Understanding the Dairy Cow

JOHN WEBSTER, MA, Vet MB, PhD, DVM (Hon), MRCVS, is Emeritus Professor of Animal Husbandry in the School of Veterinary Science at the University of Bristol, Bristol, UK.

Acknowledgements xiii


Preface to the Third Edition xiv


About the Companion Website xvi


Part I How the Cow Works 1


1 Introduction - The Dairy Cow of Today 3


Milk as Food 6


Nutrient Supply 7


Healthy Digestion 8


Taste and Appetite 9


Do no Harm 9


Biological Efficiency of Milk Production 10


Milk Production: Species and Breed Comparisons 11


Efficiency of Feed Conversion to Milk, Eggs and Meat: Competitive and Complementary Feeds 12


Behaviour and Welfare 14


2 Digestion and Metabolism 18


Structure of the Digestive Tract 18


Eating and Rumination 22


Grazing 22


Salivation 23


Rumen Movements 23


Rumination 25


Digestion 26


Fermentation of Carbohydrates in the Rumen 28


Utilization of Metabolizable Energy for Maintenance and Production 31


Digestion of Crude Protein 32


Microbial Protein Synthesis 35


Truly Absorbed Amino Nitrogen 37


Urea Recycling 38


Digestion of Lipids 38


Absorption and Secretion of Minerals 39


Calcium Exchange 41


Appetite and Food Intake 42


3 Reproduction and Lactation 45


Anatomy of the Female Reproductive Tract 45


Follicle Development and Ovulation 45


The Oestrus Cycle 49


Puberty 49


Fertilisation 50


Pregnancy 51


Placental Transfer and Foetal Nutrition 53


Parturition 53


Dystocia 55


Lactation 56


Anatomy of the Udder 56


Milk Yield 58


Extended Lactations 59


Hormonal Control of Lactation 60


Reproduction in the Male 61


4 Environment, Behaviour and Welfare 64


Environmental Needs 64


Behaviour 65


Physical Comfort 66


Thermal Comfort 68


Sensible Heat Loss 68


Evaporative Heat Loss 69


Metabolic Heat Production 71


Climate, Production and Welfare 73


Tropical Climates 73


Cold Climates 74


Security and Social Behaviour 74


Sexual and Maternal Behaviour 75


Behaviour as an Indicator of Welfare 76


Part II Feeding the Dairy Cow 77


5 Nutrition: Supply and Demand 79


Nutrient Requirements and Responses 81


Nutrient Allowances for the Lactating Cow 84


Mineral Requirements 88


Nutritive Value of Feeds 90


Ration Formulation 93


Prediction of Food Intake 93


Assessment of an Existing Ration 94


Feeding Plans for Dairy Cows 95


Inputs 95


Outputs 96


Allowances for Growing Heifers 97


6 Feeds and Feeding Strategies 99


Pasture 100


Grazing Strategies 102


Legumes 104


Grass Silage 104


Dry Matter 105


Metabolisable Energy 106


Protein 106


Silage Additives 107


Hay 107


Straw 108


Ensiled Whole-crop Cereals 108


Other Green Feeds 109


Root Crops 109


Cereals 109


By-products 111


Oilseed Cakes and Meals 111


Miscellaneous By-products 113


Sugar Beet Pulp 113


Maize Gluten 113


Brewers' and Distillers' Grains 114


Wheat Bran 114


Balancing Forages and Concentrates 114


Feeding Strategies 117


Feeding to Yield 117


Total Mixed Rations and Flat Rate Feeding 119


7 Feeding Problems and Metabolic Diseases 121


Feeding Problems 123


Rumen Acidosis 123


Abomasal Disorders 125


Bloat 126


Metabolic Disorders 127


Ketosis 127


Prevention and Treatment 129


Parturient Hypocalcaemia ('Milk Fever') 130


Prevention and Treatment 131


The Downer Cow 132


Hypomagnesaemic Tetany (Grass Staggers) 133


Prevention and Treatment 135


Other Mineral Deficiencies 136


Phosphorus 136


Copper and Molybdenum 137


Cobalt 138


Selenium 138


Vitamin Deficiencies 139


Vitamin A 139


Vitamin D 140


Vitamin E 140


Last Words on Minerals and Vitamins 141


Part III Housing Health and Management 143


8 Healthy and Humane Housing and Handling 145


Accommodation 145


The Cow House 146


Cubicle Design 150


The Cubicle Bed 153


Passageways 154


Calving and Isolation Boxes 154


Heifer Yards 156


Handling Facilities 156


Lameness 157


Conditions that Cause Lameness 159


Sole Haemorrhage and Sole Ulcers 159


White Line Disease 161


Digital Dermatitis 161


Interdigital Necrobacillosis 'Foul' 162


Aseptic Laminitis, 'Founder' 162


Risk Factors for Lameness 162


Transport and Slaughter 164


Loading and Unloading 164


The Journey 165


A Gentle Death 166


9 Milking and Mastitis 168


The Milking Machine 171


The Milking Parlour 174


Hygiene in the Milking Parlour 174


Mastitis 175


Indicators of Mastitis 176


Contagious Mastitis 177


Environmental Mastitis 178


Summer Mastitis 180


Dry Cow Therapy 181


10 Miscellaneous Maladies 182


Signs of Disease 183


Sudden Death 183


Drooling 185


Abdominal Symptoms 186


Nervous Symptoms 187


Fever 187


Inappetence and Anorexia 188


Notifiable Diseases 189


Bovine Tuberculosis 191


Foot and Mouth Disease 192


Other Infectious Diseases 193


Bovine Viral Diarrhoea (BVD) 193


Johne's Disease 194


Salmonellosis 194


Leptospirosis 195


Parasitic Diseases 195


Part IV Breeding and Fertility 197


11 Breeding 199


Selection Criteria 202


Genomic Selection 206


Sexed Semen 206


Cow Selection 207


Beef Bulls 209


12 Fertility 211


Fertility Management 212


Behaviour at Oestrus 212


Aids to Oestrus Detection 213


Synchronisation of Oestrus 216


Time of Insemination 217


Pregnancy Diagnosis 217


Rebreeding 219


Infertility 219


Ovarian Dysfunction 220


Uterine Disorders 221


Retained Placenta 221


Endometritis 222


Early Foetal Death 222


Abortion 223


Nutrition and Infertility 223


Condition Score at Calving? 225


Condition Score at the Time for Rebreeding? 225


Milk Yields in Early and Mid-lactation? 225


How Well Does Nutrient Supply Match Requirements? 226


Transition Management 226


Part V Cows, People and the Environment 229


13 Cows, People and the Living Environment 231


Most of Those who can Consume Too Much Meat and Milk 232


Food We Could Eat is Fed to Animals While the Poor Grow Hungry 233


Intensive Livestock Production is Incompatible with Animal Welfare 233


Livestock's Long Shadow is Destroying the Planet 235


Methane Production and Climate Change 237


Pollution from Dairy Units 238


Alternative Husbandry Systems 240


Organic Dairy Farming 240


Traditional and Village Systems 241


Fair Play for Cows, People and the Planet 242


Herd Health and Welfare 242


Herd Health Management 243


Animal Welfare: Quality Assurance and Quality Control 243


Further Reading 247


Index 252