Hostname: page-component-78c5997874-dh8gc Total loading time: 0 Render date: 2024-11-05T12:11:04.608Z Has data issue: false hasContentIssue false
  • English
  • Français

Alternatives to anthelmintics for the control of nematodes in livestock

Published online by Cambridge University Press:  01 November 2006

M. J. STEAR ,
M. DOLIGALSKA  and
K. DONSKOW-SCHMELTER
M. J. STEAR
Affiliation:
Veterinary Genes and Proteins Group, Institute of Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
M. DOLIGALSKA
Affiliation:
Department of Parasitology, Institute of Zoology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
K. DONSKOW-SCHMELTER
Affiliation:
Department of Parasitology, Institute of Zoology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
Get access Rights & Permissions [Opens in a new window]

Abstract

Efficient and welfare-friendly livestock production demands the control of nematode infection. Current control measures rely upon anthelmintic treatment but are threatened by the widespread evolution of drug-resistance in parasite populations. Several methods have been advocated to control nematodes without relying on effective anthelmintics. These include grazing management, biological control, nutritional supplementation, vaccination, and genetic approaches. Each method has its advantages and disadvantages. There are several grazing management schemes that can reduce the severity of infection but they are insufficient on their own to control infection. Biological control includes the use of predatory fungi to control nematode populations and the use of pasture species that can reduce the intensity of infection. Fungi can control nematodes but the current requirement for daily feeding means that this approach will be most useful for animals that are handled daily. Feeding supplementary protein can control nematode infection. The method is simple but can be expensive and may not be cost-effective for some marginal enterprises. Genetic approaches include the use of resistant breeds and selective breeding. Some breeds will thrive in conditions that kill animals from other breeds but substitution of resistant breeds is not always feasible. Selective breeding is effective and inexpensive but requires a high level of expertize. The most appropriate method or set of methods to minimize the adverse consequences of nematode infection may vary among farms.

Keywords

nematodegrazing managementbiological controlnutritiongeneticsvaccinationparasite control
Type
Review Article
Information
Parasitology , Volume 134 , Issue 2 , February 2007 , pp. 139 - 151
Copyright
2006 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Abbott, E. M., Parkins, J. J. and Holmes, P. H. ( 1984). Studies on the pathophysiology of chronic ovine haemonchosis in Merino and Scottish Blackface lambs. Parasitology 89, 585–596.CrossRefGoogle Scholar
Abbott, E. M., Parkins, J. J. and Holmes, P. H. ( 1985). Influence of dietary protein on parasite establishment and pathogenesis in Finn Dorset and Scottish Blackface lambs given a single moderate infection of Haemonchus contortus. Research in Veterinary Science 38, 6–13.Google Scholar
Abbott, E. M., Parkins, J. J. and Holmes, P. H. ( 1986). The effect of dietary protein on the pathogenesis of acute ovine haemonchosis. Veterinary Parasitology 20, 275–289.CrossRefGoogle Scholar
Abbott, E. M., Parkins, J. J. and Holmes, P. H. ( 1988). Influence of dietary protein on the patho-physiology of haemonchosis in lambs given continuous infections. Research in Veterinary Science 45, 41–49.Google Scholar
Abbott, E. M., Parkins, J. J. and Holmes, P. H. ( 2000). Influence of dietary protein on the pathophysiology of ovine haemonchosis in Finn Dorset and Scottish Blackface lambs given a single moderate infection. Research in Veterinary Science 38, 54–60.Google Scholar
Albers, G. A. A., Gray, G. D., Piper, L. R., Barker, J. S. F., Lejambre, L. and Barger, I. A. ( 1987). The genetics of resistance and resilience to Haemonchus contortus infection in young Merino sheep. International Journal for Parasitology 17, 1355–1363.CrossRefGoogle Scholar
Armour, J., Jarrett, W. F. H. and Jennings, F. W. ( 1966). Experimental Ostertagia circumcincta infections in sheep: Development and pathogenesis of a single infection. American Journal of Veterinary Research 27, 1267–1278.Google Scholar
Bahirathan, M., Miller, J. E., Barras, S. R. and Kearney, M. T. ( 2000). Variation in susceptibility of Suffolk and Gulf Coast Native suckling lambs to naturally acquired strongylate nematode infections. Veterinary Parasitology 65, 259–268.Google Scholar
Bain, R. K. ( 1999). Irradiated vaccines for helminth control in livestock. International Journal for Parasitology 29, 185–191.CrossRefGoogle Scholar
Baker, R. L., Mwamachi, D. M., Audho, J. O., Aduda, E. O. and Thorpe, W. ( 1999). Genetic resistance to gastro-intestinal nematode parasites in Red Maasai, Dorper and Red Maasai×Dorper ewes in the sub-humid tropics. Animal Science 69, 335–344.CrossRefGoogle Scholar
