Evaluate & Strategize - Bull Body Condition Maintenance

Originally Published in Gulf Coast Cattleman

There’s no one-size fits all formula when it comes to maintaining body condition in bulls. Finding the formula that works for your operation is going to require some investigation and strategy. Your investigation needs to start well before you’re ready to turn bulls out on females. You’ll need to consider bull age, current body condition, and breeding season. Then, you’ll need to know what nutrients you have to work with through forage and water testing. Cargill ruminant nutritionist and technical service specialist, Justin Ramirez, said to start by breaking your bulls into groups based on age.

“So often producers tend to lump all their bulls together, no matter their age, and they wonder why their younger bulls aren’t maintaining their weight or have more open cows,” Ramirez said. “We need to look at our bulls who are less than two years of age separately from our mature bulls. They have more requirements since they’re still growing. An animal’s body is going to think of itself first, and then use nutrients for reproduction second. On a mature bull you want to keep him at a body condition score five to six. On a young bull you’ll want to keep him closer to a BCS six. A mature bull is going to maintain his condition easier than a young bull who is still growing.”

Brett Richard, a producer and cattle specialist with Cargill Animal Nutrition, said grouping his bulls by age makes pulling bulls to rest them easier.

“When you have them grouped by age, each group is going to maintain the same kind of condition,” Richard said. “You won’t have to go pull one bull out of a pasture. Since younger bulls are more likely to lose condition, I can pull them all off at the same time and clean up with a different set of bulls. You can let them drop from a six to a four. Then pull them out and let another set finish the job while the first set puts some condition back on. I evaluate body condition on my bulls just as often as I can put eyes on them. I know as cattle producers we always want to be optimistic, our cattle are never skinny, but I try to be as honest with myself as I can. When they start falling off, it’s time to rest them.”

Ramirez recommends preconditioning bulls at least 90 days before breeding season as spermatogenesis takes an average of 61 days for sperm development. He said young bulls should be turned out at a BCS six and mature bulls can be turned out at a BCS five if pressed for time. Research suggests bulls in a BCS five to six have the best semen quality. Semen quality then begins to decline outside of those two target conditions.

“Preconditioning 90 days before breeding season is especially important for younger bulls as they need time to develop healthy sperm,” Ramirez said. “No matter their age, I recommend providing organic trace minerals as research shows a positive impact on spermatogenesis. It’s better for their longevity to start making supplement adjustments and to get them in the preferred body condition at least 90 days before breeding season.”

Ramirez explained a 1600-pound bull would need to gain approximately 100 pounds to go up one BCS. That’s a little more than one pound of gain per day if you’re starting the process 90 days before turn out, but if you’re only starting 60 days before turn out that’s closer to two pounds of gain per day.

“The longer you wait to precondition them, the harder you’re going to have to push them and that’s when economics start to play a role,” Ramirez said. “Plus, if you’re having to push them that hard, their rumens are going to be set up for more of a grain-based diet rather than a forage-based diet. That’s an unfavorable situation for turning bulls out on pasture. If you push him hard, then immediately turn him out for breeding season and his available nutrients/energy change, he’s not going to hold condition. If we can start preconditioning 90 days in advance, we’re giving them a better opportunity to develop healthier sperm and we’ll see fewer open females. The last 30 days of preconditioning, I would start transitioning them to the type of diet they’ll be on once they’re out on females. Especially on young bulls, if you precondition them on a grain diet then turn them out on pasture, their rumen has been set up for grain and they will go downhill quickly. You also don’t want to get them to an excessive weight at a BCS seven because that will make it harder for them to mount females and they will run out of energy sooner.”

Beyond differentiating between different age groups, you’ll also want to approach maintenance differently based on the time of year. In fall breeding bulls, forage quality will likely be lower requiring more supplementation.

“Supplementation needs depend on forage quality so I recommend doing a forage analysis,” Ramirez said. “This will allow you to base your supplementation on what your forage is lacking. You can then be strategic in how you want to supplement energy. Using arbitrary numbers for example, let’s say a 1500-pound bull needs 16 pounds of total digestible nutrients to gain half a pound daily and 20.5 pounds TDN to gain 1.73 pounds per day. If my forage has 55 percent TDN, voluntary feed intake is going to be roughly two percent. That two percent is 30 pounds of forage multiplied by 55 percent TDN which would come out to 16.5 pounds of TDN. So that bull is already getting the energy he needs based on that forage quality to provide energy for half a pound of average daily gain, but falls short of 1.73 ADG. In this situation, this bull would probably only need 1.5 to two pounds of protein for their growth. You would use that same 30 pounds multiplied by the forage protein, in this case 7.5 percent protein which comes out to 2.25 pounds. So now you know you only need to supplement mineral unless you’re looking for more energy for gain.”

Richard recommends running a forage analysis on every batch of hay to build an accurate representation of your forage nutrient content.

“If you aren’t going to test every batch then at least take a good broad sample,” Richard said. “Try taking four to five samples across several batches of hay. We’re also seeing an increased need for water testing as good water sources are tougher to find.”

Richard said when he turns bulls out, he typically supplements to the average condition of the cows and makes sure he can rest bulls when they need to recoup condition.

“You can run 25 to 30 cows to a bull, but I try to only run 20 cows to one bull,” Richard said. “If I need to rest a bull, I have other bulls to put on those cows. Typically, pulling bulls off cows will start making a difference in their condition. Then if we have some green forage or rye grass available, I’ll put them on that for a little while until they’re where I want them. If I have bunks available, I’ll supplement with some feed. I don’t recommend bulk feeding because a bull is going to eat more feed than he needs. If you do put them on bulk, you need to put a limiter in the ration, but it’s still pretty hard to limit them down to what they actually need. If at all possible, hand feeding is the best option. Hand feeding allows you to feed just what they need and it’s going to keep them gentle.”

In spring breeding bulls you’ll need to consider forage availability and how much green vegetation you have as grass tetany can become a problem without proper supplementation.

“That’s where we need to be a little more mindful of lush green grass bringing up a lot of potassium,” Ramirez said. “That can cause grass tetany which is a toxicity. To avoid grass tetany, we need to start providing a mineral supplement with higher magnesium levels at least 30 days before they are on green grass. From there it will again depend on our forage quality.”

If you’ve had past issues with infertility, weight loss, or sickness, Ramirez recommends testing your water.

“Water is the number one nutrient cattle require above all else,” Ramirez said. “We need to know what the water is providing. Is it contributing a lot of iron or sulfur? Those are two antagonists that will tie up other nutrients like copper. If you do have high levels of iron or sulfur your animals are not going to be able to absorb copper like they normally would and that’s going to impact a number of things.”

No matter the season, your primary goal should be to understand your available nutrients based on your forage resources. You have to know what you’re already providing to know what they still need. You can then strategize your supplementation to meet those specific requirements and maintain appropriate condition.

“Whatever nutrient you don’t have is the one that’s the problem,” Richard said. “That’s why forage testing and water testing is so important. I cover a lot of country and I see a different situation on every place. You have to know your operation’s specific needs and supplement to those needs.”