No Advantage To Late Cattle Castration; Is Chemical Castration An Option?

The notion of better gains on calves as bulls because of testosterone is a fallacy, as studies indicate a calf must be about 40 weeks of age before he gets a boost from testosterone.

July 28, 2014

8 Min Read
No Advantage To Late Cattle Castration; Is Chemical Castration An Option?

It’s always better for the calf buyer if the calves are steers rather than young bulls. Daryl Meyer, a practicing DVM in North Platte, NE, reminds stockmen they need to remember that the next owner is a customer. “You want the customer to be happy with what you’re selling.”

Mark Hilton, a Purdue University DVM, says people who buy bull calves, even at a discounted price, aren’t getting a good deal. “They’re making less money than if they had bought steers, and good research backs this up. There are setbacks in growth – and health risks – if calves are castrated late. The health is better, carcass quality is better, welfare of the calf is better, and profit for the feedlot is better, with early castration,” he says.

He adds that the notion of better gains on calves as bulls because of testosterone is a fallacy. “Studies show that a calf must be about 40 weeks of age before he gets a boost from testosterone, and that’s 10 months! It’s not enough reason to leave them as bulls, and it’s not fair to that animal to castrate that late,” he says.

There is no excuse for waiting, unless you intended for them to be bulls and then decide to make steers of the bottom end of the group. “There should be more incentive to producers to do it early. Bull calves are not discounted enough at market,” Hilton says.

“But we can’t just look at dollars. If you are selling a 500-lb. calf, instead of looking at money you lost because he’s a bull rather than a steer, you should consider the calf and realize that you did wrong for that calf – and the buyer who has to take the risk.”

 Meanwhile, the buyer is making a mistake, too, thinking the 500-lb. calf is a bargain because it’s discounted $5/cwt. “Bull calves should be discounted at least $10/cwt.,” Hilton says.

Of course, discounts between bulls and steers vary by region, but there’s always a discount. “By the time he is 500 lbs., a bull calf will be about 30 lbs. heavier than if he’d been castrated and not implanted as a baby,” Meyer says. “It would be logical to assume that if you castrate and implant the calf when he’s young, he’ll be the same size as a non-castrated calf, and worth more per pound. Plus, he’s undergone a lot less stress, and with a little implant in the ear, he’ll weigh just as much as the intact male at 500 lbs.”

Castration at this stage of growth, no matter the method, will set big calves back for a while in growth. “Even though you buy them at a discount, you’re losing days of weight gain,” Meyer says. Plus, it’s more stressful on the calf the later that castration is performed, and more potential of bleeding and infections.

Castrating calves late always entails more risk, Hilton adds. He had a client last year who got into a problem because of weather. “He was planting corn when he ordinarily would be working calves, and then harvest was late. This affected his weaning date, and he didn’t get calves castrated or vaccinated before weaning.

“In November, when he put the calves through the chute for their first vaccination, he castrated them at that time – at 500-600 lbs. He put them back on pasture with their mothers, on poor fall pasture. He weighed the calves at initial vaccination/castration, and again two weeks later when he gave final vaccinations and weaned them. The average calf had gained nothing during that period,” Hilton says.

In addition, about 35% of those calves came down with bovine respiratory disease (BRD) after weaning. “The vaccines didn’t work because the calves’ immune systems were compromised by inadequate nutrition, stress of castration, weaning, etc. It takes protein and energy for the body to heal, so castration was one more challenge.”

He says that had those calves been castrated earlier in life, they wouldn’t have undergone the additional stress at weaning and might not have had as much problem with BRD. “This was an example of the compounding effects we see time and again with disease problems. Many small negatives lead to a big problem,” he says.

Hormonal castration

There’s renewed interest today in hormonal castration as a way of eliminating some of the potential issues with pain, infection, etc. It’s not a new concept. Hilton recalls one such product being available in the U.S. several decades ago. “I was in private practice when Chem-Cast® came out, about 30 years ago,” says Hilton. "We used it in some herds and it worked, but it never caught on across the industry,” he says.

