Higher Faecal Egg Counts Research Articles

Resistance and resilience of West African Dwarf goats of the Nigerian savanna zone exposed to experimental escalating primary and challenge infections with Haemonchus contortus

We assessed the resilience and resistance to infection with Haemonchus contortus of savanna West African Dwarf (WAD) goats from northern Nigeria. Adult male goats ( n = 32) were given an escalating immunizing infection, comprising 5 weekly infections with increasing numbers of larvae. On day (D) 56 they were segregated into low (LFEC) and high (HFEC) faecal egg count phenotypes, and within each phenotype 7 goats were treated with anthelmintic and seven received no treatment. Four goats were culled for worm counts. Fourteen additional goats acted as naïve controls until D56. All, except seven naïve, were challenged with 6000 L3 of H. contortus on D63 and culled on D81, together with the seven naïve goats. The escalating infections had no effect on body weight of the goats. Neither deworming, nor challenge infection and previous experience of infection influenced body weight post-challenge (pc). There was no effect of the escalating infection on packed cell volume (PCV) of blood cells, however, the HFEC phenotypes tended to have lower values than their LFEC counterparts and controls towards the end of immunization. Virtually all goats maintained normal PCV values (28–32%) throughout, without clinical evidence of anaemia. After challenge infection the HFEC phenotypes had significantly lower PCV than the LFEC goats and naïve controls but without other symptoms of anaemia. Anthelmintic treatment had no influence on PCV pc. The anthelmintic-treated LFEC group harboured fewer worms on D18 pc than the untreated LFEC group with the superimposed challenge. In contrast anthelmintic treatment made only a small difference to the worm burdens of the HFEC group pc. In week 7 there was a strong correlation between FEC and PCV among all the goats that experienced the immunizing infection. With anthelmintic treatment taken into account, higher FEC and lower PCV in week 7 predicted higher worm burdens at the end of the experiment, but both relationships were dependent on and differed between the anthelmintic treatment groups. Overall, we found no parasitological evidence of attenuation or loss of resistance and resilience of the Nigerian savanna WAD goat ecotype to H. contortus, suggesting that significant introgression of genes from parasite-susceptible Sahelian breeds into this WAD goat population has so far not occurred.

Anthelmintic resistance of Ostertagia ostertagi and Cooperia oncophora to macrocyclic lactones in cattle from the western United States

In June 2008, 122 yearling heifers with a history of anthelmintic resistance were obtained from pastures in northern California and transported to a dry lot facility in southwestern Idaho, USA. Fifty heifers with the highest fecal egg counts were selected for study enrollment. Candidates were equally randomized to treatment with either injectable ivermectin (Ivomec ®, Merial, 0.2 mg kg −1 BW), injectable moxidectin (Cydectin ®, Fort Dodge, 0.2 mg kg −1 BW), oral fenbendazole (Safe-Guard ®, Intervet, 5.0 mg kg −1 BW), oral oxfendazole (Synanthic ®, Fort Dodge, 4.5 mg kg −1 BW), or saline. At 14 days post-treatment, nematodes were recovered from the abomasum, small intestine, and large intestine. Parasitism was confirmed in the control group when 10/10 animals were infected with adult Ostertagia ostertagi and 9/10 animals with both developing and early L 4 stages of O. ostertagi. Similarly, 9/10 animals were parasitized with adult Cooperia spp. Fenbendazole and oxfendazole efficacy verses controls were >90% against adult Cooperia spp., while moxidectin caused an 88% parasite reduction post-treatment ( P < 0.05). Ivermectin treatment resulted in no reduction in adult Cooperia spp. Based on geometric mean percent reduction versus saline controls, all four treatments were ≥90% efficacious against adults of O. ostertagi, while moxidectin and fenbendazole were equally effective against developing and inhibited early L 4 stages ( P < 0.05). Ivermectin was not efficacious for developing or inhibited early L 4 stages of O. ostertagi. Oxfendazole failed to decrease O. ostertagi developing L 4 larvae by >90% but was efficacious for inhibited early L 4 larvae. Based on the results of this study, a source of multi-species anthelmintic resistance in cattle has been identified in the western United States.

