From University of Missouri Extension
MT. VERNON – During the last three years the beef industry has been wrapped up in the expected herd expansion according to Eldon Cole, livestock specialist with University of Missouri Extension.
“I believe as we look at the cattle inventory we see expansion has arrived. During the expansion, there’s a tendency to save every heifer that can walk and see,” said Cole. “Those walk and see heifers may or may not breed on schedule and they may not be something you should spend time and money on.”
Since 1997, the Missouri Show-Me-Select (SMS) Beef Heifer Development Program has focused attention on selecting heifers as yearlings that deserve a chance to be considered as a replacement female.
“As we approach the selection and breeding season, it is a good idea to review research and practical information to improve your chances of saving a heifer that should stay in the herd,” said Cole. “Remember reproduction is not a highly heritable trait. That means a lot of your breeding and reproduction success depends on your nutrition, health and management practices.”
The SMS protocol is the place to start with a pre-breeding vaccination program and veterinary exam. This is required between 30 and 60 days prior to breeding. Included are leptospirosis (5-way) and vibriosis. A booster vaccination against IBR and BVD is to be given at this time.
Follow your veterinarian’s advice whether to use modified live or killed viral vaccines. Modified live virals are recommended for IBR and BVD by SMS.
Options to also be considered with counsel from your veterinarian is whether to calfhood vaccinate for brucellosis, testing for Johnes disease and BVD-PI.
The pre-breeding exam requires a vet to tract score the heifer to assess her readiness to breed. “It can be surprising what the vet can tell you that helps attain a higher first-service conception rate. It’s not uncommon to find pregnant heifers in a group of 14-month olds,” said Cole.
Another surprise that affects conception rates is immature reproductive tract scores. Most are familiar with the free martin condition that results from a heifer calf born twin with a bull calf. About 90 percent of those heifers will not breed according to Cole. The owner will say “she’s a single, there’s no way she can be a freemartin.” But apparently, the male calf or fetus could have been there early in the pregnancy but was lost.
Some vet examinations may reveal unexplained problems. In those cases they usually reject the heifer as a replacement candidate. “Recently, in a SMS herd the vet found a heifer with a “mass” in her repro tract. There was no explanation other than she wasn’t a good prospect and the owner quickly decided to cull her,” said Cole.
The veterinarian will also measure the pelvic area. The SMS goal is for the area to be 150 square centimeters when they’re 13 to 15 months of age. When breeding to calve at 30 months they must be 180 square centimeters.
“Unless a question-mark heifer has a good excuse, it’s best to let her go,” said Cole.
In the SMS program, extension livestock specialists assist in the screening process. They evaluate heifer prospects for body condition, blemishes, muscling, frame size, structure and temperament. At certain seasons they may even appraise their haircoat for early shedding. This is important for heifers grazing toxic fescue.
Expected progeny differences (EPDs) that are enhanced with genomic predictions can be incorporated in the selection process. Thus far reproduction traits do not possess the impact and accuracy several of the other EPD’s do. Some breeds do report a heifer pregnancy EPD that is designed to evaluate the chance of a sire’s daughters becoming pregnant as first-calf heifers.
“As more data is reported greater emphasis may be placed on that trait,” said Cole.
Herd replacements do not need to be the biggest heifers but most cattle producers do prefer saving older heifers that were born at the beginning of the calving season. This indicates their dam herself bred early whether by artificial insemination or natural service.
As for size/weight, a target weight of 65 percent of their expected mature weight has been used. A heifer expected to mature at 1200 pounds should weigh 780 pounds (1200 x .65 – 780 lbs.).
Research does support that a lower percentage down to 55 percent of their mature weight is acceptable if later nutrition allows them to catch up. Also breed makeup is involved.
“Here’s where using an actual scale helps evaluate a heifer’s readiness to be bred along with the vet’s tract score and pelvic measurement,” said Cole.
For more information on using technology to improve virgin heifer conception rates, contact any MU Extension livestock specialists in southwest Missouri: Eldon Cole in Lawrence County, (417) 466-3102; Andy McCorkill in Dallas County at (417) 345-7551; Dr. Randy Wiedmeier, in Howell County at (417) 256-2391 or Douglas County at 417-683-4409; or Dr. Patrick Davis in Cedar County at (417) 276-3313.