The Relationship Between Cow Size & Production

The amount of beef produced per cow has seen an 18% improvement over the past 20 years.The average cow size across all breeds is 1,390 lbs., with less than 100 lbs. separating the heaviest and lightest breeds.

December 27, 2011

5 Min Read
The Relationship Between Cow Size & Production

Producing heavy feeders that perform and provide quality carcasses start with cows that are able to produce that type of calf, and still work in the ranching environment, says Ken Olson, South Dakota State University Extension beef specialist.

Addressing the recent Range Beef Cow Symposium in Mitchell, NE, Olson began by talking about feeder cattle. He cited work by Kansas State University’s Justin Waggoner, who is involved in an ongoing feedlot project called ‘Focus on Feedlots.’ The project has amassed 20 years of data from Kansas feedyards varying in size from 10,000-head to 75,000-head capacities.

“There is a steady trend upward over the 20 years for both steers and heifers, and we’re putting on an additional 150-170 lbs. at finishing today. That equates to about 14% larger weights. They do spend about eight more days to get there, but their average daily gains are about 60% faster, and they’re more efficient,” Olson says.

He says this data demonstrates how the industry has maintained steady beef production with a third less cows than in 1974.

“When you put all that information together, and divide the weight of beef slaughtered by the number of cows, we have a very steady trend line over time of increasing the amount of beef produced per cow. There’s about an 18% improvement over that same 20-year period.”

To comprehend how much cow size has increased, Olson provided EPD numbers as one indicator. For the Angus breed, yearling weight, which is considered a reliable indicator of mature weight, has increased 96 lbs. since the early 1970s. In that same time period, Angus steer weights have increased 300 lbs., and heifers are up 239 lbs., on average.

“Another source of information on mature cow size weights comes from actual research data from USDA’s Germplasm Evaluation Program. They conducted a direct, head-to-head comparison of nine sire breeds, all representing the character of those sire breeds when bred to common genetic resource cows and allowed to grow to full genetic maturity, and weighed at five years old as a measure of mature weight,” Olson explains.

The average cow size across all breeds was 1,390 lbs., with less than 100 lbs. separating the heaviest and lightest breeds. Herefords came in heaviest, at 1,419 lbs., followed by Angus at 1,410 lbs., then Red Angus at 1,409 lbs. In the middle were Simmental cows at 1,404 lbs., and the lightest three breeds were Gelbvieh at 1,323 lbs., Limousin at 1,391 lbs. and Charolais at 1,371 lbs.

“It looks upside down when you start putting the breeds with numbers. The British breeds have aggressively chased growth and added a lot of growth potential and size to their breeds. The continental breeds have probably focused on other traits, and while they’ve had growth trending upward, it’s not at nearly as steep a rate,” commented Olson on the findings.

Bigger Cows, More Feed

“So, cows have gotten bigger, and we’ve documented how much bigger, and we want to stay in that 1,200-1,400 lb. range. That’s where management comes into play in terms of a producer deciding where his perfect range is, where he wants to be within that range, and what would provide acceptable carcass sizes,” Olson notes.

Knowing actual cow size is a critical first step in managing cow weight, he continues. While many ranchers don’t have access to a scale, Olson encourages getting a mature cow weight if at all possible. Looking at cull-cow weights, and adjusting that weight based on how those cows compared to a herd’s average, is another way ranchers can get a general idea of how big their cows are.

“Of course, bigger cows need more nutrients. The neat thing is nutrient requirements don’t go up in direct proportion to the size of the cow. They actually go up at a ¾ powers ratio, or 75%, not one to one. So, the maintenance energy required by the 1,400-lb. cow is about 11% higher than that required by the 1,200-lb. cow, despite the fact that she is about 16% heavier,” Olson explains.

But, what about finding the additional feed resources to maintain that bigger cow?

“Annual dry matter intake will be 9,353 lbs., and 10,406 lbs. for the 1,200- and 1,400-lb. cows, respectively. There is that 11%, or 1,053-lb., difference for the larger cow. So, you’re going to have to allocate more resources, if your environment allows that. But, that bigger cow is going to have to do something to pay that bigger feed bill. How much more does she need to produce?”

To determine the answer, Olson divided the 9,350 lbs. of feed consumed by a 1,200-lb. cow by a 500-lb. weaning weight, which resulted in that size cow using 18.7 lbs. of feed to produce 1 lb. of weaned calf. A 1,400-lb. cow will produce a 550-lb. calf at a rate of 18.9 lbs. of feed/1 lb. of calf weaned.

“The conclusion I draw is, as you add 200 lbs. to the cow, you need to add 50 lbs. more weaning weight to the calf just to break even on the additional feed cost you’re going to put in that cow, Olson says, adding that his conclusion is based on the additional feed being the same forage, and not a more expensive supplement.

Producers also need to consider their ranch environment, and what impact larger cows have on stocking rates, he says.

“Simply put, if cows weighed 1,200 lbs. in the past, and they now weigh closer to 1,400 lbs., that’s a 17% increase in size and an 11% increase in forage intake. Therefore, those cows should get a similar increase in pasture allocation (adjusted stocking rate), or pasture productivity needs to have increased in a similar proportion.

“The bottom line is that production systems need to be considered on an integrated approach. As we make adjustments to genetics, we need to consider the ramifications on all other aspects of the operation, including range management, and feed/nutrient supplies, if we want the system to be productive and profitable,” Olson says.

Heather Hamilton is a freelance writer based in Lance Creek, WY.

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