Fecal egg counts after anthelmintic administration to aged horses and horses with pituitary pars intermedia dysfunction

To determine effects of pituitary pars intermedia dysfunction (Cushing's disease) and age on fecal egg count and time to egg reappearance after anthelmintic treatment in horses residing in similar environments. Cross-sectional study. 29 healthy horses (4 to 35 years old) and 13 horses with PPID (13 to 33 years old). Fecal egg counts were performed by use of a modified Wisconsin flotation method at 2-week intervals before and after ivermectin treatment. Horses with PPID had higher fecal egg counts before and 8, 10, and 12 weeks after ivermectin treatment, compared with counts for site-matched healthy horses. There was no difference in the period for < 90% reduction in fecal egg counts between the 2 groups. Age did not affect fecal egg counts at any time point. For similar environmental conditions, horses with PPID were more likely to have higher fecal egg counts than were healthy horses. Therefore, horses with PPID may need to have a more aggressive parasite prevention program than do healthy horses. Age did not affect fecal egg counts or time to egg reappearance after anthelmintic treatment, which suggested age alone does not likely require special consideration when designing a parasite control program for adult horses.

Epidemiology of nematode parasites of sheep around Jimma, southwestern Ethiopia

An investigation was made into the epidemiology of nematode infections of sheep in two districts of Jimma zone, southwestern Ethiopia. We used two approaches--long-term monitoring of identified sheep for nematode infection and abattoir or market survey for analysis. In the first monitoring regime, we used 80 lambs [40 sheep (20 per sex) from each district (Dedo and Yebu)] averaging 4-5 months of age. Faecal egg counts (FEC), packed cell volume (PCV) and body weight changes were monitored over a period of 1 year. Additionally, faecal samples were collected (on a weekly basis) from sheep brought to abattoir/market for 1 year to monitor faecal egg counts. The nematode parasite burden, as judged by FEC and PCV, was generally low indicating that the climatic conditions are not conducive to the development and survival of nematode eggs and the free-living stages; hence, little transmission occurred. In the experimental flocks, the highest FEC and lower PCV were recorded during the long rainy season (June to September) with peak in August and September. Faecal samples collected from abattoir/market also followed the same trend. Results from experimental sheep indicated that location had a significant (P < 0.01) effect on FEC, PCV and average daily body weight gain. The FEC and PCV for sheep in Yebu (mid-altitude) district were 126 +/- 3.33 and 30.6 +/- 0.26, whereas the values for Dedo (highland) were 93 +/- 4.35 and 32.0 +/- 0.21, respectively. The results indicate that the highland areas are comparatively less favourable to the survival and development of nematodes. Female lambs had lower FEC and higher PCV compared to male lambs (P < 0.05). The overall nematode parasite challenge in the area, however, is low. We, therefore, recommend rotational grazing management combined with monitoring parasite load and selective treatment to reduce productivity loses and pasture contamination.

Effect of high tannin grain sorghum on gastrointestinal parasite fecal egg counts in goats

The objective of three experiments was to determine the influence of high condensed tannin (CT) grain sorghum on gastrointestinal parasite fecal egg counts (FEC). Sixteen naturally infected Boer crossbred mixed-sex goats were used. Animals that were supplemented with grain daily were removed from pasture and placed in individual pens and fed treatment diets for 21 or 14 days (Experiment 3). Goats were allowed ad libitum access to water and diets containing high or low CT cracked grain sorghum. On day 0 and every 7 days thereafter, PCV, FEC and FAMACHA ® eyelid color scores (EYE; Experiment 1 only) were recorded. For Experiment 1, percentage of animals dewormed, PCV and EYE were not influenced by treatment and averaged 13.6 ± 4.5% per treatment period, 23.4 ± 0.8% and 3.2 ± 0.12, respectively, for all animals. The FEC increased after day 0 for control but not high tannin grain sorghum fed goats (treatment by day interaction, P < 0.02). As expected, EYE and PCV were negatively related ( r = −0.45; P < 0.0005). For Experiment 2, there was no influence of diet on PCV or FEC, but there was an effect of day on FEC ( P < 0.002) in which all goats had higher FEC on day 0 (1956 ± 219 eggs/g) than any other sampling day. For Experiment 3, there was no effect of feeding high CT grain sorghum on FEC (2992 ± 591 eggs/g) or PCV (25.1 ± 0.5%). In these studies, high CT grain sorghum did not consistently influence FEC and did not impact PCV or number of animals requiring chemical anthelmintic treatment.

