How to read a bull proof

Good Bulls Guide

Listed in the latest Good Bulls Guide.

 

Balanced profit Index (BPI)

The Balanced performance Index is an economic index that blends production, type and health traits for maximum profit.

 

Health weighted Index (HWI)

The Health weighted Index allows farmers to fast track traits such as fertility, mastitis resistance and feed efficiency.

 

Type weighted Index (TWI)

The Type weighted Index allows farmers to make greater progress for type while still maintaining emphasis on production and health.

 

Production ABV

These are calculated from information provided by Australian farmers who participate in a recognised herd recording program. They are expressed as a percentage deviating (+-) from the base (average) of 100. In this example, 102 for milking speed indicates that the bull is 2% above average for this trait i.e. his daughters on average milk faster. The reliability percentage is generated from the number of daughters and contemporaries scored and the number of herds. Production traits are expressed in their units of measurement from a rolling base of 0, which represents the average cow currently milking in Australia. The reliability figure is an estimate of potential proof change based on the number of daughters, herds, test days and genomic data. The higher the reliability of a trait, the lower the chance of proof movement.

 

Australia Selection Index (ASI)

Like the BPI, the ASI is expressed as a dollar value. This production based index is weighted using a similar ratio of milk:fat:protein to what most Australian dairy farmers are paid for their milk. Index weightings are as follows: (6.92 x Protein kg ABV) + (1.79 x Fat kg ABV) – (0.10 x Milk ABV).

 

Type

Type is the assessment at the confirmation of the bull’s daughter. The base for Type is 100. All type traits have a standard deviation of 5 units. A bull that is 110 for a particular trait is 2 standard deviations above the base (average). This would place him in the top third of the population. A bull that is 115 for a particular trait is 3 standard deviations above the base and would be placed in the top 1% of the population.

 

Health Traits

Health Traits such as Cell Count, Survival, Liveweight and Daughter Fertility can be interpreted the same way as the workability traits. They are expressed as a percentage deviating (+-) from the trait’s base (average), which is set at 100. The reliability figure represents the amount of information that has been used to calculate this publishable data. An ‘n/a’ indicates that the reliability figure is too low to give a meaningful indication of what value you can expect to be transmitted. For all traits, except liveweight, a figure greater than 100 is more desirable. Liveweight above 100 is indicative of the bull siring heavier daughters, pick bulls below 100 for overall liveweight reduction.

 

Calving Ease

Like the Workability and Health Traits Calving Ease is expressed as a percentage deviating (+-) from the trait’s average, which is set at base (average) of 100. Easier calving sires have figures greater than 100.

 

Feed Saved

Feed Saved is Australia’s Feed Conversion Efficiency breeding value. It combines genomic data with estimates of maintenance requirements to predict the feed intake of a bulls daughters. It is expressed as kgs of feed saved per lactation. E.g. if a bull has an ABV of 100, then on average his daughters will eat 100 kgs less of feed than the daughters of an average (0) bull. If a bull has an ABV of -50, then this bulls daughters will eat 50 kgs more feed than daughter of the average bull.