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Be leery about buying fat bulls

It may look good in the sale ring, but too much fat can lead to permanent damage

Most of the bulls that go through a sale ring are over-conditioned to some extent. Fat is beautiful because it covers up a lot of conformational faults, but it is also very detrimental for reproduction, good health, and future soundness.

Many young bulls have gone through a bull test/feeding program to measure rate of gain and feed efficiency, and are overly fat. Although most stockmen know that fat is unhealthy for a bull, they still tend to buy the biggest, best-looking animals, and many breeders keep overfeeding them because it’s harder to sell a bull that isn’t carrying extra weight.

Professor John Kastelic, with Cattle Reproductive Health, Department of Production Animal Health at the University of Calgary has done many studies on nutrition in bulls. His research has long focused on beef bulls, and more recently with dairy bulls.

“In beef bulls historically people focused on nutrition after weaning,” he says. “There has been a lot of study on that, going back to the 1970s when Glenn Coulter (a former colleague at the Lethbridge Research Centre) and other people did a lot of the research.

“Back then, purebred operators fed their young bulls practically a feedlot ration, to achieve gains up to four pounds per day to see how fast they gained. There is good evidence to show if you feed bulls high-energy diets after weaning, you get very rapid weight gain but you also create a lot of problems with excessive fat in the scrotum, reduction in semen quality, more risk for laminitis/founder, liver abscesses, rumenitis, and other physical conditions. Feeding young bulls this much is counterproductive.”

Producers are recognizing this and realize that a bull should be fed for a long life of breeding rather than being fed like a steer destined for slaughter. A bull needs to be athletic, not fat.

Damage may be long term

“It is very detrimental to feed bulls high-energy rations post-weaning for rapid gains, resulting in over-conditioned bulls,” says Kastelic. “The thinking used to be that if a bull is not fat he must be a hard keeper and poor doer. Sale bulls were always fat but producers thought they could just take them home and put them on a diet before they put them out with cows and then they would be in breeding shape. Unfortunately, some of the damage in the overfat young bull can be permanent.”

These bulls can end up with liver abscesses, damaged claws and feet, and in some cases permanent reduction in the number of sperm produced and often poor semen quality. “There is no sense or justification in grossly overfeeding bulls in the post-weaning period,” he says.

Even though most purebred operators realize this, many bulls are still fed to be a little too fat. Even though buyers realize a bull should be fit, not fat, they tend to think there is something wrong with a bull that’s not carrying extra weight at sale time. There are still many bulls offered for sale that are too fat, unless they’ve been raised on a growing ration.

“If bulls are fed post-weaning on a mostly forage diet, the bulls with genetic potential for rapid and efficient gain will still gain the fastest although the difference between the top and bottom is smaller,” he says. “You should feed test, but on a forage-based ration with a modest amount of grain you will still be able to identify the top-performing bulls. There is no excuse to push them with a feedlot ration, because you can do permanent damage. It is detrimental, and a waste of feed resources.”

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