Leman Swine Conference: US study confirms Improvest® reduces water use, boosts feed efficiency in pigs
Zoetis research validated that immunocastration with Improvest reduced water disappearance by more than 12% and improved feed efficiency by 10%
20 January 2026
3 minute read
By: Dr. Micah Jansen, managing pork technical services veterinarian at Zoetis, was recently interviewed by The Pig Site’s Sarah Mikesell in St. Paul, Minnesota at the 2025 Leman Swine Conference about new research conducted on Improvest.
To start, tell me about Improvest – what is it; what does it do; how does it work?
Improvest is a product we offer from Zoetis that is a production tool, allowing for immunocastration of males as an alternative to physical castration. It is a product that's approved for use in gilts as well, but for this study we just looked at it in males.
Describe the research you conducted – what inspired it and how was the study set up?
Just a little background on why we chose to pursue this study, it has been shown previously that we can see a reduction in the amount of water usage or water disappearance in pigs that receive Improvest, specifically males that received Improvest when compared to physically castrated males.1 We wanted to see if we could replicate that benefit in the US because the work that was done previously was conducted globally.
Because of the nature of what we're looking at, this was a pen-based study. We assigned those treatments by pen, and the two treatments were either males that received Improvest or males that had been physically castrated.
We weighed them throughout the growth period of their lives, capturing weights at changes in rations. This allows us to understand what their intake looks like on a ration-by-ration basis. Then we captured weights at the very end, so we could understand what they looked like at the time of market and compared the differences between the two treatment groups.
What did the results indicate?
Improvest is a very consistent product, so the results were very similar to what we've seen in previous studies.1 Average daily gain (ADG) improved by 1.8%. We saw lower average daily feed intake which is what we expected because those males get to grow as an intact male until they receive Improvest.
The big focus of our study was understanding what water usage looked like. We measured water disappearance on a pen-by-pen basis. We saw a 12.6% reduction in water disappearance for males that received Improvest compared to males that had been physically castrated.1
We also saw a 10% improvement in feed efficiency, which is a huge advantage. Again, that's very consistent with what we expected with males that receive Improvest.
Those two things often go together, water intake and feed, right?
Yes, water intake often tracks with feed intake. Immunocastrated barrows end up requiring less feed to produce the same amount of pork essentially, and they end up with a larger carcass.
What does improved feed efficiency and decreased water usage mean in dollars and cents for swine operations, Micah?
We see an improvement in feed efficiency, which means producers are putting less feed into their animals for the same product. On top of that, producers are utilizing less water overall. So, for anyone who’s really trying to monitor, measure and improve from a sustainability standpoint, we see not only less feed usage but also less water usage as well.
IMPORTANT SAFETY INFORMATION
Pregnant women should not administer IMPROVEST. Women of childbearing age should exercise extreme caution when administering this product. Exercise special care to prevent accidental self-injection because of negative effects on reproductive physiology in both men and women. However, there is no risk associated with consuming pork from animals administered this product. Do not use IMPROVEST in male pigs or gilts intended for breeding, or in barrows, cull boars or sows. See full Prescribing Information.
Reference
1 Jansen M, Amodie D, Swalla R, Vonnahme K. Comparing feed efficiency and water disappearance in immunocastrated and physically castrated barrows in a US customer setting. in Proceedings. Allen D. Leman Swine Conference 2025.
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Sarah Mikesell
Sarah Mikesell grew up on a five-generation family farming operation in Ohio, USA, where her family still farms. She feels extraordinarily lucky to get to do what she loves - write about livestock and crop agriculture. You can find her on LinkedIn.