Baker, R. L., Nagda, S., Rodriguez-Zas, S. L., Southey, B. R., Audho, J. O., Aduda, E. O. and Thorpe, W. ( 2003). Resistance and resilience to gastro-intestinal nematode parasites and relationships with productivity of Red Maasai, Dorper and Red Maasai×Dorper crossbred lambs in the sub-humid tropics. Animal Science 76, 119–136.CrossRefGoogle Scholar
Bartley, D. J., Jackson, F., Jackson, E. and Sargison, N. ( 2004). Characterisation of two triple resistant field isolates of Teladorsagia from Scottish lowland sheep farms. Veterinary Parasitology 123, 189–199.CrossRefGoogle Scholar
Beh, K. J., Hulme, D. J., Callaghan, M. J., Leish, Z., Lenane, I., Windon, R. G. and Maddox, J. F. ( 2002). A genome scan for quantitative trait loci affecting resistance to Trichostrongylus colubriformis in sheep. Animal Genetics 33, 97–106.CrossRefGoogle Scholar
Bishop, S. C., Bairden, K., McKellar, Q. A., Park, M. and Stear, M. J. ( 1996). Genetic parameters for faecal egg count following mixed, natural, predominantly Ostertagia circumcincta infection and relationships with liveweight in young lambs. Animal Science 63, 423–428.CrossRefGoogle Scholar
Bishop, S. C. and Stear, M. J. ( 1997). Modelling responses to selection for resistance to gastro-intestinal parasites in sheep. Animal Science 64, 469–478.CrossRefGoogle Scholar
Bishop, S. C. and Stear, M. J. ( 2000). The use of a gamma-type function to assess the relationship between the number of adult Teladorsagia circumcincta and total egg output. Parasitology 121, 435–440.CrossRefGoogle Scholar
Bisset, S. A., Vlassoff, A., Morris, C. A., Southey, B. R., Baker, R. L. and Parker, A. G. H. ( 1992). Heritability of and genetic correlations among faecal egg counts and productivity traits in Romney sheep. New Zealand Journal of Agricultural Research 35, 51–58.CrossRefGoogle Scholar
Bizzell, W. E. and Ciordia, H. ( 1965). Dissemination of infective larvae of trichostrongylid parasites of ruminants from feces to pasture by the fungus, Pilobolus spp. Journal of Parasitology 51, 184.CrossRefGoogle Scholar
Blattman, A. N., Hulme, D. J., Kinghorn, B. P., Woolaston, R. R., Gray, G. D. and Beh, K. J. ( 1993). A search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to Haemonchus contortus infection in sheep. Animal Genetics 24, 277–282.CrossRefGoogle Scholar
Bouix, J., Krupinski, J., Rzepecki, R., Nowosad, B., Skrzyzala, I., Roborzynski, M., Fudalewicz-Niemczyk, W., Skalska, M., Malczewski, A. and Gruner, L. ( 1998). Genetic resistance to gastrointestinal nematode parasites in Polish long-wool sheep. International Journal for Parasitology 28, 1797–1804.CrossRefGoogle Scholar
Bown, M. D., Poppi, D. P. and Sykes, A. R. ( 1991). The effect of post-ruminal infusion of protein or energy on the pathophysiology of Trichostrongylus colubriformis infection and body composition in lambs. Australian Journal of Agricultural Research 42, 253–267.Google Scholar
Callinan, A. P. L. ( 1978). The ecology of the free-living stages of Ostertagia circumcincta. International Journal for Parasitology 8, 233–237.CrossRefGoogle Scholar
Callinan, A. P. L., Morley, F. H. W., Arundel, J. H. and White, D. H. ( 1982). A model of the life cycle of sheep nematodes and the epidemiology of nematodiasis in sheep. Agricultural Systems 9, 199–225.CrossRefGoogle Scholar
Charon, K. M., Moskwa, B., Rutkowski, R., Gruszczynska, J. and Swiderek, W. ( 2002). Microsatellite polymorphism in DRB1 gene (MHC class II) and its relation to nematode faecal egg count in Polish Heath Sheep. Journal of Animal and Feed Sciences 11, 47–58.CrossRefGoogle Scholar
Clunies Ross, I. ( 1932). Observations on the resistance of sheep to infestation by the stomach worm (Haemonchus contortus). Journal of the Council for Scientific and Industrial Research, Australia 5, 73–80.Google Scholar
Coltman, D. W., Wilson, K., Pilkington, J., Stear, M. J. and Pemberton, J. M. ( 2001). A microsatellite polymorphism in the gamma interferon gene is associated with resistance to gastrointestinal nematodes in a naturally-parasitized population of Soay sheep. Parasitology 122, 571–582.CrossRefGoogle Scholar
Coop, R. L., Graham, R. B., Jackson, F., Wright, S. E. and Angus, K. W. ( 1985). Effect of experimental Ostertagia circumcincta infection on the performance of grazing lambs. Research in Veterinary Science 38, 282–287.Google Scholar
Coop, R. L., Huntley, J. F. and Smith, W. D. ( 1995). Effect of dietary-protein supplementation on the development of immunity to Ostertagia circumcincta in growing lambs. Research in Veterinary Science 59, 24–29.CrossRefGoogle Scholar
Coop, R. L. and Kyriazakis, I. ( 2000). Influence of host nutrition on the development and consequences of parasitism in livestock. Parasitology Today 17, 325–330.Google Scholar
Coop, R. L. and Kyriazakis, I. ( 2001). Influence of host nutrition on the development and consequences of parasitism in livestock. Trends in Parasitology 17, 325–330.CrossRefGoogle Scholar
