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Winter nutrition for bulls

Heather Smith Thomas for Progressive Cattle Published on 24 September 2019
Bulls staying warm

Bulls supply half the genetics for your calf crop, so you want to make sure they are fertile, healthy and sound and in good body condition through winter.

Young bulls are still growing and need adequate energy and protein to meet their needs for growth as well as maintenance and body condition and body heat on a cold winter day.

According to Dr. John McKinnon, Saskatchewan beef industry chairman with the University of Saskatchewan, a bull’s nutrient requirements during winter depend on his age, body condition after coming off pasture and going into winter, and target weight for the next breeding season.

Yearling bulls should reach puberty at least two to four months before breeding season, and at least 50% of their mature bodyweight (preferably 60% to 65% of mature weight) by then. “This would be 1,200 to 1,300 pounds as a yearling ready to breed cows, if the bull’s mature weight will be 2,000 pounds. Two-year-olds should be 80% to 85% of their mature weight, or about 1,600 to 1,700 pounds if they will mature at 2,000 pounds,” he says.

“Yearlings and 2-year-olds are still growing, and mature bulls that lost condition over breeding season would also have a target weight (ideal for their breed and frame size),” says McKinnon. “Thus the starting point, or condition of bulls coming off pasture in the fall or coming out of breeding season enables you to estimate how much weight that bull might need to gain (or maintain) over winter to meet appropriate target weight for next breeding season. This sets up the management program for winter nutrition.”

Young studs vs. Old Man Winter

This may include putting on lost condition, or additional growth for yearlings and 2-year-olds. During winter, monitor body condition to make sure young bulls continue to grow while staying in good flesh, and monitor older bulls to make sure they are not losing weight. Bulls must carry an adequate amount of fat cover to provide insulation during cold weather and supply energy reserves, but you don’t want bulls too fat or this can interfere with fertility next breeding season.

Overly fat bulls usually have poor semen quality, reduced semen production, reduced conception rates, fewer cows bred (lack of libido) and may fall apart during breeding season – losing too much weight.

For a winter-feeding program, separate younger bulls from the older ones because their nutritional needs are different. You may also need to separate bulls according to body condition and feed them accordingly.

McKinnon says it’s also important to have your feed analyzed to know whether your forages are meeting expectations or if you need to add protein or energy to the diet. You may also need to provide mineral supplementation and perhaps vitamins if forages are deficient. It’s also crucial to increase energy levels during cold weather, and provide enough protein to enable rumen microbes to process and create heat energy from forages.

Jack Holden of Holden Herefords, Valier, Montana, raises registered Herefords in northwestern Montana. “We run our coming 3-year-olds and older bulls together and keep them on good hay and a mineral program. The younger bulls – coming 2-year-olds – are in a different group, and we give them either some protein tubs along with their hay or feed them a little bit of a high-energy pellet. Our young bulls get a few pounds of high-energy feed per day or a 12% protein supplement that contains a little energy.”

“All our bulls have windbreak protection and bedding to help prevent cold stress and scrotal frostbite. In cold weather, they also need more feed just to generate body heat. Some of the bigger, older bulls may eat 50 pounds of hay per day in cold weather. If you shortchange cattle on feed, they’ll lose weight,” says Holden.

After this past winter many producers had bulls with frosted scrotums, according to Buddy Westphal of Valley View Charolais Ranch, Polson, Montana. “A bull stands with his hind end to the wind and his head away from the wind, and this doesn’t give any protection for his testicles. Bulls need adequate bedding and windbreaks,” he explains.

Breeding season prep and recovery

Westphal says some people don’t think about the fact that semen is developed for 60 days prior to when it is mature and ready for breeding a cow. “You are depositing semen in the bank for several weeks before you turn the bull out; if you breed cows early (for January or February calves – breeding in April or May), the bull is still developing that semen in the winter. You need to be taking good care of him then, nutritionally, or you won’t have good semen in the bank,” says Westphal.

“For body condition, I like to have bulls in a score 6 before breeding season. This provides some reserve and they are not too thin or too fat. An overly fat bull has too much fat (insulation) in the scrotum. For viable sperm, temperature of the testicles must be 4 degrees lower than body temperature, or the extra heat will kill sperm,” he says.

“Likewise, if a bull is too thin, he may be in trouble. Nutritionally, bulls need an adequate balanced diet, and adequate exercise. We always feed them where they have to walk a ways between feed and water. We want them to be well-conditioned athletes so their muscles are toned and have them walking a lot so their feet are hard. If they are standing around in mud in a feedlot, they may end up with bad feet.”

“You start preparing for next year’s breeding season the day you pull the bulls from the cows,” says Westphal. “Some need to regain lost weight. It’s common for a bull to lose 200 pounds during breeding season. A yearling bull needs to be gaining back that 200 pounds plus another 400 pounds of growth by next breeding season.”

“He needs to be gaining 600-plus pounds in his 200-plus days of recovery before the next year. This means a gain of 3 pounds per day and he can’t do that eating low-quality grass hay through winter.” He needs a diet with adequate protein, energy and balanced nutrients.

“I figure that a mature bull needs a diet that is 10% to 12% protein and 60% to 70% TDN. Yearling bulls need 14% protein. To have good semen quality, the vitamins and minerals are also important – especially vitamins A and E. In terms of minerals, calcium and phosphorus in feeds can vary from region to region. In our area we are deficient in phosphorus. You need to know the mineral content in your feeds. Some minerals tie up availability of others,” says Westphal.

Toil of the work

“Bulls are crucial to your breeding program – so you don’t want to neglect them,” says Holden. “If they can’t breed as many cows, you’ll have more costs in replacing some bulls – and open cows are very expensive. It’s worth a little extra time and management taking care of bulls so they can get the cows bred the next year.”

If young bulls spent their first breeding season on the range and had to travel a lot, they may have lost weight, especially if they were left out all summer. This is different than breeding cows in a lush green pasture. Some bulls may have been working hard for 90 days or longer; some ranchers don’t pull their bulls out, and they are on dry range pastures into late fall. “They don’t need to be out there that long, traveling and losing weight. They should be brought home and put on good-quality feed,” Holden says.

Good-quality hay may be enough. “You are not trying to fatten them like feedlot cattle; they just need something a little extra to keep them growing and in good shape. If they are efficient cattle they will do this very well on a little extra feed. Just monitor and make sure they are doing well; don’t just turn them out somewhere and forget about them,” he says.  end mark

PHOTO: Whether young or old, your herd sires need a plan and careful observation to make sure they’re nutritionally prepped and recovered for breeding season. Staff photo.

Heather Smith Thomas is a freelance writer based in Idaho.