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.
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.
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.
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.
Scottish Agricultural College
UK-EH26 0PH Penicuik, Midlothian
Tel.: +44 1315 35 32 23
Fax: +44 1315 35 31 21
- Joaquin URIARTE
Servicio de Investigación Agroalimentaria
Deputación General de Aragon
Tel.: +34 976 57 63 36
Fax: +34 976 57 55 01
- 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
- Herve Frederic HOSTE
Unité Associé INRA/ENVT
Chemin des capelles 23
Tel.: +33 5 61 19 38 75
Fax: +33 5 61 19 39 44
- Norman LOGIE
Highlands and Islands Sheep Health Association
UK-IV2 4JZ Inverness
Tel.: +44 1463 71 36 87
Fax: +44 1463 71 36 87