Expected Progeny Differences (EPDs)
EPDs are the most powerful tool that is available for making genetic progress. EPDs incorporate the performance of the individual, along with the performance of all its relatives.
Here is a breakdown of EPDs and what you can expect to see in our sale catalogs:
• BW: Birth weight. A lower EPD predicted lower birth weights.
• WW: Weaning weight. Higher weaning EPDs predict higher weaning weights.
• YW: Yearling weight. Higher yearling EPDs indicate greater expected yearling weights.
• Milk: Milk EPD should be used to predict the milking ability of the daughters of the bulls in question (or direct milking potential in the case of heifers). Higher Milk EPDs project more milk.
• TM: Total maternal. Should be used to predict the total weaning weight performance (milk _ weaning weight) of a bull’s daughters. Higher total maternal EPDs predict greater weaning weight from daughters.
• STAY: Stability is primarily a measure of sustained fertility in female offspring.
Why do birth weights vary from year to year?
Typically the Red Angus breed has tried to maintain low to moderate birth weights (60-85 lbs.). We find when we have a really severe winters (as we had in 1996-1997) our birth weights go higher than normal. The theory being in cold weather cows eat more and concentrate the blood supply in the vital organs and the calf gets an increased blood supply thus increasing birth weight. We find that calves with larger birth weights (85-100 lbs.) have better survival (provided there is no calving difficulty) because they have more body mass and can take the adverse weather better. Research substantiate this conclusion. Growth is also highly correlated to birth weight! Most costs can have an 85- to 100-lb. calf with no difficulty.