Lamb Rib Fractures Preliminary Investigation

Dr Colin Trengove University of Adelaide Ian McFarland PIRSA Rural Solutions - Meat & Livestock Australia

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

Whilst previously considered a result of primary trauma due to poor husbandry it is now thought that rib fractures are secondary to pathologically weakened bones. With a greater understanding of neonatal and juvenile animal bone pathology the cause of these fractures may be identified and potentially eliminated.

 

What is the problem?

Rib fractures in lambs is a costly condition that results in a significant economic loss estimated to be $3 million per annum to producers and processors and raises significant welfare concerns.

The Enhanced Abattoir Surveillance (EAS) program was introduced in 2007 by the Department of Primary Industries and Regions of South Australia (PIRSA) Animal Health in order to monitor health conditions in South Australian sheep.

This Program’s target was:

-To explore practical predisposing factors on-farm leading to rib fractures diagnosed in lambs at slaughter, concentrating on the potential role of copper (Cu) deficiency.

-To investigate possible predisposing factors on-farm leading to rib fractures diagnosed in lambs at slaughter, concentrating on the potential role of copper (Cu) deficiency.

What did the research involve?

  • On-farm survey
  • Liver sample analysis
  • Pasture sampling – samples were collected from each of the 12 participating farms on Kangaroo Island and 17 in the South East of South Australia.
  • Pasture sample analysis – for mineral analysis including nitrate, nitrogen, phosphorus, potassium, calcium, magnesium, sodium, sulfur, boron, copper, zinc, manganese, iron, aluminum, cobalt, molybdenum, chloride and selenium.
  • Copper supplementation trial  was set up on a property 25 km south-east of Naracoorte on the Victorian border.
  1.  Control – no treatments given.
  2. Amount of copper capsule given at joining & no other treatments.
  3. Amount of copper capsule given at joining followed by a Multimin (including copper) injection pre-lambing & to lambs at marking.
  4. Multimin only (including copper) given pre-lambing & to lambs at marking.
  • Data analysis -The historic information of rib fractures for a particular property
  • Liver trace element content
  • Bone measurements – A total of 49 lamb humerus’ were analyzed using DEXA and CT scan.
  • Pasture mineral content
  • Copper supplementation trial
  • Ewe liver biopsies
  • Lamb slaughter results
  • Lamb liver copper & selenium results

What were the key findings?

  • On-farm survey – The original aim was to include 10 positive and 10 negative properties for rib fracture incidence in the study, but a much larger sample was included to allow for an anticipated drop out rate.
  • Liver trace elements – The objective of this investigation was to identify possible predisposing factors on-farm leading to rib fractures diagnosed in lambs at slaughter, concentrating on the potential role of copper deficiency.
  • Bone strength – There was no statistical difference in bone density, cortical thickness or a cortical value between properties with or without a history of rib fractures.
  • Pasture analysis -The minerals of particular interest from these results are calcium, copper, iron, manganese, molybdenum, selenium and sulfur due to their role in bone development either independently or in combination.
  • Supplementation trial – The liver biopsies taken mid-pregnancy three months after the trial was set up indicated that both the control and treated groups had adequate copper.

Following 698 lambs through the abattoir revealed a mixed outcome, that had no clear relation to the treatments given.

An overall prevalence of 4.4% rib fractures was in line with expectations, but the lack of correlation with copper treatments further casts doubt over a direct relationship between copper status and the incidence of rib fractures.

Final comment

The results indicate that copper deficiency is not a principal cause of bone weakness in neonatal lambs that may ultimately lead to rib fractures. A larger sample size is required to improve the statistical significance of these findings

2015 - Australia - Dr Colin Trengove University of Adelaide Ian McFarland PIRSA Rural Solutions - Meat & Livestock Australia
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