Estimated Change in PTA for Production Traits for August 2000

The estimates below are an approximation of what changes will occur in PTA due to updating the base from cows born in 1990 to cows born in 1995.

These numbers were derived from the difference between average PTA of cows born in 1995 and those born in 1990. A positive value indicates the PTA of that trait will decrease by that amount due to the base change. This shows that improvement has been made in the three yield traits as well as in productive life.

TRAIT Ayrshire Brown Swiss Guernsey Holstein Jersey Milking
Shorthorn
Milk 367 539 515 668 549 393
Fat 12 22 20 20 18 13
Protein 11 18 18 21 20 12
Prod. Life 0.5 0.3 0.5 0.5 0.9 0.6
SCS1 0.22 0.14 0.13 0.10 0.03 -0.14
1For SCS, the change includes the phenotypic change as well as the genetic change.

The table above shows that the PTA for SCS will decrease in all breeds except Milking Shorthorn, but this was primarily due to a change in phenotype. The changes in PTA SCS due to genetics were near zero in all breeds and are shown in the following table. Because low scores are desirable in SCS, a negative value for a breed (for example Guernsey) indicates that genetic progress was made toward lowering SCS.

TRAIT Ayrshire Brown Swiss Guernsey Holstein Jersey Milking
Shorthorn
SCS 0.00 0.00 -0.01 0.00 0.04 0.01