Breech bareness reduces flystrike in New Zealand crossbred sheep
D. R. Scobie A B and D. O’Connell AA AgResearch, Lincoln Research Centre, Private Bag 4749, Christchurch 8140, New Zealand.
B Corresponding author. Email: scobie@agresearch.co.nz
Animal Production Science 50(6) 599-602 https://doi.org/10.1071/AN09198
Submitted: 11 December 2009 Accepted: 14 April 2010 Published: 11 June 2010
Abstract
Two experiments on the effect of breech bareness on flystrike are reported here. Sires from commercial sources (n = 2) and from a mixed breed flock selected for breech bareness (n = 5) were mated to ewes from the same flock and Romney ewes. Lambs (n = 211) were run as one mob from docking to weaning. Within 2 days before weaning, flystrike affected several lambs. At weaning the lambs were inspected for breech bareness score and dag score. Flystruck lambs were recorded, treated and removed at weaning. The remaining lambs (n = 185) were regularly inspected and treated for flystrike, and the incidence of flystrike was recorded again 1 month later. There were no significant differences between sire groups, but the progeny of Romney dams were more likely to be flystruck (18.7 vs 3.4% and 24 vs 3.7%) on both occasions (P < 0.05). Flystrike increased with increasing dag score (P < 0.001) but dag score decreased with increasing breech bareness (P < 0.001).
The ewe progeny (n = 800) of 17 Romney sires were run as one flock following weaning on a commercial farm in the North Island of New Zealand. The lambs were inspected for breech bareness, dag score and the incidence of flystrike following a brief period of fly challenge. As breech bareness score increased, dag score declined (P < 0.001) with a significant effect of sire on dag score (P < 0.001). Breech bareness had a significant influence on the proportion of lambs with flystrike (P = 0.028), most likely through dag score which explained a greater proportion of variation in flystrike in multiple linear regression (P < 0.001). Selection against dags in New Zealand crossbred sheep could lower flystrike risk, but selection for increasing breech bareness will reduce both dagginess and flystrike risk.
Additional keywords: mulesing alternative, sheep welfare, tail docking.
Acknowledgements
We thank David and Maureen Smith of Holly Farm Romneys for their enthusiasm in this research and Dave Saville of Saville Stat for assistance with the analysis of the data. John Carson the farm manager of Winchmore Research Station is also gratefully acknowledged for his tolerance of long tails. Funding was obtained from the Humphrey M. Russell Award, Meat and Wool New Zealand and the Foundation of Research Science and Technology to support this work.
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