Faecal Worm Egg Counts Research Articles

Pyrantel pamoate resistance in horses receiving daily administration of pyrantel tartrate

16 horses treated daily with pyrantel tartrate (2.64 mg/kg [1.2 mg/lb], PO) as part of a prophylactic anthelmintic program. Fecal worm egg counts (FWECs) were obtained on all 16 horses. Mean FWEC was 478 eggs/g (epg; range, 0 to 4,075 epg). Three of the 16 horses were responsible for 85% of the total fecal egg output for the herd on the day of sampling. Six horses had FWECs < 200 epg. Three horses that had arrived within 4 months of the sampling date had FWECs < 100 epg. An FWEC reduction test was initiated the day after FWECs were obtained; all horses with FWECs > 100 epg (9 horses) were treated with pyrantel pamoate (6.6 mg/kg [3 mg/lb], PO), and 14 days later, the FWEC was repeated. During the 14-day period, all horses received pyrantel tartrate (2.64 mg/kg, PO) daily. Fecal worm egg count reduction was calculated for each horse. Mean FWEC reduction for the group was 28.5% (range, increase of 21% in FWECs 14 days after treatment to a decrease of 100% in FWEC 14 days after treatment). Farms should be monitored for cyathostomes resistant to pyrantel pamoate prior to use of pyrantel tartrate. Fecal worm egg counts should be monitored routinely in horses before and after treatment to ensure efficacy of cyathostome control measures.

Selection response in fecal worm egg counts in the Rylington Merino parasite resistant flock

The Rylington Merino internal parasite resistant selection line was initiated in 1987 from a wide genetic base of 100 ewe flocks. Selection for parasite resistance was based on selecting animals with a low worm egg count in a natural parasite challenge environment. The realised annual genetic gain for estimated breeding value of worm egg count is 2.7%. The genetic gain in parasite resistance has been achieved without any adverse genetic correlations with the other economically important production traits. There is an unfavourable genetic correlation between worm egg count and scouring traits. The recommendation to industry is to select for both low worm egg count and reduced diarrhoea and combine these traits with other economically important production traits. The relative weighting applied to each component trait will vary according to the local parasite challenge situation and the time frame available to achieve sustainable parasite control.

The Effect of Providing Feed Supplementation and Anthelmintic to Donkeys during Late Pregnancy and Lactation on Live Weight and Survival of Dams and Their Foals in Central Ethiopia

Anthelmintic treatment (A), feed supplementation (F), anthelmintic and feed supplementation (A+F) or traditional management (Control) was given to 166 pregnant female donkeys in three localities (Holetta, Debre Zeit and Adami Tulu) in Ethiopia during an on-farm study. Treatments started during the last trimester of pregnancy and continued until 6 months after parturition when the foals were weaned. The same treatments were administered to foals once they reached 1 month of age. Live weights of adults and foals were measured throughout the study along with work output of adult donkeys and survival to weaning of the foals. Faecal worm egg counts (FEC) and blood packed cell volumes (PCV) were recorded monthly. When applied alone, anthelmintic treatment (A) or feed supplementation (F) had no significant effect on live weight gain or foal survival. However, when combined, anthelmintic and feed supplementation (A+F) significantly (p<0.05) improved both live weight gain in adults and foals and foal survival. Workout was not affected by any of the treatments. Treatments A and A+F resulted in a highly significant (p<0.001) reduction in FEC in all three localities during the course of study and for at least 6 months after the last dose of anthelmintic in one of the study areas (Holetta). None of the treatments had any significant effect on PCV. Donkey owners in Ethiopia should be encouraged to adopt both anthelmintic treatment and feed supplementation if they expect tangible benefits in animal performance.

