Nutritional influences on the expression of genotypic resistance to gastrointestinal nematode infection in sheep

Title
Nutritional influences on the expression of genotypic resistance to gastrointestinal nematode infection in sheep
Publication Date
2003
Author(s)
Walkden-Brown, SW
( author )
OrcID: https://orcid.org/0000-0002-0638-5533
Email: swalkden@une.edu.au
UNE Id une-id:swalkden
Eady, SJ
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/EA03003
UNE publication id
une:59
Abstract
This paper reviews experiments investigating the responses of resistant and susceptible genotypes of sheep to gastrointestinal nematode infection under differential nutrition. Using faecal egg count as a measure of host resistance, differences between genotypes appeared to be greatest under conditions of low nutrient availability and under such conditions both resistant and susceptible genotypes generally responded to supplemental protein by reducing faecal egg count. However, when nutritional conditions were moderate to good, responses to additional protein tended to be observed only in susceptible genotypes. In general, host genetic resistance was associated with reliable reductions in faecal egg count of moderate to large magnitude, while nutritional intervention was less reliable at reducing faecal egg count, and induced reductions of smaller magnitude. The situation was very different when examining host resilience to infection, as determined by sheep productivity in the face of infection. Increased host resistance was rarely associated with improved growth or production during the period of infection. In contrast, nutritional supplementation reliably increased host productivity irrespective of infection status and prevailing nutritional conditions. A general model of the relationship between nutrient availability and host resistance and resilience in resistant and susceptible genotypes is postulated. Taken together, the studies reviewed in this paper suggest that selection for host resistance and strategic nutritional intervention have complementary roles in the integrated control of gastrointestinal nematode infection in sheep. The former will contribute primarily to the epidemiology of the disease by reliably reducing faecal egg output over a wide range of conditions, reducing host challenge and the number of treatment interventions required. The latter will reliably boost host resilience to infection, with lesser effects on resistance, and the economic rationale for use will require accounting for the full spectrum of production and disease responses
Link
Citation
Australian Journal of Experimental Agriculture, 43(12), p. 1445-1454
ISSN
1446-5574
0816-1089
1836-5787
1836-0939
Start page
1445
End page
1454

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