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SUMMER FEED ING
SUMMER 2012 ISSUE
LIVESTOCK MATTERS
10
Taking Action
Afternoon buffer
feeding
Figure 1:
Energy status of 6 cows, as indicated by Ketone (BHB) levels
Figure 2:
Conception rates of a herd 2009-2011
Knowing the energy status of your
cows allows informed decisions to
be made on the management of
freshly calved cows and high
yielding cows through the late
summer period.
For example, it may be advisable to
group the more at-risk cows so that they
receive extra feed. Although grouping
cows over the grazing season can be a
hassle, it is nevertheless highly effective
in an all-year round calving herd. Cows
in middle and late lactation can still
be allowed to graze whilst those
giving more milk receive more buffer
feeding opportunity.
Where body condition scores are
falling, or blood tests reveal low energy
status, then it may be necessary to house
the herd at night and give free access
to buffer feed, which itself, may need
re-formulating.
Other practical issues to consider centre
around the availability of feed and water:
l
Is there enough trough space to allow
all cows to feed at the same time
?
Ideally, there should be at least
0.75m/cow.
l
Is your trough and silage pit
management good enough to minimise
the ration heating up which reduces its
appeal and depresses intakes
?
l
How far do cows have to walk
to drink
?
l
Would you drink out of their water
trough
?
If not, it is unlikely your cows
will. Is there enough space for several
cows to drink at once, and can water
supply keep up with the demand
?
Ideally, all high yielding cows/fresh
calvers should be housed for 2-4 hours
before afternoon milking with access to
just enough buffer feed, that they clear
the troughs before being milked.
This is because in the evenings, the grass
will contain higher amounts of highly
digestible sugars and a higher dry matter
content (as water is lost from the leaves).
So it's best to buffer feed before milking
and then turn them out to graze grass
afterwards. They will eat more in total,
helping meet their energy requirements.
Conversely, if cows have buffer feed
after milking, or in the field, then they
are substituting buffer feed for the good
(cheap) grazing available at the end
of the day.
Figure 1 shows the ketone levels (also known
as beta-hydroxybutyrate or BHB) found on one
farm where as part of their regular routine visit,
blood samples were taken each month from
6 cows at 40 days post-calving, through the
2010 grazing season.
The aim is to keep as many cows as possible
in the green and as few cows as possible in
red. However, the graph clearly shows a
worsening trend in the freshly calved cows
which was only rectified properly in October,
when the herd was housed and moved onto
full winter rations.
The second graph (figure 2) shows conception
rates of another herd through the year. The
percentage of PD positive cows (ie % of
services actually resulting in the cow getting in
calf) falls from June through to August 2009,and
although a general improvement in herd fertility,
a drop in July - September is seen. This is typical
of a situation where summer grazing is not
providing sufficient energy supply to the cow.