Coop, R. L., Sykes, A. R. and Angus, K. W. ( 1977). The effect of a daily intake of Ostertagia circumcincta larvae on body weight, food intake and concentration of serum constituents in sheep. Research in Veterinary Science 23, 76–83.Google Scholar
Coop, R. L., Sykes, A. R. and Angus, K. W. ( 1982). The effect of three levels of Ostertagia circumcincta larvae on growth rate, food intake and body composition of growing lambs. Journal of Agricultural Science (Cambridge) 98, 247–255.CrossRefGoogle Scholar
Cooper, D. W., van Oorschot, R. A. H., Piper, L. R. and LeJambre, L. F. ( 1989). No association between the ovine leucocyte antigen (OLA) system in the Australian Merino and susceptibility to Haemonchus contortus infection. International Journal for Parasitology 19, 695–697.CrossRefGoogle Scholar
Crawford, A., McEwan, J. C., Dodds, K. G., Wright, C. S., Bisset, S. A., Macdonald, P. A., Knowler, K. J. J., Greer, G. J., Green, R. S., Shaw, R. J., Paterson, K. A., Cuthbertson, R. P., Vlassoff, A., Squire, D. R., West, C. J. and Phua, S. H. ( 1997). Resistance to nematode parasites in sheep: How important are the MHc genes? Proceedings of the Association for the Advancement of Animal Breeding and Genetics 12, 58–62.Google Scholar
Dalton, J. P., Brindley, P. J., Knox, D. P., Brady, C. P., Hotez, P. J., Donnelly, S., O'Neill, S. M., Mulcahy, G. and Loukas, A. ( 2003). Helminth vaccines: from mining genomic information for vaccine targets to systems used for protein expression. International Journal for Parasitology 33, 621–640.CrossRefGoogle Scholar
Doligalska, M., Moskwa, B. and Stear, M. J. ( 1999). Relationships among peripheral eosinophilia, eosinophil peroxidase activity, interleukin-5 concentration and faecal nematode egg count during natural, mixed gastrointestinal nematode infection. Veterinary Immunology and Immunopathology 70, 299–308.CrossRefGoogle Scholar
Dominik, S. ( 2005). Quantitative trait loci for internal nematode resistance in sheep: a review. Genetics, Selection, Evolution 37 (Suppl. 1), S83–S96.CrossRefGoogle Scholar
Donald, A. D., Morley, F. H. W., Waller, P. J., Axelsen, A., Dobson, R. J. and Donnelly, J. R. ( 1982). Effects of reproduction, genotype and anthelmintic treatment of ewes on Ostertagia spp. populations. International Journal for Parasitology 12, 403–411.CrossRefGoogle Scholar
Donaldson, J., van Houtert, M. F. J. and Sykes, A. R. ( 1998). The effect of nutrition on the periparturient parasite status of mature ewes. Animal Science 67, 523–533.CrossRefGoogle Scholar
Douch, P. G. C., Green, R. S., Morris, C. A., McEwan, J. C. and Windon, R. G. ( 1996). Phenotypic markers for selection of nematode-resistant sheep. International Journal for Parasitology 26, 899–911.CrossRefGoogle Scholar
Eady, S. J., Woolaston, R. R., Lewer, R. P., Raadsma, H. W., Swan, A. A. and Ponzoni, R. W. ( 1998). Resistance to nematode parasites in Merino sheep: correlation with production traits. Australian Journal of Agricultural Science 49, 1201–1211.CrossRefGoogle Scholar
Emery, D. L. ( 1996). Vaccination against worm parasites of animals. Veterinary Parasitology 64, 31–45.CrossRefGoogle Scholar
Gamble, H. R. and Zajac, A. M. ( 1992). Resistance of St. Croix lambs to Haemonchus contortus in experimentally and naturally acquired infections. Veterinary Parasitology 41, 211–225.Google Scholar
Gettinby, G., Armour, J., Bairden, K. and Plenderleith, R. W. J. ( 1987). A survey by questionaire of parasitic worm control in cattle and sheep at the Glasgow University Lanark practice. Veterinary Record 121, 487–490.CrossRefGoogle Scholar
Gettinby, G., McKellar, Q. A., Bairden, K., Theodoridis, Y. and Whitelaw, A. ( 1985). Comparison of two techniques used for the recovery of nematode infective larvae from pasture. Research in Veterinary Science 39, 99–102.Google Scholar
Gibbs, H. C. and Barger, I. A. ( 1986). Haemonchus contortus and other trichostrongylid infections in parturient, lactating and dry ewes. Veterinary Parasitology 22, 57–66.CrossRefGoogle Scholar
Gibson, T. E. and Everett, G. ( 1972). The ecology of the free-living stages of Ostertagia circumcincta. Parasitology 64, 451–460.CrossRefGoogle Scholar
Good, B., Hanrahan, J. P., Crowley, B. A. and Mulcahy, G. ( 2006). Texel sheep are more resistant to natural, nematode challenge than Suffolk sheep based on faecal egg count and worm burden. Veterinary Parasitology 136, 317–327.CrossRefGoogle Scholar
Gorski, P., Niznikowski, R., Popielarczyk, D., Strzelec, E., Gajewska, A. and Wedrychowicz, H. ( 2006). Natural parasitic infections in various breeds of sheep in Poland. Archiv für Tierzucht Dummerstorf 47, 50–55.Google Scholar
Gray, G. D., Presson, B. L., Albers, G. A. A., Le Jambre, L. F., Piper, L. R. and Barker, J. S. F. ( 1987). Comparison of within- and between-breed variation in resistance to haemonchosis in sheep. In Merino Improvement Programmes in Australia (ed. MCGuirk, B. J.), pp. 365–369. Australian Wool Corporation, Melbourne, Australia.