Increased IL-4 and decreased regulatory cytokine production following relocation of Icelandic horses from a high to low endoparasite environment

Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis of horses caused by bites of Culicoides spp. IBH does not occur in Iceland where Culicoides are absent. However, following importation into continental Europe where Culicoides are present, ≥50% of Icelandic horses (1st generation) develop IBH but ≤10% of their offspring born in Europe (2nd generation) do so. Recently, we showed that PBMC from 1st generation horses produce more IL-4 than 2nd generation horses. Since helminths and allergens induce Th2 responses, we investigated whether horses domiciled in Iceland are Th2-biased, and whether this is determined by helminth infection. We compared the parasite burden and T cell responses between Icelandic horses living in Iceland or Switzerland. Horses in Iceland have higher faecal egg counts, higher tapeworm-specific IgG(T) levels and higher total serum IgE levels than horses in Switzerland. Nevertheless, horses in Iceland displayed a low proportion of IL-4-producing cells in PBMC cultures after polyclonal or parasite extracts stimulation. No IL-4-producing cells were found in PBMC from horses after stimulation by Culicoides extract. Addition of anti-IL-10 and anti-TGF-β1 to PBMC cultures of horses in Iceland increased the proportion of IL-4-producing cells after polyclonal or parasite antigens stimulation but not stimulation with Culicoides extract. This paralleled the high levels of IL-10 and TGF-β1 found in supernatants from PBMC cultures of horses in Iceland. Collectively, horses living in Iceland have a high parasite burden but low IL-4 production. This supports the hypothesis that heavy helminth infections have a suppressive effect on IL-4 production mediated by IL-10 and TGF-β1.

Growth and meat quality of kids of indigenous Greek goats ( Capra prisca) as influenced by dietary protein and gastrointestinal nematode challenge

The effect of dietary protein and gastrointestinal nematode (GIN) parasitism on growth and meat quality of growing kids was assessed using sixty (60) kids in three groups ( n = 20); A: control, B: regularly treated with ALBENDAZOLE ® and C: supplemented with dietary protein. The kids grazed in a pasture contaminated with L3 larvae of GIN. Growth and condition score were assessed at 21-day intervals. After 86 days all kids were slaughtered. Carcasses were assessed for conformation, fatness, ultimate pH and other meat quality characteristics. Parasitic challenge was assessed by means of faecal egg counts (FEC), pasture larvae and adult nematodes in the GI tract of kids at slaughter. Groups C and B had higher growth rates and body condition score and produced significantly heavier ( P < 0.05) carcasses with better ( P < 0.01) conformation and fatness when compared to those of group A. Total unsaturated and monounsaturated fatty acids were higher ( P < 0.05) in fat tissue of groups B and C. Group A had the highest FEC and group C had the lowest ( P < 0.05) FEC. The parasitic challenge of L3 on pasture reached its highest point at 42 days and there were significant ( P < 0.01) differences between the numbers of Teladorsagia spp., Trichostrongylus spp., Haemonchus contortus, Oesophagostomum spp. and Chabertia spp. found in the GI tract of kids between the three groups; group A had the highest numbers. Overall, the results showed that the increased protein content in the diet of growing kids grazing on a pasture contaminated with L3 nematode larvae resulted in the production of acceptable carcasses.

Effects of worm control practices examined by a combined faecal egg count and questionnaire survey on horse farms in Germany, Italy and the UK

