“Make sure young bulls have had an initial series of vaccinations as recommended by the vaccine manufacturer,” adds Barclay.
Most veterinarians recommend deworming the bulls on the same schedule as the cows. “Bulls need to be able to maintain condition, and thus should be maintained on the same deworming schedule as cows,” notes Barclay. Wolfe adds that for much of the Southeast the optimal timing of deworming is early to mid-summer to minimize pasture contamination.
Both internal and external parasite control are important to optimize breeding performance, states Barclay. “Heavy parasite loads can diminish the overall health of the bull and therefore decrease breeding performance.”
Don’t forget about bull body condition through the breeding season. Barclay likes to see a body condition score (BCS) of 5-6 in bulls prior to the breeding season. Poor body condition (either too fat or too thin) will have a negative effect on sperm quality. “In our area, if pasture conditions are adequate, then mineral supplementation is all that’s needed,” Barclay says. “However, in dry conditions or if breeding for fall calving, protein supplementation becomes very important.”
Many bulls tend to lose one body condition score while breeding which may impair their breeding efficiency later in the season. Young bulls usually require more attention to maintain body condition than mature bulls. “Bulls that are excessively fat at the onset of breeding season may have decreased sperm quality compared to bulls in more moderate condition,” Wolfe explains. “Additionally, over-conditioned bulls may lack the athleticism and stamina of bulls that are more fit. On the other side of the coin, bulls that are excessively thin may also have decreased semen quality, libido, and athleticism.”
Laurin looks for a BCS of 4.5-5 at the time of the BSE and, at least 5 at the time of bull let out. “Some producers are better than others at checking BCS toward the end of breeding season,” she says. “A drop in BCS by end of the season can indicate too much activity in the pasture — from either inability to settle cows, to plenty of bull power where cows are settled early in season, or bulls left in too long and not having anything else to do but fight. Bulls should never be fed to be fat, especially in the down season.”
Laurin has seen a few cases of bulls raised with poor nutrition, especially too little protein, and then fail a BSE for lack of a good enough sperm morphology. “The higher the number of cows per individual bull, the more importance placed on providing enough nutrients for ample sperm production.”