A breeding soundness exam should be conducted annually on a bull, regardless of its past rate of successful breeding, an LSU AgCenter veterinarian advised at the sixth annual beef cattle and forage field day at the LSU AgCenter Dean Lee Research Station in October.

Dr. Christine Navarre said the $50 to $80 exam is well worth the expense, and the testing should be done early enough to allow time to find a replacement if a bull fails the test.

The exam involves more than a semen evaluation, she said. A complete physical exam by a veterinarian will determine if a bull is capable of successfully breeding a herd. Scrotal circumference is a key indicator of a bull’s potential, with a recommended measurement of 40 to 45 centimeters.

Bulls with low fertility are likely to pass that trait to offspring, including females, Navarre said.

Dr. Chris Thompson, a veterinarian in Pineville, La., said bulls should not be fed cotton byproducts, which could affect sperm production.

Both veterinarians urged cattle owners to obtain trichomoniasis tests on all new bulls. Cows can recover from the venereal disease, but bulls cannot, Thompson said.

Parasites

The fight against parasites is becoming more difficult because of the limited options of dewormers. Some cattle are dying of diseases from the pests. “I haven’t seen that in 30 years,” Navarre said.

A veterinarian’s assistance with fecal sampling is needed to determine which dewormer to use and to determine if the product has been effective, she said.

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Controlling parasites was once easy, and now many cattle herds lack natural resistance. Cattle owners will have no options if the current dewormers become ineffective because of resistance.

“There are no products in the pipeline that we know of,” Navarre said. “We’ve got to maintain what we have.”

Weaning calves is essential to enable cows to get back in shape and ready to breed again, said Jeff Gurie, livestock manager and research associate at the Dean Lee Research Station.

Calves should be vaccinated before weaning, Gurie said, and they should be dehorned and castrated as early as possible.

One option is to move calves away from their mothers, completely separated. An alternative is to keep calves with their mothers but use nose flaps on the calves to prevent nursing. A more preferred option is “fence line” weaning that uses a fence to separate calves and cows, Gurie said.

Studies have shown that fence line weaning is most effective and results in less stress and weight loss for calves, Gurie said.

Smutgrass control

Velpar is the best option for selective smutgrass control, said AgCenter weed specialist Ron Strahan. But he recommended checking the weather before an application. “We’ve got to get rain when we put it out,” he said.

Broomsedge thrives in soil with low fertility, and it can’t be killed selectively without killing the desired forage, he said.

Sendero works well on honey locust, and Chinese tallow trees can be killed with a mixture of three parts diesel and one part Remedy sprayed as a basal treatment, Strahan said.