The Holstein Association USA will add a new fertility index and a feed efficiency rating to its Total Performance Index (TPI) formula, reported Jonathan Lamb, chairman of the Association's Genetic Advancement Committee, at the breed's 129th annual convention in Dubuque, Iowa. "The new TPI formula will debut in December 2014 to coincide with the December 2014 genetic update and base change where PTAs (predicted transmitting abilities) will be rolled back to a 2010 base," he told breeders.
The new fertility index will be comprised of three major components: 18 percent heifer conception rate (HCR), 18 percent cow conception rate (CCR) and 64 percent daughter pregnancy rate (DPR).
"The good news is we are making progress on fertility," noted Lamb, a New York dairyman. From 1995 to 2000, pregnancy rates in cows slid back -0.27 percent; from 2000 to 2005, fertility held steady at -0.02; and in the latest five-year window there was a +0.21 improvement.
"With the addition of this index and raising the emphasis to 13 percent of the TPI formula, we hope to make even more progress," said Lamb who stated the prior TPI formula weighted fertility at 11 percent. To make room for the extra emphasis, 2 points were taken away from productive life (PL) that will now carry a weight of 7 percent.
The addition of the feed efficiency index involves a formula that calculates the "Dollar value of milk produced." It then subtracts "feed costs of the extra milk" and "extra maintenance costs." To make room for the feed efficiency index, type or PTAT will go from 10 to 8 percent, while selection emphasis for udders will move from 12 to 11 percent. Hence, feed efficiency will make its first entry to the TPI formula at 3 percent.
How will this new TPI formula work on the farm?
Lamb shared some research with convention goers developed by Holstein Association geneticist Tom Lawlor. In studying the new formula, he divided the top half of the breed's cows that averaged 1700 TPI into one group and the bottom half that averaged 1448 TPI into another group. Here's what they found:
- The top half earned $159 more profit per lactation through extra feed efficiency.
- The top half had 9.2 fewer days open.
- The top half were +2.2 points higher for final score; +2.3 on udders and +2.9 feet and legs.
- The new TPI formula will also slow the rate of stature increase.
