Contents 1 Abstract 2 Introduction 3 Relationships between Fertility and Other Economically Important Traits 3.1 Milk Yield and Fertility 3.2 Body Condition Score and Fertility 3.3 Mastitis and Fertility 4 Genetic Selection for Female Fertility 5 Genetic Selection for Animal Health 6 Conclusions 7 Literature Cited 8 Author Information

Abstract

Prospects for improving female fertility in dairy cattle via genetic selection are reviewed. Today’s high-producing cows have …

Contents 1 Summary 2 Introduction 3 Annual Herd Turnover Rates 4 Reported Reasons for Culling 5 Timing of Culling within the Lactation 6 Indirect Selection for Conformation Traits 7 Direct Selection for Length of Productive Life 8 Incorporating Data from Correlated Traits 9 Genetic Trends in Productive Life 10 Recording of Health Traits 11 Incorporation of Health Traits into Selection Programs 12 Implications for Dairy Cattle Selection Programs 13 References 14 Author Information

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Contents 1 Introduction 2 Performance of inbred dairy cattle 3 Inbreeding in today’s dairy populations 4 Consequences of inbreeding 5 Identification is essential 6 Summary 7 References 8 APPENDIX 8.1 Calculation of Inbreeding Coefficients 8.2 Inbred bulls in AI service 9 Author

Introduction

The mating of related individuals is called inbreeding. New dairy animals created by AI or natural service inherit a random sampling of the genetic …

Two of the biggest headaches, as well as financial drains, on a modern dairy farm are calving complications and stillborn calves. Heifers and cows that go through a difficult calving tend to have impaired health, fertility, and production in the following lactation. Death of the calf or its dam can also occur, and calving difficulty is a leading cause of stillbirths. However, many normal-sized calves that are born without complications are also stillborn or die shortly thereafter. Substantial variation exists …

Contents 1 Background 2 Selection for Increased Income 3 Selection for Reduced Expenses 4 Summary 5 Author Information

Background

Improvement of food animal species through genetic selection began long ago, but little genetic progress was made in dairy cattle until four major developments occurred in the 20th century. First was the development of a national milk recording system, known as the Dairy Herd Improvement (DHI) program, that …

Contents 1 Introduction 2 Why Consider Crossbreeding Now? 3 What Are the Breed Resources? 4 What Issues Should Be Considered in Crossbreeding? 5 Three-Breed Rotational Systems with Purebred AI Sires 6 Identification Is Important 7 References 8 Author Information

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