Gruner, L., Aumont, G., Bouix, J. and Mandonnet, N. ( 2001). The genetic resistance to nematode parasites in small ruminants: a more and more well known trait. (In French.) 8emes Rencontres autour des Recherches sur les Ruminants, Paris, France, 5–6 Decembre 2001.
Hein, W. R., Shoemaker, C. B. and Heath, A. G. C. ( 2001). Future technologies for control of nematodes in sheep. New Zealand Veterinary Journal 49, 247–251.CrossRefGoogle Scholar
Hilderson, H., De Graaf, D. C., Vercruysse, J. and Berghen, P. ( 1993). Characterisation of Ostertagia ostertagi antigens by the different bovine immunoglobulin isotypes. Research in Veterinary Science 55, 203–208.CrossRefGoogle Scholar
Houdijk, J. G. M., Kyriazakis, I., Coop, R. L. and Jackson, F. ( 2001 a). The expression of immunity to Teladorsagia circumcincta in ewes and its relationship to protein nutrition depend on body protein reserves. Parasitology 122, 661–672.Google Scholar
Houdijk, J. G. M., Kyriazakis, I., Jackson, F. and Coop, R. L. ( 2001 b). The relationship between protein nutrition, reproductive effort and breakdown in immunity to Teladorsagia circumcincta in periparturient ewes. Animal Science 72, 595–606.Google Scholar
Houdijk, J. G. M., Kyriazakis, I., Jackson, F., Huntley, J. F. and Coop, R. L. ( 2003). Is the allocation of metabolisable protein prioritised to milk production rather than to immune functions in Teladorsagia circumcincta-infected lactating ewes? International Journal for Parasitology 33, 327–338.Google Scholar
Hulme, D. J., Nicholas, F. W., Windon, R. G., Brown, S. C. and Beh, K. J. ( 1993). The MHC class II region and resistance to an intestinal parasite in sheep. Journal of Animal Breeding and Genetics 110, 459–472.CrossRefGoogle Scholar
Israf, D. A., Coop, R. L., Stevenson, L. M., Jones, D. G., Jackson, F., Jackson, E., MacKellar, A. and Huntley, J. F. ( 1996). Dietary protein influences upon immunity to Nematodirus battus infection in lambs. Veterinary Parasitology 61, 273–286.CrossRefGoogle Scholar
Jackson, F., Jackson, E. and Williams, J. T. ( 1988). Susceptibility of the pre-parturient ewe to infection with Trichostrongylus vitrinus and Ostertagia circumcincta. Research in Veterinary Science 45, 213–218.Google Scholar
Jorgensen, L. T., Leathwick, D. M., Charleston, W. A. G., Godfrey, P. L., Vlassoff, A. and Sutherland, I. A. ( 1998). Variation between hosts in the developmental success of the free-living stages of trichostrongyle infections of sheep. International Journal for Parasitology 28, 1347–1352.CrossRefGoogle Scholar
Kahn, L. P., Knox, M. R. and Gray, G. D. ( 1999). Enhancing immunity to nematode parasites in pregnant and lactating sheep through nutrition and genetic selection. Recent Advances in Animal Nutrition in Australia 12, 15–22.Google Scholar
Kambara, T., McFarlane, R. G., Abell, T. J., McAnulty, R. W. and Sykes, A. R. ( 1993). The effect of age and dietary protein on immunity and resistance in lambs vaccinated with Trichostrongylus colubriformis. International Journal for Parasitology 23, 471–476.CrossRefGoogle Scholar
Kao, R. R., Leathwick, D. M., Roberts, M. G. and Sutherland, I. A. ( 2000). Nematode parasites of sheep: a survey of epidemiological parameters and their application in a simple model. Parasitology 121, 85–103.CrossRefGoogle Scholar
Kloosterman, A., Albers, G. A. A. and van den Brink, R. ( 1978). Genetic variation among calves in resistance to nematode parasites. Veterinary Parasitology 4, 353–368.CrossRefGoogle Scholar
Knox, D. P. ( 2004). Technological advances and genomics in metazoan parasites. International Journal for Parasitology 34, 139–152.CrossRefGoogle Scholar
Knox, D. P., Redmond, D. L., Newlands, G. F., Skuce, P. J., Pettit, D. and Smith, W. D. ( 2003). The nature and prospects for gut membrane proteins as vaccine candidates for Haemonchus contortus and other ruminant trichostrongyloids. International Journal for Parasitology 33, 1129–1137.CrossRefGoogle Scholar
