Selecting Heifers for Replacements
By Ron Gill Ph.D., professor and Texas Cooperative Extension livestock specialist

Keep this philosophy in mind when selecting replacement heifers: Match the cow to the environment and the bull to the market.

Whether heifers are purchased or come from within your operation, it’s critical to select heifers adaptable to the actual production environment. Although cattle raised within a geographic area are normally considered environmentally adapted, this is changing as we increasingly focus selection and genetics solely toward production of “carcass cattle.”

Don’t get the wrong idea. Production of high marbling carcasses is important to long-term prosperity of the cow-calf industry. Heifers produced from such systems, however, aren’t necessarily the most adapted and efficient cows for most of Texas.

Excessive heat, humidity and low-quality forages create need for cows capable of withstanding environmental stress that will hustle a diet of low-quality forage to maintain body condition with minimal supplementation. This is necessary to produce and market a live calf every year at a cost profitable and sustainable over time.

Where to secure heifers is an age old question. For more in-depth discussion, please refer to Buying vs. Raising Replacement Heifers ( E-371), by Jason Cleere, Ph.D. in the general management section at http://animalscience.tamu.edu/main/academics/beef/pubs/.html

Keep own heifers or buy from others?
One of the major factors affecting where you go for replacement heifers depends on the breeding system you’ve chosen. If heifers produced in a system which focuses on carcass marbling or high yield aren’t the best cows for your area, then selecting replacements from another source will be a better option.

Brahman-influenced females are still the most productive cows for most of Texas. They have fallen out of favor, however, with many producers who are focusing on what they perceive to be carcass quality issues. This year’s drought and heat may cause many to rethink the genetic paths they’ve chosen when reproductive and weaning performance are evaluated this year.

Physical traits to consider
Once correct genetic type is determined, frame size and body weight are two important factors to examine within a group of heifers. Frame size can’t be accurately determined without knowing the heifer’s age. Without scales, you are simply guessing at her weight.

Acceptable frame size ranges from frame score 3 to 6. Cattle within this range can easily be managed to meet the carcass weight target for their offspring. (Refer to Matching Breeding Programs with Industry Targets: Use of Frame Score and Weight in Beef Cattle Selection and Texas Adapted Genetic Strategies for Beef Cattle X: Frame Score and Weight at the previously mentioned web site http://animalscience.-tamu.edu/main/academics/beef/pub/genetics/ASWeb021-targets.pdf.)

Body weight is important to know. A determination must be made to see if each individual heifer can reach the minimum target of 65 percent of her projected mature weight prior to breeding and 85 percent prior to calving by using economical grazing or feeding programs. By attaining these targets, you can increase first and second conception rates in heifers and minimize dystocia.

Selecting replacements from the oldest heifers within the group allows selection of heifers from cows bred early in the breeding season, indicating fertility and adaptability from the maternal side. A problem with using just size is, unless actual age of calves is known, you wind up selecting the biggest heifers, not necessarily the oldest.

Selection for “biggest” leads to selection for increased frame size and/or milk production. Selection for one or both traits can lead to decreased production efficiency within a herd over time.

What’s her mother like?
Knowing the dam of the heifer is invaluable. Does she have longevity or other traits deemed desirable?

The most valuable piece of information gained from the dam might be teat size and udder quality. The commercial cow-calf producer often doesn’t place enough emphasis on udder traits when selecting replacements or sires. Udder quality and teat size are highly heritable, and poor udder and teat traits are responsible for increased calf mortality and morbidity due to inadequate colostral intake.

Temperament is always an important consideration when selecting heifers. If they’re goofy as yearlings, they’ll be worse as cows. Don’t keep a heifer thinking she’ll calm down as she gets older.

Fleshing ability is another often overlooked trait. Cattle that are “easy keepers” either have lower maintenance requirements or are more environmentally adapted than other cattle. This may due to more moderate milking ability, frame size, or genetics.
Selecting heifers with fleshing ability isn’t easy. You need to know the dam to select individuals with genetic ability to store more flesh under given environmental conditions.

Structure
Muscling and structural soundness should be given strong consideration. Sound feet and legs are critical to longevity of range cows. Muscling in commercial cows shouldn’t be extreme. Selection of heifers with adequate muscling allows for selection of sires from a wider genetic pool. When you don’t have to compensate for lightly muscled cows through bull selection, you can select sires for more or equally economically important traits.

Other information useful in selecting heifers is measurement of pelvic area and assessment of reproductive tract development. These are culling tools. Either they’re adequate or not. Use pelvic measurement to determine heifers with abnormal shape or dimension to the pelvic opening. Heifers should have adequate reproductive tract development and ovarian activity for their age. These tools need to be used at the proper time to have any real value. Measurements need to be taken from 12-14 months of age.