of a great concern as probably more than 70% of the flocks are involved. As there are very few other anthelmintic options during the lactating period, we have evaluated the efficacy of copper oxide needles (CON, Copinox, Bayer, UK) in both experimental and natural infections in goats. The curative effect of CON (2–4 g) on existing worm burdens was assessed in goats experimentally infected with Teladorsagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis, compared to controls. The preventive effect of CON (4 g) on worm establishment was monitored for 2 months in animals experimentally infected with H. contortus and for 3 months in naturally infected animals on a farm exhibiting predominant infections with T. circumcincta and Oesophagostomum venulosum. In both experimental and natural conditions, the efficacy of CON was nil against Teladorsagia, Trichostrongylus and Oesophagostomum infections. In contrast, the efficacy of CON against Haemonchus was clearly established in reducing the worm burden (75%) as well as in lowering the egg output (37–95%) in relation to the establishment of new infections over several weeks. Copper oxide needles may represent an alternative to conventional anthelmintics in the control of Haemonchus infection in some goat farms.

Eprinomectin in dairy goats : dose influence on plasma levels and excretion in milk

Abstract The plasma levels and milk excretion of eprinomectin were determined in goats following topical application at doses of 0.5 mg kg−1 and 1.0 mg kg−1. The area under the concentration–time curve (AUC) was 2 times lower for 0.5 mg kg−1 (8.24 ± 3.50 ng day−1 ml−1) than for 1.0 mg kg−1 (15.68 ± 8.84 ng day−1 ml−1), suggesting that the pharmacokinetics of eprinomectin in goats is dose independent. The bioavailability of eprinomectin in lactating compared with non-lactating goats is low. This is probably due to the physiological status of dairy animals, which present a marked decrease in body fat. Comparison of the eprinomectin concentrations in the milk and plasma demonstrated a parallel disposition of the drug with a milk-to-plasma ratio of 0.10–0.25. The amount of drug recovered in the milk was 0.3–0.5% of the total administered dose. In all cases, the maximum level of residue in milk remained below the maximum acceptable level of 30 ng ml−1 permitted in lactating cattle.

Giardia duodenalis and Cryptosporidium parvum infections in adult goats and their implications for neonatal kids

During the kidding season between January and April 2003, 10 farms were selected and divided into two groups of five. The farms in group A had had serious diarrhoeal illness and losses in neonatal kids the previous year, and there were Cryptosporidium parvum infections in kids associated with diarrhoea during the survey. On the farms in group B, there was no history of diarrhoeal disease the previous year and neither C parvum oocysts nor diarrhoea were detected in neonatal kids during the survey. Faecal samples were collected once from 10 adult goats aged between one and seven years on each farm. To assess more accurately the pattern of output of oocysts of C parvum and cysts of Giardia duodenalis by periparturient adult goats, one farm was selected from each group, faecal samples were collected weekly before and after kidding from 12 goats on the farm in group A and from 10 goats on the farm in group B. There was no significant difference in the prevalence of G duodenalis cysts between the group A farms (14 per cent) and the group B farms (12 per cent), and the numbers of cysts excreted ranged from 143 to 400 cysts per gram of faeces (cpg) on the group A farms and 72 to 334 cpg on the group B farms. There was a significant difference (P=0·03) in the prevalence of C parvum oocysts at the group level between the group A farms (20 per cent) and the group B farms (6 per cent). All the adult goats excreted cysts and oocysts at some date around the kidding period; the number of animals excreting cysts of G duodenalis or oocysts of C parvum increased when they gave birth, and seven to 10 times more cysts and oocysts were shed in the three weeks around kidding than in the period more than three weeks from kidding (P<0·001).

