Polypay
NSIP Notebook
December 19, 2005 Number 8
The Fall, 2005 Polypay National Genetic Evaluation
David Notter, Bindu Vanimisetti, and Larry Kuehn
Department of Animal and Poultry Sciences
Virginia Tech
Introduction
The fall 2005 Polypay genetic analysis is now complete and results are available for distribution. Genetic trends for Polypay production traits are again presented, and remain strongly positive.
The Data
Data were received on 449
breeding ewes and 670 live lambs from 11 flocks, including one newly enrolled flock. The lambs represented offspring of 44 Polypay rams. Following editing, valid records were received for 372 weaning weights, 278 postweaning gains, and 344 litter sizes.The entire NSIP Polypay across-flock database now contains records from 38 flocks with 17,181 weaning weights, 10,863
postweaning gains, and 15,185 litter sizes. EPDs were calculated for a total of 30,699 animals, including 7,496 breeding ewes and 870 sires.Means for reported traits are shown below. Weaning weights were adjusted to a weaning age of 60 days and to a twin birth and rearing, adult dam, and ewe lamb basis. Litter sizes were adjusted to an adult-ewe basis.
Trait Mean
60-day adjusted weaning weight—twin lamb basis 47.0 lb
postweaning gain .63 lb/day
litter size 2.21 lambs
The current performance records were received at the genetic evaluation center on Oct 26, 2005. The results of the EPD analysis were provided to the breed coordinator on November 29 to give a turnaround time of 34 days.
EPD Reports
Results of the genetic analysis were provided in a single spreadsheet containing animal identification and EPDs for all animals in each flock. Animals in the spreadsheet were listed in the following order:
The listing contains all breeding animals listed on the preprinted data entry spreadsheet, any breeding animals that were added to inventory, and all surviving lambs from the current lamb crop. Animals that were culled or died were identified; EPDs will be provided for these animals, but they will not appear on next year's spreadsheet.
The 2005 Polypay Sire Summary
The 2005 NSIP Polypay Sire Summary is now also available for distribution to breeders and other interested parties. In order to be eligible for the Sire Summary, a ram must have at least five progeny with weaning weight records or at least 10 daughters with litter size records. Rams listed in the Sire Summary must also have a prediction error of not more than 0.95 pounds for weaning weight, 2.5 pounds for 120-d postweaning weight, or 0.95 pounds for maternal milk. Only sires born after July 1, 1997 were listed. The current sire summary contains EPDs for 126 rams, 6% increase over last year.
Genetic Trends in the Polypay Breed
Patterns of change in EPDs since establishment of NSIP in 1986 are shown in Figure 1. These results document the traits that have received emphasis in participating Polypay flocks. Each point represents the average EPD of all animals born in each year since 1986. Since 1990, consistent and significant changes have been observed for 60-day weaning weight, maternal milk, and 120-day postweaning weight EPDs. EPDs for number of lambs born changed less rapidly over this period, but have had a consistent positive trend since 1997. As discussed before in this Notebook series, these values could be increased further by more intense selection, but represent gradual and consistent changes in the breed that are appropriate to its role as a general purpose maternal breed.
Figure 1. Genetic Trends in NSIP Polypay Flocks
