- Genetic evaluation tools help simplify the interpretation of dairy genetics.
- Sire selection is the most effective method for improving herd genetics quickly.
- Breed choice and crossbreeding impact farm productivity and profitability.
- Farm-specific genetic goals should be identified to focus on traits that matter most.
Measuring Dairy Genetics
- Genetic indexes help assess dairy genetics by combining multiple traits to rank animals based on specific goals.
- Reliability of traits should be considered when selecting animals for breeding.
Predicted Transmitting Abilities (PTA)
- PTA is a key genetic evaluation tool comparing animals based on estimated genetic values for specific traits.
- Traits measured include milk yield, protein, fat, somatic cell score, calving ease, and more.
- PTA values are breed-specific and cannot be used to compare animals across different breeds.
- Reliability percentages indicate confidence levels in PTA values, increasing with more data.
Net Merit Index (NM$)
- Net Merit is a composite index that evaluates traits with economic importance.
- Expressed in dollars, higher values indicate greater profitability over an animal’s lifetime.
- Commonly used in commercial dairy herds to rank genetic potential.
Other Genetic Indexes
- Total Performance Index (TPI): Used for Holsteins, incorporating production, health, fertility, and conformation.
- Jersey Performance Index (JPI): Measures Jersey breed genetic merit, focusing on traits impacting lifetime income.
Genetic Influence: Bulls vs. Cows
- Sire selection is the primary driver of genetic progress, contributing more than half of the genetic improvements.
- Cow families and pedigrees also play an important role in herd genetics.
Choosing the Right Breed
- Breed selection affects size, milk composition, production, and temperament.
- Economic and personal factors such as tradition and market demand influence breed choice.
Crossbreeding Benefits
- Crossbreeding combines genetic traits from different breeds to improve fertility, health, and longevity.
- Heterosis (hybrid vigor) leads to improved overall performance and profitability.
- Common crossbreeding strategies include Jersey sires with Holstein cows for easier calving.
Selecting for Optimal Traits
- Identify specific farm goals to guide selection decisions.
- Avoid single-trait selection—use genetic indexes like Net Merit, TPI, and JPI.
- Genetic companies offer sires grouped by producer goals.
- Milk production strategies vary: Some farms prioritize volume, while others focus on fat and protein components.
- Productive longevity is key to lifetime profitability, requiring good fertility and health traits.
- Health-focused selection reduces the risk of issues like mastitis, ketosis, and displaced abomasum.
By using genetic tools strategically, dairy producers can improve herd productivity, profitability, and long-term sustainability.
