The challenge to balance livestock and farm-level methane emissions against production has had scientists, industry and policy-makers working together for several years.
Methane research involving feed additives has been ongoing at Ellinbank Research Farm, in West Gippsland, Vic, particularly measuring cows' burps against milk production.
In 1980, the methane intensity of producing Australian milk was 33.6g methane/kg of milk produced.
Thirty years later, with increasing milk production per cow, the methane intensity was measured at 19.9g methane/kg milk.
Research undertaken by Dr Peter Moate at the time indicated genetics, feeding and pastures caused these reduced measures.
Feeding supplements at the time was shown to have more impact when fed in summer and dry, warmer months of the year.
Feeding a mix of starch and fat additives was shown to be effective in fresh cows, if they also had access to low NDF (neutral detergent fibre) forages.
Ellinbank Research Farm is a premier facility for investigating a range of industry-led and commercial-in-confidence research activities involving animal health and welfare, fodder, pasture production, and renewable energy projects.
Milking about 400 cows off a 150-hectare grazing system, with supporting country, provides opportunity to identify projects that could be investigated for results that can be extrapolated for industry.
Dairy Australia and Agriculture Victoria are key funders of projects implemented at Ellinbank Research Farm.
A major focus of Ellinbank is reducing the methane footprint of the dairy industry.
A decade ago, Ellinbank scientists developed a sulphur-hexafluouride (SF6) technique to measure methane/kg/dry matter eaten by pasture-fed cows, as burps.
This technique enabled them to measure the burps using a tube suspended over the animal's nose, which sucked the air through and into a saddle apparatus around its body.
At the time, the technique measured 21g methane/kgDM eaten, applied against diets where the cow is eating more than 70 per cent forage.
As few years later, using the SF6 technique, an international team of scientists from Ellinbank and Penn State University, United States, discovered a feed additive included in the diet of 48 barn-stalled dairy cows reduced their methane emissions.
One gram of the feed additive, 3-nitrooxyproponal (NOP), was added to the daily grain feed ration for each cow for 12 weeks and methane emissions were measured using the SF6 technique.
About 6 per cent of the food consumed by the cow was converted to methane gas and the NOP additive reduced this amount by 30pc.
The reduced methane production was converted into increased body weight without reduction in milk production or composition.
Ongoing research has continued to investigate if feed additives reduce methane emissions in cows.
Read more: Milk production sluggish across the globe
Dr Pablo Alvarez Hess has been leading recent Ellinbank research projects identifying the effect of feed additives added to wheat, maize or commercial grain feed, on cows' methane emissions.
The cows used for these investigations have been fed silage on a feedpad, to mimic a grazing system.
Forty cows with the same condition score and age were removed from the main herd, with half of these 40 used as a control group.
The other 20 cows received the feed additive, in the form of canola oil.
With only 20 cows in the experiment, canola oil was hand mixed with wheat and corn and fed to each cow in the bale during milking.
"By adding additional fats to grain, we saw cows reduce methane emissions," Dr Hess said.
"The cows were fed wheat and corn separately. We wanted to see if the fat behaved the same in the gut, and it did.
"We saw methane reduced about 10pc."
In another recent experiment, grape mark was fed in a similar style to a small group of cows.
"There was some minor reduction in methane," Dr Hess said.
Neither of these experiments extrapolated into analysing milk manufacturing properties.
In a grazing based system, feeding supplements like this at milking time in the bale is the most practical method.- Dr Pablo Alvarez Hess
Two more recent experiments, completed in spring 2021, did analyse milk manufacturing properties, as well as methane production.
The two experiments investigated the addition of red seaweed Asparagopsis taxiformis and commercial microbial liquid feed supplement Mylo
Again, 40 cows were used in each experiment, with 20 as control markers and 20 cows identified for treatment. All were fed silage on the feedpad.
The seaweed and Mylo supplement were mixed into a commercial grain-based feed, by hand, and fed in the bale twice-daily during milking, over a period of 35 days.
"Hay mimics a grazing system and we can measure consumption because it's being fed on the feedpad," Dr Hess said.
"That's very valuable for us for measuring intake.
"In a grazing based system, feeding supplements like this at milking time in the bale is the most practical method."
Both additives created a methane reduction, but there were variations in the effects on production.
"There was a moderate reduction in methane for the cows fed grain with Mylo added, and a strong reduction in methane from the seaweed additive," Dr Hess said.
"With the seaweed, we didn't see any productive benefits.
"With the Mylo (a probiotic fed as a liquid), we measured productive benefits - there was a slight increase in milk and a slight increase in feed conversation - and a moderate decrease in methane."
Dr Hess said the milk was analysed for change in manufacturing properties - yoghurt and cheese production - but that data was not yet available.
Deakin University is involved in a project measuring the effect of adding Asparagopsis armata to the feed of dairy cows. A. armata is harvested in Victoria's coastal waters.
Milk processing company Fonterra has funded commercial trials to identify if seaweed is a worthwhile additive on-farm, testing commercial viability, operational application and food safety.
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