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Genetic and phenotypic aspects of foot lesion scores in sheep of different breeds and ages

Published online by Cambridge University Press:  01 September 2008

G. J. Nieuwhof ,
J. Conington ,
L. Bűnger ,
W. Haresign  and
S. C. Bishop
G. J. Nieuwhof*
Affiliation:
Meat and Livestock Commission, PO Box 44, Milton Keynes MK6 1AX, UK Roslin Institute and Royal (Dick) School of Veterinary Studies, Roslin BioCentre, Midlothian EH25 9PS, UK
J. Conington
Affiliation:
SAC, West Mains Road, Edinburgh EH9 3JG, UK
L. Bűnger
Affiliation:
SAC, West Mains Road, Edinburgh EH9 3JG, UK
W. Haresign
Affiliation:
Institute of Rural Sciences, University of Wales, Aberystwyth SY23 3AL, UK
S. C. Bishop
Affiliation:
Roslin Institute and Royal (Dick) School of Veterinary Studies, Roslin BioCentre, Midlothian EH25 9PS, UK
*
E-mail: Gert.nieuwhof@dpi.vic.gov.au
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Abstract

Footrot is a costly endemic disease of sheep. This study investigates the potential to decrease its prevalence through selective breeding for decreased lesion score. Pedigreed mule and Scottish Blackface (SBF) ewes were scored for lesions on each hoof on a 0 to 4 scale for up to 2 (SBF ewes) or 4 (mules) times over 2 years. One score was obtained for SBF lambs. An animal was deemed to have lesions (severe lesions) if at least one hoof had a score of at least 1 (2). The prevalence of lesions was 34% in lambs, 17% in SBF ewes and 51% in mules. The heritability of lesions (severe lesions) analysed as repeated measurements of the same trait in a threshold model was 0.19 (0.26) in SBF ewes and 0.12 (0.19) in mules. Estimates for the sum and maximum of scores as well as the number of feet affected were much lower, as were estimates for permanent animal effects (i.e. non-genetic effects associated with an animal). When successive scores on the same animal were analysed as correlated traits, heritability estimates for most traits tended to be higher, except for severe footrot in mules where estimates varied greatly over time. The phenotypic correlations between successive scores in SBF ewes were close to 0, genetic correlations were moderately positive (0.18 to 0.55). Correlations in mules were generally of a similar size, but some genetic correlations were higher (up to 0.92). There was a clear trend for heritabilities for lesions and severe lesions to increase with higher prevalence of lesions, even when analysed in a threshold model. Heritability estimates for traits that combine scores over several events in mules, identifying the more persistently affected animals, ranged from 0.12 to 0.23 with the highest estimates for the average number of feet that were (severely) affected in animals scored for a minimum at two events. The heritability of all lesion traits in lambs was estimated as 0. It is concluded that selection for lower lesions is possible in ewes but not lambs, and that a simple binary score at an animal level is at least as effective as a comprehensive score at hoof level. Given the low repeatability of lesion scores, repeated measures over time will improve effectiveness of selection. Selection across environments (flocks, seasons) with different prevalences of lesions scores will need to take account of variation in the heritability.

Keywords

sheepfootrotprevalencegeneticsrepeatabilityfoot lesions
Type
Full Paper
Information
animal , Volume 2 , Issue 9 , September 2008 , pp. 1289 - 1296
Copyright
Copyright © The Animal Consortium 2008

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References

Bulgin, MS, Lincoln, SD, Parker, CF, South, PJ, Dahmen, JJ, Lane, VM 1988. Genetic-associated resistance to foot rot in selected Targhee sheep. Journal of the American Veterinary Medicine Association 192, 512–515.Google ScholarPubMed
Burke, JM, Parker, CF 2007. Effect of breed on response to foot rot treatment in mature sheep and lambs. Small Ruminant Research 71, 165–169.CrossRefGoogle Scholar
Clements, ACA, Mellor, DJ, Fitzpatrick, JL 2002. Reporting of sheep lameness conditions to veterinarians in the Scottish Borders. Veterinary Record 150, 815–817.CrossRefGoogle ScholarPubMed
Conington, J, Bishop, SC, Lambe, N, Bunger, L, Simm, G 2006. Testing new selection indices for sustainable hill sheep production – lamb growth and carcass traits. Animal Science 82, 445–453.CrossRefGoogle Scholar
Conington J, Hosie B, Nicoll L, Nieuwhof GJ, Bishop SC and Bünger L 2008. Breeding for resistance to footrot – using hoof scoring to quantify footrot in sheep. Proceedings of the British Society of Animal Science 2008, 31 March–2 April 2008, Scarborough, UK, poster no. 197.Google Scholar
Egerton, JR 2000. Foot-rot and other conditions. In Diseases of sheep (ed. WB Martin and ID Aitken), pp. 243–249, 3rd edition. Blackwell Science, Oxford, UK.Google Scholar
Egerton, JR, Roberts, DS 1971. Vaccination against ovine foot-rot. Journal of Comparative Pathology 81, 179–185.CrossRefGoogle ScholarPubMed
Emery, DL, Stewart, DJ, Clark, BL 1984. The comparative susceptibility of five breeds of sheep to foot-rot. Australian Veterinary Journal 61, 85–88.CrossRefGoogle ScholarPubMed
Gilmour, AR, Cullis, BR, Welham, SJ, Thompson, R 2002. ASReml Reference Manual. NSW Agriculture, Orange NSW, Australia.Google Scholar
GrogonoThomas, R, Cook, AJ, Johnston, AM 1998. Lame excuses? Proceedings of the Sheep Veterinary Society 22, 77–82.Google Scholar
Nieuwhof, GJ, Bishop, SC 2005. Costs of the major endemic diseases of sheep in Great Britain and the potential benefits of reduction in disease impact. Animal Science 81, 23–29.CrossRefGoogle Scholar
Parker, CF, Cross, RF, Hamilton, KL 1985. Genetic resistance to foot rot in sheep. Proceedings of the Sheep Veterinary Society 9, 16–19.Google Scholar
Raadsma, HW, Egerton, JR, Nicholas, FW, Brown, SC 1993. Disease resistance in Merino sheep I. Traits indicating resistance to footrot following experimental challenge and subsequent vaccination with an homologous rDNA pilus vaccine. Journal of Animal Breeding and Genetics 110, 281–300.CrossRefGoogle ScholarPubMed
Raadsma, HW, Egerton, JR, Wood, D, Kristo, C, Nicholas, FW 1994. Disease resistance in Merino sheep III. Genetic variation in resistance to footrot following challenge and subsequent vaccination with an homologous rDNA pilus vaccine under both induced and natural conditions. Journal of Animal Breeding and Genetics 111, 367–390.CrossRefGoogle ScholarPubMed
Skerman, TM, Johnson, DL, Kane, DW, Clarke, JN 1988. Clinical footscald and footrot in a New Zealand Romney flock: phenotypic and genetic parameters. Australian Journal of Agricultural Research 39, 907–916.CrossRefGoogle Scholar
Statistical Analysis Systems Institute 1989. SAS/STAT User’s Guide, version 6, vol. 2, 4th edition. Cary, NC, USA.Google Scholar
Van Heelsum, AM, Lewis, RL, Davis, MH, Haresign, W 2006. Genetic relationships among objectively and subjectively assessed traits measured on crossbred (Mule) lambs. Animal Science 82, 141–149.CrossRefGoogle Scholar
Wassink, GJ, Green, LE 2001. Farmers’ practices and attitudes towards foot rot in sheep. Veterinary Record 149, 489–490.CrossRefGoogle ScholarPubMed