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A field study of nematode parasite populations in the lactating ewe

Published online by Cambridge University Press:  06 April 2009

B. M. O'Sullivan  and
A. D. Donald
B. M. O'Sullivan
Affiliation:
Department of Veterinary Pathology, University of Sydney, N.S.W., 2006, Australia
A. D. Donald
Affiliation:
McMaster Laboratory, C.S.I.R.O., Division of Animal Health, Glebe, N.S.W., 2037, Australia
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Extract

A typical postparturient rise of parasite egg output occurred in a group of lactating ewes. At parturition these animals carried few inhibited fourth-stage larvae and the rise was associated with a net increase in parasite populations, which did not occur in non-lactating ewes. Lactating ewes whose established parasite populations were effectively removed just prior to parturition showed a similar rise derived entirely from infection acquired during lactation, which was of much greater magnitude than that seen in similarly treated non-lactating animals. Circumstantial evidence of increased fecundity of T. colubriformis females in lactating ewes was also obtained.

It was concluded that the postparturient rise of egg output may derive from an increase in adult parasite populations by an increased rate of establishment of newly ingested infective larvae which develop to the adult stage without inhibition, as well as by the resumption of development of previously inhibited fourth-stage larvae. In addition, both newly acquired and established adult female parasites may show increased fecundity.

Ewes whose lambs were removed at birth or after a period of lactation showed a rapid fall in faecal egg counts associated with rejection of part of their existing worm burden and a pronounced increase in resistance to new infection.

All of the differences observed between lactating and non-lactating ewes in the behaviour of their parasite populations were found to be qualitatively the same as those that have been frequently reported in susceptible and resistant non-reproductive sheep. The hypothesis is suggested, therefore, that the postparturient rise derives from a pronounced but temporary relaxation of immunological control of gastro-intestinal nematode infection associated with the endocrine status of the lactating ewe.

Type
Research Article
Information
Parasitology , Volume 61 , Issue 2 , October 1970 , pp. 301 - 315
Copyright
Copyright © Cambridge University Press 1970

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References

REFERENCES

Arundel, J. H. & Ford, G. E. (1969). The use of a single anthelmintic treatment to control the post-parturient rise in faecal worm egg count of sheep. Australian Veterinary Journal 45, 89–93.CrossRefGoogle ScholarPubMed
Brunsdon, R. V. (1964). The seasonal variations in the nematode egg counts of sheep: A comparison of the spring rise phenomenon in breeding and unmated ewes. New Zealand Veterinary Journal 12, 75–80.CrossRefGoogle ScholarPubMed
Connan, R. M. (1966). A post-parturient rise of faecal nematode egg counts in sows. Veterinary Record 79, 156–7.Google Scholar
Connan, R. M. (1967 a). Observations on the post-parturient rise in the faecal nematode egg count of ewes. Veterinary Record 80, 401–5.CrossRefGoogle ScholarPubMed
Connan, R. M. (1967 b). Observations on the epidemiology of parasitic gastro-enteritis due to Oesophagostomum spp. and Hyostrongylus rubidus in the pig. Veterinary Record 80, 424–9.CrossRefGoogle ScholarPubMed
Connan, R. M. (1968). Studies on the worm populations in the alimentary tract of breeding ewes. Journal of Helminthology 42, 9–28.CrossRefGoogle ScholarPubMed
Crofton, H. D. (1954). Nematode parasite populations in sheep on lowland farms. I. Worm egg counts in ewes. Parasitology 44, 465–77.CrossRefGoogle ScholarPubMed
Dunsmore, J. D. (1965). Ostertagia spp. in lambs and pregnant ewes. Journal of Helminthology 39, 159–84.CrossRefGoogle ScholarPubMed
Field, A. C., Brambell, M. R. & Campbell, J. A. (1960). Spring rise in faecal worm-egg counts of housed sheep, and its importance in nutritional experiments. Parasitology 50, 387–99.CrossRefGoogle ScholarPubMed
Gibbs, H. C. (1967). Some factors involved in the spring rise phenomenon in sheep. In Veterinary Medical Review. The Reaction of the Host to Parasitism. Ed. Soulsby, E. J. L.. Proceedings of the Third International Conference of The World Association for the Advancement of Veterinary Parasitology,Lyons,1967. pp. 160–73.Google Scholar
Herlich, H. (1956). A digestion method for post-mortem recovery of nematodes from ruminants. Proceedings of the Helminthological Society of Washington 23, 102–3.Google Scholar
Jansen, J. Jr (1968). Enkele Waarnemingen omtrent de ‘spring rise’ bij schapen. Tijdschrift voor diergeneeskunde 93, 422–30.Google Scholar
Morgan, D. O., Parnell, I. W. & Rayski, C. (1951). The seasonal variations in the worm burden of Scottish hill sheep. Journal of Helminthology 25, 177–212.CrossRefGoogle Scholar
Naerland, G. (1949). Nutrition in relation to nematode parasitism in sheep. Report of the XIVth International Veterinary Congress, London, 1949, 2, 65–70.Google Scholar
Parnell, I. W. (1961). Modifications of a digestion technique for recovery of bursate nematodes of sheep at post-mortem. New Zealand Veterinary Journal 9, 60–1.CrossRefGoogle Scholar
Soulsby, E. J. L. (1957 a). Studies on the serological response in sheep to naturally acquired gastro-intestinal nematodes. II. Responses in a low ground flock. Journal of Helminthology 31, 145–60.CrossRefGoogle Scholar
Soulsby, E. J. L. (1957 b). Some immunological phenomena in parasitic infections. Veterinary Record 69, 1129–39.Google Scholar
Taylor, E. L. (1935). Seasonal fluctuation in the number of eggs of Trichostrongylid worms in the faeces of ewes. Journal of Parasitology 21, 175–9.CrossRefGoogle Scholar
Taylor, E. L. & Michel, J. F. (1953). The parasitological and pathological significance of arrested development in nematodes. Journal of Helminthology 28, 199–205.CrossRefGoogle Scholar