By Darren Sutton, FarmWise consultant.
What is at
Basically the next three months of pasture and milk production. We can be fairly safe in assuming that we
will get rain and good pasture growth from now until the middle of
January. So, during this period the goal
is to maximise the cheap feed that is leaping out of the ground. What is the prize? Getting more milk from less dry matter (DM).
Cows don’t need ‘dry matter’ as such.
They mainly need energy, protein and some minerals from the
pasture. The dry matter is just the
delivery box, which we want to be as high quality in energy as it can be.
As pastoral farmers we are energy farmers. We use soils, water, nutrients and solar radiation
to make energy units to put through the ruminant to create milk.
Why is energy
Metabolisable energy is the fuel running the machine of the cow. The more energy a cow can consume through
late spring, the more milk she will produce and have a higher chance of getting
back in calf.
For a cow to produce 2 kg milk solids (MS) per day she will need about
160 megajoules of metabolisable energy (MJME).
For a cross bred cow she will need about 55 MJME per day for her body to
function and a further 10 MJME to do some walking. So in order to aim for no weight loss or gain
she needs to consume 225 MJME each day.
If your pasture is of high quality at 12.5 MJME, then she needs to
consume 18 kgs of DM each day.
So what am
I trying to achieve?
The highest quality pasture each day.
How you do that is by leaving the correct residual each day. You never want a ‘fully-fed’ cow on your
farm. To do that on a grass based system
would require you to have cows going into covers of 3000 kg/ha and leaving a
residual at 2500. You are trying to
achieve that sweet spot of what is best for your cows and what is best for your
pastures each and every day.
A residual between 1500 and 1600 has been proven through research many
times to be the best residual for cows and pasture. A residual of 1550 achieved this month allows
you to still have high energy intakes next month.
happens if I get this wrong?
The month of September is not about milk production. It is about setting up the farm to maximise
energy harvested (and therefore milk production).
If you do a rotation of the farm in September and October leaving
residuals of 1700, then the next round will mean that every bite of pasture
that cow takes has fallen to 12 ME and is harder to harvest and process. Therefore, your cows may still eat the 18 kgs
DM, but have now only harvested 216 MJME.
This results in either milk production falling or, if she is a high PW
animal, the cow is likely to fall into a slight energy deficit and start losing
weight as she keeps producing 2 kgs MS/day.
This means that your repro performance is likely to suffer.
are there to get it right?
Plate metering and spending 15 minutes each day planning feeding
decisions can make a massive difference!
Look at what the cows are telling you.
The person getting the cows out of the paddock must pass the residual
information to the person making the feeding decisions. The best way to get the right residual is to
work out the right pre-graze.
If there is a genuine surplus that cows cannot eat, then skip grazing for
1-2 weeks and cut for silage.
If you must, pre-mow or top behind cows to correct mistakes.