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Continued selection of Romney sheep for resistance or susceptibility to nematode infection: estimates of direct and correlated responses

Published online by Cambridge University Press:  18 August 2016

C. A. Morris ,
A. Vlassoff ,
S. A. Bisset ,
R. L. Baker ,
T. G. Watson ,
C. J. West  and
M. Wheeler
C. A. Morris
Affiliation:
AgResearch, Ruakura Agricultural Research Centre, PB 3123, Hamilton, New Zealand
A. Vlassoff
Affiliation:
AgResearch, Wallaceville Animal Research Centre, PO Box 40063, Upper Hutt, New Zealand
S. A. Bisset
Affiliation:
AgResearch, Wallaceville Animal Research Centre, PO Box 40063, Upper Hutt, New Zealand
R. L. Baker*
Affiliation:
AgResearch, Ruakura Agricultural Research Centre, PB 3123, Hamilton, New Zealand
T. G. Watson*
Affiliation:
AgResearch, Ruakura Agricultural Research Centre, PB 3123, Hamilton, New Zealand
C. J. West
Affiliation:
AgResearch, Wallaceville Animal Research Centre, PO Box 40063, Upper Hutt, New Zealand
M. Wheeler
Affiliation:
AgResearch, Ruakura Agricultural Research Centre, PB 3123, Hamilton, New Zealand
*
†Present address: ILRI, PO Box 30709, Nairobi, Kenya.
‡Present address:Pfizer Pty Ltd, PO Box 57, West Ryde, Sydney, NSW 2114, Australia.
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Abstract

Divergent breeding lines of Romney sheep, selected as lambs for consistently high or low faecal worm egg count (FEC) following natural multi-species challenge by nematode parasites, were established in New Zealand at Wallaceville Animal Research Centre in 1979 and at Rotomahana Station in 1985. In 1988 the Rotomahana lines, including an unselected control line maintained under the same management conditions, were transferred to Tokanui Station where they remained for 4 years. In 1993 elite high and low FEC animals from Tokanui, along with the controls, were transferred to Wallaceville, where merged lines have since been managed together. Selection responses from the lines at Rotomahana and Tokanui, and from a further 5 years of divergent selection in the merged lines, are reported here. For the two most recent lamb crops (1996 and 1997 birth years), log-transformed FECs of the high and low lines were 1·27 and -1·46 phenotypic standard deviation units from the control. After back-transformation to the original scale, where the FEC for control line lambs averaged 1255 eggs per g, the means for the high and low lines were 3Ό5 and 0·27 times the control mean. Animal-model restricted maximum likelihood estimates of her it ability and repeatability for single-record FEC (following separate infections) were 0·28 (s.e. 0·02) and 0·42 (s.e. 0Ό1), respectively. Correlated responses in production traits include significantly decreased post-weaning weight gain and increased dags (breech soiling) in lambs, and decreased fleece weight in yearlings and ewes in the low FEC line, compared with those in the high line. However the low FEC line had proportionally 0·11 more lambs weaned per ewe mated than the high FEC line (F < 0·01). It is concluded firstly that selection for high or low FEC in Romney s has achieved an 11-fold difference between the divergent lines. Secondly, it will generally be necessary in a commercial environment to apply index selection for a combination of increased productivity, decreased FEC and possibly decreased dags, when potential candidates are recorded under conditions of nematode challenge.

Keywords

immunitynematodaparasitesselectionsheep

Information

Type
Breeding and genetics
Information
Animal Science , Volume 70 , Issue 1 , February 2000 , pp. 17 - 27
Copyright
Copyright © British Society of Animal Science 2000

