8 June 2011
AgResearch at the New Zealand National Agricultural Fieldays 2011
New research helps scientists break the pasture feed barrier
With funding from the Pastoral 21 feed programme (a joint investment by DairyNZ, Fonterra, Beef + Lamb New Zealand and
the Ministry of Science and Innovation), new research has investigated how improvements in both the quantity and quality
of pasture species could help farmers to break the pasture feed barrier. The research will feature at the AgResearch
exhibit during the National Fieldays at Mystery Creek on 15-18 June 2011.
To improve pasture production, the plant breeding team at AgResearch Grasslands in Palmerston North, has led research to
bring new seeds to farm using a different breeding system – one that captures hybrid vigour and makes it available in
seeds.
In particular the research team, led by Brent Barrett, has looked at the use of hybrid vigour to improve breeding
progress. Hybrid vigour is the occurrence of genetically superior plants from mixing favourable complementary genes of
both parents. It has the potential both to increase yield and to enhance the plant’s resilience to conditions such as
disease or drought.
Mr Barrett’s team conducted their first trial to measure pasture yield using perennial ryegrass managed under sheep
grazing at Aorangi Farm in the Manawatu Plains for two years, so that the results would better reflect on-farm
conditions. This work found that hybrids improved yield by up to 7% per year above the better parent, and some hybrids
showed up to 19% higher yield in certain seasons.
This initial research used six hybrid combinations, and has shown that the concept of using hybrids has good potential
for delivering value to farmers via an improved pasture breeding system. The next steps are to test more combinations to
search for a hybrid that is successful across all seasons, and to use DNA markers to fingerprint relatedness patterns
and help predict hybrid vigour. With ongoing support, hybrid vigour in forages will be able to deliver on-farm benefits
within five years.
A second project funded by DairyNZ and led by Dr David Pacheco has focused on improving productivity by exploiting
diurnal changes in the composition of pasture species to enhance animal nutrition.
Generally, soluble carbohydrates and dry matter concentrations are at their lowest in pasture offered during the morning
and increase to a maximum level by mid afternoon (up to about 1 to 2 hours before sundown). This means that if animals
are fed grass in the afternoon, they get a better balance of protein and carbohydrates than if they are offered a fresh
grass break in the morning, which is currently common practice.
This simple change in management resulted in an 8% increase in milk solids in trials conducted in Palmerston North with
cows in late lactation. Similar responses have been obtained in trials elsewhere.
In some cases, this management strategy also reduced the amount of nitrogen that animals released into the environment,
but this depended on the magnitude of the dilution of protein by carbohydrate.
Moreover, there is an interaction between pasture quality and behaviour, because animals having a new feed break in the
afternoon extended their grazing time during the night. Importantly, they obtained more of their intake while the forage
offered a greater nutritive value, compared to their herd mates that had access to a new feed break in the morning.
Dr Pacheco says that harnessing these natural feedback loops can multiply the effect of pasture quality, so that
“farmers have opportunities through small changes in management to have greater responses in productivity than could be
expected from the difference in quality alone.”
ENDS