Relationship between helminth species diversity, intensity of infection and breeding management in dairy goats

Helminth infection, species diversity (proportion of each species in the community), species number, intensity of infection and anthelmintic resistance were investigated in 16 dairy-goat farms of south-western France. The aim of the study was to estimate which breeding management factors may affect diversity and intensity of infection. Anthelmintic resistance was investigated because this factor may modify composition of nematode communities. Farm history and breeding management were recorded by means of a questionnaire. Natural and experimental infections were compared to determine which strategy was the best to estimate diversity index and number of species from nematode community of a whole herd. A total of 17 species of helminths, among which 14 nematodes, one cestode (Moniezia spp.) and two trematodes (Paramphistomum daubneyi and Dicrocoelium lanceolatum) were recovered in the 26 necropsied culled goats. One culled goat worm burden represented conveniently species number but not species diversity (Shannon index) of parasite community harboured in the whole herd. Experimental sheep infection with larvae from pooled faeces of 15 goats was the best strategy to estimate species diversity in farms. Diversity could be predicted from the number of farms from which goats originated at constitution of the herd, the duration of goat winter withdrawal from pastures, and intensity of infection. Anthelmintic resistance was correlated with the number of farms of origin, area of permanent pastures and intensity of infection. The strategy adopted for the herd constitution was a critical step as species diversity and risk of anthelmintic resistance increased with the number of farms of origin. Intensity of infection was negatively correlated with species diversity. This suggested that more diverse communities were better controlled by the host, in agreement with the widespread statement that diversity would beget stability.

Some Pharmacokinetic Parameters of Eprinomectin in Goats following Pour-on Administration

Some pharmacokinetic parameters of eprinomectin were determined in goats following topical application at a dose rate of 0.5 mg/kg. The plasma concentration versus time data for the drug were analysed using a one-compartment model. The maximum plasma concentration of 5.60±1.01 ng/ml occurred 2.55 days after administration. The area under the concentration–time curve (AUC) was 72.31±11.15 ng day/ml and the mean residence time (MRT) was 9.42±0.43 days. Thus, the systemic availability of eprinomectin to goats was significantly lower than that for cows. The low concentration of eprinomectin in the plasma of goats suggests that the pour-on dose of 0.5 mg/kg would be less effective in this species than in cows. Further relevant information about the optimal dosage and residues in the milk of dairy goats is needed before eprinomectin should be used in this species.

Prevalence of anthelmintic resistance in gastrointestinal nematodes of sheep and goats in Norway

In the period of 2008–2009, the efficacies of the benzimidazole (BZ) albendazole and the macrocyclic lactone (ML) ivermectin against gastrointestinal nematodes (GIN) of small ruminants were evaluated by means of the fecal egg count reduction (FECR) test and by post-treatment identification of surviving third stage (L3) larvae after coproculture. Sheep (n = 28) and goat (n = 28) flocks from three areas of Norway were randomly selected to assess the prevalence of anthelmintic resistance (AR), whereas only lambs from non-randomly selected sheep flocks (n = 32) with a farm management that could select for AR were investigated the second year. Only flocks with a mean excretion of nematode eggs per gram feces (EPG) ≥150 at time of treatment were included in the survey. In total, 48 (80%) and 13 (46.4%) of the selected sheep and goat flocks, respectively, fulfilled the inclusion criteria. The proportions of flocks classified as resistant (i.e., FECR <95% and with a lower 95% confidence interval of <90%) for the BZ drug albendazole were 10.5% and 31.0% in the randomly and non-randomly selected sheep flocks, respectively. When restricting the area to Rogaland County, eight flocks out of ten (80%) non-randomly selected sheep flocks showed BZ resistance. The efficacy of ML was 100% in all surveyed sheep and goat flocks. In post-treatment coprocultures from the non-randomly selected flocks, the main nematode genera were Teladorsagia/Trichostrongylus in five flocks, Haemonchus in two flocks, and a mixture of these genera in the remaining two flocks. In the goat flocks, the pre-treatment infection levels of GIN were low compared to what was found in the sheep flocks. Still, in one flock, AR against BZ in Teladorsagia/Trichostrongylus was found. New strategies and recommendations to face the emerging AR situation in Rogaland County in order to limit the spread of resistant nematodes within and into other areas are urgently needed.

Herd-level risk factors for Cryptosporidium infection in dairy-goat kids in western France.