Genetic evaluation of crossbred lamb production. 2. Breed and fixed effects for post-weaning growth, carcass, and wool of first-cross lambs

The study evaluated post-weaning growth, carcass characteristics, and wool production of crossbred progeny of 91 sires from more than 7 maternal breeds (including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester). The sires were joined to Merino and Corriedale ewes at 3 sites over 3 years with 3 link sires in common at each site and year. Post-weaning weight at an average age of 200 days of 2841 ewes and 3027 wethers was analysed using mixed model procedures. The wethers were slaughtered at an average age of 214 days and carcass weight, fat, muscle, meat colour, and ultimate pH (24 h post-slaughter) were analysed. For ewes, hogget fleece weight, yield, fibre diameter, and faecal worm egg count (FEC) were analysed. Sire breed was significant (P &lt; 0.01), with a range of 32.8–39.0 kg for post-weaning weight, 19.1–22.8 kg for hot carcass weight, and for carcass fat levels (11.1–17.2 mm at the GR site (FatGR) and 3.4–6.5 mm at the C site, adjusted to 22 kg carcass weight), with the East Friesian cross carcasses being very lean (FatGR 11.1 mm). Sire breed was significant for eye muscle area (P &lt; 0.01) but not for eye muscle depth, meat colour L* (brightness), or ultimate pH. Sire breed was significant (P &lt; 0.01) for greasy and clean fleece weight (CFW), yield, and fibre diameter (FD), with ranges of 0.9 kg (CFW) and 4.6 μm (FD). Sire breed was not significant for FEC. Type of birth and rearing classification was significant for most traits. National estimated breeding values for the sires that were entered by industry breeders indicated that they covered a range of genetic merit for most traits within their respective breeds and were generally representative of the maternal genetics available in the industry. Where there were large differences between the sire mean and breed mean breeding values the effects on crossbred progeny performance would be small and not expected to affect our conclusions about the breed differences reported. The results provide lamb producers with comparative information on sire breeds for growth, carcass and wool traits. The considerable variation among individual sires within the respective breeds will be reported in later papers.

Seasonal Variation in the Parasite Burden and Body Condition of Working Donkeys in East Shewa and West Shewa Regions of Ethiopia

A survey of donkeys arriving at markets in three localities in East and West Shewa regions of central Ethiopia was carried out during 2002. Total faecal worm egg counts and body condition scores were measured for a total of 963 donkeys over a 12-month period. Total faecal worm egg counts did not differ significantly between localities but there was significant (p < 0.001) seasonal variation within localities. Levels of helminth infection closely followed rainfall patterns, being lowest (956 eggs per gram of faeces, e.p.g.) at the end of the long dry season (February) and highest (2022 e.p.g.) in the middle of the long wet season (August). Body condition score was associated closely with level of helminth infection (Goodman-Kruskal measure of association 0.60-0.80). Seasonal variation in body condition score reflected the temporal changes in worm burden and the availability of forage. It is suggested that a body condition score of 3 or less could be used as a simple means of identifying donkeys that require therapeutic treatment with anthelmintic. It is further proposed that economically viable strategic control of helminths in donkeys could be achieved by administering a single annual dose of avermectin-based anthelmintic at the start of the long rainy season (May-June). This may allow donkeys to recover body condition when available forage is most abundant and nutritious. It is also recommended that protein-rich feed supplementation be provided during the later part of the dry season (November-January). This may help maintain body condition when forage is scarce and the helminth challenge is at its lowest.

The point prevalence of gastro-intestinal parasites in calves, sheep and goats in Magadi division, south-western Keny

Helminths cause great economic loss in livestock in Africa, and can be categorized as either direct or indirect losses. Arid and semi-arid lands (ASAL) in Kenya comprise 71% of total land area and harbour the largest population of cattle, sheep and goats. However, little information on the distribution and impact of gastro-intestinal (GIT) parasitism in these animals is available. This survey was conducted to establish the prevalence of GIT parasites infecting calves, sheep and goats and their relative importance in Magadi division, which is semi-arid. Faecal samples were obtained directly from the rectum of 109 calves, 133 goats and 20 sheep and submitted to the laboratory for faecal worm egg counts, and coccidial oocysts examination using a modified McMaster method. The significance of differences in mean egg count per gram (epg) between animal species and herds (farms) were assessed using analysis of variance. The overall prevalence of nematodes in the calves, sheep and goats was 69.2%, 80% and 82%, respectively. About 10% of sheep and goats had epgs higher than 1 000, the remainder having light to moderate infections. The overall prevalence of coccidial oocysts in calves, sheep and goats was 30%, 44% and 45%, respectively. Poor productivity in ASAL areas, where nutrition is often poor, is likely to be pronounced in the presence of parasite infections. These findings indicate that viable internal parasite control should be implemented in the study area in order to increase the productivity of the livestock there.