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References

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.Google Scholar
Baker, R. L., Clarke, J. N., Meyer, H. H., Harvey, T. G. and Bigham, M. L. 1987. Genetic variation among six strains of Romneys and Border Leicester and Coopworth crosses. Proceedings of the New Zealand Society of Animal Production 47: 101–105.Google Scholar
Baker, R. L., Watson, T. G., Bisset, S. A. and Vlassoff, A. 1990. Breeding Romney sheep which are resistant to gastro-intestinal parasites. Proceedings of the Australian Association of Animal Breeding and Genetics 8: 173–178.Google Scholar
Bisset, S. A. and Morris, C. A. 1996. Feasibility and implications of breeding sheep for resilience to nematode challenge. International Journal for Parasitology 26: 857–868.Google Scholar
Bisset, S. A., Vlassoff, A., Douch, P. G.C, Jonas, W. E., West, C. J. and Green, R. S. 1996. Nematode burdens and immunological responses following natural challenge in Romney lambs selectively bred for low or high faecal worm egg count. Veterinary Parasitology 61: 249–263.Google Scholar
Bisset, S. A., Vlassoff, A., West, C. J. and Morrison, L. 1997. Epidemiology of nematodosis in Romney lambs selectively bred for resistance or susceptibility to nematode infection. Veterinary Parasitology 70: 255–269.Google Scholar
Brunsdon, R. V. 1988. The economic impact of nematode infection in sheep: implications for future research and control. In The economic importance of parasites of livestock in New Zealand (ed. Heath, A. C. G.), New Zealand Society for Parasitology, miscellaneous publication no. 1, pp. 4–16.Google Scholar
Douch, P. G .C, Green, R. S., Morris, C. A., McEwan, J. C. and Windon, R. G. 1996. Phenotypic markers for selection of nematode-resistant sheep. International Journal for Parasitology 26: 899–911.Google Scholar
Eady, S. J., Woolaston, R. R., Lewer, R. P., Raadsma, H. W., Swan, A. A. and Ponzoni, R. W. 1998. Resistance to nematode parasites in Merino sheep: correlation with production traits. Australian Journal of Agricultural Research 49: 1201–1211.Google Scholar
Gavora, J. S. and Spencer, J. L. 1978. Breeding for genetic resistance to disease: specific or general? World’s Poultry Science Journal 34: 137–148.Google Scholar
Gilmour, A. R. 1997. ASREML for testing fixed effects and estimating multiple trait variance components. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 12: 386–390.Google Scholar
Howse, S. W., Blair, H. T., Garrick, D. J. and Pomroy, W. E. 1992. A comparison of internal parasitism in fleece weight-selected and control Romney sheep. Proceedings of the New Zealand Society of Animal Production 52: 57–60.Google Scholar
Johnson, D. L. and Thompson, R. 1995. Restricted maximum likelihood estimation of variance components for univariate animal models using sparse matrix techniques and average information. Journal of Dairy Science 78: 449–456.Google Scholar
Lawes Agricultural Trust. 1994. Statistical package: GENSTAT 5, release 3.1. Lawes Agricultural Trust, Rothamsted Experimental Station, UK.Google Scholar
McEwan, J. C., Dodds, K. G., Greer, G. J., Bain, W. E., Duncan, S. J., Wheeler, R., Knowler, K. J., Reid, P. J., Green, R. S. and Douch, P. G. C. 1995. Genetic estimates for parasite resistance traits in sheep and their correlations with production traits. New Zealand Journal of Zoology 22: 177 (abstr.).Google Scholar
McKenna, P.B., Allan, C. M., Taylor, M. J. and Townsend, K. G. 1995. The prevalence of anthelmintic resistance in ovine case submissions to animal health laboratories in New Zealand in 1993. New Zealand Veterinary Journal 43: 96–98.Google Scholar
Miller, F. M., Blair, H. T., Reynolds, G. W. and Reveil, D. K. 1998. The role of cysteine in the increased parasite susceptibility of Romney sheep selected for hogget fleece-weight. Proceedings of the New Zealand Society of Animal Production 58: 150–153.Google Scholar
Morris, C. A., Bisset, S. A., Baker, R. L., Watson, T. G., Johnson, D. L. and Wheeler, M. 1993a. An investigation of sire by location interactions for faecal nematode egg counts in lambs. Proceedings of the New Zealand Society of Animal Production 53: 231–233.Google Scholar
Morris, C. A., Bisset, S. A., Vlassoff, A., Baker, R. L., Watson, T. G. and Wheeler, M. 1997a. Yearling and ewe fleece weights in Romney and Perendale flocks selected for divergence in faecal nematode egg count. Proceedings of the Association for the Advancement of Animai Breeding and Genetics 12: 50–53.Google Scholar
Morris, C. A., Bisset, S. A., Vlassoff, A., West, C. J. and Wheeler, M. 1998. Faecal nematode egg counts in lactating ewes from Romney flocks selectively bred for divergence in lamb faecal egg count. Animal Science 67: 283–288.Google Scholar
Morris, C. A., Clarke, J. N., Watson, T. G., Wriggles worth, A. L. and Dobbie, J. L. 1996a. Faecal egg count and food intake comparisons of Romney single-trait selection and control lines. New Zealand Journal of Agricultural Research 39: 371–378.Google Scholar
Morris, C. A., Towers, N. R., Watson, T. G., Wheeler, M., Amyes, N. C. and Hosking, B.C. 1996b. Faecal nematode egg counts and facial eczema susceptibility in Romneys. Proceedings of the New Zealand Society of Animal Production 56: 84–86.Google Scholar
Morris, C. A., Vlassoff, A., Bisset, S. A., Baker, R. L., West, C. J. and Hurford, A. P. 1997b. Responses of Romney sheep to selection for resistance or susceptibility to nematode infection. Animal Science 64: 319–329.Google Scholar
Morris, C. A., Watson, T. G., Baker, R. L., Hurford, A. P. and Hosking, B.C. 1993b. Repeatability estimates and selection flock effects for faecal nematode egg counts in Romney breeding ewes. Proceedings of the New Zealand Society of Animal Production 53: 227–229.Google Scholar
Watson, T.G., Baker, R. L. and Harvey, T. G. 1986. Genetic variation in resistance or tolerance to internal nematode parasites in strains of sheep at Rotomahana. Proceedings of the New Zealand Society of Animal Production 46: 23–26.Google Scholar
Williamson, J. F., Blair, H. T., Garrick, D. J., Pomroy, W. E., Douch, P. G.C., Green, R. S. and Simpson, H. V. 1995. Parasitism and production in fleece-weight-selected and control sheep. New Zealand Journal of Agricultural Research 38: 381–387.Google Scholar
Woolaston, R. R. and Piper, L. R. 1996. Selection of Merino sheep for resistance to Haemonchus contortus: genetic variation. Animal Science 62: 451–460.Google Scholar