A trial adding a bespoke blend of Australian seaweeds to the diets of cows at a south-west Victorian farm has shown early promise in improving cow health and milk production.
The research by the DeakinSeaweed Research Group also has the potential to improve sustainability and reduce the industry’s environmental impacts.
The research is being led by Senior Lecturer in Marine Biology and Ecology at Deakin University’s Warrnambool campus, and head of the DeakinSeaweed Research Group, Alecia Bellgrove.
“We think this could be a win for the environment, a win for the cows, a win for the farmers,” Dr Bellgrove said.
Fifty-six cows at the Eastern Creek Road farm near Port Campbell were each fed one of four different diets including a mixed seaweed supplement and a biochar supplement, each in isolation and in combination, along with a base control diet as part of the field research.
While lab and data analysis won’t be completed until at least the end of 2023, preliminary results look promising.
“The cows lost weight across the course of the trial which was expected at that stage of their lactation, but the preliminary results suggest those supplemented with both seaweed and biochar lost less than the control cows,” Dr Bellgrove said.
“That is possibly linked to changes in metabolic activity within the rumen.”
After some initial hesitation, the cows soon accepted the seaweed and biochar supplements into their diet.
The cows were fed the supplements at each afternoon milking for 30 days.
The 60-cow rotary dairy at the Eastern Creek Road farm enabled the researchers and farm staff to work safely while minimising impact on the animals.
The computerised dairy measured daily milk yields and allowed safe and easy drafting of the cows in the experiment from the main herd when sample collection was required.
“The farm staff were all incredibly helpful and flexible in enabling our team to conduct this research around their daily activities, and enthusiastic about the research and potential impacts. We are really grateful for their support,” Dr Bellgrove said.
The research aims to see if the changed diet can improve milk production and quality, as well as animal health and in doing that, potentially reduce methane and nitrous oxide greenhouse gas emissions through changes to the gut microbiome.
The study didn’t measure methane production directly but looked at changes in the gut microbiome. This data is still to be analysed.
Dr Bellgrove emphasised that there are thousands of different seaweeds in our oceans, but relatively few are available in the quantities required for agricultural supplements, and imported seaweeds carry significant carbon miles and potential toxicity risks.
The bespoke mixed seaweed supplement used in this study was blended from a range of Australian seaweed species for which large amounts of biomass could be sustainably sourced from existing or emerging aquaculture production or sustainable wild harvest.
“We’re looking at species that we know have good nutritional quality and the potential to improve the nutrition of the cows and potentially the nutritional quality of the milk, creating a cost benefit to the farmer rather than a financial cost,” Dr Bellgrove said.
The seaweeds’ biochemical composition was tested from nutritional and food safety perspectives for the cows.
“We looked at their nutritional profiles and palatability of individual seaweeds to develop an optimised mixed seaweed supplement,” Dr Bellgrove said.
“Seaweeds are a fantastic source of trace minerals, for example, which are important to animal and human health, but if they are too high, they can become toxic, so we needed to find the sweet spot.
“Seaweeds are known to have antibacterial, antiviral and antioxidant properties so we also predict that they could improve animal health, which could increase production and reduce veterinary costs.”
The supplements could also improve the nutritional value of milk for human consumption, including increases in important trace minerals commonly deficient in Australians and omega-3 fatty acids for improved brain health, among other benefits.
Dr Bellgrove said seaweed supplements could offset some of the environmental impacts of terrestrially-produced feed, given that seaweeds don’t require freshwater or fertiliser inputs.
“We expect the manure from cows will have a relatively high carbon load compared to normal feed, meaning it could enhance the quality of the soil and potential carbon sequestration,” she said.
Milk, urine and faecal samples were taken during the trials and are being analysed, along with a suite of animal health and production data. Milk taste trials will also be conducted to ensure the supplements don’t negatively affect the palatability of the milk for consumers.
“We are looking at a holistic approach to make it a cost benefit to farmers with healthier and more productive animals, which could mean less animals to produce the same volume of milk,” Dr Bellgrove said.
“Another potential benefit of the nutritional seaweed supplement could be to reduce heat stress which will become increasingly important in a warming climate, via changes to the gut microbiome.”
Although still early days with a lot of results to analyse, the initial results are encouraging.
“Even after a 30-day field trial, we’re seeing significant changes in the microbial metabolism within the gut,” Dr Bellgrove said.
“We are still trying to determine what those changes mean for potential improvement to animal health and potential reductions in methane and nitrous oxide production, but if it does end up being as positive as initial results suggest, there are opportunities to scale up and create demand for Australian seaweeds.
“We have incredible biodiversity of seaweeds in south-eastern Australia and they may be significantly high in favourable molecules that have the potential to improve human and animal health, whilst also being grown in some of the cleanest waters globally.”
Dr Bellgrove said that humans benefit from a “rainbow” on their dinner plate, and cows could do the same.
“There is a higher diversity of seaweeds compared to plant life on land, and nutritionally they offer something very different. If you can eat a number of seaweeds, it’s likely to do different and better things for you.”
Dr Bellgrove said the study had potential to improve soil structure, animal health, milk production and reduce greenhouse gas emissions.
“If our hypotheses are supported, this research has the potential to future-proof Australian dairy farming in a warming climate by improving sustainability in the context of environmental impacts, animal health and wellbeing, and productivity (yields, quality and value).”
The farm used for the research is managed by AAG Investment Management, who wanted to participate in the trial to help them achieve their carbon neutral target.
The Deakin University research has been in partnership with Heytesbury District Landcare Network and AAG Investment Management, and partially funded by the DemoDairy Foundation, the Federal Government Future Drought Fund and Deakin University.