Bulls Need Proper Nutrition, Protection From Cold During Winter


Regardless of age, bulls should have access to a strong mineral program, according to McCarthy.

Mineral and vitamins help bulls grow and also help their performance during the breeding season.

Selenium is critical for normal spermatogenesis (sperm production) while zinc is critical for sperm-cell plasma membrane integrity, tail morphology (structure), and motility (movement). Iodine is a mineral that is shown to help alleviate foot rot, she said.


McCarthy said cold weather can have negative effects on the fertility of bulls. Cold weather and wind chill can result in bull infertility with tissue damage to the scrotum.

DTN has written about this subject in the past. (https://www.dtnpf.com/…)

This tissue damage can cause blisters and scabs from the cold weather. Frostbite appears as discoloration, a scab or sloughing of the lower scrotal portion, she said.

Frostbite lowers semen quality in bulls, according to studies. The soundness score of semen quality of bulls with frostbite can drop significantly, she said.

McCarthy said bulls can recover from frostbite (spermatogenesis), but this process takes 61 days. Bulls should be protected from the elements with access to shelter or windbreak and they should have plenty of room available to them to get out of the cold. Bedding should also be provided to allow them to maintain body heat that can be lost from laying on frozen ground, she said.

UTILIZE a Breeding Soundness Exam

McCarthy recommends cow/calf producers use breeding soundness exams with their bulls. Research has shown that 57% of producers who purchase bulls have an exam, but only 17% of cow/calf operations had a breeding soundness exam done on bulls that were already in their operation, she said.

A breeding soundness exam is a uniform method of assessing a bull’s likelihood of establishing pregnancy in an appropriate number of open, healthy and cycling cows and heifers in a defined breeding season, she said.

There are four components of the exam: a general physical exam, a scrotal circumference measurement, sperm motility and sperm morphology.

“It is recommended to do a breeding soundness exam four to six weeks prior to turn out for breeding,” McCarthy said.

Bulls that don’t pass can be retested if they had sustained some injury, for instance frostbite damage. Getting retested can show recovery from some injury, she said.

Conducting the test weeks ahead of breeding season gives producers enough time to purchase replacement bulls if animals don’t pass. In addition to a breeding soundness exam, cow/calf producers should also complete other evaluations on their bulls before the next breeding season, McCarthy said.

These evaluations should include vaccinations, control of lice and flies and checking bulls’ feet and legs.

The UNL BeefWatch Webinar Series is free and will begin at 8:00 p.m. CT on Tuesday, Dec. 15, and Jan. 5, 12, 19 and 26.

The series can be found at: https://beef.unl.edu/…

Russ Quinn can be reached at russ.quinn@dtn.com

Follow him on Twitter @RussQuinnDTN


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