In 1978, fresh out of Auburn University, Chuck Madaris bought his first four registered Angus heifers with calves by their sides. He recorded their weights, which ranged from 935 pounds (lb.) to 1,170 lb., in Angus Herd Improvement Records (AHIR^®). Now? A recently worked set of 2-year-olds weighed 1,050-1,400 lb. when he weaned their calves. 

After weighing a group of his mature cows, he says, “The two lightest ones are 1,300 pounds. We’ve had some cows get up to 1,700 pounds. I’d say our average is 1,400 pounds. Our cow sizes have really increased, and that’s with us making a conscious effort to keep it moderate.” 

The increase in cow size isn’t just at CK Cattle, the seedstock operation he runs with his wife, Katie; son, Charlie; and daughter and son-in-law, Kathleen and Bradfield Evans. It’s a nationwide trend.

Cow size has been on the rise for decades. Cows today weigh 1.4 times as much as their predecessors in 1980. In fact, cow weight is rising 100 pounds every 10 years.” — Ron Scott, director of beef technical innovation, Purina Animal Nutrition

But Madaris says it’s not from producers selecting for bigger cows.

“It is due to selection for growth,” he explains. “When you select for weaning weight, yearling weight, growth, it’s just going to be there. EPDs [expected progeny differences] work.”

Obviously, bigger mama cows equal heavier babies and more pounds to sell at weaning. That’s what your bull customers want, so it is a good thing, right? 

It can be, but Scott warns of unintended consequences. Bigger cows may not be as efficient as their smaller ancestors, and their calves may not be enough bigger to pay for the extra groceries. 

Scott quotes a North Dakota State University study, “It shows a 1,000-pound cow weans 48.5% of her body weight, compared to 43.6 % for a 1,400-pound cow. Essentially, calves born from larger cows aren’t as efficient as calves born from smaller cows.”

However, even though those bigger cows do need more energy, protein, vitamins and minerals than smaller cows, it isn’t quite as much as you may think. 

Ethan Blom, beef technical specialist, also with Purina, says, “The one advantage big cows do have is as they get bigger, they don’t need quite as high a proportion of energy and protein to catch up compared to their smaller counterparts. The easy math on that is a 1,500-pound cow is 50% larger than a 1,000-pound cow, but the amount of energy she requires just for maintaining her body weight is only about 36% greater than that 1,000-pound animal. So, she can be a bit more efficient with energy compared to a smaller cow.” 

For Madaris, it’s hard to measure exactly how much his cows’ supplement needs have gone up with their increased size. Currently, around 75% of the 700-cow herd gets corn silage and whole cottonseed from around mid-December through the first of March. The rest of the herd gets free-choice hay. 

While he says the amount of supplement per cow probably has increased, he keeps the length of time he feeds about the same.

Along with the increase in supplemental feed, Scott says a decreased stocking rate is often needed to meet the demands of larger cows.

Unfortunately, many producers don’t weigh their cows, so they don’t realize just how much their average cow size has gone up. The result is thin cows and/or overgrazed pastures.

Madaris says his stocking rate, which he estimates is around a cow and calf per three or four acres, hasn’t changed but it is hard to measure precisely since he also grazes replacement heifers and sale bulls, which he sells at either 18 months or as 2-year-olds.

“We work hard at growing grass,” he says. The warm-season base is Bermuda grass, crabgrass and Dallis grass. During cooler months, ryegrass, which he manages as a perennial, along with fescue, fuels the cow herd. Madaris has tried to plant earlier-maturing rye and oats for his cows to graze to cut down on the amount of supplemental feed needed in the winter, but says the prairie-type land turns into a boggy mess. He’s found it works better to feed for 60 or 70 days. 

He says, “They are on pasture while we feed, but the grass is just holding the ground together.”

How big is too big? 

Is there a sweet spot between cow size, efficiency and increased input costs? 

“It really depends on the situation and the environment,” Blom says. “A big cow in North Dakota might be different than a big cow in New Mexico. The environment is a lot different. The available feed resources might be a lot different. It’s about matching up our environment and feed resources and trying to match that up with a cow size we can run most efficiently.”

Madaris agrees. 

“We don’t use an EPD for mature weight. We probably look more at fertility and fleshing ability as selection tools. We want our cows to breed back from year to year.” 

Although it fluctuates, he says his preg rates tend to average from 85-90% on a 70-day breeding season that includes both artificial insemination (AI) and natural service. 

“Fertility and longevity are the two most important traits in a cow herd in terms of profitability,” Madaris explains. “Longevity, cows that stay in a herd and a cow that can have a calf year in and year out — those are going to be your bigger profit drivers in a commercial cow herd.We’re trying to use enough of our bulls to keep our cattle somewhat relative to our environment. EPDs have a difficult time adjusting from the southeastern environment to the Northern Plains environment. It’s two different environments.” 

He’s also careful to keep a balance of traits in his selection process. 

“We don’t have very many people who are buying bulls that are worried about carcass traits, so we don’t put as much emphasis on them. Birth weight, weaning weight, yearling weight are still the base ones. We do look at mature height, hair shedding score and disposition and pay attention to feet structure.” 

Milk usually doesn’t make his list of selection criteria; he says there is already plenty of milking ability in the herd. 

He also says, “We’re looking at an animal that’s not necessarily in the top 10 percentile, but something that’s better than average. I look more at herd averages, where they fit in with our herd.” 

Even keeping mature cow size in mind, and his customers’ demand for calving ease, he still says the growth traits, weaning and yearling weight, get top billing. 

“If you don’t, you’re going to get left behind.”