Friday, March 29, 2024

Planet’s gain is no loss to sheep quality

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Researchers look at effect on meat quality of breeding for lower emissions.
AgResearch scientist Suzanne Rowe says farmers need to know if they commit to breeding their animals for lower methane that they are not going to compromise their productivity.
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Farmed animals bred for less impact on the climate produce meat quality just as good, if not better, according to newly published results of long-running research on sheep.

After three generations of breeding and more than 10 years of research, results revealed the lowest-emitting sheep in a research flock produced close to 13% less methane per kilogram of feed eaten than the highest emitters. 

However, while successful independent breeding strategies for improved production and lower methane are in place, the unanswered question was whether these strategies can be combined and how they affect one another both physically and economically.

And how this affected the quality of the meat produced was the question. It has now been answered in a series of papers published in Frontiers in Genetics. 

AgResearch senior scientist Suzanne Rowe says the research provides valuable insight into any implications for breeding for lower methane.

“Once we knew we could breed for less methane, we set about determining what the impact on the animal might be from birth through to parenthood.

“The work was carried out in flocks across New Zealand using thousands of measures over several years to demonstrate that low methane emissions can be included into breeding goals without sacrificing other key health and performance traits.”

Rowe says some animals naturally emit less methane as a product of their digestion and this trait can be bred for and passed down through generations.

Sheep selection lines bred for divergent methane production and large numbers of their relatives were used to determine the genetic and phenotypic correlations between enteric methane emissions, carcase yield and meat quality.

The primary objectives were to determine whether previously shown physiological differences between methane selection lines result in negative impact on meat production and quality by measuring close relatives.

Gross methane emissions were highly correlated with liveweight and measures of carcase weight and negatively correlated with dressing-out percentage and fat yield.

These trends were similar but not significant for methane yield.

The results show no negative effects of breeding for lowered methane on meat quality or carcase traits.

Low-emitting animals may even have greater economic value through slightly higher dressing-out rates, decreased fat and increased meat yields. 

This is critical because farmers need to know that if they are committing to breeding their animals for lower methane that they are not going to compromise their productivity and earnings.

“These results are of importance for all ruminant livestock production systems with this knowledge providing greater incentive to make changes on farms that contribute to NZ’s methane reduction goals and to climate change globally.

“They are of particular relevance for meeting the globally agreed targets through the development of robust selection indices that aim to reduce methane emissions while also increasing productivity.

“Meat production and meat quality are increasingly important goals in sheep production and therefore accurate estimates of genetic and phenotypic parameters of these traits with methane production are essential for any industry implementation,” Rowe says.

Research relating to the health of the sheep also suggests that breeding for low methane is unlikely to affect issues such as internal parasites, the fertility of adult ewes and the survival of lambs.

For wool, low-methane breeding was favourable to fleece weight. 

The current research work will underpin methane reduction via genetics in the NZ livestock industry with the results relevant to other ruminant species and in the assessment of other mitigation technologies, Rowe says.

Similar research is underway for cattle and the deer industry is also kicking off projects.

Having the ability to select for less methane emitting is something that could be useful for deer farmers, Deer Industry NZ (DINZ) science and policy manager Emil Murphy says. 

“But we need to be able to do that while maintaining productivity and eating quality in particular, so it’s good to see these findings being published.

“We can’t put animals through the portable accumulation chambers you can use for sheep, so we are looking at other ways of measuring emission profiles from lots of animals to then create breeding values. 

“We’re looking to use what is known about sheep and cattle to translate it for deer,” Murphy says.

At a recent NZ Deer Farmers Association branch chairs meeting, AgResearch deer scientist Jamie Ward outlined three projects that are kicking off a low-GHG deer systems research programme.

These include finding the gaps in research and knowledge and modelling various scenarios; understanding deer biology and behaviours to enable the development of prototypes of deer-suitable methane measuring technologies; and modelling current deer system GHG-reduction opportunities.

While the information gained in sheep and cattle will be useful in deer, Rowe says transferring this to deer will require different methods as the behavioural patterns of different species require different approaches.

“We have found rumen profiles are very predictive of feed intake in sheep so rumen sequencing profiles work very well, but we can’t put deer in a chamber situation.

“We are looking at rumen fluid off deer as one of the best technologies for deer going forward.”

With research in sheep showing microbes on oral swabs as predictive, this is looking to be a more straightforward option for deer.

“For deer we can collect samples at the plant and use that information to rank sires,” Rowe says.

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