$PROFIT INDEXES ˱ WHAT ARE API AND TI? $ Ind Though EPDs allow for the comparison of genetic levels for many economically important traits, they only provide a piece of the economic puzzle. That’s where $ Indexes come in. Through well conceived, rigorous mathematical computation, $ Indexes blend EPDs and economics to estimate an animal’s overall impact on your bottom line. The same technology that led to the dramatic progress in swine, poultry and dairy genetics over the last several decades was used to develop the following $ Indexes: All-Purpose Index (API): Evaluates sires for use on the entire cow herd (bred to both Angus rst-calf heifers and mature cows) with the portion of their daughters required to maintain herd size retained and the remaining heifers and steers put on feed and sold grade and yield. Terminal Index (TI): Evaluates sire for use on mature Angus cows with all o spring put on feed and sold grade and yield. U ng API n TI First, determine which index to use; if you’re keeping replacements, use API...if not, then use TI. Just as with EPDs, zero in on the unit di erence between bulls (as described above, index units are in dollars per cow exposed). The di erence can be used to determine how much a bull is worth compared to another. Or, put another way, how much you can pay for one bull compared to another. For example, when buying an all-purpose-type sire, you can quickly gure a bull scoring +100 for API is worth an extra $6,000 over a +50 bull if both are exposed to 30 cows over 4 years ($50 di . x 30 hd. x 4 yr. = $6,000). A percentile-ranking chart is required to determine where a bull’s index value ranks him relative to other bulls in the breed.
For percentile rankings or more detailed information about EPDs and $ Indexes visit www.simmental.org.
Expected Progeny Di erence (EPD) — The di erence in expected performance of future progeny of an individual, compared with expected performance of future prog- eny of an individual of average genetic merit in the base time frame for the genetic evaluation. EPDs are estimated from phenotypic merit of an individual and all of its relatives and are estimates of one-half the breeding values. EPDs are generally reported in units of measurement for the trait. UNDERSTANDING EPDs
Average Daily Gain (ADG) — Measurement of daily body weight change over a speci ed period of time of an animal on a feed test. Back Fat Thickness (BF) — Estimates the average di erences that are expected in fat thickness at the 12th and 13th rib between progeny of di erent animals. Birth Weight (BW) — The weight of a calf taken within 24 hours after birth (re- ported in pounds). The EPD value predicts the di erence in average birth weight of a bull’s progeny compared to progeny of all other bulls evaluated. A positive value indicates heavier-than-average birth weights while a negative value indi- cates lighter-than-average birth weights. Calving Ease (CE) — The ease with which a bull’s calves are born to rst calf heif- ers. When comparing calving ease EPDs of two sires, the larger EPD indicates a higher percent of unassisted births for calves sired by this bull. Carcass Weight (CW) — The EPD predicts the di erence in average carcass weight of a bull’s progeny compared to progeny of all other bulls evaluated. A positive number indicates heavier-than-aveage carcass weights while a negative value indicates lower-than-average carcass weights. Frame Score (FRAME) — A score based on subjective evaluation of height or actual measurement of hip height. Maternal Calving Ease (MCE) — Percent of unassisted births in rst calving daughters. Marbling Score (MARB) — A subjective evaluation of the amount and distribu- tion of intramuscular fat. The EPD value predicts the di erence in average mar- bling score of a bull’s progeny compared to progeny of all other evaluated bulls. A positive value indicates higher-than-average marbling scores while a negative value indicates lower-than-average marbling scores. Maternal Weaning Weight (MWW) — The weaning weight of a bull’s daugh- ters’ calves. The EPD value predicts the di erence in average 205-day weight of a bull’s daughters’ calves compared to daughters of all other bulls evaluated. A positive value indicates heavier-than-average weaning weights while a negative value indicates lighter-than-average weaning weights.
Milk (MILK) — The milking ability of a bull’s daughter. The EPD value predicts the di erence (due to milking ability) in average 205-day weight of a bull’s daugh- ters’ calves compared to calves of all other bulls evaluated. Positive values indi- cate above average milking ability of daughters while negative values indicate below average milking ability. Most Probable Producing Ability (MPPA) — An estimate of a cow’s future pro- ductivity for a trait (such as progeny weaning weight ratio) based on her past productivity. For example, a cow’s MPPA for weaning ratio is calculated from the cow’s average progeny weaning ratio, the number of her progeny with weaning record, and the repeatability of weaning weight. Ribeye Area (REA) — The average di erence in ribeye area in an animal’s prog- eny when compared to the progeny of another animal at a given age endpoint. Scrotal Circumference (SCROTAL) — A measure of testes size obtained by mea- suring the distance around the testicles in the scrotum with a circular tape. Stayability (STAY) — The expected di erence, in percentage probability, that a bull’s daughters will remain in the herd until at least six years of age. Weaning Weight (WW) — Calf weight taken between 160 and 250 days of age and adjusted to 205 days of age and a mature dam equivalent (reported in pounds). The EPD value predicts the di erence in average 205-day weight of a bull’s progeny compared to progeny of all other bulls evaluated. A positive value indicates heavier-than-average weaning weights while a negative value indi- cates lighter-than-average weaning weights. Yield Grade (YG) — Predicts di erences in USDA Yield Grade score. This EPD is calculated using the genetic predictions of CW, REA, and BF EPDs. Yearling Weight (YW) — Weight taken between 330 and 440 days of age and adjusted to 365 days of age and a mature dam equivalent (reported in pounds). The EPD value predicts the di erence in average 365-day weight of a bull’s prog- eny compared to progeny of all other bull’s evaluated. A positive value indicates heavier-than-average yearling weights while a negative value indicates light- er-than-average yearling weights.
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