Abstract

Increasing breech wrinkles, breech cover and dags increase flystrike susceptibility of Merino sheep. Urine stain has been implicated in flystrike, although there is a paucity of data. At tail docking in 2007, 2008 and 2009 on a property breeding Merino rams, breech wrinkle (1 to 5) was scored on 238, 202 and 337 lambs that were the progeny of 12, 9 and 9 sires respectively. Dag score (0 to 5), urine stain (0 to 5) and breech cover (1 to 5) were scored at 100 days of age. Breech wrinkle score (h² = 0.51 ± 0.11) and breech cover (h² = 0.27 ± 0.08) were heritable, and phenotypically (0.16 ± 0.04, P <0.05) and genetically correlated (0.77 ± 0.14, P <0.05). Dag and urine stain scores were skewed towards low scores and the heritability estimates for these traits were low (h² = 0.08 ± 0.07 and 0.04 ± 0.06 respectively). Yearling clean fleece weight was heritable (h² = 0.28 ± 0.13) and genetically correlated with breech cover (-0.62 ± 0.26, P <0.05). There was no evidence of flystrike during the investigation, but there was potential to decrease susceptibility by decreasing breech cover and breech wrinkles in this flock.

DR, Scobie, SM Hickey, DP Maslen, and GM Black

Proceedings of the New Zealand Society of Animal Production, Volume 71, Invercargill, 251-256, 2011