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Estimation of risk factors associated with difficult birth in ewes


Horton, BJ and Corkrey, R and Hinch, GN, Estimation of risk factors associated with difficult birth in ewes, Animal Production Science, 58, (6) pp. 1125-1132. ISSN 1836-0939 (2018) [Refereed Article]

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Copyright 2018 CSIRO

DOI: doi:10.1071/AN16339


In eight closely recorded Australian Merino and crossbred sheep flocks, all lamb deaths were examined and the cause of deaths identified if possible. Dystocia was identified as one of the major causes of lamb death and this study examined factors that could be used to identify ewes at high risk of dystocia, either to avoid dystocia or to assist with early intervention where possible. Dystocia was least common in lambs of ~4.8 kg, but there was a higher risk at both lower and higher birthweights. Dystocia with both low and high birthweight was more common in older ewes, ranging from negligible low birthweight dystocia in ewes less than 3 years old at lambing, to 5% in older ewes. Low birthweight dystocia increased with increasing litter size, with 40% dystocia in ewes at least 4 years of age with triplets. In contrast, high birthweight dystocia was not affected by litter size. A previous record of low birthweight dystocia was a risk factor for future low birthweight dystocia, but the same relationship was not observed for high birthweight dystocia. A high lambing ease score (difficult birth) with high birthweight was a risk factor for future high birthweight dystocia, but this was not the case for low birthweight dystocia. These differences between the risk factors for low and high birthweight dystocia suggest that they have different causes. High ewe liveweight and condition score during pregnancy may be additional indicators of the risk of dystocia, particularly for ewes with high liveweight in the first 60 days of pregnancy. For most ewes dystocia was difficult to predict, but there was a small proportion of ewes with a very high risk of dystocia and if these could be identified in advance they could be monitored much more closely than the rest of the flock.

Item Details

Item Type:Refereed Article
Keywords:animal reproduction, animal welfare, lambing, lamb survivial, twinning
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Animal production
Research Field:Animal reproduction and breeding
Objective Division:Animal Production and Animal Primary Products
Objective Group:Livestock raising
Objective Field:Sheep for meat
UTAS Author:Horton, BJ (Dr Brian Horton)
UTAS Author:Corkrey, R (Dr Ross Corkrey)
ID Code:127491
Year Published:2018
Web of Science® Times Cited:2
Deposited By:TIA - Research Institute
Deposited On:2018-07-31
Last Modified:2019-03-20

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