Nutrient Requirements Of Dairy Cattle:
An Update On National Research
Council Recommendations
Gabriella Varga
Professor of Animal Science
Many of you may wonder how
we know what to feed dairy cattle
and how nutrient requirements are
established for the different
phases of an animal’s life. A
government committee,
sponsored by the National
Research Council (NRC), was
charged with revising and
updating the 1989 sixth edition of
“Nutrient Requirements of Dairy
Cattle.”
The NRC is a private,
nonprofit society, chartered by
Congress. The NRC’s role is to
associate the broad community of
science and technology, advise
the federal government, and
provide service to the public, and
the scientific and engineering
communities. Because of my
expertise in protein and
carbohydrate nutrition in the
prepartum and postpartum
lactating dairy cow, I was asked
to participate.
This update of the NRC will
reevaluate the requirements and
will provide an up-to-date,
comprehensive review of the
scientific literature on dairy cattle
nutrition. This edition is intended
as a guide for diet formulation
and the nutritional management
of dairy cattle during various
phases of the life cycle. It will be
a useful tool for producers,
extension personnel, teachers,
students, and research scientists.
Nutrient requirements of
animals are determined in a
variety of ways. The best way to
measure all inputs and outputs is
through the use of calorimetry
chambers. To determine the
energy value of feeds, dairy cattle
are placed in these chambers to
measure all nutrients consumed
and* all nutrients digested. All
feces, urine and gases are
collected and measured to
determine the energetic efficiency
of how various feedstuffs are
utilized by the animal.
Hie majority of the energy
value of feedstuffs for dairy cattle
was determined in the 60’s and
70’s in calorimeters at USDA in
Beltsville, MD. Since these data
were developed, the amount of
dry matter consumed and milk
produced by the cow has
increased. Therefore, these
changes in energetic requirements
must be reflected in the revised
version of the NRC.
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New recommendations will be
made with consideration for the
increased performance of
different types of dairy cattle, the
effects of the environment on
nutrient requirements, and the
effects of feed additives, and
other types of growth enhancers
and metabolic modifiers on
nutrient requirements.
Quantitative information on
rumen tissue requirements for
degradable and undegradable
protein will be incorporated, as
well as new information on
bioavailabilty of various
nutrients, such as phosphorous.
This revision also will include
mathematical models to predict
animal performance based on
nutrient mput/production
response relationships.
These mathematical equations
NORCROSS, Ga. Winter is
a time when many producers
make decisions for the next sea
son. This year, low crop prices
will be causing many to take a
hard look at their operations.
What can a producer do to make
his or her operation more prof
itable?
Profitability surveys have
identified factors that lead to
increased profitability. Surveys
from lowa, Kansas and
Minnesota have shown that
increased profitability comes
from:
• Reducing costs. Assessment
of a farm operation should not
only be based upon total produc
tion, but also upon other factors,
such as production efficiency.
Spreading fixed costs over more
bushels and more acres can
improve efficiency. Cost cutting
should be done wisely. Too much
cost cutting reduces profits. The
goal is to increase efficiency
without endangering proven
income-earning practices, such
as higher yields. Assets such as
land, machinery, etc., should be
evaluated to determine if they
add to the value of production.
Land value should be carefully
assessed, to ensure that prices
will be incorporated on a compact
disk to provide the user with a
method of predicting nutrient
requirements of cattle under
individual management situations.
There has been a great deal of
new data since the last NRC that
must be compiled, and new data
sets must be developed and
validated. For example, new and
updated requirements for calves
and growing heifers will be added
as well updated requirements for
the transition dairy cow. New
information on availability of
minerals will also be provided.
All this information has to be put
together into one program that has
to be user friendly and then
validated with other data sets to
assure the numbers are correct.
A great deal of time and effort
has gone into to this revised
What To Do During Low Crop Prices
paid reflect the land’s productiv
ity.
•Increasing yields. Higher
yields lead to increased produc
tion. This translates into
increased income and greater
profitability. In addition,
increased yields can lower the
unit costs of production.
• Focusing on management.
Higher profit farmers spend
more time gathering informa
tion, analyzing choices, plan
ning activities, and evaluating
results. Formal education or
continuing education develops
mental tools that help these
processes. Consider adopting
new technology before it
becomes standard practice. Tb
find more time to conduct these
activities, a farmer may find it
wise to spend less time driving a
tractor. Someone else can drive
the tractor, but someone else
can’t make the farmer’s own
decisions. Try to adopt an opti
mistic view of the future.
Optimism renews interest in
learning more about the farming
operation and how to improve it.
Potash and phosphate are
essential for higher yields.
Higher yields have been shown
to lead to greater profitability.
From the Department of Dairy and Animal Science
This regular column from Penn State’s Department of Dairy and Ani
mal Science features the research findings, student opportunities, and
reports on other important topics generated in the Department. The back
issues of the column are archived on Lancaster Farming’s Internet
www.lancaslerfarming.com home page. Look for them.
edition since the first committee
meeting m February 1997. The
goal of the NRC is for this
publication to be printed
sometime late in the year 2000.
Other committee members
include: Jimmy Clark, University
of Illinois, chair; David Beede,
Michigan State University;
Richard Erdman, University of
Maryland: Ric Grummer,
But how can you know if
potash or phosphate applica
tions will be profitable? The
answer is to test your soil. Soil
tests are inexpensive but pro
vide very valuable information.
Knowing your soil test level
allows you to follow well
researched recommendations.
Consult university fertilizer rec
ommendations in your area, but
be prepared to make refine
ments for your own agronomic
and economic circumstances.
Local crop advisers can assist
with that process. Many areas
Lancaster Farming
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iw; LASF CORPORATION
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Lancaster Firming, Saturday, May 1, 1999-A27
University of Wisconsin; Jesse
Goff, USDA; Alice Pell, Cornell
University; Chuck Schwab,
University of New Hampshire;
Jim Linn, University of
Minnesota; Bill Weiss, Ohio State
University; and Trevor Tompkins.
Milk Specialties Co. These
committee members represent
some of the foremost dairy
nutritionists in the country.
see added benefits of starter fer
tilizer applications, sometimes
even at high or very high soil
test levels.
In times of low crop prices,
smart management decisions
are critical to the sustainability
of a farming operation. Lower
costs, higher yields, and atten
tion to soil test levels and a
sound fertility program are
essential components of a suc
cessful operation. A fertility pro
gram is not fat to be cut in lean
times, but rather a guidepost
that leads to survival.
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