Effects of Fenbendazole Slow-Release (sr) bolus on productivity of indigenous cattle on communal pasture in Sanyati area, Zimbabwe

A study was conducted to determine the effects of treatment with Fenbendazole Slow-Release (SR) bolus on productivity of indigenous cattle on communal pasture in Sanyati area, Zimbabwe. Animals were divided into two groups: 1) Fenbendazole group (animals received the Panacur SR bolus) and 2) Control group (animals did not receive the Panacur SR bolus). Worm eggs per gram of faeces (EPG), packed cell volume (PCV), albumin and live-weight gain were monitored. Faecal worm egg counts were significantly lower in the bolus treated group than in the control group (p

Across flock (co)variance components for faecal worm egg count, live weight, and fleece traits for Australian merinos

A field data set was used to estimate heritability of resistance to gastrointestinal nematode parasites and phenotypic and genetic correlations between resistance and production traits in Australian merinos. Faecal egg count (FEC) was measured at two different ages, namely, around 1 year on 16,669 animals out of 650 sires and on 5110 animals from 157 sires at hogget age (16 months). Wool production and live weight data were known for the animals at both yearling and hogget ages. An animal model was used to estimate variance components accounting for birth type, dam age, age of animal, and contemporary group. Maternal effects were small but significant ( P≤0.05) for yearling faecal egg count (YFEC), yearling greasy fleece weight (YGFW), yearling clean fleece weight (YCFW), hogget greasy fleece weight (HGFW), and hogget clean fleece weight (HCFW), and nonsignificant for hogget faecal egg count (HFEC) and other production traits. Heritability (±S.E.) of YFEC was 0.21±0.02 and, for HFEC, it was 0.38±0.03. Genetic and phenotypic correlations between YFEC and HFEC were 0.27±0.13 and 0.37±0.04, respectively. Genetic correlations of FEC with CFW, GFW, fibre diameter, and body weight were 0.11±0.08, 0.07±0.07, −0.05±0.07, and −0.14±0.07 at yearling age and −0.01±0.08, 0.07±0.04, −0.05±0.02, and −0.10±0.07 at hogget age.

Lifetime Wool. 10. Progeny faecal worm egg counts

Lifetime Wool. 10. Progeny faecal worm egg counts

Seasonal evolution of faecal egg output by gastrointestinal worms in goats on communal farms in eastern Namibia.

As a more detailed continuation of a previous study, faecal samples for worm egg counts were collected per rectum from ten marked adult animals in selected flocks of goats, in each of six villages evenly spread out in the communal farming district of Okakarara in eastern Namibia. The study was conducted on a monthly basis from August 1999 to July 2000. Average faecal worm egg counts (FECs) were highest during the warm-wet season, much lower during the cold-dry months and moderate during the hot-dry season. Least square means of FECs were 2140, 430 and 653 per gram of faeces for the three seasons, respectively. Seasonal variation in egg counts was significant (P < 0.0001). Gastrointestinal strongyles, and to a lesser extent Strongyloides species, were the predominant parasite groups identified in goats. Kidding rates peaked in the cold-dry season and mortality rates in the hot-dry season. Results of this study suggest that gastrointestinal parasitism may be a problem that accentuates the effect of poor nutrition on small ruminants during the season of food shortages in the east of Namibia and that the use of FECs per se to assess the severity of gastrointestinal parasitic infection in goats followed by chemoprophylactic strategic and/or tactical treatment, may not be the best approach to addressing the worm problem under resource-poor conditions. The use of the FAMACHA system that identifies severely affected animals for treatment is technically a better option for communal farmers.

Little anthelmintic drenching required for lambs finished over winter and spring on annually re-established irrigated pasture on the Highveld of Gauteng Province, South Africa.