BackgroundFor the control of worm infections, the strategic use of anthelmintics, often accompanied by additional farm and/or pasture management procedures, is currently applied on most horse farms in industrialized countries. However, the particular effects of the specific worm control procedures are often unclear and have only been investigated to a limited extent. We examined faecal egg count (FEC), faecal egg count reduction (FECR) and questionnaire data on farm and pasture management procedures. The aim of this study was to determine whether specific worm control practices reported to be applied in European horse farms affect worm prevalence.ResultsThis study involved 20 German, 26 Italian and 16 UK horse farms for each of which FEC were performed on a minimum of 16 horses. In total, 2029 horse faecal samples were quantitatively analysed for helminth eggs, resulting in 56.3% of the faecal samples being positive for strongylid eggs. The prevalence in the 742 German horse samples (48.1%) was significantly lower than that in the 737 Italian (61.1%) and the 550 UK (60.9%) samples. As expected, a significant effect of horse age on the infection prevalence was observed, with adult horses showing lower prevalences and lower mean FEC than foals and yearlings. The majority of the participating farms were stud farms (n = 29), followed by riding stables (n = 27) and racehorse stables (n = 6). The prevalence of strongyle infection by farm type differed between countries. While in Germany, horses on riding farms were significantly less often strongyle positive, in the UK horses on stud farms showed the lowest strongyle prevalences, whereas in Italy, no significant difference between farm types were seen. On all farms, horses received routine/preventive anthelmintic treatment. An effect of treatment frequency on strongyle prevalence was only encountered with adult horses. On farms performing more than one annual treatment, faecal samples were significantly less often positive. Furthermore, by comparing the FECR results of individual horses with their pre-treatment FEC, it was found that high pre-treatment FEC were associated with a significantly higher probability for a FECR below 90%.ConclusionOverall, age-dependent strongyle infection patterns and general worm control approaches were found to be similar on horse farms in the three countries. Also, a negative association of pre-treatment FEC and treatment efficacy was consistently found in all countries. However, mean strongyle prevalences and frequencies of anthelmintic treatments were considerably different. In addition to the age-dependent prevalence patterns, the finding of a possible negative association between high FEC and reduced FECR might argue for a focus on horses showing high pre-treatment FEC when monitoring anthelmintic treatment efficacy in the field.

ContaminaÇão da pastagem com larvas infectantes de nematoides gastrintestinais após o pastejo de ovelhas resistentes ou susceptíveis à verminose

The degree of contamination of herbage with third stage larvae of gastrointestinal nematodes was evaluated in paddocks grazed by resistant or susceptible ewes. The trial occurred from November 23, 2007 to July 22, 2008. Initially, fecal egg counts (FEC) were performed with individual samples of 130 adult ewes of the Bergamacia breed. Of those animals, nine ewes with the highest FEC (susceptible group) and 10 with the lowest counts (resistant group) were selected and moved to separate paddocks. The resistant ewes presented lower FEC, higher values of packed cell volume, total plasma protein and blood eosinophils than the susceptible ewes. The weight was also higher in the resistant group. Haemonchus spp., Trichostrongylus spp. and Oesophagostomum spp. third stage larvae were recovered from pasture. In average, the amount of Haemonchus spp. and Trichostrongylus spp. third stage larvae in the pasture were 2.19 and 2.31 times, respectively, higher in the paddocks grazed by susceptible group in comparison with those grazed by the resistant animals. Therefore, the susceptible animals should be eliminated from the flock in order to reduce pasture contamination and optimize the prophylaxis of gastrointestinal nematode infections.

Faecal Cyathostomin Egg Count distribution and efficacy of anthelmintics against cyathostomins in Italy: a matter of geography?

BackgroundIn the framework of a trial carried out in 2008 in Europe to evaluate the efficacy of major parasiticides against horse cyathostomins, pre- and/or post-treatment Faecal Egg Counts (FEC) were evaluated in a total of 84 yards and 2105 horses from nine different regions from the South, the Center, the North-Center and North-East of Italy. Specifically, on the basis of FECs of the horses present in each property, 60 out of the 84 yards were enrolled for a Faecal Egg Count Reduction Test (FECRT) using fenbendazole, pyrantel, ivermectin and moxidectin.ResultsOf the 1646 horses bred in the 60 recruited yards, 416 animals had a FEC between 50 and 150 Eggs Per Gram (EPG) of faeces and 694 a FEC >150 EPG (i.e. with total of 1110 positive animals). Of the 1110 positive animals, those with the highest FECs (i.e. 988) were included in the FECRT. The FECRT for four anthelmintic compounds showed remarkable differences in terms of prevalence of reduced and equivocal efficacy against cyathostomins in the different areas of Italy. Administration of fenbendazole and pyrantel resulted in resistance present or suspected in about half of the yards examined while resistance to ivermectin was found in one yard from central Italy and suspected resistance was detected in three more yards, one in each the North, the Center and the South. Treatment with moxidectin was 100% effective in all yards examined.ConclusionCyathostomin populations in the South and the Center of Italy were more susceptible to fenbendazole and pyrantel than the populations present in the Center-North and North-Eastern areas of Italy. Fenbendazole and/or pyrantel were ineffective in almost all properties from the North of Italy. The reasons for such a difference among the Italian regions in terms of FECs and efficacy of antiparasitic drugs are discussed, together with the role that veterinarians, and horse owners and managers should have for effective worm control programs in this country.

