Suffolk NSIP

Genetic analysis of the 2006 Suffolk lamb crop has now been completed. Results of the analysis have been sent to the breed coordinator for distribution to participating NSIP Suffolk flocks. Genetic trends in Suffolk performance traits are again included in the report.

Suffolk NSIP Data for 2006

For 2006, data were received on 1,068 adult breeding ewes with mating records and 1,735 live lambs from 22 flocks. The lambs were offspring of 97 Suffolk rams. Following editing, valid records were received on 1,270 weaning weights, 771 postweaning gains, and 1,004 litter sizes.

The entire NSIP Suffolk across-flock database now contains records from 83 flocks with 27,411 weaning weights, 12,066 postweaning gains, and 17,601 litter sizes. EPDs were calculated for a total of 42,210 animals, including 11,700 breeding ewes and 2,596 sires.

Means for reported traits are shown below. Weaning weights were adjusted to a single 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 74.0 lb

postweaning gain .87 lb/day

litter size 1.89 lambs

The 2006 Suffolk data were received at the genetic evaluation center on June 22, 2006. The results of the EPD analysis were provided to the breed coordinator on July 19 to give a turnaround time of 27 days.

2006 Suffolk Sire Summary

The 2006 NSIP Suffolk Sire Summary is also now available for distribution to breeders and other interested parties. In order to be eligible for the Sire Summary, a ram must have at least 5 offspring with weaning weight records or at least 10 daughters with lambing records. Prediction errors of 1.9 or less for weaning weight, 3.7 or less for 120-d postweaning weight, or 1.0 or less for maternal milk are also required. This year’s sire summary contained EPDs for 578 rams, an 8% increase over last year. From these, only rams born after January 1, 1999 were listed in the main sire summary, which contained EPDs for 190 rams.

Genetic Trends in the Suffolk 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 Suffolk flocks. Each point represents the average EPD of all animals born in each year since 1986. Consistent and significant increases were observed for 60-day weaning weight and 120-day postweaning weight, with substantial increases for 2006. Maternal milk EPDs likewise continue to increase but by much less than the EPDs for growth traits. EPDs for number of lambs born, in contrast, show only a very slight long-term positive trend. These patterns are consistent with the primary role of the Suffolk as a terminal sire breed used to add growth and leanness in crosses with other breeds. It is not expected or desirable that changes in EPDs be observed for all traits. For example, the mean litter size of adult Suffolk ewes is approximately 1.9 lambs born per ewe lambing. There may be little value in increasing prolificacy beyond this point and the stability in EPDs observed over time for this trait in Figure 1 confirm that most Suffolk breeders see little value in selecting for further increases in prolificacy.