Friday, March 29, 2024

Sheep lead methane research

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A mob of low methane sheep are proving it is possible to produce less methane and grow a healthy, productive animal that farmers will want to put into their flock bloodlines in coming years.
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For the past decade New Zealand scientists have largely flown below the radar with the work, but are enjoying world leading success in identifying high and low methane emitting sheep. 

The work means today researchers including AgResearch scientists, with the support of farmers through the Pastoral Greenhouse Gas Research Consortium  have two flocks of sheep, one high and one low methane emitting, and have established a genomic profile over three breeding generations. 

These provide sheep breeders with useful and accurate data on what their animal’s “methane value” is, relative to its breeding value.

Three generations in, they are now able to collect data on the feed efficiency, carcass yield, growth rates and gut bacteria, which influence how their methane emissions stack up against the average.

Dr Suzanne Rowe, senior AgResearch scientist says on average the low methane sheep are emitting 11% less of the gas than the average, per kilogram fed.

“These low methane emitting sheep have 20% smaller rumens but have a similar surface area and this appears to be a physiological adaptation. 

“They tend to eat more dry matter, but it is a little and often, and have different microbial fermentation which enables us to predict if they will be high or low emitters, based on their gut bacteria.”

The scientists have identified some upsides in the quality of the animal’s production. This includes more lean growth over fat production, and higher wool production.

“They are profitable and healthy sheep, and we are comfortable the changes have done no harm,” says Dr Rowe.

Researchers are now able to draw a syringe of rumen fluid from trial animals and gain a sequential DNA profile of the rumen bacteria community. They are observing heritable variations in the microbes present, beyond what feed regimes determine.

“So now the microbes and the animal’s genomic profile provide us with an accurate picture of the animal’s low methane nature.”

Scientists are now taking rumen samples from ruminants all over the world and assimilating that data enabling them to come up with more predictive ability about what animals will prove to be lower methane than others.

“We know the volatile fatty acids and microbiomes differ in low methane animals, so we wanted to see – what that does to their milk?”

The result of profiling ewe’s milk determined a difference in low methane animals, with more polyunsaturated fats in their milk and different ratios of fatty acids in high methane versus low methane animals.

“The 10-20% difference between them is significant.” 

Scientists have also found the meat quality from low methane sheep good, with good eating characteristics.

Sheep breeders can already choose to measure their animals’ methane breeding value, working with scientists to get rams measured so they can answer the question if clients ask about it. 

The low methane breeding value (BV) is available to any breeder choosing to measure it, or has  animals with a genomic profile very closely related to animals already measured. 

It is updated in the national system automatically with all other BVs on a fortnightly basis. 

“From a commercial standpoint, whether a commercial breeder is using methane as a criteria for ram purchase will depend on market forces. If there is a demand for low methane stock nationally the roll out could happen within a couple of years.”

Based on their experience with sheep, the researchers can see a similar pathway for dairy cattle that may help identify suitable animals quicker.

Sampling a wide population of dairy females could be hastened by using the portable accumulation chambers (PAC)s developed during the sheep research. 

Developed initially from the sheep research, they enable scientists to hold animals in comfort, feed them a pre-set diet and draw off the CO2 and methane emitted. 

It is regarded as a low cost, high proof tool for measurement that is capable of sampling dozens of animals, and could be utilised for other ruminants including goats and calves.

“It would be possible for us to go out now and screen dairy herds to see if we find profiles we know of, based off the sheep research. We can turn the research already done on its head by starting with the answers we already know we have, from sheep.”

The scientists are reasonably optimistic about the time it will take to breed lower methane traits into livestock.

“It has taken 2.5-3 generations to achieve a 11% reduction to date,” says Dr Rowe.

“Our hope would be these breeding values are a characteristic of on farm calculations, so the status of the stock is incorporated into the farm environment plan.”

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