How to strategically select your replacement heifers at weaning
November 4, 2015
Now that calves are weaned and pregnancy checks are occurring, it's time cattle producers begin thinking about selecting replacement heifers to breed in the spring, explained Taylor Grussing, SDSU Extension Cow/Calf Field Specialist.
"Due to the differences in goals and needs between operations, there is no one-size-fits-all selection equation that producers can follow," Grussing said. "However, there are some common characteristics and questions that all producers should consider to help them select replacement heifers strategically and not at random."
Grussing outlines these below.
Select heifers born early in the calving season that will reach puberty and first estrus before their younger herd mates. "These females are then also more likely to become bred and calve earlier in subsequent years, consistently weaning more pounds and being more profitable than later calving counterparts," Grussing said.
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"Replacement heifers should contain the best genetics in your herd," Grussing said.
She said the best way to begin when selecting these high quality genetics is by analyzing the genetics of herd sire and dam.
Scrotal circumference (SC) of the sire is associated with when his daughters reach puberty, as there is a moderate negative correlation between larger SC and earlier attainment of puberty.
On the dam side disposition, calving ease, udder quality and milking ability are important parameters that should be analyzed. "By selecting heifers from cows that are easy to care for and can take care of their calves, you will also select for longevity and see her daughters and granddaughters being retained in consecutive years," Grussing said.
While it is important for some weight be placed on phenotype, Grussing said it should not be where the most focus is placed during heifer selection. "But while we are looking, we want to strive for selecting structurally correct females that can get around the pasture to graze," she said.
Heavy structured and large footed females, with a more correct angle to their shoulder and hock will rise to the top.
Size of the heifer is also important to consider. What will be her mature size and maintenance cost? Does your operation have the resources and environment to support her? "In this case, if the older females being selected are also larger, they may require more input to be maintained in the herd than smaller framed counterparts," Grussing said. "However, small females can be very inefficient also."
Having a good balance between the heifer's phenotype, weight per day of age, as well as the cows mature size is important for profitability and efficiency of the cow herd.
Are you maintaining or expanding the size of your cow herd?
Grussing said, the way a cattle producer answers this question will help them decide how many replacement heifers should be kept. "If the size of the cow herd is to be maintained, the culling rate should equal the replacement rate right? Not necessarily," she said. "No matter if you are maintaining or expanding your herd, it is best to keep 10 – 15 percent more replacement heifers than actually needed, to account for the 5 – 10 percent of females that will be late bred or never become pregnant at all."
This way Grussing said cattle producers will have enough to replace culled females, as well as extras to expand the herd or be marketed. "In addition, if more females become pregnant than you need, you can increase selection pressure on which females have the best genetics to add to the cow herd," she said.
How will I develop them?
Replacement heifers are one of the most important management groups in the herd and it can be a costly investment to develop heifers that won't provide returns for two years.
Therefore, cattle producers need to make sure they have the resources and management to develop them correctly. "This is vital to attaining genetic progress in your herd," Grussing said.
When resources are limited to develop heifers, custom heifer development companies are available to complete the development for a cost.
If producers have the resources but need assistance in designing a heifer development protocol, contact an Extension Livestock Specialist or visit iGrow.org.