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OCR for page 1
Overview
Since 1944, the National Research Council has pub-
lished six editions of Nutrient Requirements of Dairy Cat-
tle. This seventh revised edition, Nutrient Requirements of
Dairy Cattle 2001, applies new information and technology
to current issues in the field of dairy cattle production.
Reflecting the rapidly changing face of dairy cattle produc-
tion and dairy science, it includes more comprehensive
descriptions of management and environmental factors
that affect nutrient requirements and provides expanded
discussions of nutrient needs for various life stages and
levels of production. A revised approach to predicting
nutrient requirements increases the user's responsibility
for accurately defining animals, diet, and management con-
ditions to estimate nutrient requirements. A benefit associ-
ated with the increased responsibility is the ability of the
user to make more-informed decisions in the field.
A substantial part of the increase in decision-making
power comes from the presentation of requirements with
a computer model. Computer models are the only effective
means of taking animal variation into account. Unlike static
tabular values, computer models such as the one provided
in this edition can describe animals in different states with
differing needs. A model can accommodate fluctuations
caused by the effect of feed ingredients on nutrient absorp-
tion and consequently on the animal's performance poten-
tial, which affects its nutrient requirements. The model
prepared in this publication was designed to provide practi-
cal, situation-specif~c information in a user-friendly format.
Chapter 1 presents a discussion of dry matter intake,
including factors that affect intake and methods of predict-
ing it. Characteristics of the animal's diet, environment,
and physiologic makeup are considered, as are relevant
management issues. After a brief description of available
equations for predicting dry matter intake, the chapter
discusses the dry matter intake equations included in this
edition and closes with tables and graphs of intake across
a lactation.
Chapter 2 addresses energy, defining energy units and
expressing methods of obtaining, estimating, and express-
ing energy values of feeds. The chapter discusses energy
requirements for maintenance, lactation, activity, and preg-
nancy. Tissue mobilization and repletion and the effects
of environment are discussed. The chapter concludes with
a section on body condition scoring, which is accompanied
by a reference chart.
Chapter 3 covers digestibility and energy values of fat.
It contains information on effects of fat on rumen fermenta-
tion and the use of fat in lactation diets. A table of fatty
acid composition of fats and oils is presented.
A comprehensive review of carbohydrates is provided
in Chapter 4. Nonstructural and structural carbohydrates
are discussed, with special attention to requirements for
neutral detergent fiber (NDF) and acid detergent fiber
(ADF).
Chapter 5 covers all aspects of protein and amino acid
nutrition. This chapter documents an extensive literature
base used in the development of equations and provides
detailed explanations for estimating metabolizable-protein
requirements for maintenance, pregnancy, lactation, and
growth. The amino acid section is a substantial advance
over the previous edition and provides readers with a
discussion of predicting passage to the small intestine
and equations for estimating lysine and methionine
requirements.
Requirements for macrominerals and trace minerals,
and information on toxic minerals appear in Chapter 6.
Each category includes an extensive list of minerals and
covers their function, bioavailability, requirements by dif-
ferent classes of dairy animals, toxicity, and symptoms of
mineral deficiency.
Chapter 7 covers vitamins in a similar fashion, dividing
them into fat-soluble and water-soluble categories. Like
the minerals in Chapter 6, the vitamins in Chapter 7 are
1
OCR for page 2
2 Overview
discussed in the context of the animals that will be ingesting
them. Sources and bioavailability of vitamins are provided,
followed by a discussion of the functions of each vitamin,
animal response to it, requirements for it, and factors that
affect the requirements.
Metabolism and requirements open the discussion of
water in Chapter 8. This chapter furnishes information on
factors in the environment and the water itself that affect
intake. Among the factors considered are nutrients in the
water and the presence of bacteria and algae.
Chapter 9 addresses important issues peculiar to dairy
nutrition. It considers the feeding of the transition cow,
metabolic disorders (such as udder edema and milk fever),
and performance modifiers (such as buffering agents and
directly fed microbials).
Chapter 10 offers information specifically on the nutri-
ent requirements of the young calf and Chapter 11 on the
heifer, and aspects of growth, maturity, and body reserves.
One of the most important features of this revision is
the inclusion of a discussion on the effect of dairy cattle
feeding on the environment. Chapter 12 provides an over-
view of nutrients of concern and applies science to the
challenges faced by managers in reducing nutrient
excretion.
Chapter 13 provides a discussion of feed chemistry and
processing. Analytic procedures are described, and the
effects of processing on energy in feed are reviewed.
Nutrient requirement tables are presented in Chapter
14. These tables were generated with the accompanying
computer model. Tables are provided for small- and large-
breed cows at various stages of lactation.
Chapter 15 provides a greatly expanded set of feed com-
position tables and an explanation of their use. The tables
include nutrient breakdowns for a comprehensive list of
foodstuffs commonly present in dairy cattle diets and some
feeds that are less common.
Chapter 16 presents an evaluation of the computer
model. Data from experiments in which 100 different diets
were fed in continuous feeding trials and published in the
Journal of Dairy Science were used in the evaluation. After
the evaluation, the anatomy and use of prediction equations
in the computer program are presented. An introduction
to this edition's computer model is present in a user's guide.
Finally, a glossary of terms used in this edition is pro-
vided to increase readers' ease of use and comprehension.
Although the science base for predicting nutrient
requirements summarized here has greatly expanded since
the previous edition of this report, there are still gaps in
our knowledge, particularly for specific animals of different
ages and levels of production. The users of this volume
are encouraged to seek a firm understanding of the princi-
ples and assumptions described here, because this under-
standing is essential for proper use of the tables and text
and of the computer model and its output.
The estimates of nutrient requirements that are pre-
sented in this report for different classes of animals were
generated as examples and are intended for use as guide-
lines by professionals in diet formulation. Because there
are many factors that affect requirements of animals under
various conditions, the values presented here cannot be
considered all encompassing and should not be interpreted
as accurate or applicable in all situations.
Representative terms from entire chapter:
dairy cattle
