New research helps scientists break the pasture feed barrier

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.

his 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