David Rethorst, a DVM and director of outreach for Kansas State University’s (KSU) Beef Cattle Institute, says the injections didn’t provide consistent results. “It didn’t work as well as people had hoped, and that product was taken off the market,” he says.

Jerry Reeves, who retired from Washington State University as emeritus professor in 2008, says there’s currently a vaccine being used in Brazil for pigs, and a cattle product recently debuted in the same market. He says the vaccine alters the cascade of events in hormone production necessary for reproduction.

Under normal conditions, the hypothalamus in the brain produces GnRH (gonadotropin-releasing hormone), which acts on the pituitary to release LH (leutenizing hormone) and FSH (follicle-stimulating hormone). These act on the testes to produce testosterone and create spermatogenesis, and on the ovary to produce estrogen and create follicular development. The hormonal vaccine alters this sequence by blocking GnRH, and is effective on all mammalian species, and in both sexes.

“Before I retired from WSU, one of my graduate students, Jennifer Hernandez, did a study with me in Brazil in 2003. We vaccinated one group of bulls, castrated another group, and left a third group intact. The vaccine was 95% effective in the vaccinated group,” Reeves reports.

Rethorst hopes to conduct trials with the vaccine, but gaining clearance for use in the U.S. may be a hurdle. “I think we can do it, but part of our concern is consumer acceptance and human safety. When Europeans started using a similar product, they encountered consumer opposition,” he says.

“The vaccine is a monoclonal antibody against natural hormones. It is a manmade antibody, and people in Europe didn’t want meat from an animal that had been injected with this antibody. Due to consumer resistance, the vaccine currently isn’t being used very much over there,” he explains.

“The main concern we’ve had is safety and handling issues. This vaccine works in all mammals. There is risk of accidental injection, or risk of it falling into the wrong hands and someone intentionally injecting another human. We need a product like this, but the challenge is to figure out how to come up with one that is specific for cattle and more foolproof,” Rethorst adds.

“Here at KSU we hope to do a project but that plan is on hold as we try to decide how to approach it,” he says.

Another problem with vaccines is none are 100% reliable. There are always some animals that, for whatever reason, don’t mount an adequate immune response. “A problem with using a sterilization vaccine is that you want it to be 100% sure, and it won’t be. Some animals just don’t have the immune system to make it work,” Reeves explains.

“The vaccine is beneficial to ranchers in Brazil because they raise bulls on grass until they are three years old and then slaughter them. They’d like to castrate at two years, after getting the benefit of growth from testosterone – since they can’t use growth implants. Then – after using immunocastration – by three years of age the meat would be more like that of a steer. They don’t want to cut or band two-year-old bulls. Not only is there more risk for bleeding, infection and complications when castrating mature bulls, but in Brazil there are also screwworms,” he says. The vaccine would be a solution to that problem.

“The concept is appealing, and with pressure on the U.S. livestock industry from animal welfare and human groups to use analgesia for pain management, there may be more interest in this vaccine. It’s easier to use a pocket knife, but if someday we have to use anesthetic to castrate calves surgically, it becomes more complicated and expensive. The drawback to immunization is that it takes two shots – a primary vaccination and a booster. Some people may not be able to run the animals through twice,” Reeves adds.

“Brazilians can’t use growth implants and are interested in the vaccine – for both males and females. They can’t use MGA in feed, or hormones. They have to raise beef naturally and are starting to feed heifers in feedlots. The heifers are cycling, and this creates a challenge. The Brazilians are excited about the vaccine to keep heifers from cycling and prevent stress and bruising.” The heifers gain better if they are not constantly riding one another.

Reeves says there are indications that the vaccine product works well in Bos indicus cattle, but not as well in Bos taurus. This makes sense, as Bos indicus cattle have more disease resistance – a stronger immune system – and the vaccine works because of how well they are able to build an antibody. He adds that the immune system is always stronger in a crossbred animal, and especially strong in the Bos indicus Nelore cattle in Brazil. 

Heather Smith Thomas is a freelance writer and rancher based in Salmon, ID.


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