Predicting Feed Intake of Food-Producing Animals Subcommittee on Feed Intake

Predicting Feed Intake of Food-Producing Animals 1
Copyright 2
Preface 3
Contents 7
1 Introduction: Feed Intake Control Mechanisms 11
INTRODUCTION 11
OVERVIEW OF CONTROL SYSTEMS 11
Digestive Tract 11
Metabolites 12
Hormones 13
Brain 14
Other Factors 15
REGULATORY PEPTIDES 16
Cholecystokinin 16
Opioid Peptides 18
THE ROLE OF FEED INTAKE IN THE REGULATION OF ENERGY BALANCE 18
SUMMARY 20
REFERENCES 22
2 Fishes 26
INTRODUCTION 26
ENVIRONMENTAL FACTORS 27
PHYSIOLOGICAL FACTORS 28
DIETARY FACTORS 29
Nutrient Deficiency 29
Food Particle Size and Composition 29
Feeding Stimulants 30
Feed Quality 30
PREDICTING FEED INTAKE 31
Feeding Equation Derivation 31
REFERENCES 33
3 Swine 35
INTRODUCTION 35
FEED INTAKE OF GROWING PIGS 35
Suckling Pig 35
Weanling Pig 36
Growing Pig 37
VOLUNTARY FEED INTAKE DURING GESTATION 39
VOLUNTARY FEED INTAKE DURING LACTATION 39
FACTORS AFFECTING VOLUNTARY FEED INTAKE 39
Physiological Factors 39
Environmental Factors 41
Nutritional Factors 44
PREDICTING VOLUNTARY FEED INTAKE 46
EXAMPLE PREDICTIONS 46
Validation 47
REFERENCES 47
4 Poultry 52
INTRODUCTION 52
FEED INTAKE CONTROL MECHANISMS 52
Glucostatic Theory 52
Thermostatic Theory 52
Lipostatic Theory 53
Aminostatic Theory 53
Ionostatic Theory 53
Role of Brain Structure 53
Summary 53
ESTIMATING FEED INTAKE OF LAYING HENS 54
ESTIMATING FEED INTAKE OF BROILERS 55
CALCULATIONS OF DRY MATTER INTAKE 55
SUMMARY 56
REFERENCES 56
5 Dairy Cattle 58
INTRODUCTION 58
LACTATION RESPONSE 58
LIMITING FORAGE INTAKE 59
COMPUTING ESTIMATES OF DRY MATTER INTAKE 60
Environmental Temperature 61
Metabolites 61
Meals and Meal Patterns 61
Grinding and Pelleting 63
SUMMARY 63
REFERENCES 64
6 Beef Cattle 66
INTRODUCTION 66
PHYSIOLOGICAL FACTORS 66
Body Size and Production Demands 66
Mature Size and Sex 68
Age 69
Genetic Variance 69
Breed Type 69
ENVIRONMENTAL EFFECTS 70
Temperature and Weather 70
Photoperiod and Timing of Feeding 70
Forage Availability for Grazing Cattle 71
DIETARY FACTORS 71
Diet Water Content 71
Degree of Fermentation 72
Dietary Protein 73
Feed Processing 73
AN EVALUATION OF ALTERNATIVE SYSTEMS FOR PREDICTING INTAKE BY BEEF CATTLE 74
Limitations 74
Limitations 74
Limitations 74
Limitations 75
Limitations 75
Limitations 75
Limitations 75
Limitations 75
SUMMARY OF FACTORS INFLUENCING INTAKE OF BEEF CATTLE 75
APPLICATION OF EQUATIONS AND ADJUSTMENTS 77
Yearlings 77
Calves 80
Beef Cows 81
REFERENCES 82
7 Sheep 85
INTRODUCTION 85
PHYSIOLOGICAL AND DIETARY FACTORS 85
PREDICTING DRY MATTER INTAKE OF SHEEP 87
EVALUATION OF EQUATIONS TO PREDICT INTAKE OF SHEEP 89
MANAGEMENT TO MAXIMIZE INTAKE IN SHEEP 91
REFERENCES 92
Index 93