Genetic control of resistance to gastro-intestinal parasites in crossbred cashmere-producing goats: responses to selection, genetic parameters and relationships with production traits

D Vagenas*, F Jackson, AJF Russel, M Merchant, IA Wright, SC Bishop

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This paper investigates the genetic control of the resistance of goats to nematode parasites, and relationships between resistance and production traits. The data set comprised faecal egg counts (FECs) measured on 830 naturally challenged (predominant species Teladorsagia circumcincta), crossbred cashmere-producing goats over 5 years (1993-1997) and production traits (fibre traits and live weight) on 3100 goats from the same population in Scotland, over 11 years (1987-1997). Egg counts comprised repeated measurements (4 to 11) taken at 12 to 18 months of age and production traits, i.e. live weight and fibre traits, were measured at approximately 5 months of age. The goats for which FECs were available were subdivided into a line selected for decreased FECs, using the geometric mean FEC across the measurement period and goats not selected on the basis of FECs, acting as controls. The selected line had significantly lower FECs, compared with the control, in 4 out of 5 years (back transformed average proportional difference of 0.23). The heritability of a single FEC measurement (after cubic root transformation) was 0.17 and the heritability of the mean FEC was 0.32. The heritabilities; of the fibre traits were moderate to high with the majority in excess of 0.5. The heritability of live weight was 0.22. Genetic correlations between FECs and production traits were slightly positive but not significantly different from zero. Phenotypic and environmental correlations were very close to zero with the environmental correlations always being negative. It is concluded that selection for reduced FEC is possible for goats. Benefits of such selection will be seen when animals are kept for more than 1 year of productive life.

Original languageEnglish
Pages (from-to)199-208
Number of pages10
JournalAnimal science
Volume74
Publication statusPublished - Apr 2002

Keywords

  • cashmere
  • genetic parameters
  • goats
  • nematoda
  • selection
  • OSTERTAGIA-CIRCUMCINCTA INFECTION
  • GASTROINTESTINAL NEMATODE PARASITES
  • GRAZING LAMBS
  • FIBER TRAITS
  • ROMNEY SHEEP
  • LIVE WEIGHT
  • EGG COUNTS
  • SUSCEPTIBILITY
  • INHERITANCE
  • TROPICS

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