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Winter nutrition for bulls

When feeding bulls, the main thing is to assess your goals for those animals, says Dr. Bart Lardner

The bull supplies half the genetics for a calf crop so producers will want to make sure bulls are fertile, healthy and sound, and in good body condition through winter. Young bulls are still growing, so they need adequate energy and protein to support growth as well as maintenance and body condition, and body heat on a cold day. Winter feed requirements vary depending on whether the bulls are weanlings, yearlings or mature bulls. Seedstock producers may feed bulls a little differently than ranchers do, depending on their target market for selling bulls.

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Dr. Bart Lardner, research scientist in the department of animal and poultry science at University of Saskatchewan, says many ranchers are prudent in how they feed and manage bulls and less apt to overfeed them.

“The main thing is to assess your goals for bulls. They have two functions — to impregnate cows and heifers, and to pass on certain genetics to their progeny. You want to make sure they are fertile and sound, with adequate libido,” he says.

According to Dr. John McKinnon, consulting nutritionist and professor emeritus at the University of Saskatchewan, a bull’s nutrient requirements during winter will 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, and should have reached at least 50 per cent of their mature body weight, although 60 to 65 per cent of mature weight is preferable.

“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-old bulls should be 80 to 85 per cent of mature weight, or about 1,600 to 1,700 pounds if they will mature at 2,000 pounds.”

Yearlings and two-year-olds are still growing. Mature bulls that lost condition during breeding season would also have a target weight that’s ideal for their breed and frame size.

“The starting point or condition of bulls coming off pasture in the fall or finishing the breeding season enables you to estimate how much weight that bull might need to gain or maintain over winter to meet target weight for next spring/summer’s breeding season. This sets up the management program for winter nutrition,” says McKinnon.

This may mean putting on lost condition or more growth for yearlings and two-year-olds. Body condition should be monitored to make sure young bulls keep growing while staying in good flesh. Older bulls should be monitored to make sure they don’t lose weight. They need enough fat cover to provide insulation during cold weather and supply energy reserves, but too much fat can interfere with fertility next breeding season.

Body condition score of three to 3.5 on a five-point scale (one being emaciated and five being obese) is usually best, according to McKinnon. Over-fat bulls usually have poor semen quality, reduced semen production, reduced conception rates and fewer cows bred due to lack of libido. They also may lose too much weight and fall apart during breeding season.

“Proper levels of energy, protein, minerals and vitamins are key,” says Lardner. Energy sources include carbohydrates from forages, such as hay, green feed and concentrates like cereal grains.

Protein sources include good alfalfa hay and supplements like soybean meal, canola meal and dried distillers’ grain, he adds. Producers also need to pay attention to necessary minerals, calcium-phosphorus ratio, and the trace minerals.

“Copper, zinc and manganese are the important trace minerals for fertility,” Lardner says.

Lardner says that he likes to see 13 to 14 per cent protein and about 60 to 65 per cent energy (total digestible nutrients) in a winter diet for a weanling bull.

“And as young bulls reach puberty we want to reduce that to about 10 or 11 per cent protein and about 58 per cent energy. Thus it is important to test your feeds to assess nutrient levels. Don’t just guess,” he says.

Young bulls need adequate nutrition for growth and development.

“You only have about 160 days from weaning until yearling, and today we are seeing more yearling bulls offered for sale because seedstock producers don’t want to feed them for two years. It’s harder now to find two-year-old bulls for sale,” says Lardner.

“During that 160 days of development, producers should make sure those growing bulls have adequate protein and energy on a forage-based diet, with maybe five to six pounds of supplement per day,” he says. Lardner adds that bulls often lose as much as 200 pounds during breeding season.

“A bull with high libido will be out doing his job, chasing after cows,” he says. This means they need some reserve fat as a buffer going into the breeding season.

“You want bulls to have body condition of about 3.5, which equates to about 20 per cent body fat. This is a good reserve for bulls,” he says. Pay attention to diet over winter to make sure they achieve this, and make sure they have adequate water. If they are not drinking enough they will not be eating enough.

“End of June is the start of breeding season for most herds here, so we assess bull condition coming out of winter to make sure they have that extra bit of condition and adequate weight by breeding time. We build the winter diet to meet those target points,” Lardner says.

When managing bulls it helps to keep younger ones together as a group, separate from older bulls. This enables the younger ones to gain confidence and not be so beat up or intimidated by older bulls. You can help the younger bulls a lot by managing them separately.

“Also make sure that wherever bulls are wintered they have adequate shelter and bedding, to prevent scrotal frostbite,” Lardner says. Adequate windbreaks can help reduce cold stress and reduce the need for so much extra feed to generate body heat.

Over the years we’ve learned about detrimental effects of too much fat, and how it can create soundness problems and hinder fertility.

“You don’t want to overfeed bulls, but you do want to meet their requirements for energy and protein — and this will vary depending on whether they are weanlings, yearlings or six-year-olds,” he says.

“High-quality, grass-legume forage or green feed will usually do the job. In drought years it is more difficult to find good forage, so each producer must figure out what can work best in a given situation. It pays to start early, to allow thin bulls to put weight back on gradually,” says Lardner.

The goal is to have the bull back in proper body condition before cold weather.

