Udder Composite and PPR Formulae Revised for December Evaluations

UDDER COMPOSITE AND PPR FORMULAE REVISED FOR DECEMBER EVALUATIONS

The Brown Swiss Board of Directors has adopted revisions to the Udder Composite and PPR formulae based on recommendations from the Genetics Committee.  These changes to the formulae weights will be effective with the December Genetic Evaluation run. 

Working with the Genetics Committee during the last two years, Dr Chad Dechow of Penn State along with his student Keith Gibson have been using the current data available from Brown Swiss and records from the DHI processing centers to determine correlations on traits for production and type.  After looking at the actual numbers, the weighting of the current formulae for Udder Composite and for PPR need to be adjusted.  Reasons behind the current weighting were valid and the breed has seen the positive results from them.

a)  Somatic Cell Score will be reduced from 8% to 4% weight since Brown Swiss already have an advantage in this trait.

b)  Productive Life will be reduced from 12% to 10% weight since some of the other traits are highly correlated to Productive Life. 

c)  Daughter Pregnancy Rate will increase from 4% to 10% weight to further progress in the reproductive area.

UDC

The following changes to the Udder Composite formula weights were made to better reflect increased herdlife:

a)  Fore Udder Attachment will increase from 21% to 22%.

b)  Rear Udder Height will increase from 6% to 18% as it is highly correlated to Productive Life.

c)  Rear Udder Width will increase from 1% to 22% as it is highly correlated to Productive Life.

d)  Udder Cleft will increase from 2% to 18% as it is highly correlated to Productive Life.

e)  Udder Depth will decrease from 35% to 10%.

f)  Teat Placement will decrease from 11% to 10%.

e)  Teat Length (currently 24%) will be eliminated as there is lower need for this trait emphasis because of breed improvement.

The Revised UDC formula is based on genotypic correlations with Productive Life obtained from research on Brown Swiss data by Dr. Chad Dechow. The original UDC formula was based on Holstein type data. The Brown Swiss type data shows there is a much higher correlation for Rear Udder Height, Rear Udder Width, and Udder Cleft with Productive Life.  The changes to the formula reflect this shift in emphasis derived from the BS data. These changes will significantly affect the rankings of bulls for Udder Composite.