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Genetics for the cowherd depend on environmental factors, herd age

by Wyoming Livestock Roundup

“Efficiency for the cowherd is a different beast,” said Matt Spangler, beef genetics specialist for University of Nebraska-Lincoln. “Particularly when producers think about the energy consumed and their true input costs into their cows, efficiency is important.”

Spangler added that a better job could be done to collect the exact cost of efficiency and input costs for cow/calf productions.

Spangler spoke during a webinar for the University of Nebraska-Lincoln on Jan. 14.  

Demands of cows

The goals producers have for their cows can be quite demanding at times by having them be fertile at a relatively young age, developing a short post-partum interval, calve unassisted, have maternal calving ease and be adaptive to any stress on a production environment. 

They also must have an optimal level of milk because not enough or too much milk can be problematic, as well as have optimal docility, good mothering abilities, be an efficient grazer and be able to maintain herself on un-harvested forage. 

“Efficiency of growth in cows is not the target. We are not trying to grow mature cows,” explained Spangler. “Maintenance requirements and efficiency are the target, and we are making them more efficient relative to their maintenance costs.”

High or low maintenance 

Spangler described a study that was done by Gordon Dickenson that partitioned energy intake to the animal and how it goes to the dam’s maintenance, gestation, lactation, progeny maintenance and food deposition of protein and fat. 

“Beef cattle have more life cycle energy intake per kilogram of edible product,” described Spangler. “A big chunk of this is because the dam’s maintenance can make a lot of improvements by simply improving the efficiency of maintenance.” 

High maintenance cows generally have higher milk production and higher visceral organ weight. Due to that high visceral organ weight, high milk-producing cows have increased maintenance requirements even when they are dry. Thus, they require more energy to maintain themselves. 

“The trick is knowing which production environment a high or low maintenance female will fit in,” commented Spangler. 

Production potential 

When feed is low in an environment, a cow with high production potential is unable to consume enough energy for their maintenance requirements and be able to have a fully functional reproductive system. 

Even though the cow may have the genetic potential to milk a lot, without the proper energy to surpass her energy requirements to maintain herself, her reproduction ability will decrease. 

On the opposite side, a cow with low production potential in an environment high in energy will only become fatter. The cow’s maintenance requirements have been met and the excess energy is unable to go towards producing milk or calf growth because the cow did not have the genetic potential to do that in the first place. 

“A cow with high production potential that does have a high genetic potential to milk more and weigh more can put that extra energy into lactation,” explained Spangler. “It’s important to understand the production environment and then fit the animals to that production environment.”

Expected progeny differences

To help figure out an animal’s genetic potential, estimated progeny differences, more commonly known as EPDs, are used. 

“Over the years as producers look at EPDs and select for increased weaning weight or increased yearly weight, we have never stopped to contemplate how much feed those animals are going to eat and will it balance out when we sell them,” commented Spangler. 

Spangler added, “The paradigm needs to shift in terms of thinking about genetic selection from just increasing a response in one trait to increasing profit potential by contemplating several traits at same time.” 

Genetic correlations 

Characteristics Spangler suggests to focus on are growth and how it relates to the animal’s mature size. Additionally, he recommends a focus more on the genetic correlations between mature weight and immature weight of birth weight, weaning weight and yearling weight. 

“If we select for increased weaning weight and yearling weight, there is certainly a potential to have a correlated response in terms of increased mature cow weight,” said Spangler.

He added that producers also need to be cognizant of mature cow size in all breeds and how they have changed through the years as people have selected to increase or decrease the prevalence of a certain trait. 

“Producers should also recognize that selection for all of the traits that are important to a cow/calf operation are not necessarily straight forward because there are so many traits that impact the bottom line,” explained Spangler. 

Madeline Robinson is the assistant editor of the Wyoming Livestock Roundup and can be reached at 

Reverting back to basics

Producers can become confused and frustrated when deciding on which genetic traits to select for and if the prevalence of those traits will be increased or decreased in the herd. They can also become concerned about how those traits are going to contribute to the efficiency of a herd. 

“Anytime the matter of cow efficiency becomes overwhelmingly complex, we should revert back to the basics,” explained Matt Spangler, beef genetics specialist for University of Nebraska-Lincoln. 

An equation Spangler uses to help him revert back to the basics of a cow/calf operation is:

Profit = Weaning Weight x Percentage of Calf Crop x Dollars per Pound x Number of Cows – Annual cost to the cow/calf operation

“This is a very simple profit equation producers can use to help them calculate their profit and annual costs,” reiterated Spangler. 



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