Boar taint is a significant challenge for the global pork industry, characterized by an unpleasant odor or flavor that develops when meat from some male pigs is heated. For decades, surgical castration has been the standard preventative measure, yet the procedure is increasingly scrutinized due to animal welfare concerns. In a study published in the Journal of Animal Science, lead author Melissa Parent and a team of researchers from the University of Guelph evaluated a sustainable alternative: dietary biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More. Biochar as a binding agent can bind to non-polar compounds like androstenone, the primary steroid responsible for boar taint, and prevent them from accumulating in the animal’s fat. By investigating boars from two distinct genetic lines—Alliance Genetics Canada and Pig Improvement Company—and analyzing their natural hormone production levels, the researchers aimed to determine how effectively this treatment could be applied across the broader swine industry.

The results of the four-week feeding trial were highly promising, demonstrating that biochar treatment is effective across different genetic backgrounds. Among the pigs that had the biological capacity to develop boar taint, 89% of the Alliance Genetics Canada group and 67% of the Pig Improvement Company group responded positively to the 5% biochar diet. During the treatment period, the fat androstenone concentrations in these animals remained below the critical threshold of one microgram per gram of fat, effectively neutralizing the risk of off-odors. The study utilized a unique design where the biochar was removed for a two-week recovery period, during which fat androstenone levels rose significantly. This confirmed that the biochar was actively suppressing the odor-causing compounds rather than the pigs simply lacking the ability to produce them.

One of the most critical findings involved the influence of steroidogenic capacity—the animal’s natural ability to produce steroids. By measuring plasma estrone sulfate levels, researchers classified the boars into high and low steroid production groups. The data revealed that biochar was 100% effective in boars with low steroidogenic capacity. In contrast, the pigs that did not respond to the treatment were exclusively from the high steroidogenic capacity group. This suggests that while biochar is a powerful tool, pigs with extremely high natural hormone levels might require a higher dose or a longer treatment duration to achieve the same results. This distinction is vital for farmers, as it provides a biological marker to identify which pigs will benefit most from a dietary intervention.

Importantly, the researchers found that adding 5% biochar to the diet did not negatively impact the pigs’ growth performance. Parameters such as average daily gain and body weight remained consistent between the treatment and recovery periods, as well as between the different genetic lines. While there were minor differences in feed efficiency during specific phases, these were attributed to the natural genetic variation between the breeds rather than the biochar itself. This is a major advantage for commercial pork producers, as it means they can prioritize animal welfare and meat quality without sacrificing the productivity or economic efficiency of their operations.

The mechanism behind this success is believed to be the disruption of enterohepatic circulation. Steroids like androstenone are naturally released into the intestinal tract, where they can be reabsorbed into the bloodstream and recycled back to the liver. The researchers suspect that biochar acts like a sponge in the gut, binding these steroids and forcing them to be excreted in the feces rather than recycled. Interestingly, while fat androstenone levels dropped significantly, plasma levels did not always show a corresponding decrease. This highlights the complexity of the animal’s internal systems and suggests that fat accumulation is a more accurate measure of treatment success than blood samples alone.

Ultimately, this research establishes biochar as a broadly applicable and sustainable dietary treatment for controlling boar taint. By identifying that steroidogenic capacity is a key predictor of treatment response, the study paves the way for targeted feeding strategies that can replace the need for physical castration. As the industry moves toward more humane and eco-friendly practices, these findings offer a practical pathway for maintaining high sensory standards in pork while significantly improving the welfare of male pigs.

Source: Parent, M., Bone, C., Huber, L.-A., & Squires, E. J. (2026). Effect of genetic line and steroidogenic capacity on response to dietary supplementation of biochar to control fat androstenone levels in boars. Journal of Animal Science, skaf463.