Glenn Selk: How Many Heifers To Keep?

Replacement heifers
Replacement heifers
(UNL)

Matching the number of cattle to your grass and feed resources on the ranch is a constant challenge for any cow-calf producer.  Also, producers strive to maintain cow numbers to match their marketing plans for the long-term changes in the cattle cycle.  Therefore, it is a constant struggle to evaluate the number of replacement heifers that must be developed or purchased to bring into the herd each year. 

As a starting place in the effort to answer this question, it is important to look at the “average” cow herd to understand how many cows are in each age category.  The Dickinson, North Dakota Research and Extension Center reported on the average number of cows in their research herd by age group for a span of 20 years.  The following graph depicts the “average” percent of cows in this herd by age group.

Average Percentage of Cows by Age in North Dakota Research Herd

The graph indicates that the typical herd will, “on the average”, introduce 17% new first calf heifers each year.  Stated another way, if 100 cows are exposed to bulls or AI each year, 17 of them will be having their first baby.  Therefore, this gives us a starting point in choosing how many heifers we need to save each year.

Next, we must predict the percentage of heifers that enter a breeding season that will become pregnant.  The prediction is made primarily upon the nutritional growing program that the heifers receive between weaning and breeding.  If heifers are grown slowly and weigh 50% to 55% of their mature weight at the start of breeding then about half of the heifers will be cycling early in the breeding season. 

In this 100-cow herd scenario, about 30 heifers need to be kept and exposed to AI or the bull to assure the target number of pregnant heifers is met.  This allows for natural selection pressure on early puberty and reproductive soundness if the breeding season is short (30 to 45 days).  More pasture space and breeding costs will be needed because of the larger number of heifers kept. 

Growing the heifers at a higher rate of gain would be necessary to reach 60% to 65% of the mature weight at breeding.  Utilizing a growing program such as wheat pasture (for spring calving heifers) would allow the heifers to gain 1.5 to 2 lbs per day and about 90% or more of the heifers should be cycling early in the breeding season.

Even in the very best scenarios, a few heifers will be difficult or impossible to breed.  Most extension specialists and researchers write about the need to always expose at least 10% more heifers than you need even when they are grown rapidly and all weigh at least 65% of the expected mature weight. Therefore in the example of a 100 cow herd, if the heifers are fed to reach over 60% of the mature weight at breeding, we expect to keep back 19 or 20 heifers to go into the growing program and breeding season.  Fewer heifers are started in this growing program, but higher feed costs per heifer will be necessary to reach the higher rate of gain. 

Like so many decisions in the beef industry, there is more than one answer to important questions.

 

Latest News

Biden Administration Restores Wildlife Protections
Biden Administration Restores Wildlife Protections

The U.S. Fish and Wildlife Service plans to reinstate rules protecting endangered plants and animals, action that would reverse changes made during the Trump Administration that weakened the Endangered Species Act.

Across Breed EPD Adjustment Factors
Across Breed EPD Adjustment Factors

EPDs from multiple breeds can be compared by adding/subtracting the appropriate adjustment factors to the EPDs resulting from the most recent genetic evaluations for each of 18 breeds.

APHIS Now Thinks Wild Birds Are to Blame for Highly Pathogenic Avian Influenza's Arrival on Four U.S. Dairies
APHIS Now Thinks Wild Birds Are to Blame for Highly Pathogenic Avian Influenza's Arrival on Four U.S. Dairies

The livestock industry continues to grapple with the first confirmed cases of HPAI in cattle, while federal and state agencies continue to assure consumers there's no concern about the safety of the U.S. milk supply.

Skills Survey Reveals U.S. Agriculture & Food Industry Workforce Needs and Gaps
Skills Survey Reveals U.S. Agriculture & Food Industry Workforce Needs and Gaps

U.S. employers report challenges in finding suitable job candidates with work-ready skills to fill open roles in ag. The AgCareers.com U.S. Skills Survey offers insights, data and trends to address skill development.

USDA Authorizes CRP Graze and Hay Donations to Wildfire Victims
USDA Authorizes CRP Graze and Hay Donations to Wildfire Victims

Conservation Reserve Program (CRP) participants can donate emergency grazing authority to ranchers in Nebraska, Oklahoma and Texas impacted by recent wildfires.

New Guide Helps Producers Maximize Values of Cull Cows
New Guide Helps Producers Maximize Values of Cull Cows

A new resource developed by the National Cattlemen’s Beef Association and CattleFax helps cattle producers maximize profitability from their culling decisions.