Mature Weight and Cow Energy Requirement EPD Released in Research Format

Expected progeny differences (EPD) for mature weight (MW) and cow energy requirement (CER) have been released by the American Simmental Association (ASA) in a research release format. Mature weight and energy requirements have a direct economic impact through cow salvage value and annual feed costs. These EPD provide breeders with tools to better assess cow productivity and efficiency.

The MW and CER EPD were developed by International Genetic Solutions (IGS). IGS and ASA are committed to the development of genetic tools that aid breeders in making selection decisions on economically and commercially relevant traits. 

MW EPD:

The MW EPD is expressed as the difference in pounds of cow body weight at six years of age and a body condition score (BCS) of 5. A higher MW EPD indicates a genetic tendency for heavier daughters at maturity, while a lower MW EPD indicates a genetic tendency for lighter daughters at maturity. For example:

Bull A = 100 MW EPD

Bull B = 50 MW EPD

You would expect daughters from Bull B to weigh 50 pounds less, on average, at age six and BCS 5 compared to daughters from Bull A. 

Mature cow weights can be collected at any age after yearling. Entire cow groups should be weighed on the same day and within 45 days of weaning their calf. Members are encouraged to take a BCS at the same time as mature weight collection. Entire cow groups should be scored on the same day, and by the same person, for contemporary grouping.  

Members can submit weights and BCS for cows of any age between two and 12. Records on the same cow across multiple years are also accepted.

CER EPD:

The CER EPD is expressed as the yearly difference in pounds of total digestible nutrients (TDN) required for a cow aged six years. A lower CER EPD indicates a genetic tendency for daughters that require less energy to support production, while a higher CER EPD indicates a genetic tendency for daughters that have higher energy demands. For example:

Bull A= 100 CER EPD

Bull B= 50 CER EPD

You would expect daughters from Bull B to require 50 pounds of TDN less per year at age six, on average, compared to daughters from Bull A. 

Birth weight, milk, and mature weight EPD are utilized in prediction equations to estimate cow energy requirements representing the primary cow energy expenditures: gestation, lactation, and maintenance. 

To view the research release of MW and CER EPD on high-use sires and high-accuracy MW and CER EPD animals, click here. As research EPD, these traits will not yet be evaluated weekly or published on an animal page on Herdbook.org.

As part of their development, these EPD have undergone an extensive validation process. Membership is encouraged to review the research release predictions for MW and CER. Members that have feedback on this evaluation or any questions should contact Dr. Elizabeth Dressler, ASA Geneticist, at edressler@simmgene.com.