heritability or the amount of observed variation that can be explained by the genetic component.
Generally low for fertility traits. Around 0.01 to 0.20 depending on the trait and how it is measured.
In terms of longevity, there are several ways to describe longevity for genetic analysis. The most common is stayability (if a cow has a calf and is still in the herd at 6 she gets a 1) heritability of this ranges around 0.1 to 0.25.
Another way to look at it is number of calves by opportunities to calve. Heritability is generally lower than stayability.
Basically these traits are slower (harder?) to change than traits like growth, carcass and temperament that have moderate to high heritabilities.
As well, heritability may differ depending on the breed and whether the data is from a tropical or temperate environment. All heritability tells us is how much difference we can explain through genetics. As we gain more knowledge of genetics (better models, gene markers, etc) these values may be increased. It is pretty common for a breed to reevaluate their heritability esitmates every so often, and it is one of the first steps done when developing new trait evaluations. heritability also depends on how a trait is defined. For example the heritability of marbling is different when calculated on a carcass weight endpoint, versus and age endpoint, versus a fat endpoint.
Often hard to measure traits have a low heritability just because it is hard to get good data/information on them, and/or because there are a lot of other factors involved.
There are some pretty neat non-standard evaluations including:
stayability/longevity - takes a long time measure and to change
heifer pregnancy
docility
tenderness
days to calving
Mature size/maintenance energy
Net/residual feed intake
Generally low for fertility traits. Around 0.01 to 0.20 depending on the trait and how it is measured.
In terms of longevity, there are several ways to describe longevity for genetic analysis. The most common is stayability (if a cow has a calf and is still in the herd at 6 she gets a 1) heritability of this ranges around 0.1 to 0.25.
Another way to look at it is number of calves by opportunities to calve. Heritability is generally lower than stayability.
Basically these traits are slower (harder?) to change than traits like growth, carcass and temperament that have moderate to high heritabilities.
As well, heritability may differ depending on the breed and whether the data is from a tropical or temperate environment. All heritability tells us is how much difference we can explain through genetics. As we gain more knowledge of genetics (better models, gene markers, etc) these values may be increased. It is pretty common for a breed to reevaluate their heritability esitmates every so often, and it is one of the first steps done when developing new trait evaluations. heritability also depends on how a trait is defined. For example the heritability of marbling is different when calculated on a carcass weight endpoint, versus and age endpoint, versus a fat endpoint.
Often hard to measure traits have a low heritability just because it is hard to get good data/information on them, and/or because there are a lot of other factors involved.
There are some pretty neat non-standard evaluations including:
stayability/longevity - takes a long time measure and to change
heifer pregnancy
docility
tenderness
days to calving
Mature size/maintenance energy
Net/residual feed intake
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