For older bulls, lameness, penile injuries and degeneration in sperm quality are common reasons for BSE failure. Laurin adds that in older bulls seminal vesiculitis leading to prostatitis and pain on electrical stimulation can occur.
“The more common reason older bulls are not satisfactory potential breeders is inadequate percentage of morphologically normal sperm in the ejaculate,” Wolfe explains. “These bulls frequently have chronic lameness from problems such as arthritis, interdigital fibromas, or chronic laminitis with abnormal hoof growth.”
Regardless of age, Laurin says the bull should be an agile athlete. “Ability to maintain condition is a requirement, and it is important for producers to understand the importance of nutrition and the influence that overfeeding while maturing can harm subsequent physical and reproduction performance.”
Disease and biosecurity
Screening for diseases is dependent on the immediate destiny of the bull, says Wolfe. Bulls may be sampled for Johne’s disease, trichomoniasis, camplyobacteriosis or BVDV depending upon sale or shipping requirements or herd goals and biosecurity plans for the owner.
At the edge of the Flint Hills of Kansas, Laurin says the top three diseases she screens for are BVDV, bovine leukosis and anaplasmosis. “We periodically screen for lepto and trich depending upon age of introduction to the herd or herd health status,” she says.
Barclay will commonly collect samples for trichomoniasis PCR in conjunction with a BSE. “Because we have more producers striving toward BVDV-free herds, PI testing is important for all new bulls,” he adds. Bulls should be vaccinated against IBR, BVDV, leptospirosis and campylobacter regardless of their age, says Wolfe, and he typically recommends that bulls be vaccinated the same as the cow herd they will be used in.
Laurin recommends two modified-live virus (MLV) 5-way vaccinations below one year of age, and one MLV 5-way and vibrio/leptospirosis vaccination between 12–18 months of age. She likes to give a 7-way clostridial at least twice by 12 months of age, then yearly for two years, then every two to three years. “We also vaccinate for tetanus in our area, vibrio/lepto before every breeding season, and depending upon herd status, a 5-way every year to every third year.” She suggests that clients give bulls pinkeye vaccination prior to summer breeding season, and a Fusobacterium vaccination at least once to young bulls, or before breeding season in pastures with endemic footrot.