Knox, M. R., Josh, P. F. and Anderson, L. J. ( 2002). Deployment of Duddingtonia flagrans in an improved pasture system: dispersal, persistence, and effects on free-living soil nematodes and microarthropods. Biological Control 24, 176–182.CrossRefGoogle Scholar
Knox, M. R. and Steel, J. W. ( 1999). The effects of urea supplementation on production and parasitological responses of sheep infected with Haemonchus contortus and Trichostrongylus colubriformis. Veterinary Parasitology 83, 123–135.CrossRefGoogle Scholar
Koski, K. G. and Scott, M. E. ( 2003). Gastrointestinal nematodes, trace elements, and immunity. Journal of Trace Elements in Experimental Medicine 16, 237–251.CrossRefGoogle Scholar
Kyriazakis, I., Anderson, D. H., Coop, R. L. and Jackson, F. ( 1996). The pathophysiology and development of immunity during long-term subclinical infection with Trichostrongylus colubriformis of sheep receiving different nutritional treatments. Veterinary Parasitology 65, 41–54.CrossRefGoogle Scholar
Leighton, E. A., Murrell, K. D. and Gasbarre, L. C. ( 1989). Evidence for genetic control of nematode egg-shedding rates in calves. Journal of Parasitology 75, 498–504.CrossRefGoogle Scholar
Leignel, V., Cabaret, J. and Humbert, J. F. ( 2002). New molecular evidence that Teladorsagia circumcincta (Nematoda: Trichostrongylidea) is a species complex. Journal of Parasitology 88, 135–140.CrossRefGoogle Scholar
Littledike, E. T. and Young, L. D. ( 1993). Effect of sire and dam breed on copper status of fat lambs. Journal of Animal Science 71, 774–778.CrossRefGoogle Scholar
Mackinnon, M. J., Meyer, K. and Hetzel, D. J. S. ( 1991). Genetic variation and covariation for growth, parasite resistance and heat tolerance in tropical cattle. Livestock Production Science 27, 105–122.CrossRefGoogle Scholar
Marley, C. L., Cook, R., Barrett, J., Keatinge, R., Lampkin, N. H. and McBride, S. D. ( 2003). The effect of dietary forage on the development and survival of helminth parasites in ovine faeces. Veterinary Parasitology 118, 93–107.CrossRefGoogle Scholar
McCririe, L., Bairden, K., Britton, C., Buitkamp, J., McKeand, J. B. and Stear, M. J. ( 1997). Heterogeneity in the recognition of Ostertagia circumcincta antigens by serum antibody from mature, infected sheep. Parasite Immunology 19, 235–242.CrossRefGoogle Scholar
McEwan, J. C., Dodds, K. G., Greer, G. J., Bain, W. E., Duncan, S. J., Wheeler, R., Knowler, K. J., Reid, P. J., Green, R. S. and Douch, P. G. C. ( 1995). Genetic estimates for parasite resistance traits in sheep and their correlations with production traits. New Zealand Journal of Zoology 22, 177.Google Scholar
Meeusen, E. N. T. and Piedrafita, D. ( 2003). Exploiting natural immunity to helminth parasites for the development of veterinary vaccines. International Journal for Parasitology 33, 1285–1290.CrossRefGoogle Scholar
Michel, J. F. ( 1985). Epidemiology and control of gastrointestinal helminths in domestic animals. In Chemotherapy of Gastrointestinal Helminths. Handbook of Experimental Pharmacology ( ed. van den Bossche, H., Thienpont, D. and Janssens, P. G.), 77, 67–123. Springer-Verlag, Berlin.
Morris, C. A., Green, R. S., Cullen, N. G. and Hickey, S. M. ( 2003). Genetic and phenotypic relationships among faecal egg count, anti-nematode antibody level and live weight in Angus cattle. Animal Science 76, 167–174.Google Scholar
Morris, C. A., Watson, T. G., Bisset, S. A., Vlassoff, A. and Douch, P. G. C. ( 2000). Breeding sheep in New Zealand for resistance or resilience to nematode parasites. 77–98. In Breeding for Resistance to Infectious Diseases of Small Ruminants. ( ed. Gray, G. D., Woolaston, R. R. and Eaton, B. D.) ACIAR Monograph No 34, Canberra, Australia.
