Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-30T23:28:02.864Z Has data issue: false hasContentIssue false
  • English
  • Français

Selection of Merino sheep for resistance to Haemonchus contortus: genetic variation

Published online by Cambridge University Press:  02 September 2010

R. R. Woolaston  and
L. R. Piper
R. R. Woolaston
Affiliation:
CSIRO Division of Animal Production, Armidale NSW, 2350, Australia
L. R. Piper
Affiliation:
CSIRO Division of Animal Production, Armidale NSW, 2350, Australia
Get access

Abstract

An animal model was used to estimate heritabilities of faecal egg count (FEC) and packed cell volume decline (PCVD) in lines of Merinos selected for divergent levels of resistance to Haemonchus contortus. The estimated heritability of FEC was 0·23 (s.e. 0·03) and of PCVD was 0·21 (s.e. 0·03). A cube root transformation was found to be effective in normalizing FEC data and reducing the range of within selection line-birth year variances from 118-fold to 10-fold. Transforming FEC data increased the heritability estimate to 0·29 (s.e. 0·03) and reduced selection bias due to heterogeneity of variance, but the further step of pre-adjusting the transformed data to a common variance had only a trivial effect. Heritability estimates for FEC in years with high means and variances were similar, as were estimates for transformed FEC. The estimated genetic correlations between measurements in years with high and low means and variabilities were 0·77 to 0·91.

PCVD and pre-adjusted transformed FEC had a phenotypic correlation of 0·48. Estimates for the genetic correlation ranged from 0·76 in the decreased resistance line to 1·00 in the increased resistance line and 0·87 with pooled data. Other effects on resistance included birth type and dam age, with twins and progeny of maiden dams being more resistant than their cohorts. Sex effects were unimportant for FEC but males had higher PCVD than females in most, but not all, years. Younger animals had higher FEC and PCVD than older animals. Maternal genetic effects were found to be unimportant, as were the effects of low levels of inbreeding.

