Sustainability Index A breeding tool for a greener future

The Australian dairy industry has committed to a 30 per cent reduction in the intensity of greenhouse gas emissions on-farm by 2030.

Dairy farmers have a range of management tools to reduce greenhouse gas emissions (GHG) and breeding is the latest tool to be added to their kit.

Introduced in August 2022, the Sustainability Index allows dairy farmers fast track genetic gain for reduced emissions intensity.

Leading Irish research found that genetics is one of the most cost-effective strategies to reduce greenhouse gas emissions, but it’s not the only tool.

Breeding should be used in conjunction with other management decisions, such as energy use and feeding, to reduce a farm business’s overall carbon output.

Reducing greenhouse gas emissions 

There are two approaches to reducing emissions on a dairy farm – reducing the total or gross emissions or reducing emissions intensity.

The Sustainability Index focuses on reducing emissions intensity; that is, decreasing the amount of carbon emitted relative to milk production.

This is calculated by dividing the amount of carbon emitted by the amount of milk produced.

The reduction in emissions intensity is achieved through dilution – higher production per cow means more milk per tonne of carbon.

This index places greater emphasis on traits that contribute to reducing emissions, such as feed saved and survival, while also considering production, health, fertility, type, and workability traits.

Sustainability Index 

Breeding indices combine more than one trait at once, to make it easier to make animal selection decisions.

The Sustainability Index is a standalone index and prioritises an animal’s ability to product more milk with less greenhouse gas emissions, while also considering other traits that affect profitability.

The Sustainability Index is a relative ranking of animals expressed as a unit against a base of 0. The higher the Sustainability Index value, the more efficient the animal is at producing milk per kilogram of greenhouse gas emissions.

The reliability – or confidence – in the Sustainability Index is similar to the reliability for the Balanced Performance Index (BPI).

To fast-track genetic gain for sustainability, breed replacements from animals that rank highly for Sustainability Index also rank highly on Australian Breeding Values (ABVs) for fertility, mastitis resistance and cell count (and udder depth for Jerseys).

Dairy farmers can choose a short list of animals based on the bulls that are also highly ranked on the BPI and have high ABVs for fertility, cell count and mastitis resistance. DataGene’s Good Bulls App is an easy way to do this. 

Expected impact

Holstein and Red breeders using the Sustainability Index should achieve faster gain for emissions reduction and production, compared to the BPI. However, there will be a slightly slower genetic gain for mastitis resistance, cell count and fertility compared to the BPI.

In Jerseys, the Sustainability Index is likely to result in slower gains for mastitis resistance, cell count and fertility, and neutral to slightly declining udder depth compared with the BPI. If this is a concern for your herd, look for Jersey bulls that are high for both Sustainability Index and Daughter Fertility or Udder Depth ABV.

DataGene is an initiative of Dairy Australia and the herd improvement industry.

DairyBio provides the research pipeline to develop and maintain ABVs. For more information, contact DataGene on 1800 841 848 or by email.

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