Using pasture quality measurements to optimise animal nutritions

There are currently no off-the-shelf devices available to farmers for measuring pasture quality in real time. However, the development of prototype devices such as the one shown here will speed the delivery of this technology on-farm in the near future.

Pasture quality varies widely with pasture composition, season and even time of day. These variations make it difficult to accurately measure the true intake of carbohydrate and protein by animals. This is important because the variations in quality have a direct
impact on animal production and environmental performance.

With funding from the Pastoral 21
programme, a team led by Dr Robyn Dynes, in collaboration with Prof Ian Yule at
Massey University, is working to develop
real-time pasture quality measurements
that can be used to create simple, practical
tools for improving farm performance.

In the past, to get measurements of
pasture quality parameters such as protein, carbohydrate, minerals and fibre, farmers would have to cut a sample of grass and send it off to a laboratory for analysis. They would then wait anywhere from three days to three weeks to get the results, by which time pasture conditions had changed and the measurements were no longer relevant to farm management.

Dynes’s team are developing new methods that can measure pasture quality
parameters in real time, which will enable farmers to respond to diurnal and seasonal changes in nutrients such as protein and carbohydrates.

For example, protein is often too high in pasture grass relative to its carbohydrate content, which leads to sub-optimal animal production. Real-time measurements would enable farmers to address such an imbalance by feeding animals supplemental carbohydrates in the shed, thereby improving their productivity.

In addition, such feeding could also improve environmental performance.
When animals ingest too much protein, they excrete the excess in their urine,
which is a primary source of nitrogen leaching into groundwater and
nearby waterways. High carbohydrate supplementary feed can reduce
excreted nitrogen.

Another example of how knowledge of pasture quality can be used to improve
animal nutrition is by monitoring diurnal changes in carbohydrate levels (see
Afternoon Delight on following page).

One further example of how pasture quality measurements can be used to
drive both increased production and environmental performance is by using
real-time measurements of nitrogen content in pasture to determine whether
fertilisers are needed, and to develop a finely tuned, more efficient system for
applying fertilisers, rather than simply using a crude calendar schedule. Such a
system could improve pasture production, reduce fertiliser costs and limit nitrogen losses to the environment.

Although currently no affordable devices are available to farmers for measuring
pasture quality in real time, such a device should soon be available for some
parameters. The device may operate similar to the C-DAX Pasturemeter, using an
attachment on a quad bike to take realtime measurements.