As part of a trial to test the profitability of finishing weaner lambs over winter and spring on the Highveld of Gauteng province, an investigation was carried out over 4 consecutive years as to whether or not worm control was necessary while the lambs were on irrigated, improved pastures. Pastures that had not been grazed by sheep or other livestock for at least 5 years were planted to annual ryegrass (Lolium multiflora) that was ploughed under and replanted annually. Weaner lambs were randomly divided into either 2 (A and B) or 3 (A, B and C) groups and finished from April/May to November/December on a separate pasture per group. While Group A lambs were dewormed before being placed on pasture, those in Groups B and C were not. Faecal egg counts were performed at irregular intervals, and when the lambs were sold at the conclusion of each year's trial, the gastrointestinal tracts of 4-5 lambs per trial group were processed for worm recovery. Haemonchus contortus was the dominant worm species, while Trichostrongylus colubriformis, Ostertagia circumcincta and Trichuris spp. were encountered sporadically. From the results obtained it seems unlikely that there is appreciable 'carry-over' of the various worm species from year to year on pastures that are ploughed and replanted annually; thus it is improbable that there will be a build-up of anthelmintic-resistant worms. While on pasture, no drenching was required for the Group A lambs (dewormed before placing on the pasture), nor in 2 of the 4 years in Groups B or B+C that were not drenched and were lightly infected at the start. In the remaining 2 years Groups B or B+C were drenched once only during the course of each trial. Thus, under the conditions as in this study, little worm control is necessary, provided faecal worm egg counts are done to gauge the levels of infection before the lambs are placed on pasture, and to guard against the possibility of an increase in worm burdens thereafter in some years. Also, because of the apparent lack of carry-over between years, anthelmintic treatment at the time of introduction of the lambs or during the period of finishing should be safe as regards progressive selection for anthelmintic resistance. It is also likely to be cost-effective, considering the low cost of anthelmintics in relation to the price of lambs, to counter the possibility of a loss in production if lambs were to harbour relatively heavy worm burdens when introduced.

Management of drug-resistant cyathostominosis on a breeding farm in central North Carolina.

Possible anthelmintic resistance on a breeding farm where a rapid rotation anthelmintic programme had been implemented for 9 years was investigated. Cyathostomins resistant to fenbendazole and pyrantel were documented by faecal worm egg count reduction test (FWECRT). To 1) manage small strongyle transmission in a herd of horses in which resistance to both pyrantel pamoate and fenbendazole was identified and thereby reduce the risk of clinical disease in the individual animal, 2) monitor the change in resistance patterns over time and 3) monitor the efficacy of ivermectin over the study period. Targeted ivermectin treatment of horses on the farm was instituted for mature horses with faecal worm egg counts (FWEC) > 200 eggs/g (epg) and for horses < age 2 years with FWEC > 100 epg. Over a 30 month period, targeted ivermectin treatment achieved acceptable control in mares, as judged by FWEC, and improved control of patent cyathostome infection in consecutive foal crops. Egg reappearance time (ERT) after treatment with ivermectin was < 8 weeks in mares and foals more frequently in the second year of the study than in the first year. Numbers of anthelmintic treatments were reduced by 77.6 and 533% in the mare and foal group, respectively. Targeted ivermectin treatment may be an economically viable method of managing multiple drug resistant cyathostominosis. Use of ivermectin should be monitored closely for development of resistance.

Expression of acquired immunity to a local isolate of Haemonchus contortus by the Nigerian West African Dwarf goat

