Determining Replacement Rates for Your Herd

Author: Kristy

How many replacement heifers should you keep and how many cows should you cull?
By: Brandi Karisch, Extension Beef Cattle Specialist, Mississippi State University

Fall brings with it (hopefully) cooler temperatures and decision making time for many beef
producers. Fall brings with it a time to evaluate the cow herd, and each cow’s productivity and a
time to mark those cows to replace and those replacement heifers to include in the keeping pen.
The decision of what to keep and what to cull has been made even more complicated with the
current cattle market. Record high prices make producers think long and hard before selling a
cow when even a poor calf that she might raise could bring in good profits. Still it is important to
have a plan to evaluate the replacement rate for your herd, which may vary from year to year.

For spring herds, weaning is a good time to evaluate your cow herd for pregnancy status, mouth
scores, and productivity. While pregnancy status is often the number one factor in determining if
a cow needs to be replaced, it is also important to keep close tabs on those cows who may be the
biggest, fattest cows in your herd, but wean the lightest scrawniest calf year in and year out. For
fall calving herds, calving season is a good time to evaluate udders, body condition, and
disposition. No one particularly enjoys dealing with disposition issues or having to nurse a calf
because a cow’s teats are too large during calving season, but those memories may fade quickly
when weaning time rolls around.

One factor that greatly influences herd productivity is cow age. Typically as a cow advances in
age past her prime, that cow’s productivity will be eventually diminished. This can lead to
decreased profits if a cow is retained too long. A recent poll from BEEF magazine asked “What
is the average age of the beef cows in your herd?”. As I write this article, the poll is ongoing, but
shows that the majority of producers have an average age of 6-8 years old, followed by those
with herds age 3-5 years old, and the fewest with an average age of 9 years in the herd.

Culling rates and replacement rates are greatly influenced by a producer’s choice to expand or
contract herd size, the decision to keep herd size the same. In recent years the nation’s cowherd
as well as Mississippi’s has been declining, with the nation’s cow herd at a 60 year low in terms
of cattle numbers. Typically culling rate for most herds is approximately 10-15%, with a
replacement rate of 10-20%. This replacement rate is a direct result of a producer’s decision on
whether or not to expand the herd. This becomes an even tougher decision with current prices
making the waters even muddier. For example, the Summary of Mississippi Cattle Auctions for
the week of September 5, shows 500 lb heifers selling at an average of $1,062.50 per head, and
cull cows selling for close to $1,500 per head. The recent Southern Producers Replacement
Heifer Sale saw record bred heifer prices at an average of $2,774/head.

The replacement heifer is the foundation of a productive cow herd, and her selection and
development can greatly impact the economics of an operation through genetics, futureperformance, and longevity. It has been shown consistently that a cow has paid for herself by 6
years of age, so the longer she stays in the herd the more profitable she becomes for the
producer. Therefore it is so important that replacement heifers are selected and developed with
longevity in mind. It is important to first select heifers that offer this opportunity, and then to
properly develop and manage them throughout their lifetime to ensure that they will be
productive cows for many years. Too often the largest group of open cows culled from a herd are
first calf heifers that did not rebreed for their second calf. Proper management and nutrition can
go a long way toward ensuring reproductive success.

The decision to purchase vs. raise replacement heifers can have a big impact on replacement
rates, particularly in current times with record high prices and a shortage of females available.
Several factors that impact this decision include economics, available resources, experience,
genetic improvement, and convenience. The financial concerns of developing replacement
heifers are related to diverting cash flow and resources. If immediate revenue is required to
maintain normal production capacity, consider selling weaned heifers and purchasing bred
replacements later. Also consider purchasing replacements if higher returns can be generated by
an alternative use for the proceeds from market cow and feeder calf sales. Farm or ranch
resources also direct this decision. If forage or feed supplies are already maximized or
overextended by the mature cow herd, purchasing replacement heifers would be an obvious

Opportunity costs are often overlooked when making management decisions. The convenience
of having someone else raise replacements is a valid consideration, especially when the cattle
operation is not the primary source of income, or operator time or labor time is limiting. Custom
heifer development centers have become a support-business of the cow-calf sector. Consigning
heifers to a custom developer is the best way to retain herd genetics while not diverting money
and resources from the cow herd to raise heifers. More information on heifer development can be

A pivotal decision in determining replacement and culling rates is the operation’s goals for the
future. Do you plan to keep herd numbers steady? Do you plan to grow your herd? Do you plan
to downsize? All of these are questions that must be asked, and will impact your culling and
replacement rates. Economics also play a big role in this decision. Record cattle markets have led
many producers to rush to take advantage of the feeder market prices, by choosing to sell their
entire calf crop at weaning or shortly afterward and not retaining any females for replacements.
Regardless of the final number chosen for culling and replacement rates, the most important
point is that this number is based on your goals. Having a plan in place is vital.

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