Variation in genetics is the different way traits are expressed. For example, animals that have higher or lower average daily weight gain can be variation of the same gene. 

Heritability is the percentage of observed variation that is explained by genetics. For example, a heritability of 0.3 means that 30% of the variation observed in the trait is due to genetics and the remaining 70% is due to environmental factors.

Most production traits are moderately heritable, with the heritability of BREEDPLAN traits typically ranging from 0.5 to 0.65.

In beef genetics, when we talk about low heritability, it means that the traits we observe in cattle, such as certain characteristics related to size or weight, are influenced by factors other than genetics, like the environment. On the other hand, high heritability indicates that the observed traits are mainly influenced by genetics, and selective breeding can have a more significant impact on improving those specific characteristics in future generations of beef cattle.

Improvements in genetics can happen for all characteristics that can be passed down from one generation to the next, even for those with limited heritability. Take “Days to Calving,” a trait related to fertility, which usually has low heritability. Despite this, we can still make noteworthy genetic advancements because there is observable genetic diversity within this particular trait.

Key messages

Heritability is the percentage of observed variation that is explained by genetics.

Genetic progress can be made even in lowly heritable traits as genetic variation still exists.