The capacity of young Nigerian West African Dwarf (WAD) goats to express good acquired immunity to their native geographic strain of Haemonchus contortus and the correlates of this responsiveness were studied in a laboratory experiment involving forty 7–8 month old kids. A primary immunising infection with 2000 L3 (equivalent to 260–450 L3/kg body weight) with or without challenge on D42 with 2000 L3 resulted in a mild chronic infection with a pre-patent period of 18–20 days and little or no reduction in worm burden between D14 and D56. In contrast, another group (D) of kids, whose immunising infection had been truncated with fenbendazole on D35 and later received similar challenge infection, developed good protection against challenge. Thus, worm burdens were largest in group E (challenge control), larger in group C (primary+challenge) and least in group D. Of the measures of infection used, namely faecal worm egg counts (FECs), circulating eosinophil (EOS) responses, packed cell volume (PCV) and body weight, FEC and EOS responses exhibited marked individual variability, but only FEC (geometric mean of transformed counts) and PCV showed strong correlation with worm burden. There was also a significant negative correlation between FEC and PCV. The size of inoculum used was well tolerated by the kids, as it induced only mild changes in PCV in some goats and no effect at all on body weights. This suggests that the WAD goat may possess a good measure of resistance to the pathogenic effects of its native strain of H. contortus. The wide individual variability in FEC and its strong relationships to worm burden and PCV are pointers to its likely genetic basis. There are, therefore, good prospects for further studies to identify H. contortus resistant genotypes among the WAD goat population.

Selection of sheep for response to Trichostrongylus colubriformis larvae: genetic parameters

AbstractData were analysed from a long-term selection experiment with Merino sheep, based on immunological responsiveness to the intestinal nematode Trichostrongylus colubriformis. For the first 14 years of selection, the criterion was the mean of five fortnightly faecal worm-egg counts (FECs) of pen-housed lambs that were vaccinated with irradiated larvae then challenged with normal T. colubriformis larvae. For most of the lambs born in the subsequent 6 years, the selection criterion was the mean of three weekly FECs of grazing lambs following a secondary challenge with T. colubriformis larvae. Data from 2233 lambs were included in the analyses.At the end of the experiment, the lines selected for high and low response to challenge differed by 2·3 to 2·9 phenotypic standard deviations. The heritability of average pen-tested FEC was 0·38 (s.e. 0·04), similar to that for average FEC after secondary field challenge (0·37, s.e. 007). Average FECs from the primary field challenge were less heritable (0·21, s.e. 006). Counts recorded on pen-tested animals at 3, 5, 7, 9 and 11 weeks after infection were all highly correlated genetically (estimates 0·93 to 0·99) and of similar heritability (0·33 to 0·39) with a non-significant tendency for later FECs to be more heritable. Phenotypic correlations were lower, ranging from 0·60 for counts 8 weeks apart, to 0·78 to 0·81 for adjacent samples 2 weeks apart. Single-record heritability estimates at 3, 4 and 5 weeks after secondary infection in grazing lambs did not differ statistically from each other but were highest at the 5th week after infection at 0·33 (s.e. 007).FECs determined in pens were imperfectly correlated with FECs determined at pasture (genetic correlation 0·72, s.e. 013). Phenotypic correlations of single-record FECs across primary and secondary field challenges were low (around 0·2), although the genetic correlation between mean primary FEC and mean secondary FEC was not significantly different from unity. Testing under standardized conditions in pens did not result in consistently higher heritabilities than testing immunologically primed lambs at pasture. Repeated measurement in a breeding programme offers little additional benefit, except when lambs have had ample prior experience of parasite infection, with the two measures separated by an anthelmintic treatment. If an objective of a Merino breeding programme is to reduce FEC under field conditions, then using one measure in the field, approximately 3 to 5 weeks after a secondary artificial infection, is likely to lead to long-term progress.

Effects of anthelmintic treatment and feed supplementation on grazing Tuli weaner steers naturally infected with gastrointestinal nematodes.

A study was carried out to determine the epidemiology of gastrointestinal nematodes in indigenous Tuli cattle and the effect of dietary protein supplementation and anthelmintic treatment on productivity in young growing cattle. Forty steers with an average age of 18 months were divided into 4 groups; 1) fenbendazole (slow release bolus) and cottonseed meal (FCSM group), 2) fenbendazole (FBZ group), 3) cottonseed meal (CSM group) and 4) control (no cottonseed meal and no fenbendazole) (control group). Performance parameters measured included worm eggs per gram of faeces (EPG), packed cell volume (PCV), albumin and live-weight gain. Results showed that faecal worm egg counts were lower and PCV was higher in the FCSM and FBZ groups than in the CSM and control groups (P < 0.01). Weight gains were higher in the CSM and FCSM groups than in the FBZ and control groups (P < 0.05). The cost benefits of anthelmintic treatment and dietary supplementation were apparent in this study. The improved growth performance of the FCSM, FBZ and CSM groups reflected a financial gain over the controls on termination of the study. The dominant genera of gastrointestinal nematodes on faecal culture, pasture larval counts and necropsy were Cooperia and Haemonchus. The incidences of Trichostrongylus, Oesophagostomum and Bunostomum were low.

