Sheep resilience and productivity compared in CSIRO study

The project is an offset of the Merino Lifetime Productivity trial and is being carried out at the Armidale research station in partnership with Australian Wool Innovation.

Senior experimental scientist and team leader Amy Bell said the sheep were raised in commercial conditions and all data was recorded to make it as relevant to a commercial flock as possible.

Establishing immune competence was based on measurements taken from two different parts of the immune system, she said.

Blood samples were taken from lambs during weaning due to the added stress and the antibody levels were then recorded.

The sheep were also vaccinated with commercial clostridial vaccines.

"We don't obviously deliberately want them to be stressed, but we want to know which ones are really resilient when there's external pressures on them," Dr Bell said.

"We vaccinate them to help their immune system but some of them have a better immune system than others.

"By measuring what the actual circulating antibody is, we can measure which of those ones have those higher levels of antibody - they're our naturally more resilient ones."

The second measurement involved cell mediated immunity, where a fraction of the clostridial vaccine was injected into the skin and the size of the lump was measured a couple of days later.

Those two measurements were put together to give a resilience measurement for that animal.

It was early days but there was some correlation between resilience and productivity in certain traits, such as fleece weight and meat quality traits, she said.

The study tested 1450 animals this year and would measure a similar number next year. The goal was to develop genomic predictions to help producers with selection, she said.

"We have seen some encouraging correlations but they're not as accurate as we would like - that's why we're doing another two years worth of work," she said.

"Our aim of this is to really ensure that the correlations we're seeing for animals that are productive and but also resilient, that they're really strong.

"Every producer has lots of different things they need to consider when they're making these selection decisions, so we want to make sure we're giving them the right information."

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