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Heifer Replacement Rate

What is the replacement rate in your beef herd?  I think we all know that a lower replacement rate will be more cost effective than a higher one, as we all know raising or buying replacement heifers is a major cost in maintaining a cow herd.  If you can keep more of your cows in your herd longer, your replacement rate will be lower.  But what is the cost advantage to lowering the replacement rate, and how do we accomplish this? 

Advantage of a 4% lower replacement Rate:

I had the opportunity to listen to Dr. Andy Roberts of the USDA Fort Keogh Research Station give a presentation on some recently published work (J. Anim. Sci. 2015.93:4235–4243) on the economic differences between an 18% replacement rate and a 14% replacement rate.  This was based on data they examined from two different ranches/herds. 

From the graph above, you can see that the average age of the herd with a 14% replacement rate will be older (fewer cows from 2-5 years of age, and more cows from 7-12 years of age). Older cows will generally have heavier calves when you wean them.  Additionally, the weight of the cull cows that you do have, will likely also be heavier, as these cows should be older (on average) when they are culled.  This all translates to more pounds of beef marketed each year.  The Researchers calculated that the total annual production pounds per retained heifer would be 27% greater for the herd with the 14% replacement rate.  On a lifetime basis, the increase in production per heifer calf retained could be 24%.  Pretty substantial numbers.

How do we lower replacement rate?

Lowering the replacement rate of your herd is not something you can just do via a management decision one day.  If you intend to maintain the size of your herd, your replacement rate is essentially dictated to you by how many cows fall out of your herd each year.  But therein lies the answer, how do we keep more cows in the herd longer? 

Generally speaking most cows fall out of the herd because they are open.  And, more cows fail to rebreed at younger ages.  So how can we do a better job of getting younger cows to re-breed? 

One idea put forth, is that perhaps we make it a little too easy for (some of) our heifers to breed as 2-year-olds, if we are feeding them too well during heifer development.  Said another way, if we were to increase the nutritional selection pressure on our retained heifers, perhaps heifers that may fail to re-breed as a 3 or 4-year-old, will not breed as a 2-year-old.  Thus, they will be eliminated from the breeding herd before you spend even more dollars on them.   I think it makes good sense that heifers that can breed the first time on a nutritional plane that is similar to the nutritional plane that they will be expected to survive on as cows in your herd, are more likely to stay in your herd.  There are other reasons that cows maybe culled.  These reasons can be impacted by genetics, but it is more likely the environment.  The better adapted a cow is to your environment the better her chances are of staying in the herd.  It would appear that cows that are more energetically efficient have a better chance of staying in a herd/rebreeding.  

Additionally, data shows that heifers that conceive in the first 21 days of the breeding season are more likely to stay in the herd than heifers that conceive in later cycles.

How soon will I see results?

You cannot move your replacement rate down by 4% in a year or two.  This will take much more time than that.  However, I do believe one can see that there is a great benefit if you continually strive to lower your replacement rate.  You can make progress towards this goal by choosing replacements that may have relatively lower maintenance requirements, and are better adapted to your ranch, thereby much more likely to conceive every year.

Nutritionally, you want to ensure that adequate levels of protein, phosphorus, trace minerals and vitamins are available to your cow herd.  CRYSTALYX® Breed-Up® Supplements are an easy way to provide these in a block that’s available 24/7.  Breed-Up® Supplements contain higher levels of trace minerals and vitamins (200% of NRC) as well as Bioplex® trace minerals which are better absorbed, stored and utilized by the animal than inorganic mineral sources.