An evaluation of anthelmintic properties, assessed using faecal nematode egg counts, of New Zealand native flax (Phormium tenax)

AIM: To investigate the anthelmintic properties of New Zealand native flax (Phormium tenax) for cattle, using a faecal egg count reduction test (FECRT). METHODS: Twenty-six heifer calves with high (>300 epg) faecal nematode egg counts (FEC) were paired into two groups and fed either chopped flax leaves ad libitum, or barley straw at an equivalent dry matter (DM) rate, from Day 0–7; all were supplemented with 1.5 kg/head/day cereal feed supplement. On Days 8–10, all heifers were fed a common diet of 3.5 kg DM/ head/day barley straw and 1.5 kg/head/day cereal feed supplement. Heifers were weighed and faecal samples were collected on Days —6, 0, 7, and 10; samples were analysed in triplicate for FEC. The nutritive value of the flax and straw was analysed. RESULTS: Both the flax and straw had low dry matter digestibility (DMD) and protein content. Although the flax-fed claves grew more than the controls, this may have been related to gut fill. Total daily faecal egg output was similar for flax and straw groups on Day 7 (14.7 vs 15.0 x 106 eggs/day, respectively) and Day 10 (14.9 vs 15.1 x 106 eggs/day, respectively). There was no difference in the change in FEC with time between the calves fed flax or straw diets. CONCLUSION: Consumption of flax leaves did not reduce FEC in calves with a mixed nematode infection.

Haemonchus contortus and Trichostrongylus colubriformis did not adapt to long-term exposure to sheep that were genetically resistant or susceptible to nematode infections

We tested the hypothesis that Haemonchus contortus and Trichostrongylus colubriformis would adapt to long-term exposure to sheep that were either genetically resistant or susceptible to H. contortus. Sheep genotypes were from lines with 10 years prior selection for low (resistant, R) or high (susceptible, S) faecal worm egg count (WEC) following H. contortus infection. Long-term exposure of H. contortus and T.colubriformis to R or S genotypes was achieved using serial passage for up to 30 nematode generations. Thus, we generated four nematode strains; one strain of each species solely exposed to R sheep and one strain of each species solely exposed to S sheep. Considerable host genotype differences in mean WEC during serial passage confirmed adequate nematode selection pressure for both H. contortus (R 4900 eggs per gram (epg), S 19,900 epg) and T. colubriformis (R 5300 epg, S 13,500 epg). Adaptation of nematode strain to host genotype was tested using seven cross-classified tests for H. contortus, and two cross-classified and one outbred genotype test for T. colubriformis. In the cross-classified design, where each strain infects groups of R, S or randomly bred control sheep, parasite adaptation would be indicated by a significant host genotype by nematode strain interaction for traits indicating parasite reproductive success; specifically WEC and, for H. contortus strains, packed cell volume. We found no significant evidence of parasite adaptation to host genotype (P>0.05) for either the H. contortus or T. colubriformis strains. Therefore, we argue that nematodes will not adapt quickly to sheep bred for nematode resistance, where selection is based on low WEC, although selecting sheep using a subset of immune functions may increase adaptation risk. Our results support the hypothesis that nematode resistance is determined by many genes each with relatively small effect. In conclusion, selection of sheep for nematode resistance using WEC should be sustainable in the medium to long-term.

