March 8, 2012
“Just because she’s a heifer doesn’t mean she’s capable of conceiving.” And that means, says Buddy Faries, Jr., you are money ahead if you identify heifers that likely won’t breed and cull them from the pool of replacement prospects early.
Faries, Texas AgriLife Extension Service state veterinarian, suggests cattlemen conduct a breeding soundness exam (BSE) on replacement heifers 1-3 months prior to breeding, with a minimum age of 10 months. Heifers less than 10 months old likely won’t be reproductively mature, he says.
First, Faries says he eyeballs the heifers, looking at general conformation, body condition, feet and legs, teeth and eyes. On conformation, he zeros in on the legs and feet. While the front legs need to be straight, the hind legs should have some angulation. He also wants to see angulation from the ankle to the tip of the toes to prevent foot problems – 50° in the front and 45° in the rear.
Faries says heifers should be in a body condition score (BCS) 6 prior to breeding, so they have enough energy in the tank to ovulate, develop a fetus, continue growing themselves. and be able to recover and rebreed. At a BCS 6, he says the ribs, as well as the backbone and the hooks and pins, should be well covered. “We want them in a little bit more flesh” than cows, he says, which can be at BCS 5 at breeding.
Beyond that, he looks for a well-balanced, well-developed udder that will produce enough milk – at least 3 gal./day. And, since they’re in the chute for a BSE anyway, he suggests a peek at the teeth, to make sure they’re healthy, followed by the eyes to ensure they’re bright, clear and free of infection.
“Now we’re going into the BSE and I’ve got three areas there –reproductive tract score, pelvic measurements and breeding weights,” he says.
Evaluating the reproductive tract can be done by a veterinarian, or the vet can train you to do it. “Go into the rectum and pick up the two horns of the uterus,” he says. “You can feel the left ovary in the left horn and the right ovary in the right horn. Tone (or firmness) is what you’re feeling for,” he says.
If there’s no tone, if it feels like a wet noodle, there’s no life to it, that’s a score of 1 or 2. “And those go out the gate. If it’s got slight tone, that’s a 3, which is a maybe. You may want to keep a 3 based on other characteristics you see. Four and 5 are good tone. When the vet picks up the horn, it’s alive, it’s got some firmness to it.”
Then the vet will feel for the diameter of the uterus. Ones and 2s will be less than 1 in., he says, while 4s and 5s are 1¼-in. And the vet will estimate the size of the ovaries. On 4s and 5s, the length is more than 1 in., with the height close to 1 in., with some tone and thickness. Ones and 2s are smaller with less tone.
“The point is to get rid of the 1s and 2s,” Faries says. “They will probably never breed because they’re not sexually mature enough.”
Then he takes a pelvic measurement. “You don’t depend on it 100%,” he says, “but you want to get out those that are small – less than 140 sq. cm.” That’s not to say a heifer with a pelvic measurement above 140 won’t have trouble calving. “But at least I’ve reduced the risk. The rule of thumb is if you take that measurement and divide it by two, that gives you a birth weight.” So a heifer with a 140-sq.-cm opening in her pelvis should be able to birth a 70-lb. calf.
It’s important to measure because you can’t tell just by looking. “A lot of heifers are 120 sq. cm., but they look big. And it’s genetic,” he says.
Beyond that, Faries says it’s best to have heifers at 65% of their mature weight at breeding (to help ensure sexual maturity), and 85% of mature weight at calving. He also suggests vaccination and testing for persistently infected (PI) BVD while performing the BSE.
For more information on reproductive management, check out these resources:
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