Wednesday, September 1, 2021
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A new genetic index to help breed more carbon-friendly cows

A new genetic index to help farmers breed more environmentally friendly cows will be launched next week by AHDB Dairy.

The index, called EnviroCow, reflects the important part genetics and breeding have to play in improving the environmental efficiency of milk production. Incorporating cow lifespan, milk production, fertility and, most importantly, the brand-new Feed Advantage index, EnviroCow is the first independent genetic index in the world to focus solely on breeding cows for their environmental credentials.

Marco Winters, head of animal genetics for AHDB, said: “The environmental focus of EnviroCow reflects the important role cattle breeding can play in helping the farming industry reach its goal of net zero greenhouse gas (GHG) emissions.

“We know from past performance that genetic selection can play a significant part in improving dairy cow efficiency.

“We have seen this in genetic traits farmers have selected for over many decades, including milk, fat and protein production and more recently in numerous health and related traits such as somatic cell count, mastitis resistance and fertility.”

Now, he says dairy farmers can consider improving the environmental credentials of their cattle through their breeding choices, alongside other aspects of their health, efficiency, conformation and production.

“Beginning with the August 2021 genetic evaluations, they will be able to use the EnviroCow index when selecting their dairy bulls, alongside the UK’s main commercial breeding index, Profitable Lifetime Index,” he said.

“£PLI remains our recommended primary focus for genetic selection, but farmers can increase the emphasis on different individual traits to meet their own farm’s goals,” he said.

How is EnviroCow expressed?

EnviroCow will be expressed on a scale of about -3 to +3, where the highest positive figures are achieved by bulls which transmit the best environmental credentials to their daughters. These will be cows which are predicted to create the least GHG emissions in their lifetimes for each kilogram of solids-corrected milk they produce.

“This is a standardised scale rather than one which quantifies the exact carbon dioxide equivalent saved, and we are confident that using the best bulls – those scoring around +3 – will offer significant scope for genetic improvement and make a dent in the industry’s carbon footprint,” he says.

“Current estimates indicate that each year we can contribute around a one per cent reduction in CO2 equivalent for every kilogram of milk produced.”

Feed Advantage:

At the heart of EnviroCow is Feed Advantage, a new genetic index which will help producers breed animals which use the least amount of feed for their production needs.

Identifying bulls with the greatest tendency to transmit good feed conversion on to their daughters, it is expressed as a Predicted Transmitting Ability (PTA) in kilograms of dry matter intake (DMI) saved during each lactation.

“In calculating Feed Advantage, account is taken of the feed an animal is expected to eat given her solids-corrected milk production and the feed she needs for her maintenance,” said Mr Winters.

“This requirement is compared with her actual feed consumption – measured from individual cow intake data – thus identifying animals which have demonstrated they are efficient converters.”

Adjustments are also made for the size of the animal, as a smaller cow requires less feed than a larger cow giving the same level of milk production.

“This means Feed Advantage represents the kilograms of dry matter saved due to both better feed conversion efficiency and lower maintenance costs,” he said.

Thirty years in the making:

The launch of Feed Advantage represents the culmination of over 30 years of research and data collection from the award-winning Langhill herd in Dumfries. Undertaken by Scotland’s Rural College (SRUC), the studies have measured (amongst other traits) the Langhill cows’ dry matter intake throughout their entire lives.

Performance has then been compared with the animals’ DNA, identifying patterns (or SNPs –Single Nucleotide Polymorphisms) associated with feed intake.

Using this information, genomic indexes can be calculated, meaning every Holstein bull and cow which has been genomically tested will gain a PTA for Feed Advantage.

“Genomic young sires will have a reliability for their Feed Advantage of around 45 per cent,” said Mr Winters. “This is reasonably promising and reflects the fact that we have a database of over 750,000 daily DMI records. This has been obtained from both low and high feed-intake herds at SRUC and totals around 5,000 lactations from 2,000 Holstein cows throughout their full first to fourth lactations.”

How much feed can be saved?

With the most efficient cows consuming as much as 400kg less in just one lactation than the least efficient cows, given the same level of production, there is substantial scope for cutting feed use.

“Since feed represents around 70 per cent of variable costs, this offers plenty of scope for financial as well as environmental savings,” he said. “Even if you took a modest estimate of just a 100kg DMI benefit in every lactation, that’s 180,000 tonnes of dry matter saved each year across the nation’s 1.8 million dairy cows.”

As with all genetic gain, the effects are permanent and build up over the generations, offering massive scope if mirrored in savings worldwide.

“By launching EnviroCow and Feed Advantage at this time we are identifying and capturing the best genes for efficiency which, along with better management, can have a positive impact on the use of the world’s finite resources and the carbon footprint of UK dairy farming,” he said.

“Farmers have already made massive strides in improving dairy cow genetics for production, health and efficiency, much of which is already positive for the environment. Now they can move this up a gear with genetic indexes designed specifically to improve their dairy cow’s carbon emission credentials.

“Every sector of the farming industry can contribute to reaching net zero and dairy cattle genetics is no exception,” he concluded.

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