Analyze feeds

Producers may also need to provide mineral supplementation and perhaps vitamins if forages are deficient. It’s crucial to increase energy levels during cold weather, and especially important to provide enough protein to enable rumen microbes to process and create heat energy from forages.

“This year some regions of southern Sask­atchewan, Alberta and British Columbia were very dry and many forages are short on protein. Producers were putting up anything they could, and quality may have been low,” says McKinnon. Feeding those lower-quality forages this winter may create a greater need for protein supplementation.

“After coming through a dry summer, many of these bulls may have lost weight and may have a lot of body condition to put back on, as well. The drought here was spotty, but there are many areas that had a very dry summer,” he says.

Producers need to assess their own situation and their bulls, and make a feeding plan for the winter. Winter nutrition starts in the fall. Bulls are an expensive investment and it’s best to take good care of them so they will last a long time.

Forage-grown bulls

This can be a good compromise between selling yearlings (which often means overfeeding young bulls) and having to wait and sell two-year-olds. It also works nicely if a producer wants to calve in late spring or early summer, or fall calve, rather than having to calve in January or February in order to have yearling bulls old enough to sell in an early spring sale.

“That extra six months of age is a benefit when purchasing a young bull. This enables the bull to grow more and be more mature and ready to breed,” says Lardner.

Traditionally bulls have been confined during winter and fed grain as well as hay, but some producers are wintering their bulls in bigger pastures and letting them grow or maintain under more natural conditions, which often leads to better health, better fertility and longevity.

Grant Lastiwka is a livestock and forage business specialist with Alberta Agriculture and Forestry. He says it’s important to get purchased bulls acclimated as soon as possible to environments they will be working in. This is better than an abrupt change from confinement and concentrate feeds to big pastures and forage, as some young bulls encounter at their first breeding season.

One concern with bulls out in big pastures or bale grazing is windchill and cold temperatures that may result in scrotal frostbite unless the bulls have shelter and bedding.

“There are more options today for portable windbreaks, and more people are leaving bulls out to graze during winter. Bale grazing with bulls can be a challenge, however, because they like to push the bales around,” says Lastiwka.

Electric fencing can partially alleviate this problem. Another trick is to graze bales closer to an uphill fenceline rather than a downhill fence. That way the bulls are less likely to push a bale through the fence.

Some ranchers prefer to buy bulls as weaned calves in the fall and grow them out in their own environment, transitioning them into their management system, rather than buying an over-fat yearling or two-year-old at a sale. Fat sells bulls because it makes a bull look better — people look at the hindquarters but that aspect of conformation can be fed on rather than bred on. As one astute cattleman once said, there is no such thing as a bull without much hindquarter — if he were fatter he would look great.

“Part of developing young bulls is to feed and develop them as working bulls rather than feedlot animals. Yet people often buy bulls that are completely unaccustomed to the systems they have to work in,” says Lastiwka. This makes it harder for the bull to hold up and be functional for many years.

“When I buy a new bull I want to give him time to adapt to my system, with a body condition that has a bit to spare, but developed in a way that he can go out and do the job for many years. This means having bulls that are not over-fat,” says Lastiwka.

Younger bulls need to be managed for growth and proper condition, says Lastiwka. But older bulls that just need maintenance rations can easily become too fat and heavy over winter, especially if they are good-doing, efficient cattle that do well on forage alone.

“They need to be out exercising rather than confined, and we can provide windbreaks and bedding. If they are bale grazing they have material to lie on. We run our bulls out with the cows during winter, and they stay fit and not so fat,” says Lastiwka.

This is a good way to manage bulls, if the cows are all pregnant and there are no young heifers in the group. Bulls get the exercise they need and have adequate feed, eating the same feed as the pregnant cows. There is usually very little fighting among those bulls because there is no breeding and the pecking order has already been sorted out.

There are several options for bulls that simply need a maintenance ration, including stockpiled forages, swath grazing and bale grazing. Such bulls can do very well in the winter in big pastures, says Lastiwka.

“The Nerbas brothers in Manitoba raise forage-based Angus cattle and keep their bulls out on big pasture rather than in corrals, getting exercise and growing up strong and functional,” he says.

Some seedstock producers raise bulls in in similar conditions to their customers’ herds. This means being out in larger pastures where they get exercise.

“Winter nutrition should be geared toward making sure they are prepared for the job, but not overdoing it. Bulls that are grazed, rotationally moved and managed like the cow herd are also more comfortable with people and handling and easier to handle,” says Lastiwka. He thinks bulls that are busy harvesting their own feed are less apt to fight.

“What you feed will depend on the condition they come in,” says Lastiwka. “Some younger bulls may start winter in poor condition because they’ve been breeding cows all fall, and maybe shedding their teeth (which happens at about two years of age when baby teeth are shed, and permanent teeth are coming in) and not eating as well as they should.”

It costs a lot to purchase and maintain a bull when you include costs such as feed, semen testing and vaccinations.

“If bulls are managed out on pasture, like the cows, feed costs are not much greater than feeding a cow, however. They are part of the cow herd for the winter and simply add more units to that group. In my mind, this increases longevity in the bulls,” says Lastiwka.

It also eliminates the expense of having a bull-proof well-fenced facility to hold bulls during winter.

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