Genetic analysis of faecal worm egg count in South African Merinos under natural challenge

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dc.contributor.authorCloete, S. W. P. (Schalk Willem Petrus van der Merwe)en_ZA
dc.contributor.authorOlivier, J. J.en_ZA
dc.contributor.authorDu Toit, E.en_ZA
dc.contributor.authorDreyer, F. H.en_ZA
dc.date.accessioned2011-05-15T15:54:39Z
dc.date.available2011-05-15T15:54:39Z
dc.date.issued2007
dc.descriptionCITATION: Cloete, S. W. P., et al. 2007. Genetic analysis of faecal worm egg count in South African Merinos under natural challenge. South African Journal of Animal Science, 37(4):237-247.
dc.descriptionThe original publication is available at https://www.sasas.co.za/
dc.description.abstractSheep from a Merino selection experiment at the Tygerhoek research farm in the Southern Cape provided material for this study. The selection lines involved included a line selected for clean fleece weight, a "Wet and Dry" line, a fine wool line and an unselected Control line. Rectal faeces samples were obtained from individual animals at 13 to 16 months of age, after drenching was withheld for at least 10 weeks. Nematode eggs in these samples were counted. Fitting the appropriate fixed effects, the heritability of untransformed, cube root transformed and log transformed faecal nematode egg count (FEC) was obtained from single-trait analyses. The effects of sex and birth year were involved in a significant interaction. Means for FEC were generally higher in ram progeny than in ewes, but the magnitude of the sex difference was not consistent. Multiple lambs had a slightly lower mean for FEC than singles, while FEC was unaffected by dam age. The heritability of FEC was estimated at between 0.14 for untransformed data and 0.18 for log transformed FEC. Genetic correlations of log transformed FEC with two-tooth staple strength (-0.49) and coefficient of variation of fibre diameter (0.30) were favourable. Clean fleece weight was unfavourably related to FEC on a genetic level (0.19). Selection for resistance to parasitic nematodes after natural challenge should thus be feasible in the Merino lines studied.
dc.description.urihttps://www.sasas.co.za/journals/genetic-analysis-of-faecal-worm-egg-count-in-south-african-merinos-under-natural-challenge/
dc.description.versionPublisher's version
dc.format.extent11 pages
dc.identifier.citationCloete, S. W. P., et al. 2007. Genetic analysis of faecal worm egg count in South African Merinos under natural challenge. South African Journal of Animal Science, 37(4):237-247
dc.identifier.issn0375-1589 (online)
dc.identifier.urihttp://hdl.handle.net/10019.1/9325
dc.language.isoen_ZAen_ZA
dc.publisherSouth African Society for Animal Science
dc.rights.holderSouth African Society for Animal Science
dc.subjectWool
dc.subjectMerino sheep
dc.titleGenetic analysis of faecal worm egg count in South African Merinos under natural challengeen_ZA
dc.typeArticle
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