Reproduction in Cattle

Transcription

1 Reproduction in Cattle Third Edition P.J.H. BALL BSc, PhD A.R. PETERS BA, DVetMed, PhD, FRCVS, FIBiol

2 2004 by P.J.H. Ball and A.R. Peters Editorial Offices: Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK Tel: +44 (0) Blackwell Publishing Professional, 2121 State Avenue, Ames, Iowa , USA Tel: Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia Tel: +61 (0) The right of the Authors to be identified as the Authors of this Work has been asserted in accordance with the Copyright, Designs and Patents Act All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. First edition published 1986 by Butterworth & Co. Publishers Second edition published 1995 by Blackwell Science Third edition published 2004 by Blackwell Publishing Library of Congress Cataloging-in-Publication Data Ball, P.J.H. Reproduction in cattle / P. Ball & A. Peters. 3rd ed. p. cm. Rev. ed. of: Reproduction in cattle / A.R. Peters, P.J.H. Ball., Includes bibliographical references and index. ISBN (pbk. : alk. paper) 1. Cattle Reproduction. 2. Cattle Breeding. I. Peters, A.R. II. Peters, A.R. Reproduction in cattle. III. Title. SF768.2.C3B dc ISBN A catalogue record for this title is available from the British Library Set in 10 on 12.5 pt Times by SNP Best-set Typesetter Ltd., Hong Kong Printed and bound in Great Britain by T.J. International Ltd, Padstow, Cornwall The publisher s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. For further information on Blackwell Publishing, visit our website:

3 Contents v 1 Reproductive Efficiency in Cattle Production 1 2 Anatomy 13 3 Bull Fertility 28 4 The Ovarian Cycle 40 5 Fertilization, Conception and Pregnancy 56 6 Parturition and Lactation 68 7 The Postpartum Period 79 8 Oestrous Behaviour and Its Detection 92 9 Artificial Control of the Oestrous Cycle Artificial Insemination Pregnancy Diagnosis Reproductive Problems Reproductive Biotechnologies Reproductive Management Selection for Breeding 231 Index 238

4 It bears repeating from previous editions that cattle are an integral part of animal agriculture in all parts of the world. They provide the human population with products such as milk, meat, clothing, fertilizer and fuel, as well as providing draft power in many countries. Demand for some products, such as fat in meat and in milk, has declined in some markets, and in some countries (e.g., in the European Union) milk production is limited by quotas. Nevertheless, the efficient production of animal protein continues to be of vital importance. An efficient production system must maximize the output of meat and milk per unit of feed input and per animal and, in cattle production, as with other livestock systems, a high level of reproductive performance is absolutely crucial to efficient production. Efficient reproduction results in optimum calving intervals, which in turn result in optimum production of milk and calves to be reared for beef or replacements. Furthermore, cows that fail to reproduce are culled, limiting the choice of animals available to produce replacements and thus limiting genetic progress. As awareness of the ethical issues surrounding animal production increases, this wastage becomes even more unacceptable. Welfare concerns are also increasing the pressure to avoid animal ill-health and, specifically, fertility problems. This should be regarded as a positive trend since, as will become evident in the book, improved health and welfare go hand in hand with better reproductive performance. In the UK, the BSE epidemic and the subsequent outbreak of foot-andmouth disease have resulted in large numbers of cattle being culled. Those that remain need to reproduce even more efficiently to provide a good choice of replacement stock. Unfortunately, however, there is evidence that dairy cattle reproductive performance in the UK and other countries where intensive dairying is practised is declining. Conception rates are now considerably lower than they were when our first edition appeared in 1986 and oestrus detection always a major limiting factor to efficient cattle reproduction has become considerably less effective. In order to manage cattle reproduction and the specific problems that arise, it is important to understand the underlying physiology of the reproductive process. Thus, the third edition, as did the first two, aims to provide an integrated overview of the subject of bovine reproduction, describing the normal function of the reproductive system together with its modification by pharmacological, technological and management techniques in relation to the central theme of reproductive efficiency. The book continues to provide a general

5 vi background to the field of cattle reproduction for agricultural and animal science students and as an introductory text to veterinary students and postgraduate students embarking on a career in reproductive research. Furthermore, we hope that it will be used by working veterinarians and by progressive farmers to update them on new research findings and developments in the management of cattle breeding. In this new edition we have attempted to integrate the various sections covering anatomy and physiology and those on management and animal health into a more logical sequence. We have incorporated recent findings on the physiology of the oestrous cycle and its control, as well as new techniques for monitoring and manipulating reproduction, such as oestrus synchronization, pregnancy diagnosis and embryo transfer. As before, we do not intend to provide a manual of instruction for such techniques but rather to describe and explain the principles involved. The importance of adapting management procedures to take account of changing cows and conditions is emphasized. Reproductive efficiency, with an emphasis on the farmer s aims and requirements, is discussed in the first chapter. Most examples will be drawn from the cattle industry in the UK, with which the authors are most familiar, but the general principles can be extrapolated widely. The following chapters describe the anatomy and physiology of the male and female reproductive systems, with a detailed description of sperm production, ovarian cycles, fertilization and pregnancy. Subsequent chapters describe and discuss management procedures and techniques to maximize reproductive performance, including the vitally important detection of oestrus as well as oestrus control, artificial insemination and pregnancy diagnosis. This is followed by a description of the common infertility problems, after which a chapter on reproductive management puts these themes into a practical context. The book concludes with chapters on embryo transfer and related technologies, selection of animals for breeding and a final summary of the most important features and future trends in the control of reproduction in cattle. We would like to record our thanks to all those people who have provided information and permission to reproduce data and illustrations, and these are acknowledged individually in the text. We are particularly grateful to Professors Hilary Dobson, Claire Wathes and Bob Webb, Drs Emma Bleach, Will Christie, Dick Esslemont, Patrick Lonergan, Tom McEvoy and Toby Mottram, and to staff of Semex, including Dr Tom Kroetsch, to staff of Cogent, including Messrs Marco Winters and Innes Drummond, and to staff of the British Society of Animal Science, including Mr Mike Steele. P.J.H. BALL A.R. PETERS