Traits rarely move in isolation. When you select for one, you often get a change in another—sometimes for the better, sometimes not.
Selecting for higher yearling weight usually leads to higher birth weights. Genetic Parameters for Sheep Production Traits
Heritability measures how much of the variation in a trait is due to genetics rather than environment (feed, weather, management). Traits rarely move in isolation
Reproductive traits like twinning rates or lamb survival. Because these are heavily influenced by environment/management, progress through breeding is slow. 2. Genetic Correlations: The "Package Deal" Genetic Parameters for Sheep Production Traits
Enhance the overall "efficiency" of the flock—producing more output with the same input.
Traits like carcass lean meat yield and fiber diameter. You can make rapid progress just by selecting the best-performing individuals.