PSXI-12 - In vitro assessment of binding agents as an alternative to activated charcoal for the prevention of boar taint

Abstract: Boar taint is an off odour and flavour that occurs once meat from uncastrated male pigs is heated, and results from the deposition of androstenone in the fat. Androstenone circulates between the liver and gut via the enterohepatic circulation, where it can be recirculated back to the liver or deposited in the fat. Previous studies from our lab have demonstrated that adding activated charcoal (AC) to feed is effective at disrupting enterohepatic circulation and preventing boar taint, however, AC is expensive and currently not approved for use as a feed additive. Spent filter aid (SFA) is a byproduct of corn syrup production, contains up to 33% diatomaceous earth (DE), and can be used as an energy source. DE and biochar have been used to bind toxins in the gastrointestinal tract and have a high surface area and porosity like that of AC. Additionally, biochar is approved and used as a feed additive in cattle production, and both biochar and SFA are available at a much lower cost. Therefore, the objective of this study was to evaluate the androstenone binding efficiency of SFA and biochar in vitro to assess their suitability as potential dietary treatments for preventing boar taint. AC, biochar and SFA were incubated for 30 minutes at 37℃ with radiolabeled androstenone, estrone sulphate (E₁S), or estrone (E₁) dissolved in buffer. Following incubation, the unbound radioactive steroid fraction was quantified using a scintillation counter and binding efficiency was calculated using a modified Michaelis-Menten equation. Statistical analysis was conducted with a 2-way ANOVA in SAS with Tukey-Kramer’s post hoc test. The binding efficiency (B_max/K) of AC was significantly greater than both biochar (P < 0.0001) and SFA (P < 0.0001). However, the maximum binding (B_max) of androstenone by AC (97.30% ± 0.44) was 13% greater than that of biochar (84.53% ± 0.79) and nearly double that of SFA (50.50% ± 0.22). Of the binding agents tested, SFA had some selective binding for androstenone as the B_max for androstenone was significantly greater than both E­₁S (P < 0.0001) and E₁ (P=0.0013). These results suggest that biochar may be a suitable alternative to AC for use as a feed additive as it can bind high levels of androstenone, and its binding characteristics were most like AC. Future animal studies are needed to evaluate the effects in vivo to assess the efficacy of biochar as a dietary treatment for boar taint.