Continued selection of Romney sheep for resistance or susceptibility to nematode infection: estimates of direct and correlated responses

AbstractDivergent breeding lines of Romney sheep, selected as lambs for consistently high or low faecal worm egg count (FEC) following natural multi-species challenge by nematode parasites, were established in New Zealand at Wallaceville Animal Research Centre in 1979 and at Rotomahana Station in 1985. In 1988 the Rotomahana lines, including an unselected control line maintained under the same management conditions, were transferred to Tokanui Station where they remained for 4 years. In 1993 elite high and low FEC animals from Tokanui, along with the controls, were transferred to Wallaceville, where merged lines have since been managed together. Selection responses from the lines at Rotomahana and Tokanui, and from a further 5 years of divergent selection in the merged lines, are reported here. For the two most recent lamb crops (1996 and 1997 birth years), log-transformed FECs of the high and low lines were 1·27 and -1·46 phenotypic standard deviation units from the control. After back-transformation to the original scale, where the FEC for control line lambs averaged 1255 eggs per g, the means for the high and low lines were 3Ό5 and 0·27 times the control mean. Animal-model restricted maximum likelihood estimates of her it ability and repeatability for single-record FEC (following separate infections) were 0·28 (s.e. 0·02) and 0·42 (s.e. 0Ό1), respectively. Correlated responses in production traits include significantly decreased post-weaning weight gain and increased dags (breech soiling) in lambs, and decreased fleece weight in yearlings and ewes in the low FEC line, compared with those in the high line. However the low FEC line had proportionally 0·11 more lambs weaned per ewe mated than the high FEC line (F &lt; 0·01). It is concluded firstly that selection for high or low FEC in Romney s has achieved an 11-fold difference between the divergent lines. Secondly, it will generally be necessary in a commercial environment to apply index selection for a combination of increased productivity, decreased FEC and possibly decreased dags, when potential candidates are recorded under conditions of nematode challenge.

Faecal egg counts in Angora goats following natural or experimental challenge with nematode parasites: within-flock variability and repeatabilities

Phenotypic variation in faecal worm-egg count (FEC) was studied in 100 Angora goats between 6 months and 2 years old as part of a wider investigation into the potential use of FEC as a selection trait in breeding goats for improved natural resistance to nematode infection. Shortly after weaning at 4–5 months old the goats were subjected to a procedure involving successive natural and experimental challenges, which was continued at 6-monthly intervals until the goats were 2 years old. Experimental challenges consisted of Trichostrongylus colubriformis infective larvae administered orally at a dose rate of 1000 larvae/kg liveweight. FECs resulting from both natural and experimental infections varied considerably between individual goats as well as between different sampling times. Mixed model analysis of variance of natural infections confirmed that a significant component of this variation was attributable to differences between individual goats ( P < 0.01) as opposed to other potential sources of variability, indicating that although generally deemed to be more susceptible than sheep, Angora goats do nevertheless vary in their ability to resist nematode infection. Rank correlations between pairs of FECs derived from the same infection were relatively high for both natural and experimental infections ( r = 0.63–0.70 and 0.54–0.79, respectively; all P < 0.01). However, those between mean FECs measured on successive 6-monthly sampling occasions were considerably lower and more variable ( r = 0.01–0.41 and 0.19–0.62 for natural and experimental infections, respectively). Nevertheless, FECs resulting from natural infections showed moderate correlations with those from corresponding experimental infections ( P < 0.01) on all except the first sampling occasion ( r = 0.23–0.61). Correlations were marginally higher when FECs from experimental infections were adjusted for infecting dose size ( r = 0.32–0.63). FECs resulting from experimental infections were significantly higher on the first sampling occasion (at 6 months) than on subsequent occasions ( P < 0.01) suggesting that some degree of resistance to nematode establishment had developed in the goats by 12 months old. On the basis of unadjusted FECs there appeared to be no marked increase in resistance beyond that age, although analyses based on FECs adjusted for infecting dose size suggested an increase in acquired resistance up to 18 months of age. FECs following natural challenge in goats which had also received experimental infections were not significantly different from those exposed only to natural challenge, indicating that the drench-abbreviated experimental infections had had no immunizing effect. Does that had given birth and were lactating at 24 months had significantly higher FECs than ‘dry’ does in the flock ( P < 0.01), suggesting that like sheep, goats exhibit a post-parturient relaxation of immunity. The use of FECs as potential indicators of resistance status in goats and as a criterion for the selection of breeding animals is discussed.

