Isabelle Pors

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.

Molecular characterization of Cryptosporidium spp. in pre-weaned kids in a dairy goat farm in western France

A longitudinal study was undertaken to characterize the course of Cryptosporidium infection in a dairy goat farm located in western France. Two cohorts of twenty-five and fifteen animals, respectively, were sampled once a week from birth to weaning. Each individual fecal sample was screened using direct immunofluorescence (IFT) and if found positive, the Cryptosporidium species was identified using PCR analysis. Seventeen (68% [95% CI: 44-91]) animals were positive at least once during the first study and 14 (93% [95% CI: 80-100]) during the second, after IFT examination. In the first study, the age at first excretion was 17 days and the peak of excretion (mean arithmetic excretion: 22,700 oocysts per gram (opg) of feces) was recorded when kids were between 22 and 28 days old. For the second study, the age at first excretion was 10 days and the peak of excretion (mean arithmetic excretion: 3.4 × 10(6)opg) was recorded in animals aged between 10 and 14 days. Clinical signs were observed only in animals of the second cohort. DNA sequence analysis at the 18S ribosomal RNA locus was successful for 9 of the 27 IFT-positive samples in the first cohort and for 10 of the 34 positive isolates in the second cohort. All isolates were identified as Cryptosporidium xiaoi except one which was identified as Cryptosporidium parvum. Our results confirm that goat kids are hosts for C. parvum and C. xiaoi and that infection by C. xiaoi may be associated with mild clinical signs.

Efficiency of feeding Duddingtonia flagrans chlamydospores to control nematode parasites of first-season grazing goats in France

A field trial, conducted over two consecutive years, was aimed at assessing the efficacy of the administration of spores of the nematophagous fungus Duddingtonia flagrans to young goats for the control of nematode parasite infections on a French commercial dairy goat flock. For both years, the first-year grazing kids were divided into two similarly managed groups (fungus and control groups): in 2003 a daily dose rate of 5 × 105 spores/kg body weight was given to the fungus-group animals, while in 2004 a daily dose rate of 106 spores/kg body weight was used; the other half of the kids, acting as control, did not receive the spores. Parameters measured every 3 weeks included nematode egg excretion, larval development in faecal cultures and pasture larval counts. Additionally, at the beginning, the middle and the end of each grazing season, the goats were weighed and blood samples for pepsinogen determination were collected. In 2003, similar results were recorded for all the measured parameters in the control and fungus groups. In contrast, in 2004, the kids receiving the spores showed lower faecal egg counts and pepsinogen levels at the end of the season and higher growth rate compared to kids of the control group.

Periparturient rise in fecal egg counts associated with prolactin concentration increase in French Alpine dairy goats

Abstract Previous data on periparturient relaxation of immunity during gastrointestinal nematode infection in goats are scarce and conflicting; one study carried out in fiber (Angora) goats showed a positive association of fecal egg counts with prolactin concentrations around parturition, whereas the two other available studies dealing with dairy goats, gave divergent results. The objectives of the study were thus to assess the occurrence of a periparturient rise in fecal egg counts in dairy goats and to examine a possible relationship between the level of milk production and the intensity of the periparturient rise. A total of 28 French Alpine grazing dairy goats naturally infected with Teladorsagia, Trichostrongylus, and Oesophagostomum were allocated into two groups according to their reproductive status; group 1 (n = 7) consisted of nonpregnant lactating animals in the 3rd month of lactation, whereas group 2 (n = 21) was composed of dry goats at 6 weeks before term. Fecal egg counts, pepsinogen and phosphate blood concentrations, blood eosinophil counts, and prolactin concentrations were individually monitored at weekly intervals for 12 weeks (from midwinter to early spring). The mean fecal egg counts were significantly higher in pregnant goats during the 2 weeks before (668 versus 242 eggs per gram of feces (epg), P < 0.05) and the 2 weeks after (962 versus 279 epg, P < 0.01) parturition as compared with nonpregnant lactating animals. No significant difference was seen in the composition of larval cultures between the two groups of animals, with Oesophagostomum infective larvae being found predominantly, particularly at the time of parturition. Pepsinogen and phosphate concentrations as well as blood eosinophil counts were similar between the two groups throughout the survey and indicated a moderate larval challenge. The mean prolactin concentration measured in pregnant goats was significantly higher (P < 0.01) at the time of parturition (298 versus 130 ng ml−1) and at 4 weeks after parturition (387 versus 193 ng ml−1) than that determined in nonpregnant animals. Furthermore, a significant correlation (rs = 0.30, df = 79; P < 0.01) between fecal egg counts and prolactin concentrations was recorded for the pregnant goats during the 4-weeks period around parturition.

Evaluation of oral tilmicosin efficacy against severe cryptosporidiosis in neonatal kids under field conditions

Many compounds have been screened for their potential anti-cryptosporidial activity in ruminants but none of them has been totally efficient in controlling the disease. Macrolide antibiotics have demonstrated some activity against Cryptosporidium spp. in humans. Tilmicosin is a macrolide antibiotic, available in France in an oral form (Pulmotil AC, Lilly France). The preventive efficacy of tilmicosin was evaluated in a goat farm experiencing severe clinical cryptosporidiosis in kids. Twenty-two kids were separated from their dams just after birth and placed in a separated pen. They were divided into 3 groups: an untreated group (10 kids), group 1 (6 kids) receiving tilmicosin at 25mg/kg BW/day and group 2 (6 kids) receiving tilmicosin at 50mg/kg BW/day. Tilmicosin was individually given by oral route from day 2 of age for 10 days. Three times a week, individual faecal samples were performed to assess the oocyst output. Clinical data, i.e. diarrhea and mortality, were recorded. In control kids, the highest prevalence and intensity of excretion were observed between day 6 and day 16 of age and mortality reached 90%. Excretion dynamic and clinical consequences were similar in both treated kid groups. Finally, tilmicosin did not demonstrate any activity against severe kid cryptosporidiosis in field conditions.

