Saturday, March 30, 2024

Index points to greener herds

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Genetics company LIC is providing a tool for farmers wanting to considere their herd’s gas and nitrogen footprint when breeding replacements. Environment and welfare manageer Tony Fransen spoke to Richard Rennie about its new HoofPrint index and how it could help make herd environmental footprints lighter.
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LIC’s annual genetics catalogue showcasing farmers’ bull options for breeding will this year include an extra column amid the usual production and economic traits. 

The HoofPrint index ranks its sires’ estimated ability to breed greener daughters that produce less nitrogen and methane.

“The objective was to determine how we can quantify the role genetics has had in achieving environmental gains over the last 20-30 years and, from that, estimate what the cow 20-30 years from now will look like,” Fransen said.

Having access to milk production data from a sire daughter population numbering tens of thousands regularly collected through herd testing has been integrated with the Primary Industries Ministry’s agricultural greenhouse gas inventory. 

“We merged the individual daughter performance into the GHG calculations, resulting in individual sire results and identifying those sires that are more efficient in terms of their daughters’ milksolid production.”

The index ranks sires’ efficiency from 10 to 1, with 10 delivering the lowest environmental impact per kilogram of milksolids produced.

Fransen said the index is another tool farmers can use when greenhouse gas obligations need to be determined at a farm level. 

“But we know different feed, management and stock systems will all deliver different footprints. 

“HoofPrint provides an animal environmental efficiency measure for farmers. 

“We know higher genetic merit animals partition more of their feed eaten into milksolids and less into waste, that is why higher genetic merit animals on average will perform better when ranked under the HoofPrint index.”

On average for every $10 increase in a cow’s Breeding Worth there is 1.7g less urinary nitrogen produced for every kilo of milksolids. 

Total emissions from the agricultural sector have grown in the past 20 years with nitrous oxide increasing 27% from 1990 to 2016 and methane increasing 4%. 

However, the total growth has come from increases in dairy cow numbers.

Fransen said since 1990 there has actually been a 16% reduction in lifetime urinary nitrogen per kilo of milksolids from individual daughters sourced from LIC’s Premier Sires team. 

Over the past 30 years there has also been a 13% drop in lifetime enteric methane per kilo of milksolids.

“Given we have probably peaked for total cow numbers now there is a real opportunity for genetics to play a role in reducing overall losses combined with new management techniques, including pasture types.”

Further research work is now under way to link feed input to methane output in dairy cows in conjunction with the Agricultural Greenhouse Gas Research Centre.

Research in sheep has already identified genetic variation for methane production. 

Fransen said on average for every 1kg of drymatter consumed by a dairy cow 21.6g of methane is produced.

“So this work will enable us to see what genetic variability exists around that 21.6g figure.”

A special measuring device in a purpose-built barn will be used to measure bulls’ methane emissions about three times a day. Initially 12 bulls will be measured but that will be ramped up to a full trial of 300 bulls in February. 

Once their daughters have been bred and are producing milksolids it will be possible to validate whether the sires’ methane measurements are representative of their daughters’ emissions. 

Being able to measure genetic variance in emissions per unit of feed eaten will ultimately provide dairy farmers with an indication of their herd emissions. 

There are other research projects occurring to consider the effect of different feed types on methane emissions. These are all components that will give farmers a level of control through selecting the right animals and feed to optimise their system.

“Of course, it is important all valuable efficiency traits like fertility and production will also need to be taken into account,” Fransen said.

The encouraging aspect of the research is that traits for lower gas emissions appear relatively well inherited, ranking similar to many other production traits bred for.

Fransen said the advanced research work could ultimately be incorporated into the HoofPrint index.

“It could be an individual methane value but you need to be careful you do not risk eclipsing the other all-round animal efficiency values. Ultimately the animal with the lowest methane emissions could be the animal that eats the least and is not necessarily the most productive or efficient as a result.”

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