Abstract We conducted a cross-sectional study of risk factors for herd-level kid positivity for Cryptosporidium parvum oocysts in dairy-goat farms (Deux-Sèvres, western France). From January to March 2003, faeces from a convenient sample of 879 5- to 30-day-old goat kids from 60 herds were examined microscopically after staining with carbol fuschin. Oocyst shedding was scored semi-quantitatively (0 to 4+) allowing us to obtain a cumulative score per herd. Standardized questionnaires with information about management practices were collected in each farm. We found positive kids in 32 of 60 herds (53.3%) and in 142 animals out of 879 (16.2%). We used logistic regression for two risk-factor model: (1) simple positive (case: herd score ≥1+, at least one positive kid in the herd, versus control: herd score=0), (2) strongly positive (case: overall herd score ≥3+ versus control: herd score <3+). Risk factors associated with simple positive herds were period of sampling compared to the peak of births (After versus Before, OR=4.2, 95% CI 1.2, 15.3) and practice of kid grouping by age or weight (Yes versus No, OR=4.4, 95% CI 1.0, 19.1). Risk factors associated with strongly positive herds were period of investigation (February/March versus January, OR=12.7, 95% CI 2.1, 76.6), exposure to graminaceous plants in forage (OR=11.6, 95% CI 1.7, 81.0) and type of ventilation in the goat premises (Vertical versus Wind effect, OR=14.7, 95% CI 2.1, 106.1). No important association was found between kid-management practices and herd positivity. These results suggest a major role of the environment of kids during their first hours of life in the adult-goat premises regarding the transmission of C. parvum infection.

Prevalence of gastrointestinal helminths, lungworms and liver fluke in sheep and goats in Norway

The present study describes the occurrence of various gastrointestinal helminths, lungworms and liver flukes in Norwegian sheep and goats as assessed from faecal samples and post mortem examinations performed between 2007 and 2010. Faecal samples for gastrointestinal nematode egg counts were collected from 77 sheep flocks and 30 dairy goat flocks from three geographical regions in Norway. Additionally, thirty-two lambs and 16 adult goats were euthanized for necropsy examination and for identification of adult gastrointestinal nematodes and tapeworms, lungworms and liver flukes. The survey showed that there was a higher mean excretion of trichostrongyle eggs in sheep than in goats at the individual level (392 EPG vs. 154 EPG, p<0.001). For both host species, the mean prevalence and intensity of excreted trichostrongyle eggs were significantly higher in the southern coastal region compared with the inland and northern regions (p<0.001). Third stage larvae of Trichostrongylus/Teladorsagia, Haemonchus and Nematodirus type were the most prevalent ones in the coprocultures from sheep, whereas larvae of Trichostrongylus/Teladorsagia and Nematodirus type dominated in goats. The most prevalent gastrointestinal nematode species found at necropsy was Teladorsagia circumcincta (75.0 and 81.2% respectively in sheep and goats), while the largest mean worm burdens were recorded for Haemonchus contortus in sheep (724±623) and T. circumcincta in goats (377±529). Other gastrointestinal nematode species were present at low prevalence or in low numbers. Fasciola hepatica was only found in necropsied sheep from the coastal region with a prevalence of 18.8%. The lungworm Mullerius capillaris was found from all regions in necropsied goats (31.2%) and from coastal area in sheep (3.1%). The present study indicates that H. contortus and Nematodirus battus have a wider geographical distribution to the north than expected, and describes to our knowledge the northernmost occurrence of H. contortus in the Nordic countries.

Activity of eprinomectin in goats against experimental infections with Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis.

