Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-23T12:25:56.578Z Has data issue: false hasContentIssue false
  • English
  • Français

Merino ewes bred for parasite resistance reduce larval contamination onto pasture during the peri-parturient period

Published online by Cambridge University Press:  24 September 2009

A. R. Williams ,
J. C. Greeff ,
P. E. Vercoe ,
R. J. Dobson  and
L. J. E. Karlsson
A. R. Williams*
Affiliation:
School of Animal Biology, University of Western Australia, 35 Stirling Hwy Crawley, WA 6009, Australia
J. C. Greeff
Affiliation:
Department of Agriculture and Food Western Australia, Locked Bag 4, Bentley Delivery Centre, WA 6983, Australia
P. E. Vercoe
Affiliation:
School of Animal Biology, University of Western Australia, 35 Stirling Hwy Crawley, WA 6009, Australia
R. J. Dobson
Affiliation:
CSIRO Livestock Industries, Wembley, WA 6913, Australia
L. J. E. Karlsson
Affiliation:
Department of Agriculture and Food Western Australia, Locked Bag 4, Bentley Delivery Centre, WA 6983, Australia
*
†E-mail: [email protected]
Get access

Abstract

The peri-parturient period is crucial for controlling worms as the acquired immunity of ewes is disrupted, resulting in an increase in faecal worm egg counts. Two hypotheses were tested in this experiment – that ewes bred for worm resistance would have lower faecal worm egg counts than unselected control ewes, during late pregnancy and lactation, under similar but separate grazing areas; and also that numbers of infective nematode larvae would be lower on pastures grazed by resistant ewes than pastures grazed by unselected control ewes. Faecal samples were collected from resistant and unselected ewes in late pregnancy and early lactation, during the winter rainfall season, and analysed for numbers of Trichostrongylus colubriformis and Teladorsagia circumcincta. Pasture samples were taken 1 week before and 7 weeks after lambing started and analysed for infective larvae. In all sheep, worm egg counts rose 2 weeks prior to lambing and continued into lactation. Worm egg counts were significantly lower in the resistant ewes from 1 week before lambing to 2 weeks after lambing. There were no differences in egg counts between single- and twin-bearing ewes in the resistant line. However, twin-bearing control ewes had significantly higher egg counts than single-bearing control ewes. Following lactation, plots grazed by resistant ewes had substantially less contamination with T. colubriformis larvae, but there were no differences in numbers of T. circumcincta larvae. Our results demonstrate that sheep bred for worm resistance has lower worm burdens during the peri-parturient phase and that lambs born to resistant ewes face a lower larval challenge during their introduction to grazing. In our environment, selection for low worm egg counts has produced sheep highly resistant to T. colubriformis, but has had less impact on resistance towards T. circumcincta.

Keywords

genetic resistancesheepnematodespasture contaminationperi-parturient rise
Type
Full Paper
Information
animal , Volume 4 , Issue 1 , January 2010 , pp. 122 - 127
Copyright
Copyright © The Animal Consortium 2009

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, GAA, Gray, GD, Piper, LR, Barker, JSF, Le Jambre, LF, Barger, IA 1987. The genetics of resistance and resilience to Haemonchus contortus infection in young Merino sheep. International Journal for Parasitology 17, 1355–1363.CrossRefGoogle ScholarPubMed
Barger, IA 1993. Influence of sex and reproductive status on the susceptibility of ruminants to nematode infection. International Journal for Parasitology 23, 463–469.CrossRefGoogle Scholar
Bishop, SC, Stear, MJ 2003. Modeling of host genetics and resistance to infectious diseases: understanding and controlling nematode infections. Veterinary Parasitology 115, 147–166.CrossRefGoogle ScholarPubMed
Bisset, SA, Vlassoff, A, West, CJ, Morrison, L 1997. Epidemiology of nematodosis in Romney lambs selectively bred for resistance or susceptibility to nematode infection. Veterinary Parasitology 70, 255–269.CrossRefGoogle ScholarPubMed
Greeff, JC, Karlsson, LJE 2006. Breeding for worm resistance – whole farm benefits. International Journal of Sheep and Wool Science 54, 7–14.Google Scholar
Kahn, LP 2003. Regulation of the resistance and resilience of periparturient ewes to infection with gastrointestinal nematode parasites by dietary supplementation. Australian Journal of Experimental Agriculture 43, 1477–1485.CrossRefGoogle Scholar
Kahn, LP, Knox, MR, Walkden-Brown, SW, Lea, JM 2003. Regulation of the resistance to nematode parasites of single- and twin-bearing Merino ewes through nutrition and genetic selection. Veterinary Parasitology 114, 15–31.CrossRefGoogle ScholarPubMed
Karlsson, LJE, Greeff, JC 2006. Selection response in fecal worm egg counts in the Rylington Merino parasite resistant flock. Australian Journal of Experimental Agriculture 46, 809–811.CrossRefGoogle Scholar
Martin, RR, Beveridge, I, Pullman, AL, Brown, TH 1990. A modified technique for the estimation of the number of infective nematode larvae present on pasture, and its application in the field under South Australian conditions. Veterinary Parasitology 37, 133–143.CrossRefGoogle ScholarPubMed
McClure, SJ, Emery, DL, Wagland, BM, Jones, WO 1992. A serial study of rejection of Trichostrongylus colubriformis by immune sheep. International Journal for Parasitology 22, 227–234.CrossRefGoogle ScholarPubMed
Morris, CA, Bisset, SA, Vlassoff, A, West, CJ, Wheeler, M 1998. Faecal nematode egg counts in lactating ewes from Romney flocks selectively bed for divergence in lamb faecal egg count. Animal Science 67, 283–288.CrossRefGoogle Scholar
Smith, WD 2007. Some observations on immunologically mediated inhibited Teladorsagia circumcincta and their subsequent resumption of development in sheep. Veterinary Parasitology 147, 103–109.CrossRefGoogle ScholarPubMed
Stear, MJ, Strain, S, Bishop, SC 1999. Mechanisms underlying resistance to nematode infection. International Journal for Parasitology 29, 51–56.CrossRefGoogle ScholarPubMed
Whitlock, HV 1948. Some modifications of the McMaster helminth egg counting technique and apparatus. Journal of the Council for Scientific and Industrial Research 21, 177–180.Google Scholar
Williams, AR, Karlsson, LJE, Palmer, DG, Williams, IH, Vercoe, PE, Greeff, JC, Emery, DL 2008. Increased levels of cysteinyl leukotrienes and prostaglandin E2 in gastrointestinal tract mucus are associated with decreased faecal dry matter in Merino rams during nematode infection. Australian Journal of Experimental Agriculture 48, 873–878.CrossRefGoogle Scholar
Williams, AR, Karlsson, LJE, Palmer, DG, Vercoe, PE, Williams, IH, Greeff, JC, Emery, DL 2009. Faecal dry matter and nematode infection in parasite-resistant Merino sheep. Annual Conference of the British Society of Animal Science, Southport, UK, 29 pp.Google Scholar
Woolaston, RR 1992. Selection of Merino sheep for increased and decreased resistance to Haemonchus contortus: peri-parturient effects of worm egg counts. International Journal for Parasitology 22, 947–953.CrossRefGoogle Scholar
Woolaston, RR, Barger, IA, Piper, LR 1990. Response to helminth infection of sheep selected for resistance to Haemonchus contortus. International Journal for Parasitology 20, 1015–1018.CrossRefGoogle ScholarPubMed