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Breech‐strike on mulesed, clipped and unmulesed Merino ewes and hoggets in south‐eastern A ustralia
Author(s) -
Tyrell LD,
Larsen JWA,
Anderson N
Publication year - 2014
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.12228
Subject(s) - clips , breech presentation , zoology , medicine , biology , pregnancy , surgery , genetics
Objective Compare breech‐strike on Merino ewes and hoggets that were mulesed, had breech and tail clips applied (‘clipped’) or left unmulesed and treated strategically with long‐acting insecticide. Design A cohort study on two farms in southern Victoria. Methods Three treatment groups were established at lamb marking in 2008 and 2009 on each farm. The unmulesed group was treated with a long‐acting insecticide in early spring. The prevalence of breech‐strike and key risk factors, including presence of dag, urine stain and breech wrinkle, were compared between groups. Results Breech‐strike was detected from O ctober to D ecember on 1.9% and 7.2% of mulesed, and on 14.8% and 12.5% of clipped ewes, respectively, on each farm. Thus, clipped ewes had a relative risk of breech‐strike 7.8‐ and 1.7‐fold that of mulesed ewes. Unmulesed ewes treated with insecticide had similar or less breech‐strike compared with mulesed ewes (3.4% and 1.4%), but significantly more dag, stain and breech wrinkle. From J anuary, breech‐strike on unprotected unmulesed ewes was 8.5% and 2.8%, compared with 3.5% and 0% on mulesed ewes. Conclusion Early‐season treatment of unmulesed sheep prevented most breech‐strikes during spring and early summer on both hoggets and breeding ewes, confirming it as a short‐ to medium‐term option for the control of breech‐strike. Some benefits were associated with the use of clips but, to control breech‐strike, clipped sheep should be treated the same as unmulesed sheep. Genetic selection to reduce the prevalence of dag will be required for future strategies to control breech‐strike on Merino sheep in south‐eastern A ustralia.