Selective breeding supports productive and sustainable herd
19 November 2025
When it comes to breeding philosophy and sustainability, dairy farmers Graeme and Michele Hamilton aim for high production from their herd.
Optimising milk volume, the Hamiltons aim to make the most of a limited milking platform, homegrown supplementary fodder and selective breeding to produce healthy, long-lasting and highly productive Australia Reds. The approach has paid dividends with the herd ranking fourth in Australia for the Sustainability Index (SI) in the August 2025 release of Australian Breeding Values (ABVs).
The Sustainability Index is a tool developed by DataGene – an initiative of Dairy Australia and the herd improvement industry. It is produced for farmers to select bulls and cows with lower environmental footprints. It was released in August 2022 and is based on the existing Balanced Performance Index (BPI) but places greater emphasis on production, survival, health, and feed efficiency.
For the Hamiltons’ 600–head Australian Red operation ‘Hamilton’s Run’, based in Mount Gambier, South Australia, the goal of boosting production while breeding for lower emissions goes hand in hand — a herd that efficiently converts feed (protein and energy) into milk produces fewer greenhouse gas emissions per litre of milk.
“The title Sustainability Index suggests that it is all about carbon minimisation per unit out the gate,” Graeme said.
“And while it is trying to minimise the carbon and our effect on the planet, it also relates, very much, to the amount of protein and energy I need to put into the cows.
“The goal is the most production from a given quantity of energy and protein.”
The herd consumes up to 60 per cent of its diet from direct grazing, while the remainder of their forage requirements – lucerne and maize – are grown locally by the Hamiltons and fed to the herd on a feedpad at their home farm.
Graeme said the SI is used as a ‘first cut’ to select a range of bulls.
“After that, I start looking at the detailed traits, but I don’t make my final decisions based on SI or BPI (Balanced Performance Index) or HWI (Health Weighted Index), they’re just how we do a first cut to come up with a short list of bulls to work with.”
He then looks at production and conformation traits.
The milk, fat, and protein output must be balanced; the Hamiltons use the Good Bulls Guide to create a short list of bulls to use over the herd. The cow must also be robust enough to sustain high production; and her udder must be easy to manage in the dairy.
DataGene’s Good Bulls Guide is built on genetics insights from the DairyBio program, a long-term joint venture between Dairy Australia, Gardiner Foundation and Agriculture Victoria, the guide highlights sires to support long-term herd performance.
The Hamilton family takes pride in growing-out young heifers to ensure they express as much of their genetic potential as possible.
“Heifers must be properly grown by the time they calve, or they will divert energy from producing milk into growth,” Graeme said.
He said selecting an index to use as a guide for a breeding program should be based on the entire farm system.
“The selection has to be matched by the feeding regime and the healthcare – cow care – and all those things go together to make a whole,” he said.
“It is no good taking one part (of a farming system – such as breeding) in isolation and saying, ‘well, this is going to fix all the problems’. It is not a silver bullet.”
Hamilton’s Run is also ranked in the top 10 on BPI and HWI.
For more information and support in managing farm emissions, including selective breeding resources, contact your local Dairy Australia team or visit the genetics page on our website.
DataGene is an initiative of Dairy Australia and the dairy industry that is focused on improving herd development through genetics, as well as animal health and farm profitability through data-driven decision making and tools.
The Sustainability Index is a tool developed by DataGene – an initiative of Dairy Australia and the herd improvement industry. It is produced for farmers to select bulls and cows with lower environmental footprints. It was released in August 2022 and is based on the existing Balanced Performance Index (BPI) but places greater emphasis on production, survival, health, and feed efficiency.
For the Hamiltons’ 600–head Australian Red operation ‘Hamilton’s Run’, based in Mount Gambier, South Australia, the goal of boosting production while breeding for lower emissions goes hand in hand — a herd that efficiently converts feed (protein and energy) into milk produces fewer greenhouse gas emissions per litre of milk.
“The title Sustainability Index suggests that it is all about carbon minimisation per unit out the gate,” Graeme said.
“And while it is trying to minimise the carbon and our effect on the planet, it also relates, very much, to the amount of protein and energy I need to put into the cows.
“The goal is the most production from a given quantity of energy and protein.”
The herd consumes up to 60 per cent of its diet from direct grazing, while the remainder of their forage requirements – lucerne and maize – are grown locally by the Hamiltons and fed to the herd on a feedpad at their home farm.
Graeme said the SI is used as a ‘first cut’ to select a range of bulls.
“After that, I start looking at the detailed traits, but I don’t make my final decisions based on SI or BPI (Balanced Performance Index) or HWI (Health Weighted Index), they’re just how we do a first cut to come up with a short list of bulls to work with.”
He then looks at production and conformation traits.
The milk, fat, and protein output must be balanced; the Hamiltons use the Good Bulls Guide to create a short list of bulls to use over the herd. The cow must also be robust enough to sustain high production; and her udder must be easy to manage in the dairy.
DataGene’s Good Bulls Guide is built on genetics insights from the DairyBio program, a long-term joint venture between Dairy Australia, Gardiner Foundation and Agriculture Victoria, the guide highlights sires to support long-term herd performance.
The Hamilton family takes pride in growing-out young heifers to ensure they express as much of their genetic potential as possible.
“Heifers must be properly grown by the time they calve, or they will divert energy from producing milk into growth,” Graeme said.
He said selecting an index to use as a guide for a breeding program should be based on the entire farm system.
“The selection has to be matched by the feeding regime and the healthcare – cow care – and all those things go together to make a whole,” he said.
“It is no good taking one part (of a farming system – such as breeding) in isolation and saying, ‘well, this is going to fix all the problems’. It is not a silver bullet.”
Hamilton’s Run is also ranked in the top 10 on BPI and HWI.
For more information and support in managing farm emissions, including selective breeding resources, contact your local Dairy Australia team or visit the genetics page on our website.
DataGene is an initiative of Dairy Australia and the dairy industry that is focused on improving herd development through genetics, as well as animal health and farm profitability through data-driven decision making and tools.