Expected Progeny Differences (EPD’s) are the best selection tool available to beef cow-calf producers for bull selection. The data is derived from performance information collected on the given individual, its ancestors, collateral relatives and progeny. Values given to animals in the form of EPD’s predict the difference between individuals based on statistical analysis utilizing all information that is extremely expansive and inclusive.
Some within the industry have been critical of using EDP’s to select bulls for grass finishing production systems. The argument lies within the fact that the data is derived within a production system that utilizes high concentrate rations during the finishing phase. Additionally, opponents of using EPD’s argue that larger framed, less biologically efficient cows are offered supplements to mask their inefficiencies. There is little evidence to support arguments that biological efficiency changes based on the makeup of the ration.
As with any beef cattle operation, bulls should be selected based on available resources. Producers with minimal labor available during calving season can emphasize calving ease in the selection criteria. Producers that retain ownership and sell finished cattle on a carcass grid basis can place increased importance on various carcass traits. Specialist and educators at Michigan State University Extension recommend that grass finishing producers evaluate their management strategy and available resources to determine the EPD level of performance they will desire. They also need to understand the final product they wish to produce.
Growth is obviously an important trait. Cattle must have adequate growth, but care needs to be taken to select for growth while paying attention to not the select for excessive frame size and mature cow weight. A general rule of thumb is that for cattle to grade choice they will weigh 110 percent of their dam’s weight. Thus, many producers of grass finished beef look to utilize cows that possess mature weights at 1000-1300 pounds. Selecting for too much growth can lead to retaining cows that are heavier than ideal and consequently lead to steers and heifers that will reach finish weights that are higher than desired and also sacrifice quality grade. Observation of many Angus and Red Angus bulls produced to target the grass finished beef market are near breed average for growth traits. Some breeds have EPD’s for mature height and mature weight can be incorporated to help ensure moderate mature weights. Birth weight and carcass weight are two more traits that can be used to keep mature weight in check. Both measures are positively correlated with mature weight. Selection of low birth weight and moderate carcass weight EPD’s will also help keep mature cow weight in check.
Carcass traits are important for bull selection in the grass finished beef business. The final market is critical in determining carcass EPD trait selection. Some markets pay a premium based on the degree of marbling while others pay the same price regardless of quality grade. If marbling is considered in the price paid, it should also be incorporated into selection criteria.
One carcass EPD value uniquely selected by producers of grass finished beef is twelfth rib back fat. Producers of grass finished beef frequently select bulls that are greater than breed average for the amount of back fat. This is not because of premiums on cattle with greater levels of back fat but rather selection for animals with a propensity to deposit fat. Animals in the grass finished beef system consume a ration lower in caloric density, so excessive back fat is almost never a problem.
Producers of grass finished beef have the genetic tools to select bulls that best fit their operation through the use of EPD’s. For more information on selection through the use of EPD’s contact me, Ruminant Extension Educator with Michigan State University at firstname.lastname@example.org or 906-884-4386.