Moskwa, B., Doligalska, M. and Cabaj, W. ( 1998). The repeatability of haematological and parasitological parameters in Polish Wrzosowka hoggets naturally infected with trichostrongylid nematodes. Acta Parasitologica 43, 148–153.Google Scholar
Mugambi, J. M., Wanyangu, S. W., Bain, R. K., Owango, M. O., Duncan, J. L. and Stear, M. J. ( 1996). Response of Dorper and Red Maasai lambs to trickle Haemonchus contortus infections. Research in Veterinary Science 61, 218–221.CrossRefGoogle Scholar
Newton, S. E. and Munn, E. A. ( 1999). The development of vaccines against gastrointestinal nematode parasites, particularly Haemonchus contortus. Parasitology Today 15, 116–122.CrossRefGoogle Scholar
Nguti, R., Janssen, P., Rowlands, G. J., Audho, J. O. and Baker, R. L. ( 2003). Survival of Red maasai, Dorper and crossbred lambs in the sub-humid tropics. Animal Science 76, 3–17.CrossRefGoogle Scholar
Nicholas, F. W. ( 1987). Veterinary Genetics. Oxford University Press, Oxford.
Nieuwhof, G. J. and Bishop, S. C. ( 2005). Costs of the major endemic diseases of sheep in Great Britain and the potential benefits of reduction in disease impact. Animal Science 81, 23–29.CrossRefGoogle Scholar
Niezen, J. H., Charleston, W. A. G., Hodgson, J., Mackay, A. D. and Leathwick, D. M. ( 1996). Controlling internal parasites in grazing ruminants without recourse to anthelmintics: approaches, experiences and prospects. International Journal for Parasitology 26, 983–992.CrossRefGoogle Scholar
Niezen, J. H., Charleston, W. A. G., Hodgson, J., Miller, C. M., Waghorn, T. S. and Robertson, H. A. ( 1998). Effect of plant species on the larvae of gastrointestinal nematodes which parasitise sheep. International Journal for Parasitology 28, 791–803.CrossRefGoogle Scholar
O'Sullivan, B. M. and Donald, A. D. ( 1973). Responses to infection with Haemonchus contortus and Trichostrongylus colubriformis in ewes of different reproductive staus. International Journal for Parasitology 3, 521–530.CrossRefGoogle Scholar
Parsonson, I. ( 1998). The Australian Ark. CSIRO Publishing, Collingwood.
Paterson, S., Wilson, K. and Pemberton, J. M. ( 1998). Major histocompatibility complex variation associated with juvenile survival and parasite resistance in a large unmanaged ungulate population (Ovis aries L.). Proceedings of the National Academy of Sciences, USA 95, 3714–3719.CrossRefGoogle Scholar
Perry, B. D. and Randolph, T. F. ( 1999). Improving the assessment of the economic impact of parasitic diseases and of their control in production animals. Veterinary Parasitology 84, 145–168.CrossRefGoogle Scholar
Robinson, J. ( 1962). Pilobolus spp. and the translocation of the infective larvae of Dictyocaulus viviparus from faeces to pastures. Nature, London 193, 353–354.Google Scholar
Sayers, G., Good, B., Hanrahan, J. P., Ryan, M., Angles, J. M. and Sweeney, T. ( 2005). Major histocompatibility complex DRB1 gene: its role in nematode resistance in Suffolk and Texel sheep breeds. Parasitology 131, 403–409.CrossRefGoogle Scholar
Sayers, G. and Sweeney, T. ( 2005). Gastrointestinal nematode infection in sheep – a review of the alternatives to anthelmintics in parasite control. Animal Health Research Reviews 6, 159–171.CrossRefGoogle Scholar
Schallig, H. D. F. H., van Leeuwen, M. A. W. and Hendrikx, W. M. L. ( 1994). Immune responses of Texel sheep to excretory/secretory products of adult Haemonchus contortus. Parasitology 108, 351–357.CrossRefGoogle Scholar
Schwaiger, F. W., Gostomski, D., Stear, M. J., Duncan, J. L., McKellar, Q. A., Epplen, J. T. and Buitkamp, J. ( 1995). An ovine major histocompatibility complex DRB1 allele is associated with low faecal egg counts following natural predominantly Ostertagia circumcincta infection. International Journal for Parasitology 25, 815–822.CrossRefGoogle Scholar
Simm, G. ( 1998). Genetic Improvement of Cattle and Sheep. Farming Press, Ipswich.