Keywords

genetic variationHaemonchus contortusnematode infectionsresistancesheep
Type
Research Article
Information
Animal Science , Volume 62 , Issue 3 , June 1996 , pp. 451 - 460
Copyright
Copyright © British Society of Animal Science 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Albers, G. A. A. and Burgess, S. K. 1988. Serial passage of Haemonchus contortus in resistant and susceptible sheep. Veterinary Parasitology 28:303–306.CrossRefGoogle ScholarPubMed
Albers, G. A. A., Gray, G. D., Piper, L. R., Barker, J. S. F., Le Jambre, L. F. and Barger, I. A. 1987. The genetics of resistance and resilience to Haemonchus contortus infection in young Merino sheep. International journal for Parasitology 17:1355–1363.CrossRefGoogle ScholarPubMed
Baker, R. L., Watson, R. L., Bisset, S. A., Vlassoff, A. and Douch, P. G. C. 1991. Breeding sheep in New Zealand for resistance to internal parasites: research results and commercial application. In Breeding for disease resistance in sheep (ed. Gray, G. D. and Woolaston, R. R.), pp. 19–32. Australian Wool Corporation, Melbourne.Google Scholar
Benitez-Usher, C., Armour, J., Duncan, J. L., Urquart, G. M. and Gettinby, G. 1977. A study of some factors influencing the immunization of sheep against Haemonchus contortus using attenuated larvae. Veterinary Parasitology 3:327–342.CrossRefGoogle Scholar
Cummins, L. J., Thompson, R. L., Yong, W. K., Riffkin, G. G., Goddard, M. E., Callinan, A. P. L. and Saunders, M. J. 1991. Genetics of Ostertagia selection lines. In Breeding for disease resistance in sheep (ed. Gray, G. D. and Woolaston, R. R.), pp. 11–18. Australian Wool Corporation, Melbourne.Google Scholar
Dash, K. M. 1986. Control of helminthosis in lambs by strategic treatment with closantel and broad-spectrum anthelmintics. Australian Veterinary journal 63:4–8.CrossRefGoogle ScholarPubMed
Garrick, D. J. and Van Vleck, L. D. 1987. Aspects of selection for performance in severa l enviroments with heterogeneous variances. Journal of Animal Science 65:409–421.CrossRefGoogle Scholar
Groeneveld, E., Kovac, M. and Wang, T. 1990. PEST, a general purpose BLUP package for multivariate prediction and estimation. Proceedings of the fourth world congress on genetics applied to livestock production, Edinburgh, vol. 13, pp.488–491.Google Scholar
Hill, W. G. 1984. On selection among groups with heterogeneous variance. Animal Production 39:473–477.Google Scholar
Hill, W. G., Edwards, M. R., Ahmed, M.-K. A. and Thompson, R. 1983. Heritability of milk yield and composition at different levels and variability of production. Animal Production 36:59–68.Google Scholar
Juga, J. and Thompson, R. 1989. Estimation of variance components in populations selected over multiple generations. Ada Agriculturae Scandinavica 39:79–89.CrossRefGoogle Scholar
Karlsson, L. J. E., MacLeod, I. M., Leelawardana, D. H., Sissoev, K. and Simmons, J. 1991. Selection for nematode resistance in the Australian Mediterranean climate zone. In Breeding for disease resistance in sheep (ed. Gray, G. D. and Woolaston, R. R.), pp.131–138. Australian Wool Corporation, Melbourne.Google Scholar
Lax, J. and Brown, G. H. 1967. The effects of inbreeding, maternal handicap, and range in age on 10 fleece and body characteristics in Merino rams and ewes. Australian Journal of Agricultural Research 18:689–706.CrossRefGoogle Scholar
Le Jambre, L. F. 1978. Host genetic factors in helminth control. In The epidemiology and control of gastrointestinal parasites of sheep in Australia (ed. Donald, A. D., Southcott, W. H. and Dineen, J. K.), pp.137–141. CSIRO, Melbourne.Google Scholar
Le Jambre, L. F., Southcott, W. H. and Dash, K. M. 1976. Resistance of selected lines of Haemonchus contortus to thiabendazole, morantel tartrate and levamisole. International journal for Parasitology 6:217–222.CrossRefGoogle ScholarPubMed
Manton, V. J. A., Peacock, R., Poynter, D., Silverman, P. H. and Terry, R. J. 1962. The influence of age on naturally acquired resistance to Haemonchus contortus in lambs. Research in Veterinary Science 3:308–314.CrossRefGoogle Scholar
Meyer, K. 1989. Restricted maximum likelihood to estimate variance components for animal models with several random effects using a derivative-free algorithm. Genetics, Selection, Evolution 21:317–340.CrossRefGoogle Scholar
Meyer, K. and Thompson, R. 1984. Bias in variance and covariance component estimators due to selection on a correlated trait, journal of Animal Breeding and Genetics 101:33–50.Google Scholar
Mukai, F. and Ishada, T. 1991. Accuracy of genetic evaluation usin g animal model when generations traced back are limited. Animal Science and Technology 62:1015–1021.Google Scholar
Overend, D. J., Phillips, M. L., Poulton, A. L. and Foster, C. E. D. 1994. Anthelmintic resistance in Australia n sheep nematode populations. Australian Veterinary journal 71:117–121.CrossRefGoogle Scholar
Piper, L. R. 1987. Genetic variation in resistance to internal parasites. In Merino improvement programs in Australia (ed. McGuirk, B. J.), pp.351–363. Australian Wool Corporation, Melbourne.Google Scholar
Piper, L. R. and Barger, I. A. 1988. Resistance to gastrointestinal strongyles: feasibility of a breeding programme. Proceedings of the third world congress on sheep and beef cattle breeding, Paris, vol. 2, pp.593–611.Google Scholar
Ponzoni, R. W. 1992. Reducing average fibre diameter with new Woolplan options. Wool Technology and Sheep Breeding 39:136–139.Google Scholar
Prichard, R. K. 1990. Anthelmintic resistance in nematodes: extent, recent understanding and future directions for control and research. International journal for Parasitology 20:515–523.CrossRefGoogle ScholarPubMed
Scheffé, H. 1959. The analysis of variance. Wiley, New York.Google Scholar
Visscher, P. M. and Hill, W. G. 1992. Heterogeneity of variance and dairy cattle breeding. Animal Production 55:321–329.Google Scholar
Watson, D. L. and Gill, H. S. 1991. Effect of weaning on antibody responses and nematode parasitism in Merino lambs. Research in Veterinary Science 51:128–132.CrossRefGoogle ScholarPubMed
Windon, R. G., Dineen, J. K. and Wagland, B. M. 1987. Genetic control of immunological responsiveness against the intestinal nematode Trichostrongylus colubriformis in lambs. In Merino improvement programs in Australia (ed. McGuirk, B. J.), pp. 371–375. Australian Wool Corporation, Melbourne.Google Scholar
Woolaston, R. R. 1993. Factors affecting the prevalence and severity of footrot in a Merino flock selected for resistance to Haemonchus contortus. Australian Veterinary journal 70:365–369.CrossRefGoogle Scholar
Woolaston, R. R., Barger, I. A. and Piper, L. R. 1990. Response to helminth infection of sheep selected for resistance to Haemonchus contortus. International Journal for Parnsitology 20:1015–1018.Google ScholarPubMed
Woolaston, R. R., Windon, R. G. and Gray, G. D. 1991. Genetic variation in resistance to internal parasites in Armidale experimental flocks. In Breeding for disease resistance in sheep (ed. Gray, G. D. and Woolaston, R. R.), pp. 1–9. Australian Wool Corporation, Melbourne.Google Scholar