Dynamics of excretion and molecular characterization of Cryptosporidium isolates in pre-weaned French beef calves.

Studies on excretion and molecular characterization of Cryptosporidium have been mostly conducted in dairy calves, both diarrhoeic and non-diarrhoeic. Little is known about Cryptosporidium in beef calves, especially in non-diarrhoeic ones. This study was conducted in a herd of Parthenais beef cattle (France) with no history of clinical cryptosporidiosis. Twenty-five calves were sampled once a week from birth to one month of age (age range: 5-34 days). At each sampling date, presence of clinical signs of cryptosporidiosis (diarrhoea) was recorded. Oocyst excretion was assessed using the Heine staining method and a direct immunofluorescence method (Merifluor(®) C/G) which allowed quantification (oocysts per gram of faeces, opg). All samples were subjected to a two-step nested PCR protocol to amplify the 18S rRNA gene and amplification products were sequenced. None of the calves presented diarrhoea. Twenty-three of them excreted oocysts at least one sampling date. Prevalence of excretion was maximal when calves were 27-34 days old, with a percentage of excretion of 85% in this age category [95% CI: 70; 100]. Mean excretion was maximal when calves were 20 to 26 days old, with a mean excretion of 7.6×10(5) opg (range: 0-8×10(6) opg). 32 isolates were successfully identified: 27 as Cryptosporidium bovis, 4 as Cryptosporidium ryanae and 1 as Cryptosporidium parvum. C. bovis was isolated from samples of calves between 11 and 33 days old. C. ryanae was isolated from samples of calves between 17 and 34 days old. C. parvum was isolated from one calf aged 13 days. This survey demonstrated the high infection rate of non-diarrhoeic beef calves by Cryptosporidium species other than C. parvum.

Efficacy of pyrantel tartrate against experimental infections with Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis in goats

The efficacy of pyrantel tartrate was evaluated in goats against induced infections with Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis. All the strains were of sheep origin and tested for susceptibility to pyrantel tartrate in sheep at the standard dose rate (20 mg kg-1) prior to the infection of goats. Fifteen French Alpine female goats were inoculated with the three nematode species. On Day 25 post-infection, goats were randomized into an untreated control group and two pyrantel treatment groups (20 mg kg-1 bodyweight once, and 40 mg kg-1 bodyweight as two doses 24 h apart). The goats were killed and processed for worm recovery 10 days after treatment. The two dose rates achieved high and similar levels of efficacy (> 96%) against Haemonchus contortus and Teladorsagia circumcincta. Against Trichostrongylus colubriformis, however, pyrantel tartrate was less effective at both dose rates as worm reductions ranged from 55 to 62%.

Molecular characterization of Cryptosporidium isolates from pre-weaned calves in western France in relation to age.

Eighteen pre-weaned female calves from a single beef cattle herd in western France were sampled weekly from birth to 21/2 months of age in order to characterize Cryptosporidium oocyst output. 182 fecal samples were screened for the presence of oocysts after concentration using immunofluorescence analysis. DNA was extracted from positive samples and a PCR-RFLP protocol, with the restriction enzyme SspI and MboII, to amplify the partial SSU rRNA gene was performed. For the subtyping of Cryptosporidium parvum, a gp60 PCR was carried out. All animals excreted oocysts at at least one sampling date and 80% of the calves presented a mild diarrhea at at least one occasion, with no mortality. The prevalence of excretion reached 94% when calves were 17-23 days of age. The mean number of oocysts at the peak of excretion (10-16 days) was 5 × 10(5) oocysts per gram of feces. PCR-RFLP analysis was successful for 61 of 84 positive samples: 14 were identified as C. parvum, 15 as Cryptosporidium bovis, and 22 as Cryptosporidium ryanae. Ten mixed infections with all combinations of these species were also identified. Calves excreted the following Cryptosporidium species: C. parvum between 7 and 27 days of age, C. bovis between 11 and 38 days and C. ryanae from 19 to 72 days. The IIaA15G2R1 zoonotic subtype of C. parvum subtype was the only subtype identified. We observed the presence of different Cryptosporidium species depending on the age of the animals. This study showed that C. parvum and C. bovis can infect beef calf neonates at similar levels of oocyst excretion with or without clinical signs and that C. parvum isolates had zoonotic potential.

Control of cryptosporidiosis in neonatal goat kids: Efficacy of a product containing activated charcoal and wood vinegar liquid (Obionekk®) in field conditions

Many compounds have been screened for their potential anti-cryptosporidial activity in ruminants but none of them has been totally efficient in controlling the disease. A product containing activated charcoal and wood vinegar liquid demonstrated a good efficacy in controlling clinical signs and oocyst excretion in calves experimentally infected. This product (Obionekk(®), Obione, Charentay, France) was given to goat kids in field conditions. The product was administered in a preventive way at the dose rate of 3.75 g/day/kid of Obionekk(®) from the age of 3 days to the age of 17 days in suspension in milk replacer twice or three times a day. A significant reduction of oocyst excretion was observed when the product was given 3 times a day when compared to control group. The clinical signs (diarrhoea) were significantly reduced whatever the rhythm of distribution when compared to control group. These results demonstrated the efficacy of Obionekk(®) in preventing cryptosporidiosis in goat kids in field conditions.