Protein supplementation improves the performance of parasitised sheep fed a straw-based diet

A study was made of the benefits of protein supplementation for parasitised and non-parasitised lambs. Sixty, 5-month-old crossbred wether lambs were placed in individual pens indoors for 9 weeks. Half of the animals were experimentally dosed with 1500 Haemonchus contortus larvae per head per week and were fed ad libitum and the other half were worm-free, pair-fed controls. Diets were formulated to be iso-energetic (9.0 MJ of calculated metabolisable energy per kg dry matter) with five levels of protein (10, 13, 16, 19 and 22% crude protein). These diets were based on oaten chaff, with barley, cotton-seed meal, urea and mineral mix (except for the 22% crude protein diet which did not contain barley). Dietary crude protein content increased live-weight gain, feed intake, rumen fluid ammonia-N, packed cell volume, eosinophil counts and antibody responses to H. contortus L3 antigen and decreased faecal worm egg counts significantly. Infection did not significantly affect packed cell volume of animals on diets with 16, 19 and 22% crude protein content. We conclude that extra dietary protein can prevent the adverse effects of H. contortus infection on animal production.

Anthelmintic efficacy of oxibendazole against some important nematodes in dogs and cats

Summary The anthelmintic efficacy and safety of the oxibendazole component in a combination oxibendazole‐niclosamide paste were investigated in dogs and cats and in litters of pups with naturally acquired nematode infections. A single dose of 15 mg oxibendazole/kg body weight given to 70 dogs and to 29 cats reduced faecal worm egg counts (EPG) by 97.6% for Toxocara canis, 95.7% for Trichuris vulpis, 94.6% for Ancylostoma caninum, and 100% for Toxascaris leonina. In cats, 96.7% efficacy was demonstrated against Toxocara cati. In a second trial, 119 pups in 22 litters were treated with the same dosage at 2, 4, and 6 weeks of age. After treatment on two consecutive days, 95% of the pups did not shed T. canis eggs, compared with 85% after only a single treatment. Side effects were rare and only recorded in young animals. A 2‐day treatment schedule is recommended for unweaned pups.

The use of genetically resistant sheep to control nematode parasitism

Research in the last 20 years has firmly established that it is possible to exploit genetic variation in resistance to the nematode parasites of sheep by selection. Selected sheep are more resistant to infection and commercial application of this research is under way in both Australia and in New Zealand. Not all the consequences of these breeding programs have been established, particularly long-term consequences for productivity and the interaction with other control measures, but the technology is available in the public domain with no commercial restrictions. Faecal worm egg count remains the most effective way of selecting sheep although many alternatives, such as DNA markers, host antibody and parasite antigen assays are being developed for use as selection criteria. Strategic nutritional supplementation is an immediate candidate for inclusion in worm control programs and although nematode vaccines remain elusive, it is likely that some will be field-tested in the next few years. For both of these approaches, nutritional and immunological, it is critical that the response of selected genotypes are assessed under commercial conditions and as components of worm control programs. There is evidence to support the possibility that selected sheep will be more responsive to vaccination while the long-term interaction between the effect of strategic nutritional supplements and resistant genotypes needs to be investigated.