Risk factors for post-weaning mortality of Merino sheep in south-eastern Australia

Australian Veterinary Journal
A J D CampbellJ W A Larsen

Abstract

To measure associations between body weight, growth rate, sex, time of shearing and post-weaning mortality of Merino sheep. Uni- and multivariable survival analyses of sheep mortality during the first year after weaning, using records (n = 3657) from two field experiments conducted in Western Victoria from 1996 to 2003. Overall mortality was 14.3% (range 4.5-26.8%) and mean maximum mortality rate was 29 deaths/1000 weaners/month. Increased mortality risk was associated with decreases in fleece-free body weight and mean weaner growth rate, particularly at low weights and growth rates. Weaners in the lightest weaning weight quintile had a hazard ratio of 3.5, compared with the middle quintile. The hazard ratio for a 2-kg decrease in weaning weight was 1.2 to 1.7 for weaners lighter than 22 kg. The hazard ratio for a reduction in mean weaner growth rate in the first 5 months after weaning of 0.25 kg/month was 1.1 to 6.8 if mean growth rate was less than 1 kg/month, but did not differ significantly from 1 at greater growth rates. The hazard ratio for wether weaners was approximately 1.5 compared with ewe weaners. The hazard ratio for weaners shorn between December and May, compared with unshorn weaners, was 1.2 to 3.5, with the gre...Continue Reading

References

Nov 1, 1992·Australian Veterinary Journal·J H Holmes
Oct 1, 1974·International Journal of Biometeorology·J B DonnellyM E Webster
Jul 1, 1993·International Journal for Parasitology·I A Barger
Sep 1, 1995·Australian Veterinary Journal·D J Harris, G Nowara
Mar 4, 1998·Statistics in Medicine·J C Lindsey, L M Ryan
Jan 9, 1999·Lifetime Data Analysis·J K Lindsey
Jul 2, 2003·Preventive Veterinary Medicine·Brian R Radke

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Citations

Aug 14, 2009·Australian Veterinary Journal·A Jackson
Feb 28, 2014·Australian Veterinary Journal·G A KellyS W Walkden-Brown

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