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11 When feeding pre-calving energy levels
LESS CAN BE MORE
Research by University of Illinois scientists is
challenging accepted wisdom that a cow needs
a higher energy intake before calving.
Students in animal sciences professor James
Drackley’s group compared cows fed before
calving with diets containing the recommended
energy levels to cows fed reduced energy diets.
U of I FALL DAIRY CLASSES
The University of Illinois will offer three
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• A new one-credit dairy class titled
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week). Class size is limited to 20. For more
details, click here.
• Dr. Dick Wallace will offer his 10-week,
two-credit “Advanced Dairy Reproduction”
class, September through November. To
enroll, click here.
They found cows fed the reduced energy diets
performed better after calving.
Animal sciences researcher Phil Cardoso,
intrigued by those results, wondered if
diet might also be linked to reproductive
performance. Using data from seven
experiments completed at the U of I from 1993
to 2010, he constructed a database of 408
cows, containing data on prepartum diet and
physiological status. He also looked at days to
next pregnancy (DTP) after calving. On average,
cows fed the controlled energy (CE) diets (80%
of the recommended amount) became pregnant
about 10 days sooner than cows fed high-energy
(HE) diets, an average of 157 vs. 167 days.
Cows on the CE also lost less in body condition
score (BCS) and had a lower disease incidence
because they were eating more.
Cardoso said that the shorter time to
conception for cows fed the CE diet is due to the
fact that they eat more after calving than the
cows fed the HE diet.
“Just after calving, the cows have a negative
energy balance (NEB),” he explained, because
they cannot consume enough energy to
compensate for milk production. NEB, measured
by looking at metabolites in the blood, causes
them to lose weight, lowering their BCS. High
levels of the metabolites just before calving or
one to two weeks after calving are associated
with metabolic disorders and certain diseases,
which cause them to eat less. These in turn
affect reproductive performance.
Both groups of cows showed reduced energy
consumption around calving, but the drop was
about four times higher in the HE cows. Cows
fed the CE diet were able to start eating right
The researchers also noticed that cows fed the
CE diet showed less prepartum vs. postpartum
variation in how much they ate. By contrast, the
cows fed the high energy diet were eating more
than they needed before calving.
In a follow-up study that has not yet been
published, the researchers tried strategies to
make the cows eat less. One was to give them
just 80% of what they needed; the other was
to increase fiber so the diet would be lower in
energy and the cows could eat more. Results
for the two strategies were similar.
There are indications a CE diet has other
benefits. It may keep food in the rumen longer,
which is beneficial to the cow if she is stressed.
Long intervals between calvings also costs
money. Research has shown that every day
after 90 days in milk that the cow does not get
pregnant represents a cost of $2 to $3.
In short, Cardoso advised, just give the cow
what she needs and she will perform better
metabolically and reproductively.
“Prepartum Dietary Energy and Reproduction”
by F.C. Cardoso, S.J. LeBlanc, M.R. Murphy, and
J.K. Drackley, has recently been published in
Journal of Dairy Science.
This article was originally written by Susan