Smith, W. D. ( 1999). Prospects for vaccines of helminth parasites of grazing ruminants. International Journal for Parasitology 29, 17–24.CrossRefGoogle Scholar
Sreter, T., Kassai, T. and Takacs, E. ( 1994). The heritability and specificity of responsiveness to infection with Haemonchus contortus in sheep. International Journal for Parasitology 24, 871–876.CrossRefGoogle Scholar
Stear, M. J., Bairden, K., Bishop, S. C., Buitkamp, J., Duncan, J. L., Gettinby, G., McKellar, Q. A., Park, M., Parkins, J. J., Reid, S. W. J., Strain, S. A. J. and Murray, M. ( 1997). The genetic basis of resistance to Ostertagia circumcincta in lambs. The Veterinary Journal 154, 111–119.CrossRefGoogle Scholar
Stear, M. J., Bairden, K., Duncan, J. L., Eckersall, P. D., Fishwick, G., Graham, P. A., Holmes, P. H., McKellar, Q. A., Mitchell, S., Murray, M., Parkins, J. J. and Wallace, D. S. ( 2000 a). The influence of relative resistance and urea-supplementation on deliberate infection with Teladorsagia circumcincta during winter. Veterinary Parasitology 94, 45–54.Google Scholar
Stear, M. J., Bairden, K., McKellar, Q. A., Scott, I. and Strain, S. A. J. ( 1999). The relationship between the number and size of nematodes in the abomasum and the concentration of pepsinogen in ovine plasma. Research in Veterinary Science 67, 89–92.CrossRefGoogle Scholar
Stear, M. J. and Bishop, S. C. ( 1999). The curvilinear relationship between worm length and fecundity of Teladorsagia circumcincta. International Journal for Parasitology 29, 777–780.CrossRefGoogle Scholar
Stear, M. J., Bishop, S. C., Doligalska, M., Duncan, J. L., Holmes, P. H., Irvine, J., McCririe, L., McKellar, Q. A., Sinski, E. and Murray, M. ( 1995). Regulation of egg production, worm burden, worm length and worm fecundity by host responses in sheep infected with Ostertagia circumcincta. Parasite Immunology 17, 643–652.CrossRefGoogle Scholar
Stear, M. J., Bishop, S. C., Henderson, N. G. and Scott, I. ( 2003). A key mechanism of pathogenesis in sheep infected with the nematode Teladorsagia circumcincta. Animal Health Research Reviews 4, 45–52.CrossRefGoogle Scholar
Stear, M. J., Henderson, N. G., Kerr, A., McKellar, Q. A., Mitchell, S., Seeley, C. and Bishop, S. C. ( 2002). Eosinophilia as a marker of resistance to Teladorsagia circumcincta in Scottish Blackface lambs Parasitology 124, 553–560.Google Scholar
Stear, M. J., Hetzel, D. J. S., Brown, S. C., Gershwin, L. J., Mackinnon, M. J. and Nicholas, F. W. ( 1990). The relationships among ecto- and endoparasite levels, class I antigens of the bovine major histocompatibility system, immunoglobulin E levels and weight gain. Veterinary Parasitology 34, 303–321.CrossRefGoogle Scholar
Stear, M. J., Innocent, G. T. and Buitkamp, J. ( 2005). The evolution and maintenance of polymorphism in the major histocompatibility complex. Veterinary Immunology and Immunopathology 108, 53–57.CrossRefGoogle Scholar
Stear, M. J., Mitchell, S., Strain, S. A. J., Bishop, S. C. and McKellar, Q. A. ( 2000 b). The influence of age on the variation among sheep in susceptibility to natural nematode infection. Veterinary Parasitology 89, 31–36.Google Scholar
Stear, M. J., Park, M. and Bishop, S. C. ( 1996). The key components of resistance to Ostertagia circumcincta in lambs. Parasitology Today 12, 438–441.CrossRefGoogle Scholar
Stear, M. J., Strain, S. A. J. and Bishop, S. C. ( 1999). Mechanisms underlying resistance to nematode infection. International Journal for Parasitology 29, 51–56.CrossRefGoogle Scholar
Stewart, M. A., Miller, R. F. and Douglas, J. R. ( 1937). Resistance of sheep of different breeds to infestation by Ostertagia circumcincta. Journal of Agricultural Research 55, 923–930.Google Scholar
Strain, S. A. J., Bishop, S. C., Henderson, N. G., Kerr, A., McKellar, Q. A., Mitchell, S. and Stear, M. J. ( 2002). The genetic control of IgA activity against Teladorsagia circumcincta and its association with parasite resistance in naturally infected sheep. Parasitology 124, 545–552.CrossRefGoogle Scholar
Strain, S. A. J. and Stear, M. J. ( 2001). The influence of protein supplementation on the immune response to Haemonchus contortus. Parasite Immunology 23, 523–531.CrossRefGoogle Scholar
Stromberg, B. E. ( 1997). Environmental factors influencing transmission. Veterinary Parasitology 72, 247–264.CrossRefGoogle Scholar
Stromberg, B. E. and Averbeck, G. A. ( 1999). The role of parasitic epidemiology in the management of grazing cattle. International Journal for Parasitology 29, 33–39.CrossRefGoogle Scholar
Sutherland, I. A., Moen, I. C. and Leathwick, D. M. ( 2002). Increased burdens of drug-resistant nematodes due to anthelmintic treatment. Parasitology 125, 375–381.CrossRefGoogle Scholar
Sykes, A. R. and Coop, R. L. ( 2001). Interaction between nutrition and gastrointestinal parasitism in sheep. New Zealand Veterinary Journal 49, 222–226.CrossRefGoogle Scholar
Urquhart, G. M., Armour, J., Duncan, J. L., Dunn, A. M. and Jennings, F. W. ( 1987). Veterinary Parasitology. Longman Scientific and Technical, Avon, UK.
