Measuring grain for rye-grass value

By Dairy News

Agriculture Victoria research scientists have developed a quicker and more cost-effective way to measure the nutritive value of thousands of individual rye-grass plants, enabling pasture breeders to select for high-energy varieties.

The nutritive value of perennial rye-grass is an important driver of productivity for Australia’s red meat and dairy industries, as it contributes towards the total liveweight gain or milk production of grazing cattle.

However, the nutritive value of rye-grass is traditionally not targeted in pasture breeding programs because it is slow and expensive to measure with destructive sampling and laboratory-based low-throughput methods.

Research conducted at Agriculture Victoria’s Hamilton research centre is helping to overcome this.

In this research, data was collected from rye-grass plants using a field spectrometer — a scientific instrument which can measure substances in plants such as sugars or fibres.

The data collected by the spectrometer was then used to develop prediction models for eight nutritive value parameters such as protein, fibre and digestibility.

Agriculture Victoria research scientist Chaya Smith said the new field-based model was very promising for pasture breeding programs and farmers.

“This will provide a way to improve the nutritive value of forage varieties that is much faster and cheaper than anything that currently exists,” she said.

The models also provide a tool for selection in breeding programs with a high degree of accuracy comparable to laboratory-based spectrometry.

“The accuracy varies with each of the eight nutritive value parameters, but protein, dry matter and digestibility were 80 per cent accurate,” Ms Smith said.

“For more complex traits such as fibre content, we are collecting more samples from different environments and growing seasons to make the prediction model more robust.

“We are also developing a machine learning approach to improve the prediction of sugar content, which is complex as grass sugar content changes over the course of the day.”

Australia’s grazing industries will benefit significantly from pastures with better nutritive value.

Ms Smith said improvement in these herbage quality traits would increase the amount of nutrition available for stock and would decrease the need for, and reliance on, costly supplements.

“Eventually, as the model is further developed, it could also be a tool for farmers to check the quality of their pasture in the field, providing relevant, real-time information for decision-making,” she said.

This research is part of the DairyBio joint venture between Agriculture Victoria, Dairy Australia and the Gardiner Foundation.