Presenting on the environmental benefits of arable feeds at the Foundation for Arable Research (FAR) annual Crops Expo, Lincoln University livestock production expert Professor Pablo Gregorini and FAR researcher Ivan Lawrie delivered progress results of a two-year monitoring project.
The pair acknowledged achieving animal production goals while meeting social and environmental constraints is complex.
Most urinary nitrogen is deposited onto pastures and 20% to 30% is leached with 2% transformed to nitrous oxides.
In response to political and public pressures on dairying, strategies are being explored to reduce the amount of nitrogen going through dairy cows.
However, as some diets aimed at reducing urinary nitrogen might increase methane it is difficult for farmers to balance environmental, productive and profitability targets.
The study tested several thousand combinations of 51 feeds.
“This found that dairy farmers wanting to use binary diets to reduce their herds’ urinary nitrogen while maintaining or increasing milk production have surprisingly few options.
“Most of these come from cereals and beets,” Gregorini said.
If their criterion is profitability and a pasture-based system then the suitable set of diets is even smaller, being limited to supplementing pasture with low levels of conserved forages with low nitrogen content, for example, maize and cereal silage.
“There is no perfect diet, though, to optimise all objectives simultaneously. It is up to farmers to choose among the options that best suit their farming context and local environmental regulations.”
A study was run to facilitate decision making by dairy farmers aiming to reduce urinary nitrogen and methane emissions while maintaining animal production.
The 51 feeds including forage crops, silages, grains and bulbs were combined in diets consisting of two feeds and varying the proportion of each from 10-90% in 10% steps.
These combinations generated 11,256 dietary mixes.
The work showed diluting nitrogen with maize silage and or cereal silage considerably reduces urinary nitrogen and there is scope to formulate binary diets to reduce urinary nitrogen while maintaining or reducing methane production with the potential to increase animal performance.
“This has involved multi-mega processes, a very big programme and we are at the pointy end now.
“How we use our arable crops in livestock systems while mitigating the environmental footprint of pastoral livestock and productivity is complex.”
FAR’s work in the Sustainable Farming Fund (SFF) project is now focused on the monitoring four farms throughout NZ.
“We are gathering data on production versus the environmental impact and we will pass that information on to Pablo’s teams.”
Lawrie said the programme is researching multiple solutions for a complex problem.
“It has brought all parties together to gather some collaboration.
“This is one tool.
“It is not the silver bullet, nor the only tool. This is one tool to aid the situation and we think arable has a big part to play,” Lawrie said.
