Conformation PTAs

Type traits can play an important role in determining a cow’s suitability for sustained milk production. Find out about the different groups of type traits and how they’re calculated.

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Conformation traits

A cow’s durability is affected by 17 traits, which are split into three groups, as outlined below.

Type evaluations are undertaken on first-lactation cows by the breed societies, each of which has its own breed standards. The data is used to calculate genetic evaluations for males and females. As with individual production and health indexes, type indexes shouldn’t be compared across breeds.

Linear type traits

The 17 linear type traits, which describe the physical attributes that make up how a cow looks, are measured on a linear scale. These are generally presented on a bar chart, which provides a useful at-a-glance assessment of a bull’s predicted breeding pattern.  

While it’s generally considered desirable for bars to be on the right-hand side of the chart, they don’t necessarily need to be on the extreme right, depending on your breeding priorities. For example, extreme stature improvement is no longer desirable for most producers.

Two obvious exceptions are rear legs viewed from the side and teat length, each with approximately mid-score optimums. Once again, the intermediate score of zero represents the breed average for all linear traits. Linear type traits are scored on a scale of -3 to +3.

Composite type traits

The two composite traits – Feet and Legs, and Udder – also appear on a bull’s bar chart, but unlike the 17 linear traits above, these are described in terms of desirability rather than degree. Based on the type evaluator’s observations, they’re also scored on a scale of -3 to +3, with the highest scores indicating the best overall quality.

Type merit

Type merit predicts a bull’s ability to transmit overall type. It’s based on a combination of his daughters’ scores for Feet and Legs, Udder and body conformation, in order of importance. Again, it’s scored on a scale of -3 to +3.

Useful links

Find out more about genetic indexes

Learn about production PTAs

Find out about health, welfare and fitness PTAs

Learn about calf survival PTAs

Find out about management PTAs

Find out more about selection indexes

Learn about the progress made in dairy herd genetics

Find out about common genetic defects

Information on body condition scoring