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Can’t we just let boars be boars?

By Larry Rueff, DVM
Swine Veterinary Services
Greensburg, Indiana


Growing up on a small pig farm in the 1960s, we castrated boar pigs to remove taint, the odor that emanated if you fried pork from an intact boar in the skillet. Boar taint is the primary reason farmers around the world have castrated boars for hundreds if not thousands of years.

Over the past 3.5 years, I’ve had an up-close look at raising intact boars with the help of a protein compound that’s an alternative to conventional castration. The compound (gonadotropin releasing factor analog-diphtheria toxoid conjugate) uses the pig’s immune system to stop the production of androstenone and skatole, which are responsible for boar taint. It’s not a chemical castration, but a temporary, immunological castration.

My team and I have been using this FDA-approved compound at a wean-to-finish facility I own. The facility is smaller than most of today’s commercial swine operations but otherwise is standard, modern swine housing. It was initially set up with support from Zoetis to demonstrate experience with this new way of raising pigs, although now we have other projects underway such as evaluating antibiotic-free production. We welcome visitors from the swine industry to share what we’ve learned.

Outstanding numbers

I run groups of 250 intact boars at a time through our facility. As of this writing, I have collected data on the performance of these pigs over 10 groups for 3.5 years. The last group we ran through from wean to market had a feed conversion of 2.21 and an average daily gain of 2.12 pounds per day. They were marketed at 300 pounds. They have faster days to market and better carcass quality than traditionally castrated boars. The performance numbers are not the result of the protein compound — they are the result of allowing boars to be boars, which enables them to reach their full genetic potential.

I should mention these results were achieved with no antibiotics in feed or water. Individual sick pigs were treated only with injectable antibiotics, if indicated. In this group, there were 14/249 or 5.6% that needed and received antibiotic treatment, but none of the rest received an antibiotic. By eliminating castration, we’ve also eliminated the need for antibiotics that can arise due to castration-related infections. Our experience demonstrates that by allowing boars to be fed intact, we can achieve great performance in antibiotic-free production systems.

I do believe that all veterinarians are for reducing the use of antibiotics, but we also believe if pigs get sick and need antibiotics, we need to treat them. We know that pork from antibiotic-treated animals is just as safe to eat as pork raised in an antibiotic-free production system when we follow the label directions including required withdrawal times that were determined based on careful research and science.

A longer discussion on this topic is for another day, but as we look at eliminating or reducing antibiotics, we have to rely on other tools to reduce disease challenges and produce healthy pigs. In some circles, there’s been reluctance to use the protein compound for immunological castration even though it’s been approved for food production in over 60 countries and has been used in other countries for over 10 years. Here in the US, however, there has been some reluctance with retailers to utilize technology such as immunological castration. This has led some packers to not accept these castrated but intact pigs.

I think the time is right to revisit traditional castration and consider letting boars be boars.

Elephant in the room

As a practicing veterinarian, I know that even products approved by FDA have various degrees of effectiveness. It’s up to me as a veterinarian to work with producers to evaluate clinical effectiveness on their respective farms. I do have confidence in the safety of FDA-approved products when used as directed — and immunological castration has been deemed safe.

Lastly, there’s the big elephant in the room — the welfare issue.  As you’re probably aware, there’s a movement to ban physical castration of boars in the European Union.1 How much traction that gains in the US remains to be seen, but one thing is clear: Any casual observer who compares immunological castration to conventional physical castration can clearly see the difference. Immunological castration is accomplished with two simple subcutaneous injections. Physical castration, on the other hand, is surgery, which causes some degree of pain and post-surgical discomfort even if local anesthetics are used.

Most consumers are far removed from the farm, don’t know that boars are castrated and certainly don’t know why, but considering the public concern about animal welfare, my guess is they don’t favor physical castration of boars. Likewise, producers and their employees don’t much like performing the procedure either. In fact, I would venture to say that all swine farms with boars would prefer to throw away their scalpels and stop castrating. We have that option now and I say, “let boars be boars!”



1. BioMed Central. Will the EU manage to ban pig castration by 2018? https://blogs.biomedcentral.com/on-biology/2016/12/20/will-eu-manage-ban-pig-castration-2018/
Accessed May 3, 2017.





Editor’s note: The opinions and recommendations presented in this article are the author’s and are not necessarily shared by the editors of Pig Health Today or its sponsor.




Posted on March 28, 2019

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