C. Chartier, DVM, PhD, E. Etter, DVM, I. Pors, CNEVA-Niort, Laboratoire de Recherches Caprines, 60 rue de Pied de Fond, BP 3081, 79012 Niort Cedex, France M. Alvinerie, PhD, INRA-Toulouse, Laboratoire de PharmacologieToxicologie, 180 Chemin de Tournefeuille, BP 3, 31931 Toulouse Cedex 9, France EPRINOMECTIN is a new member of the avermectin/ milbemycin class of anthelmintics which have potent acaricidal, insecticidal and nematocidal activities in sheep and in cattle (Shoop and others 1996a). This novel avermectin was selected because of its low milk to plasma ratio (<0.2) allowing its development for all cattle including lactating cows (Shoop and others 1996a). There are few anthelmintics that can be used during the lactating period with a zero milk withdrawal period in ruminants in France, benzimidazoles (fenbendazole, oxfendazole, febantel) and tetrahydropyrimidines (pyrantel) are available. Due to over use, benzimidazole-resistant nematodes have become very prevalent in dairy goats in France (Cabaret and others 1995, Chartier and others 1998). This major issue in grazing goat farms is made worse by a ban on using other alternative anthelmintics such as levamisole and ivermectin during lactation, that is, 10 months per year for a dairy goat. In addition, anthelmintic drench failures in goats have also been recorded due to the use of inappropriate dose rates (McKenna 1984). This apparent lack of effectiveness is due to the requirement of a specific dosage in goats, which is higher than the standard sheep dose rates, as demonstrated for some benzimidazoles, levamisole and clorsulon (Coles and others 1989, Sangster and others 1991, Sundlof and Whitlock 1992). In this short communication, the results of a controlled trial in goats which evaluated the efficacy of eprinomectin given topically at the standard bovine dose rate of 0*5 mg/kg bodyweight against induced infections with Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta and Trichostrongylus colubriformis are presented. Eleven, twoto five-year-old Saanen goats weighing 40 to 95 kg were used. The animals were not pregnant, nonlactating and were free of trichostrongyle infections at the beginning of the experiment. The goats were housed in concrete pens and were fed barley hay with commercial concentrates. H contortus, T circumcincta and T colubriformis were INRA (Institut National de la Recherche Agronomique, Nouzilly, France) strains of sheep origin. Each goat was inoculated orally with 4000 T colubriformis, 1800 H contortus and 4000 T circumcincta infective larvae (L3) on day 0. On day 28 after infection, the goats were weighed and allocated to the following treatment groups on a random basis: five animals in the untreated control group and six in the eprinomectin treated group. Eprinomectin (0.5 per cent w/v) was applied topically with a syringe from the base of the tail to the neck at a dose rate of 0-5 mg/kg bodyweight (1 ml/ 10 kg bodyweight). A study of the pharmacokinetics of eprinomectin was undertaken on the treated goats (results not shown) and the animals were therefore necropsied 28 days after treatment. The abomasum and small intestine of each goat was removed for worm recovery. Nematode counts were performed on 1:10 aliquots. The efficacy of the treatment was determined using the formula: ([C-T]/C) x 100 where C = arithmetic mean count for the untreated control and T = arithmetic mean count for a goat treated with eprinomectin. Worm burden comparisons between groups were made using a Mann-Whitney test. No general or local adverse reaction following the topical treatment was noted. The numbers of each parasite found in individual goats together with arithmetic group means, percentage reductions and statistical significance are shown in Table 1. This is the first study to demonstrate the high activity of eprinomectin against gastrointestinal nematodes in goats when applied topically at 0 5 mg/kg bodyweight. These results are consistent with the very high nematocidal activity described in cattle by previous workers against natural or induced infections: efficacy of between 99 and 100 per cent has been recorded against adult strongyles of Ostertagia species, Haemonchus species, Nematodirus species, Oesophagostomum species and inhibited larval strongyles of Ostertagia species, when given topically at 0*5 mg/kg bodyweight (Shoop and others 1996b, Gogolewski and others 1997, Pitt and others 1997, Williams and others 1997, Yazwinski and others 1997). Nevertheless, the less than complete efficacy against T colubriformis in the present study indicates that this nematode species is probably the dose-limiting parasite for eprinomectin in goats and that the dose rate of 0-5 mg/kg when given topically could be considered as a suboptimal dosage. T colubriformis is not a nematode of cattle and in this host species the prevalence and worm burdens are usually low so that the reduction in the post-treatment worm count could be difficult to interpret. Nevertheless, efficacies lower than 90 per cent were recorded in cattle for T colubriformis in Louisiana and France at 0 5 mg/kg bodyweight (Williams and others 1997). Similarly, when the dose rate was decreased to 0-2 or 0-08 mg/kg the efficacy against T colubriformis was reduced to 98 and 87 per cent, respectively, whereas it was greater than 99 per cent for the other adult nematodes (Shoop and others 1996b).