Consider available resources when developing ‘perfect’ cows

DUBUQUE, Iowa — Resource availability has a significant impact on optimizing genetics that fit into an environment to make a perfect cow.

“A perfect cow for me in Tennessee is likely different from a perfect cow in Iowa and is certainly different from perfect cow in south Texas,” said Troy Rowan, assistant professor and Extension specialist at the University of Tennessee.

“Our environment is important for what makes cows that are going to be long-lived, profitable and productive,” said Rowan during a presentation at the Driftless Region Beef Conference, hosted by the University of Illinois Extension, Iowa State University Extension and Outreach and University of Wisconsin-Madison Extension.

“As you keep back replacement females in a commercial herd, the traits those females are going to express over the course of their lives are very important,” he said. “You need to make sure that goes into the decisions for the bulls that get brought into your herds.”

Cattlemen typically measure the efficiency of their herds by the number of cows, such as the amount of calf weight weaned per cow or the amount of carcass weight that is sold at the end of the year on a per cow basis.

“My argument is the number of cows we have on our operation is not our limiting factor,” Rowan said. “The thing that limits our production is our forage resources.”

The Extension specialist encourages cattlemen to shift from output per cow to output per acre.

“Then we will get a different understanding of what an efficient cow looks like,” Rowan said.

“My definition of efficiency is a function of three things — what we put in the system, what we get out and there is some sort of leakage in the system that I call waste,” he said.

A profitable cow is an efficient cow, Rowan said.

“It’s about what the cow needs to consume from a forage standpoint to express her genetic potential in milk production, to meet the cow’s maintenance requirements and raise a calf,” he said.

The selection tool available to cattlemen is the mature cow weight EPD, or expected progeny difference.

“Our goal should be to find cows that exist at a smaller mature weight, but still have the genetic potential to raise a heavy calf,” Rowan said.

“That’s where crossbreeding becomes really powerful,” he said. “Where we keep maternal crosses a little smaller and then bring in a high growth, heavily muscled terminal sire to get the weights up of the weaned calves.”

It is important to think about cow size as a central objective of a breeding program, Rowan said, but cattlemen can’t think about it solely because it is related to the end product that they market.

“Mature cow size is not a perfect predictor of actual forage intake, but we’ve got to figure out ways to measure real efficiency, which is feed in and product out for our cows in a forage environment,” he said.

“But for now, utilizing mature weight for selection decisions is the best tool we have for making cows a little more moderate in size and paying attention to their output of genetics, as well.”

Rowan’s rule of thumb is a cow should wean off approximately half of her body weight.

“It is a lot easier for a 1,200-pound cow to wean a 600-pound calf than it is for an 1,800-pound cow to wean a 900-pound calf,” he said.

In addition, the stocking density of a pasture can be higher with smaller cows.

“We can sacrifice a little on calf weaning weight and come out ahead in the bigger picture,” Rowan said.

Outputs from the cow is not only the calf.

“There’s genetics she passes onto the calf for growth potential,” Rowan said. “But really the output of the beef cow is milk and the driver of everything we do at the cow-calf level is how the cow turns forage resources into milk.”

Milk is one of those traits that is tricky, the specialist said.

“It is simultaneously the driver from the cow standpoint of the end product and it’s also the most energetically expensive thing that mammals do,” he said.

If a cattleman has limited resources for his herd, a super heavy milking cow will have a resource need that is too high.

“That will impair her ability to reach the genetic potential for milk,” Rowan said. “I try to keep the milk EPD somewhere between the 25th and 75th percentile.”

The waste component is the most abstract and probably the most important from a profit standpoint, the assistant professor said.

“A wasteful cow is a cow that we give resources to and she doesn’t return the full output back to us or she doesn’t return anything back to us,” he said.

“An open cow is the ultimate for inefficiency; she gets 100% of the inputs and she gives us zero outputs, so 100% of the inputs go to waste.”

The goal is a 365-day calving interval and the cow needs to do that over her entire life.

“Developing heifers is not cheap,” Rowan said. “There’s a large upfront cost we’re putting in that animal and expecting she will return to us a live calf for a number of consecutive years with a high amount of performance.”

The issue is cattlemen don’t have a perfect predictor for fertility.

“A heifer pregnancy EPD is reported in a couple of breeds,” Rowan said. “This is a prediction of the likelihood of a bull’s daughter getting bred during her first breeding season.”

He talked about data that looked at the variable costs for females and how old they are when they become profitable.

“Unless a cow reaches 7 years old, she stays in the red and has lost us money when you factor in the development and annual maintenance costs,” he said.

If a cow misses a calf and she is kept in the herd, the number of years increases.

“In most market circumstances that cow does not become profitable until she is 12 or 13 years old,” Rowan said.

Bulls have a tremendous impact on the genetics of a herd.

“A bull is going to sire 100 to 150 calves over the course of his lifetime, if not more, and we’re going to keep replacement females out of that bull,” Rowan said.

“The No. 1 determinant of a bull purchase in Tennessee is cost,” he said. “We have to think about these bulls as long-term investments, because if we get another 20 pounds in weaning weight, that bull pays off the upfront investment really quickly.”

Since efficiency and profitability are linked, the teacher said, cattlemen need to figure out what makes them money.

“All the traits involved with replacement females are much harder for us to visualize because they don’t show up in a bigger check at the end of the year,” Rowan said.

“That’s why as an industry, we’ve lagged in these, but they are just as big contributors to our operations overall profitability,” he said.