Consequences of protein supplementation for anorexia, expression of immunity and plasma leptin concentrations in parasitized ewes of two breeds

The periparturient relaxation of immunity (PPRI) against parasites in ewes has a nutritional basis. We investigated whether ewes experience a reduction in food intake (anorexia) during PPRI and if the magnitude of anorexia is affected by host production potential and dietary protein supplementation. We also investigated whether nematode infection is linked to plasma leptin concentrations in periparturient ewes. The experiment was a 2 x 2 x 2 factorial design. Two breeds of twin-bearing/lactating ewes (Greyface cross, G (n 32) and Scottish Blackface, B (n 32)) were used. Half of the ewes were trickle infected with 30,000 larvae of the abomasal parasite Teladorsagia circumcincta per week and the other half were not. During the experiment, all ewes had ad libitum access to a low-protein diet that provided less protein than the recommended allowance. In addition, half of the ewes received a protein supplement that resulted in protein intakes that exceeded recommendations. Nematode infection resulted in a breakdown of immunity to parasites and a reduction in food intake in both breeds. The breeds differed in the extent of PPRI (G ewes having higher faecal egg counts than B ewes), but not in the magnitude of anorexia. Protein supplementation resulted in a reduction in faecal egg counts, but had no effect on the magnitude of anorexia. Plasma leptin concentrations changed significantly over time, but were not affected by protein supplementation or infection. It is concluded that infection with T. circumcincta in periparturient ewes results in anorexia that is not alleviated by protein supplementation and seems unrelated to plasma leptin concentrations.

Effects of non-genetic factors on responses to gastro-intestinal nematode infections in Ethiopian sheep

The effects of non-genetic factors on responses to gastrointestinal nematode infections were examined in artificially infected indigenous Horro and Menz lambs in the central highlands of Ethiopia. The experiment involved lambs of two sexes, infection and monitoring regimens (3 levels), dam parity (4 levels) and birth types (2 levels). A total of 152 weaner lambs (103 Menz and 49 Horro) were used. Endoparasite challenge involved three infection periods (primary, secondary and tertiary) each separated by an anthelmintic treatment. Data were collected on faecal egg counts (FEC), packed cell volume (PCV), worm count, and weight gain. Female lambs were found to harbor lower numbers of T. colubriformis counts and had lower (p < 0.01) FEC in tertiary infection compared to males. Younger animals were more susceptible to the nematode infections than older animals as measured by all the parameters studied (p < 0.01). Twins had higher FEC in both secondary and tertiary infections compared to singles. Lambs born to dams of first parity had higher PCV and lower FEC values during the tertiary infection compared to other parities. These results would be used as basic information in designing a more rational control strategy and should also help to advise on better management care for less resistant sheep.

Feeding practices and effects of gastrointestinal parasite infections on live weight gain of small ruminants in smallholder mixed farms in Kenya

The objective of this study was to quantify the effects of gastrointestinal nematodosis on live weight gain (LWG) of sheep and goats kept in smallholder farms in Kenya. A total of 307 sheep and goats from smallholder farms were sampled using a 2-stage cluster and systematic random approach. Sampled farms were visited once a month for nine months during which a health and production survey questionnaire was administered, animals weighed and fecal samples taken for fecal egg count. Descriptive statistics and a generalized linear mixed model were performed in SAS. The mean LWG of suckling kids and lambs was low (mean = 46 g/day). High fecal egg count and lack of feed supplementation were identified as the main factors limiting growth. Improved helminth control and nutrition are required to optimize production.

Faecal soiling and gastrointestinal helminth infection in lambs

The accumulation of faeces in the wool of the breech area (tail, perineum and anus) of lambs, known as faecal soiling, has been shown to be one of the major factors predisposing sheep to blowfly strike. However, the causes of faecal soiling of lambs in the UK are not clearly understood. Hence, in this investigation, the relationships between faecal soiling, gastrointestinal parasitic nematode infection and resultant diarrhoea were examined in a longitudinal study of 200 lambs at two farms in south-west England. Faecal egg counts, pasture worm burdens, faecal soiling and growth rates were recorded for individually tagged lambs over the summer of 2003. Grass growth and nutritional composition (protein and fibre) and weather data were also recorded over this period. Analysis using linear mixed models showed that faecal soiling was associated with higher strongyle-type egg counts, longer periods since worming, lower live-weights, female gender, lower faecal consistency and pasture quality. The data indicate that dag scoring, especially in mid- to late summer, could be used as a rapid, non-invasive technique for selecting animals, particularly lambs, with high faecal egg counts for selective drenching to reduce the incidence of anthelmintic resistance. Selective drenching of lambs with high dag scores would also be expected to aid in the control of blowfly strike.

Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

The study was carried out to evaluate the relationship of inflammatory intestinal cells with the resistance to Trichostrongylus colubriformis infections in three breeds of sheep (Santa Ines, Suffolk and Ile de France), naturally infected. Mast cells, eosinophils, and globule leucocytes were enumerated in intestinal mucosa. Histamine concentration was estimated in intestinal tissue samples and the length of male and female specimens were determined. The three breeds of sheep showed similar cellular response in the small intestine mucosa (P&gt;0.05). There was extensive variation among sheep in the parasitological and inflammatory cell variables, even in lambs of the same breed. In general, animals presenting less inflammatory cells had a larger worm burden, higher fecal egg counts, and larger T. colubriformis worms. The inflammatory cells possibly impaired the parasite's establishment, development, and survival.

Comparing irrigated biodynamic and conventionally managed dairy farms. 2. Milk production and composition and animal health

Ten paired irrigated dairy farms under biodynamic (BD) and conventional (CV) management were compared over a 3-year period (1991–93). The paired farms were located in the irrigation districts of northern Victoria and southern New South Wales and were matched for soil type, cattle breed and farm area. The BD farms practised BD principles for an average of 16 years before the study. The effects of farm management on milk yields and composition and animal health were examined by annually surveying farm managers regarding disease incidence and chemical treatment of animals, and by measuring milk yield and composition and faecal egg counts over the experimental period. The two hypotheses tested were that (1) milk volume and milk solids per cow would be lower under BD management, and (2) the incidence of internal parasitic infection and disease would be lower under CV management. Milk production and milk components produced, both on a per hectare and per cow basis, were 24–36% higher (P &lt; 0.01) under CV management, due to significantly higher pasture intakes (P &lt; 0.001). Although the incidence of parasitic infection was similar for mature cows, CV farms consistently used a greater number of chemical treatments (P &lt; 0.05). Although BD heifer calves &lt;8 months in age had significantly (P &lt; 0.05) higher faecal egg counts, the results highlight the risk of reduced growth rates in calves due to high rates of parasite infection, under both management systems. Somatic cell counts were higher (P &lt; 0.05) under BD management, with this being consistent with the use of significantly less chemical treatments under this management system. The implications of these findings for both CV and BD management for milk production and animal health are discussed.

Heterosis analysis of Haemonchus contortus resistance and production traits in Rhoen sheep, Merino Land sheep and crossbred lambs

A crossbreeding program was conducted to evaluate the resistance status to Haemonchus contortus in reciprocal crossbred ( F 1) lambs and their Merino Land sheep (Ml) and Rhoen sheep (Rh) purebred counterparts. A total of 406 lambs were included in the study. Faecal egg counts (FEC) and haematocrit values (Hc) of all the lambs were collected 4 and 8 weeks after an artificial infection with H. contortus. FAMACHA © scores were given at the same time. Worm counts of all lambs were obtained after slaughtering at 21 weeks of age. The Ml group consistently showed the highest body weights, daily weight gains and best carcass performances, whereas the Rh group showed the lowest results. Most of the body weight parameters in the F 1 group fell intermediately between the Ml and Rh groups, though the heterosis analysis of body weight and carcass parameters showed a tendency to favour the crossbreeding group Rh × Ml. The Rh group showed, on average, the highest FEC and the lowest Hc values compared to the Ml. However, the nematode counts were not significantly different between the pure breeds. In comparison, the worm counts of the Rh × Ml crosses were significantly different from those in the Ml × Rh crosses. A heterosis analysis showed that FEC, Hc and the worm count in the F 1 group favoured the crossbreeding group Rh × Ml. These results suggested that crossbreeding Rh to Ml sheep may be a suitable way of producing lambs with improved resistance to H. contortus infection without any negative effects on production traits.

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.