As part of her Masters degree, funded by the NZAGRC, Holly evaluated the effects of dairy breed on methane emissions and what would happen to those emissions if the farmer selected cows for improved feed conversion efficiency.
At the start of Holly’s research, her hypothesis was that high feed-efficient animals (those with low Residual Feed Intake, or RFI) would emit less methane than the lower efficiency (high RFI) animals.
“Methane is an important source of digestible energy loss in ruminants, with 5-10% of their gross energy intake lost as methane. The hypothesis was based on the idea that those animals producing less methane are belching out less energy, and hence should retain greater proportions of their gross energy, leading to higher energy/feed efficiency and lower RFI,” Holly explains.
However, Holly’s research showed that breed did not affect methane production. Jersey and Holstein-Friesian cattle released 22 grams of methane per kg of dry matter intake. Similarly, selecting animals for improved feed conversion efficiency didn’t affect how much methane the animal produced each day. Holly’s research concluded that selecting dairy heifers for low RFI is unlikely to affect daily methane production (g/d).
Dr John Roche, Departmental Science Adviser for the Ministry for Primary Industries - Manatū Ahu Matua, says the findings from Holly’s research have added to our understanding of enteric methane science. “It appears that animals that are more efficient at digesting feed in the rumen will emit more methane for every kg eaten. Most people assumed that the opposite would occur.”
Born and raised on a dairy farm in Te Awamutu, Holly developed an interest in agriculture at a young age. She developed a passion for science and research, attending Massey University and studying for a Bachelor of Science in Chemistry, with a minor in Animal Science. She was also awarded a DairyNZ scholarship which reinforced herintention of working in the agriculture/dairy science sector.
“While studying I was fortunate to get the opportunity for summer internships with the Fonterra Research and Development Centre (2014/15) and DairyNZ (2015/16).” Holly worked on a project about methane production from dairy cattle which she enjoyed, and which led to her writing a literature review of the specifics of enteric methane from dairy cattle.
As a sideline to her research work Holly became involved in the validation and optimisation of a novel methane measurement technique. The world-first equipment involves multiple feeding stations that measure methane from the cow’s breath while it is eating at different times each day. It can evaluate 30 animals at a time, whereas respiration chambers can test only four. It’s also easier to test a wide range of feeds in the new facility and animals can be maintained on a treatment for much longer.
“The DairyNZ equipment was compared with AgResearch’s respiration chambers. Both methods provided the same herd methane production and yield, giving us confidence that the equipment I used in my Masters was accurate. The method was successfully validated,” she says.
The equipment and the experiments were funded by the New Zealand government to support the objectives of the Livestock Research Group of the Global Research Alliance. Holly says "NZAGRC’s support for her research pathway has been valuable to undertake further research in the methane/greenhouse gas area. It has also created the potential for experimental trials at DairyNZ (or elsewhere) which I could play a key role in.”
Now working for DairyNZ full time as a Research Associate, half of Holly’s time is spent as a research technician and the other half is developing her skills as a scientist, which will allow her to decide if she wants to pursue further study as a scientist. She has just started working on a project around dairy cow fertility.
She intends to stay within the dairy/agriculture industry, working within research and development as she is interested in helping extend recent developments directly to farmers to optimise their profitability, sustainability, and competitiveness. "I would like to help support farmers and rural professionals and help provide innovative on-farm solutions to improve resilience throughout the industry.”