Energy Nutrition in Ruminants

157 Pages·1990·3.671 MB·English

by  M. Ryle, E. R. Ørskov (auth.)

ENERGY NUTRITION IN RUMINANTS
ENERGY NUTRITION IN
RUMINANTS
E. R.0RSKOV
Applied Research Department, The Rowett Research Institute, Aberdeen, UK
and
M.RYLE
39, Hunshelf Park, Stocksbridge, Sheffield, UK
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WITH 43 TABLES AND 9 ILLUSTRATIONS
ISBN·13:978·94·010·6823·9 e·ISBN·13:978·94·009·0751·5
DOl: 10.1007/978·94·009·0751·5
© 1990 ELSEVIER SCIENCE PUBLISHERS LTD
Softcover reprint of the hardcover 1s t edition 1990
British Library Cataloguing in Publication Data
0rskov, E. R. (Egil Robert), 1934-
Energy nutrition in ruminants.
1. Livestock: Ruminants. Feeding & nutrition
I.. Title II. Ryle, M. (Margaret)
636.2084
ISBN 97&-94-010-6823-9
Library of Congress Cataloging in Publication Data
0rskov, E. R.
Energy nutrition in ruminants/E. R. 0rskov and M. Ryle.
p. em.
Includes bibliographical references.
ISBN 97&-94-010-6823-9
1. Ruminants-Nutrition. 2. Ruminants-Feeding and feeds.
3. Bioenergetics. I. Ryle, Margaret. II. Title.
SF95.077 1990
636.2'08~c20
89·71460
CIP
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PREFACE
This book is intended to be a companion volume to 'Protein
Nutrition in Ruminants' (1982, Academic Press), which emphasized
both the role of proteins and new systems for their evaluation. Here
the focus is on energy-yielding nutrients and problems involved in
evaluating them. Nonetheless in both volumes there is explicit
recognition of the interdependence of energy and protein nutrition.
I have not attempted to review comprehensively all the literature
relating to ruminant energy nutrition and must apologize to
colleagues whose work is not fully reported. Where possible tables
and figures are taken from the studies of our group at the Rowett
Research Institute since, if for no other reason, I am most familiar
with these data.
I have first considered the nutrition of the newborn and have
stressed the role of behaviour 'in determining whether nutrients
enter or bypass the rumen. The development of the rumen, the
principles of anaerobic fermentation and the roles of various
. species of rumen bacteria, protozoa and fungi in relation to
different substrates, are summarized. This is followed by accounts
of the factors affecting the utilization of different substrates and the
v
vi Preface
absorption and metabolism of the end-products of fermentation
and digestion, together with estimates of digestive capacity in
various segments of the gut. The ruminant's requirements for
energy-yielding nutrients is considered in relation to the per
formance of various activities and to environmental conditions,
particular attention being paid to the requirement for glucose
precursors.
The final chapters are largely concerned with the control of feed
intake, especially of roughages. It is argued that current feed
evaluation systems are inadequate, because they do not take into
account how much of each feed an animal actually consumes. This
deficiency is particularly important where the diet consists mainly
of roughages, ·as is typical in developing countries. A provisional
new system is proposed, based on information regarding (i) the
fraction of soluble material in the feed, (ii) the proportion of the
insoluble material which is potentially fermentable, and (iii) the
rate at which insoluble but fermentable material is degraded. Data
are presented which show that this system can predict both feed
intake by test animals and their consequent growth rate.
I hope this book will be of value to undergraduate and
postgraduate students specializing in nutrition, to nutritionists in
commercial and government-supported organizations, and to those
who teach in the fascinating field of ruminant nutrition. While the
volume is no definitive treatise, I trust that it will prove both
stimulating and challenging.
Dr. Margaret Ryle wrote Chapter 2 and edited the whole book.
We are both most grateful to Dr. R.N.B. Kay for suggesting many
constructive amendments, and to Mrs. R. Milton, who helped
greatly in the preparation of the manuscript.
E.R.0rskov
CONTENTS
Preface . v
1. Nutrient supply to the newborn ruminant 1
2. Energy nutrition of rumen micro-organisms 10
3. Manipulation of rumen fermentation and associative
effects 28
4. Host animal control of microbial fermentation and host
animal digestion 43
5. Absorption of nutrients 52
6. Energy metabolism of the host animal 63
vii
viii Contents
7. Utilization of the energy of absorbed nutrients 84
8. Feed quality and feed intake .102
9. Feed evaluation, past and present · 122
10. Towards future feed evaluation systems · 133
Index · 145
CHAPTER 1
NUTRIENT SUPPLY TO THE
NEWBORN RUMINANT
I. Introduction
II. Physiology of stomach development
A. The oesophageal groove reflex
B. Development of enzyme competence
i. Proteolytic enzymes
ii. Lipase
iii. Carbohydrases
III. Milk replacers
IV. Utilization of energy from milk
V. Transition to fermentable feeds
I. INTRODUCTION
The moment the navel cord is broken, during passage from the
uterus to the external environment, major changes occur in the
energy nutrition of the young. In fact, considering the complexity
Gfthe changes, it is remarkable that mortality is so low. One major
change is in the route by which nutrients are supplied. Before birth,
2 Energy Nutrition in Ruminants
glucose, amino acids etc. are delivered directly via the placenta.
Afterwards they must first be consumed as milk and then absorbed
from the small intestine. The high rate of success with which this
major change occurs is due to the close matching of the composition
of the colostrum, the newborn's first energy source, with intestinal
cell permeability to large molecules. At the same time, large
amounts of globulins obtained from the colostrum help to protect
against prevalent pathogens while the immune system is developing.
Another very important change requiring immediate adaptation
concerns the control of body temperature which, in itself, may
require considerable energy. This adaptation occurs rapidly after
birth, more efficiently than in humans and much more rapidly than
in newly hatched chicks, which cannot control their body
temperature at all for some hours and are better regarded as
walking eggs! For ruminants that are likely to be born in a cold
environment, other provisions also help to ensure survival. These
include a subcutaneous layer of brown fat which in effect acts like
an electric blanket. Brown fat accumulates only towards the end of
gestation so, for example, lambs that are born even one week
premature are much more sensitive to adverse temperatures than
those carried to term.
II. PHYSIOLOGY OF STOMACH DEVELOPMENT
There are many excellent books describing the development of the
ruminant stomach. Moreover, many relevant articles have been
published in the regular symposia on ruminant physiology which
are held every five years, as well as elsewhere. Therefore only a
summary will be given here.
IIA. The Oesophageal Groove Reflex
The rumen is poorly developed at birth, in contrast to the
abomasum. Indeed, the volumes of the two are similar, although in
the mature animal that of the rumen is at least ten times that of the
abomasum. Milk and milk replacers are channelled directly to the