By Dean Kreager
As we move into January the grazing season is over for most and ended long ago for many, such as me, thanks to a dry fall. Now is the time to start putting some thought into breeding decisions. Is this the year to purchase a new bull? What semen do I need to order so it will be in my tank when the cows come in heat?
In cattle, EPDs are the expected progeny differences in performance between offspring of different sires. Sheep have a similar system of EBVs (estimated breeding values) but they are not as commonly used. EPDs are available for a large number of production, maternal, and carcass traits. The use of EPDs gained value with the first national cattle summary which was published in 1971. The value of this data has improved with time. Breeds have improved data collection and DNA evaluations have become common so that now the value of EPD’s is greater than ever. These DNA enhanced EPDs can provide results equivalent to 10 to 36 calves for many traits but sometimes all these numbers get confusing.
Since this is a grazing column, let’s look at a few of the EPDs that are related to grazing management:
Milk can be very important depending on your grazing situation. This number represents the increased weaning weight due to higher milk production. If high quality pasture is what you have then a high milk EPD can bring you extra money with higher weaning weights. On the other hand, if your pastures are making use of the land that isn’t fit for other purposes and does not always have the best forage then a lower milk EPD may be a better fit. A high milk producing cow will be using her nutrient intake to produce milk at the expense of her body condition. This will increase the difficulty in getting her to rebreed and likely result in later calving next year. Milk is the highest in predictability of the EPDs. A genetic enhanced milk EPD can be equal to 36 calves.
Weaning Weight (WW) and Yearling Weight (YW) are good indicators of growth potential. We want cattle to grow quickly but we also must be aware of the size the calves will be when they reach a choice grade. A rule of thumb is that a calf will be 110% of the weight of its dam when it reaches a choice grade. A steer from a 1300-pound cow will be about 1430 pounds when it reaches choice grade. If you are placing calves in a traditional feedlot system these high weights might be fine while producers that are trying to raise a grass-fed product may struggle with getting calves to this point. One might also want to consider the Mature Weight (MW)and Mature Height (MH) EPDs. Large numbers for these indicate larger framed cattle which typically require more forage and may be very challenging to use in a grass-fed system.
Fat or Back Fat is an EPD where we often like to see a low value. This typically reflects waste; however, in a grass-fed system this could indicate cattle that tend to fatten more easily. Since over fattening in a grass-fed system is not a problem, a high number for this trait could be good for some producers.
RADG (Residual Average Daily Gain) is the increase in post weaning daily gain when comparing calves from different sires given the same amount of feed. In other words, higher RADG values would indicate sires that produced calves that convert feed more efficiently – easy keepers. We don’t have a breakdown of this based on forage compared to grain based diets but the current thought is this advantage is likely present for both forage based and grain based diets. This is a trait that is receiving more research in cattle in recent years and could have big impacts on economics. Many breeds do not currently have EPDs for this trait.
Maintenance Energy (ME) is used by the Red Angus Association as an indication of additional forage needed per month by daughters of one sire compared to another. The larger the number the more forage the animal will need.
While you contemplate purchases of semen or bulls for 2020 don’t overlook the value of EPDs in making your selections. This is certainly not a comprehensive list of traits to consider but these are some examples of traits that may have different levels of importance based on your management practices and grazing conditions. Different breeds have slightly different versions of EPDs and there are charts available to compare several EPDs between breeds. Your local Extension Educator can help with questions you may have.
Source : osu.edu