Dairy Feed Facts
Want more milk, less
methane at dairy?
Including crushed wheat in the diet of dairy cows can increase milk yield while
nearly halving methane emissions, new research from Gippsland shows.
T
wo experiments at the Centre for
Dairy Excellence at Ellinbank,
Victoria, have seen results that will
resonate through the national dairy
industry.
The first experiment, in spring, involved
feeding early-lactation cows up to 9kg of
crushed wheat, 2kg of dry matter concentrate
and sufficient freshly cut, ryegrass-dominant
pasture so the cows consumed 20kg of dry
matter per day.
As a result, the cows’ milk yield increased
21% and methane emissions fell by 29%.
This translated to a 42% reduction in
methane output per kilogram of milk and a
27% reduction in the carbon footprint of the
milk.
In the second experiment in summer, latelactation cows were fed a diet of lucerne hay
supplemented with wheat at 10kg of dry
matter per cow per day, replacing 10kg per
day of corn.
This boosted milk yield 7%, decreased
methane emissions 48% and cut methane per
kilogram of milk by 51%. So in summer, the
carbon footprint of the milk was reduced by
approximately 30%.
FEEDING STRATEGIES
The researchers, from the Victorian
Department of Environment and Primary
Industries (DEPI), said these results showed
simple changes in feeding strategies could
have major impacts on productivity.
These findings are also important to
improve dairy’s appeal to global export
markets, where many consumers are
interested in the carbon footprint of food.
In Japan, some supermarkets sell milk
with its carbon footprint displayed on the
packaging.
Senior researcher Dr Peter Moate said the
findings should be applicable not only to
dairy cows, but also to beef cattle in feedlots.
“We know on average, Australian dairy
farmers already feed about 6kg of crushed
wheat dry matter per cow each day, so the
methane emissions of Australian cows
are most likely much less than previously
thought,” he said.
The research was funded by DEPI, Dairy
Australia, Meat and Livestock Australia and
62
Farming Ahead December 2013 No. 263 the Federal Department of Agriculture.
Ellinbank’s Greg O’Brien said being in
the business of making milk from feed, there
were a couple of things that could be done
with pasture to make more dollars from milk
over summer.
FEED QUALITY
O’Brien said cows had the potential to
produce a lot of milk during mid and late
lactation. He said with a good-quality diet,
milk production decline from peak could be
limited to just 4% per month.
“Often we see a 7-10% monthly decline
due to the diet not being good enough to
sustain the higher milk production,” O’Brien
said.
“To keep the diet quality high, attention
generally turns to the amount of concentrates
in the diet. Typically, they make up about a
third of the diet over summer,” he said.
“The pasture, silage and hay in the diet
make up twice this amount, but relatively
little attention is paid to their role in
sustaining higher milk income.
“Improving the quality of the fodder by
one megajoule per kilogram of dry matter is
worth about two to three litres a day.”
O’Brien said getting this improvement in
quality was a fairly simple thing to do.
He said that basically, as plants grew they
needed to produce a strong framework to
hold them up.
FRAMEWORK JOULES
Seed heads needed more structural material
than leaves to keep them upright.
“The framework has low feed value for
a cow (e.g. low megajoules of energy),” he
said. “So the more framework in the pasture,
the less milk can be produced when eaten.
“The good news is the plant framework
doesn’t suddenly appear overnight. It is
gradually added to each day. So to get the
higher-energy pasture, it is simply a matter
of harvesting the plant at a younger stage of
growth.
“This is one reason why you hear so much
about leaf stage. Production of the plant
framework is pretty minimal up to the two to
three-leaf stage, but things change relatively
quickly thereafter.”
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O’Brien said this was also why there was
so much talk about cutting silage and hay
crops after a short lockup.
Leafy spring pasture has an energy level
of about 12 megajoules, dropping in energy
as it matured.
At four weeks, there will be some stem
development and energy of about 11
megajoules.
At six weeks it was about 10 megajoules,
while at eight weeks it was around nine units.
“So you can see how easy it is to get an
extra unit of energy and the two to three litres
a day,” O’Brien added.
“Watch the milk hold up when you feed
silage and hay made from pasture with
minimal framework development,” he said.
EXTEND PASTURE PRODUCTION
“A second way to keep milk production up in
summer is to have extra high quality pasture
on hand for grazing.
“Dense pastures produce more feed and
a greater ability to trap moisture within the
canopy.
“Pastures are often fairly open coming out
of spring because a ryegrass tiller that has
come through winter gets a signal to go to
seed in spring.
“Once it does this, the tiller dies. So in
spring, there is a big loss of tillers. These
need to be replaced by new tillers.”
O’Brien said new tillers will emerge if
light gets to the base of the plant.
He said they need to get enough sunlight
to continue to grow and compete with the
larger seed heads.
Having long lockups for silage and hay
means less new tillers will emerge and any
new tillers that have emerged are in danger
of dying due to lack of sunlight through
shading.
“The result is an open pasture that
produces less feed over late spring and into
summer which can rapidly dry out,” he said.
“So spring management has a huge
influence on the amount of summer pasture
growth.”
Contact:
Greg O’Brien, DEPI Ellinbank
Email: greg.o’[email protected]
www.farmingahead.com.au