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Environmentally sensitive approaches to nematode parasite control in sustainable agricultural systems for sheep and goats

Contract nr: FAIR-CT96-1485
Project nr:
1485
Project type:
SC
Starting date:
01/03/1997
Duration:
36 months
Total cost:
1,613,085 EUR
EC Contribution:
1,080,000 EUR
Scientific Officer:
Isabel MINGUEZ-TUDELA
Research topic:
Animal health
Acronym:
Sustainable control of gastrointestinal nematodes

Background:
Current systems of sheep and goat production within the EU rely almost entirely upon intensive chemoprophylaxis for the control of gastrointestinal nematodes. Whilst this offers some short-term economic benefits, studies in Europe and elsewhere have clearly shown that intensive anthelmintic regimes are not sustainable, due to the rapid development of anthelmintic resistance in nematodes. A reduction of chemoprophylaxis would reduce the risk of developing anthelmintic resistance, have environmental benefits, improve the marketability of sheep and goat products and may help to alleviate public concern about chemical residues in foodstuffs. However, this should be done at no risk to animal health, wellbeing and productivity, and include management options that utilise naturally acquired immunity to parasites.

Objectives:
The objective of the proposal is to develop sustainable systems for sheep and goats which meet criteria for animal health and wellbeing, and produce quality products, whilst minimising dependence on chemotherapy for the control of gastrointestinal parasitism.

Description:
The objective is reached by utilising new concepts and technologies based on well-proven methodologies. First, the available options for a reduction in the chemotherapeutical control of parasitism in existing systems in France, Greece, Spain and the UK have been considered. This has also included epidemiological surveys in the areas where information was lacking, and transferring new methodologies from France and the UK to the other two partners. Across Europe the timing of lambing with regard to the seasonal growth of pasture differs. Therefore, the relationship between timing of lambing and the periparturient relaxation in immunity to parasites has been studied in greater depth.

Protein supply and quality are implicated in the immune response to parasites. Effects of protected amino acids on the development of the immune response are currently being examined in France and the UK. New low input forage-based systems in Greece are being studied, to detect whether this may lead to major problems with nematodes and to what extent protein supplementation can avoid the adverse effects of nematodes and help reduce anthelmintic usage. Similar approaches in Spain have been undertaken, and in both countries effects on product quality have been studied. The effects of protein and energy nutrition on expression of immunity to parasites in pregnant and lactating reproducing animals (sheep and goats) which produce milk or fibre has enabled us to quantify the contribution of adult animals to pasture contamination. The very latest methodologies in the measurement of the acquisition and expression of immunity in small ruminants have been further developed and shared.

The information derived from the above studies is already being integrated and here the advantages of an existing simulation of helminth epidemiology are currently exploited. This will allow experts to integrate the components of helminth epidemiology according to the immune status of the host and its level of nutrition. The resulting information can be tested in the development of systems for sheep and goat production that are less dependent on chemoprophylaxis. This information is being disseminated using the partnerships' close links to industry and by using a farmers' cooperative SME as a model for the dissemination of the information by all partners.

Substantial economic benefit to the EU will result from the reduced dependency on chemoprophylaxis, improvement of product quality, the reduction in the economic and welfare costs associated with the ravages of anthelmintic resistance, and reduced pollution.

Results:
The three alternative approaches for the control of gastrointestinal nematodes were breeding for genetic resistance to nematodes, changes in grassland management and supplementation with protein. These alternatives were not advocated to completely replace anthelmintics; they are rather to be integrated in systems that aim at a more strategic use of anthelmintics whilst retaining their efficacy.

The epidemiological survey revealed that gastrointestinal parasitism was widespread, affecting all sheep and goat flocks studied. The distribution of the economically most important parasites depended on the time of year, type of host, level of production and the grassland management; whilst Teladorsagia spp. were present in all systems, the prevalence of Haemonchus spp. increased and that of Trichostrongylus spp. decreased with an increasing proportion of the land being irrigated. Goats had consistently lower faecal egg counts but were found to harbour more adult parasites than sheep. High-producing dairy goats in the first lactation were identified as the major contributors to nematode egg excretion. Similarly, single-rearing ewes had lower faecal egg counts than twin-rearing ewes. This allowed for selective treatment which, in dairy goats, significantly reduced the anthelmintics used whilst maintaining milk production and parasite control. The periparturient relaxation in immunity to parasites occurred in both goats and sheep studied and did not depend on the time of lambing. However, the rise in faecal egg counts around lambing differed between seasons; the highest faecal egg counts were observed in October lambing ewes. In the UK, May lambing ewes had lower faecal egg counts around lambing than March lambing ewes. May-lambing farmers avoided severe infections with Nematodirus battus.

Quantitative and qualitative protein supplementation did not influence the rate of acquisition of immunity to parasites. A nutrient partitioning framework on nutrition-parasite interactions has been developed accounting for these and earlier observations. This framework predicted that protein supplementation to immune animals at times of a scarce protein supply enhanced the expression of immunity to gastrointestinal parasites. This was indeed shown in studies with growing lambs, reproducing sheep, and lactating goats. Ewes in a good body condition showed a higher level of resistance around lambing than those in a more compromised condition. Furthermore, the impact of protein supplementation was less pronounced in ewes that were not compromised for body protein reserves during mid-pregnancy. In addition to the effects on resistance, protein supplementation lowered the impact of parasitism on lamb and goat carcass quality.

Dissemination of the results have been organised via farmers' meetings, agricultural shows and popular articles in the local press. The selective treatment of high producing goats with anthelmintics has been tested at farm level. Neither level of milk production nor parasite control differed compared to the previous season.

The information derived from the studies with periparturient ewes is currently being tested in existing simulation models of helminth epidemiology. First results are indicating that targeting the protein nutrition of periparturient ewes can reduce the use of anthelmintics in the growing lambs without compromising performance or animal wellbeing.


Coordinator
Ilias KYRIAZAKIS
Scottish Agricultural College
Bush Estate
UK-EH26 0PH Penicuik, Midlothian
Tel.: +44 1315 35 32 23
Fax: +44 1315 35 31 21
E-mail: i.kyriazakis@ed.sac.ac.uk



Partners

  • Joaquin URIARTE
    Servicio de Investigación Agroalimentaria
    Deputación General de Aragon
    Apartado 727
    E-50080 Zaragoza
    Tel.: +34 976 57 63 36
    Fax: +34 976 57 55 01
    E-mail: juriarte@mizar.csic.es

  • Dimitrios ZYGOYIANNIS
    Aristotle University of Thessaloniki
    Department of Animal Health and Husbandry
    GR-540 06 Thessaloniki
    Tel.: +30 31 99 99 54
    Fax: +30 31 99 98 92
    E-mail: stamatar@vet.auth.gr

  • Herve Frederic HOSTE
    INRA
    Unité Associé INRA/ENVT
    Chemin des capelles 23
    F-31076 Toulouse
    Tel.: +33 5 61 19 38 75
    Fax: +33 5 61 19 39 44
    E-mail: h.hoste@envt.fr

Subcontractor

  • Norman LOGIE
    Highlands and Islands Sheep Health Association
    Stratherrick Road
    UK-IV2 4JZ Inverness
    Tel.: +44 1463 71 36 87
    Fax: +44 1463 71 36 87
 
 
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