High Milk EPDS Are Not Always Best for Genetic Improvement

By Bob Long

The development of expected progeny differences (EPDs) is one of the most important advancements in animal breeding technology.  An increasing number of beef cattle breeders, both purebred and commercial, are utilizing EPDs in the selection of breeding stock.  Unfortunately, human nature is such that whenever performance is measured, beef cattle breeders tend to select for extremes rather than efficiency of production.

A typical example is the current fad for higher and higher EPDs for milk.   There is a strong positive correlation between milk production in beef cows and calf weaning weight.  However, factors other than weaning weight also affect efficiency and/or profit.

As in any business, beef producers should not expect “something for nothing.”   Milk production requires additional protein, energy, and other nutrients, which translate into higher feed costs.  Obviously, an increase in weaning weight must be worth more than the cost of the feed required to produce it, if profit is to be realized.

Genetic potential for milk varies widely.  A comparison of cows with low genetic potential for milk with those capable of high milk production helps us understand the advantages and disadvantages of each.

Cows with Low Milk Production

Generally speaking, low milk cows under range conditions are capable of weaning 350 to 400-lb. calves at 200 days of age.  Such cows can produce a spring calf, cycle and rebreed on pasture without supplemental feed.   Also, these cows store enough condition during the summer to go through the winter on dormant pasture or low-quality hay with a minimum of protein supplement and no grain.

A herd with low milk potential requires low inputs of feed, labor and management.   However, productivity per cow is also low, and quite a large herd is required to support a producer and his/her family.  Further, investment in improved pasture and/or increase supplemental feed will not increase productivity, but will result in fat cows with little change in weaning weights.

Cows with High Milk Potential

Cows capable of high milk production mated with growthy bulls can routinely wean 700- and even 800-lb. calves, provided adequate nutrition is available.   Under range conditions, heavy milking cows will milk to near their genetic potential for 4 or 5 weeks by drawing on body stores.  At this point, however, milk production not only falls drastically but these now thin cows may fail to cycle and rebreed.  This leaves producers with only a slight increase in calf weaning weights and a high percentage of open cows.   Cows with genetic potential for high milk production should only be used in operations producing large quantities of high quality and high energy feeds.

Angus Journal, March 1997.