When more isn’t better: Matching cow genetics to forage

Over the last 30 years, genetic selection tools have dramatically changed most major beef breeds. With a few exceptions, the trend has been clear — more milk, heavier calves at weaning, and larger mature cows. Expected Progeny Differences, or EPDs, have played a major role in driving that progress.

But it raises an important question for cowcalf producers: while we’ve clearly achieved “more,” have we actually achieved “better”? As the late Colorado State researcher Dr. Bob Taylor used to say, “Profitable cattle are usually productive, but productive cattle are not always profitable.”

When we look at commercial cow-calf benchmark data from across the Plains, average weaning weights — and the percentage of calves weaned per cow exposed — have changed very little over the past 15 years. That’s surprising, given how much genetic potential has increased. So why hasn’t that shown up in the real world?

One explanation is that the genetic potential of today’s cattle often exceeds the forage resources available to support them. Frequently, the added cost of maintaining larger, higher-milking cows outweighs the value of the small increases in calf weaning weight they produce. In other words, those cows never fully express their genetic potential because forage is the limiting factor.

This idea isn’t new. As far back as 1988, geneticist and cattle breeder Dr. Rick Bourdon wrote that genetic selection should aim for an optimum — not a maximum — based on what a given environment can support. When you’re selecting for optimum, success often shows up as stability, not constant increases.

That same “cows for resources” concept shows up clearly in more recent research on forage efficiency. About three-quarters of the feed required to produce a pound of beef comes from forage, yet most feed efficiency data comes from grain-based diets. Research from Oklahoma State University shows there is tremendous variation in how heifers consume and convert forage when fed medium-quality hay — and, importantly, feed efficiency rankings on grain diets do not predict efficiency on forage diets.

Some heifers eat a lot and gain very little. Others eat moderate amounts and gain efficiently. And cattle that look efficient on high-energy diets are not necessarily efficient when forage is the primary feed source.

So what does this mean for cow-calf producers, especially those selecting replacement heifers? First, it reinforces the importance of matching genetics to resources. Selecting bulls with higher feed intake will almost certainly result in daughters that eat more, which can reduce stocking rates over time or risk overgrazing. Second, replacement heifer development itself can be a powerful screening tool. Developing heifers on medium-quality forage or hay for 60 to 90 days after weaning can help identify females that fit your forage base.

The bottom line is this: profitable cow herds are built by identifying the genetic optimum for a given operation and selecting cattle that fit available forage resources. In many cases, that may mean selecting for moderate milk, moderate mature size, and cattle that efficiently convert forage into beef — because forage, not genetics, is usually the limiting factor.

-Ben Beckman is a beef systems Extension Educator serving northeast Nebraska. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-682ioremail: [email protected] mailto:[email protected]