National Sheep Improvement Program
is a computerized, performance-based program for genetic selection. NSIP is designed to help purebred sheep producers identify the best genetic stock for their breeding programs.
An Expected Progeny Difference (EPD) is an estimate of the genetic merit of an animal for a single trait. Specifically, the EPD of an animal is the expected difference between the performance of that animal's progeny and the average progeny performance of all the animals in the breed, for that trait.
MM - Maternal Milk
Maternal Milk EPD is a gain measurement from birth to weaning based on milk.
Milk and Growth is not an EPD. (1/2 of WW plus MM = M&G)
Number Born EPD is the number of lambs increase/decrease
from 3.7 you can expect from 100 ewes lambing.
Polypay's current lambing average of 221%.
WW - Weaning Weight
Weaning Weight EPD is a growth measurement from birth to 60-day weight.
PWW - Post Weaning Weight
Post Weaning Weight EPD is a growth measurement from 60-day weight to 120-day weight
Composite Index
Composite Index is the comparison of an individual's EPDs to the breed average
The breed average EPD in each trait is given a value of 20 points resulting in a composite index of 100%. Applying this formula to an individual's EPDs gives the composite index for that animal. The Polypay NSIP Breeders agreed upon this formual for comparing sheep to the average rather than the extreme, it is not an NSIP formula.