van Houtert, M. F. J., Barger, I. A., Steel, J. W., Windon, R. G. and Emery, D. L. ( 1995). Effects of dietary protein intake on responses of young sheep to infection with Trichostrongylus colubriformis. Veterinary Parasitology 56, 163–180.CrossRefGoogle Scholar
Vercruysse, J., Knox, D. P., Schetters, T. P. M. and Willadsen, P. ( 2004). Veterinary parasitic vaccines: pitfalls and future directions. Trends in Parasitology 20, 488–492.CrossRefGoogle Scholar
Vlassoff, A., Leathwick, D. M. and Heath, A. C. G. ( 2001). The epidemiology of nematode infections of sheep. New Zealand Veterinary Journal 49, 213–221.CrossRefGoogle Scholar
Waghorn, T. S., Leathwick, D. M., Chen, L.-Y., Gray, R. A. J. and Skipp, R. A. ( 2002). Influence of nematophagous fungi, earthworms and dung burial on development of the free-living stages of Ostertagia (Teladorsagia) circumcincta in New Zealand. Veterinary Parasitology 104, 119–129.CrossRefGoogle Scholar
Wallace, D. S., Bairden, K., Duncan, J. L., Eckersall, P. D., Fishwick, G., Gill, M., Holmes, P. H., McKellar, Q. A., Murray, M., Parkins, J. J. and Stear, M. J. ( 1998). The influence of dietary supplementation with urea on resilience and resistance to infection with Haemonchus contortus. Parasitology 116, 67–72.CrossRefGoogle Scholar
Wallace, D. S., Bairden, K., Duncan, J. L., Eckersall, P. D., Fishwick, G., Holmes, P. H., McKellar, Q. A., Mitchell, S., Murray, M., Parkins, J. J. and Stear, M. J. ( 1999). The influence of increased feeding on the susceptibility of sheep to infection with Haemonchus contortus. Animal Science 69, 457–463.CrossRefGoogle Scholar
Wallace, D. S., Bairden, K., Duncan, J. L., Fishwick, G., Gill, M., Holmes, P. H., McKellar, Q. A., Murray, M., Parkins, J. J. and Stear, M. J. ( 1995). Influence of supplementation with dietary soyabean meal on resistance to haemonchosis in Hampshire down lambs. Research in Veterinary Science 58, 232–237.CrossRefGoogle Scholar
Wallace, D. S., Bairden, K., Duncan, J. L., Fishwick, G., Holmes, P. H., McKellar, Q. A., Murray, M., Parkins, J. J. and Stear, M. J. ( 1996). Influence of soyabean meal supplementation on the resistance of Scottish Blackface lambs to haemonchosis. Research in Veterinary Science 60, 138–143.CrossRefGoogle Scholar
Waller, P. J., Bernes, G., Rudby-Martin, L., Ljungstrõm, B. and Rydzik, A. ( 2004 a). Evaluation of copper supplementation to control Haemonchus contortus infections of sheep in Sweden. Acta Veterinaria Scandinavica 45, 149–160.Google Scholar
Waller, P. J. and Faedo, M. ( 1996). The prospects for biological control of the free-living stages of nematode parasites of livestock. International Journal for Parasitology 26, 915–925.CrossRefGoogle Scholar
Waller, P. J., Schwan, O., Ljungström, B.-L., Rydzik, A. and Yeates, G. W. ( 2004 b). Evaluation of biological control of sheep parasites using Duddingtonia flagrans under commercial farming conditions on the island of Gotland, Sweden. Veterinary Parasitology 126, 299–315.Google Scholar
Waller, P. J. and Thamsborg, S. M. ( 2005). Nematode control in ‘green’ ruminant production systems. Trends in Parasitology 20, 493–497.Google Scholar
Wiener, G. ( 1979). Review of genetic aspects of mineral metabolism with particular reference to copper in sheep. Livestock Production Science 6, 223–232.CrossRefGoogle Scholar
Williams, B. and Warren, J. ( 2004). Effects of spatial distribution on the decomposition of sheep faeces in different vegetation types. Agriculture, Ecosystems and Environment 103, 237–243.CrossRefGoogle Scholar
Yatsuda, A. P., Krijgsveld, J., Cornelissen, A. W. C. A., Heck, A. J. R. and de Vries, E. ( 2005). Comprehensive analysis of the secreted proteins of the parasite Haemonchus contortus reveals extensive sequence variation and differential immune recognition. Journal of Biological Chemistry 278, 16941–16951.Google Scholar
Yazwinski, T. A., Goode, L., Moncol, D. J., Morgan, G. W. and Linnerud, A. C. ( 1979). Parasite resistance in straightbred and crossbred Barbados Blackbelly sheep. Journal of Animal Science 49, 919–926.CrossRefGoogle Scholar
Yazwinski, T. A., Goode, L., Moncol, D. J., Morgan, G. W. and Linnerud, A. C. ( 1981). Haemonchus contortus resistance in straightbred and crossbred Barbados Blackbelly sheep. Journal of Animal Science 51, 279–284.Google Scholar