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73
MAY 2018
www.irishfarmersmonthly.com
Management Hints
MAY 2018
Management Hints
www.irishfarmersmonthly.com
matter (DM), on a 20-day rotation and grazing down to 50cm
residual, the target PGC will be:
Stocking rate x allowance x rotation length + residual = 4.7
x 18 x 20 + 50 = 1,740kgDM/ha
The target PGC increases as the stocking rate increases (and
declines as it falls).
You must also watch your average farm covers (AFC). The
target figure is 160-200kgDM/lu. For example, at a stocking
rate of 4.7 cows/ha, the target average cover, with good grazing
management, would be:
Stocking rate x 180 = 4.7 x 180 = 846kgDM/ha
By watching both your PGC and AFC, you will be able to identify
surpluses (and deficits) before they arise. You must react to a
surplus by removing the surplus for baled silage and remember,
the quicker you react, the lower the cost of reaction!
If PGC is higher than target and AFC is also higher than target,
you must:
(a) Remove one or two paddocks, immediately, for round baled
silage; or
(b) Bring extra stock into the cow area to graze out paddocks or
reduce meal levels.
X
If PGC is lower than target and AFC is also lower than target
you are likely to go into a downward tailspin, then it looks as if
you should introduce meals or graze some silage ground if not
too strong;
X
If PGC is higher than target and AFC is lower than target then
you should continue grazing the high covers, or pre-cut to
maximise utilisation;
X
If PGC is lower than target and the AFC is higher than target,
and if growth rates are good then, unless a lot lower, you should
be safe enough;
X
The key is to measure at least once a week and twice a week if
you are making adjustments;
X
Use a plate meter/discussion group to train your eye to post-
grazing heights advised.
No topping; round bale!
No topping why?
X
Topping results in grass wastage. We advise grazing to 4cm in
May. Many farmers are only grazing to 5cm. Remember that
every extra cm left above target results in 250kgDM/ha being
wasted worth 70 in meal;
X
If under-grazing by 1cm every grazing rotation, usually nine per
year, that means 2.25 tonnes lost per hectare or 630 per year.
Topping must be carried out when the `tall grass' areas are greater
than 25 per cent of the paddock area.
X
But I favour letting these paddocks go slightly above the PGC
and then cut for baled silage as they will make good winter feed;
X
A lot of tall grass areas indicates under-grazing.
If the tall grass area is 25 per cent in May, it will be 35-40 per
cent of the paddock in June because of the fresh dung deposited
during this grazing. Tall grass is grass around dung pads and other
under-grazed areas. It will be getting nitrogen (N) and not be
eaten imagine the financial loss from this.
As every tonne of silage removes 4kg phosphorus (P) and 30kg
potassium (K), therefore every paddock baled should get an extra
1,000 gallons of undiluted slurry for every four bales taken off.
Cut paddocks will need extra N, 15 units/acre.
Apply 79 per cent of N before the first week in June
To grow 16 tonnes/ha DM on milking platform, you will require
290-300 units N/acre. But, as is happening, farmers apply a lot
less on the outside block to stay within directive guidelines.
You won't grow enough grass if you don't have 64 per cent of your
year's N allowance used by the middle of May and 79 per cent
used by early June, because there are only three applications left
for the remainder of the year.
X
Not adhering to this principle will guarantee you won't have
enough silage.
This is the month to use N.
X
Growth rates and responses now (1kg N, costing 1.15, will grow
25-30kgDM grass, worth 5 in milk produced) are best.
You must use N appropriate for your stocking rate.
X
This year, most farmers, because of the weather, are far below
the amount of N that should be used.
There is no significant difference in annual grass yield, or annual
milk yield (unpublished work), when N is bulk spread once per
month compared to spreading N after every grazing.
X
This allows N to be spread in bulk by a contractor; there will be
no confusion as to which paddocks got N and which didn't.
On light soils deficient in sulphur (S), you will grow more grass
(10-50 per cent based on research).
X
With no restriction in S use, you must use one unit of S for
every 12 units of N used;
X
If using S on copper-deficient or molybdenum (Mo)
antagonised deficiency, make sure to give animals a copper
bolus.
Some farmers think it is a good idea to allocate 12-hour grazing
blocks to cows.
X
It is not! It is an unnecessary workload for no gain, in fact
losses!
X
What happens is the cows have too small a space from which to
get their feed;
X
This results in the `bully' cows chastising the timid cows, with
the result that the timid cows' intake is greatly reduced;
X
Heifers, shy feeders suffer similarly due to this bullying;
X
High-performing cows also suffer because they have to eat more
grass to produce the extra milk.
Therefore, cows should be given areas that last for 24, 36 or 48-
hour grazings. As well as being beneficial for the cows, it will be
less laborious for the farmer.
Grass contains sugar, and the sugar content is higher in the
afternoon than in the morning:
X
All you have to do is let the cows into fresh grass after the
evening's milking;
X
Because grass has a higher sugar content in the evening, after a
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