WINTER 2014/2015 ISSUE
LIVESTOCK MATTERS
8
NUTRI T ION FOR TWINS
Ration presentation problem
The herd calves all-year-round with a slight
autumn peak. In the summer, true dry cows
go out to grass.
Transition cows are fed a full DCAB
ration, which is monitored using urine
pH measurement to ensure it is working
correctly, so as to prevent milk fever and
secondary metabolic diseases arising.
At Darfield Dairy, urine samples from five
to six cows that have been on the transition
diet for 3-4 days are tested every six
weeks. Steve uses a catheter to extract the
samples and Will measures the urine pH
as soon as he gets back to the practice
where there is a calibrated pH meter. The
target range is pH 6.2-6.8.
There is great attention to detail on this
farm: urine pH checks of transition cows
are also made whenever any changes to
the ration are made, e.g. a change in
maize silage.
However, in August/September of 2013,
there was an increase in cases of milk
fever, metritis and clinical ketosis. When
Will assessed the metabolic profiles of dry
cows and fresh calvers, he found NEFA
levels were elevated, indicating a degree
of fat mobilisation. The urine pH results in
October were also too high.
The ration was not working effectively.
The transition cows were kept out on a bare
paddock opposite the dairy, with some
access to grass, whilst still being fed a
complete transition ration. Grass can have
a high DCAB value so, in consultation with
the farm’s nutritionist, they were brought
inside and grass silage was also removed
from the ration. With no grass in the diet,
the urine pHs came down, and clinical milk
fever cases stopped.
It is now standard practice for all transition
cows to be housed in the last three-weeks
prior to calving (the close-up period). The
dry cow ration is now just maize silage,
chopped straw, a mineral blend and
DCAB salts.
However, although the average urine pH
was in the target zone, the range of
individual values was wide.
Will explains: ‘In January 2014, although
the urine pH average was 6.8, the
range was 5.49 to 8.30. In March,
there were more cases of ketosis and
some DAs too. These clinical cases will
have been just the tip of the iceberg,
there will have been many cows with
subclinical ketosis too.’
Will carried out more metabolic profiling
and was able to pinpoint the issue as
originating in the transition period.
So why was this, when on paper the diet
looked fine
?
The problem was in the way
the diet was being presented to the cows.
Steve explains: ‘There had been a change
in the type of straw we were using - from
a brittle one to a waxy one, and it wasn’t
getting properly chopped in the mixer
wagon. So the cattle were sorting out the
straw and the bitter DCAB salts.’
The problem was solved very simply
with the purchase of a straw chopper
which consistently cuts the straw to a
30mm length. The whole situation
changed ‘overnight’. The following
set of urine pH tests confirmed the
problem was resolved - they ranged
from 5.24 to 6.49. With the root cause
identified, there is no longer any sorting
and there have been no further milk
fever cases.
Further details on the effects of heat
stress on the incidence of twins can be
found on Endell Vet Group’s farm blog
at
Ration close-up
Straw chopper investment
Steve adds: ‘It’s important to keep an eye
on the cows after calving too. We keep
them on the straw yard for at least four
days, and up to two weeks, depending
on numbers and space. They need to get
settled and be eating the ration - that’s
the crux of it.’
Steve looks out for subtle changes in cow
behaviour that may indicate metabolic
issues - a drooping head, ears forward,
difficulty standing, and hard dung
instead of soft working dung.
‘We used to give propylene glycol to any
cows which looked like they had symptoms
of ketosis or if their milk yields were not
increasing. But we’ve not needed to use
it over the past year,’ says Steve.
At Darfield Dairy, cows are now
transitioning better and this has improved
fertility: the herd averages a calving to
conception of 105 days, with a calving
to first service of 58 days. And over the
past 12 months, the calving index has
reduced by 10 days to 385 days.
Post-calving care
Improved fertility
