PSVIII-13 A comparison of biochar and activated charcoal as feed additives to prevent boar taint

Abstract Boar taint is a urine or feces-like odor that occurs when meat from entire male pigs is heated and is caused primarily by the deposition of androstenone in the fat. Androstenone is thought to circulate in the body similarly to sex steroids; this may facilitate the recirculation of androstenone to the liver or systemic circulation for deposition in the fat. Previous studies from our lab concluded that feeding activated charcoal (AC) can reduce the accumulation of androstenone in fat. However, this is not a practical solution as AC is expensive and not approved for use in livestock feed. Biochar is a charcoal-based adsorbent that is approved as a feed additive and has similar physical binding properties to AC, such as high porosity and large surface area. Our in vitro binding studies showed similar binding efficiency between AC and biochar for androstenone; however, the efficacy of biochar for reducing boar taint has not been assessed in vivo. Therefore, the objective of this study was to compare the efficacy of biochar and AC as dietary treatments for reducing fat androstenone concentrations. Beginning at 71.3 ± 1.3 kg, [(Yorkshire x Landrace) x Duroc] boars (n = 34) were acclimated to a standard corn and soybean meal-based finisher diet, for 1 wk. Animals were then randomly assigned to a finisher diet containing 5% AC (n = 17) or 5% biochar (n = 17) for 4 wk, followed by a 2-wk recovery period on the standard finisher diet. Backfat biopsies were performed bi-weekly and fat androstenone concentrations were quantified using an androstenone-specific enzyme-linked immunosorbent assay. All animals were evaluated on the change in fat androstenone concentrations quantified at the end of the treatment and recovery period. Boars with increased fat androstenone concentrations at the end of recovery were classified as having a positive response to the treatment. Statistical analysis was performed using a Student’s t-test to evaluate differences in fat androstenone concentrations between the end of treatment and recovery periods in animals with positive treatment responses. Fat androstenone concentrations at the end of treatment were 1.721 ± 0.152 μg/mL and 1.431 ± 0.412 μg/mL for AC (n = 9) and biochar (n = 6), respectively; these values significantly increased to 5.475 ± 0.804 μg/mL (P = 0.0003) for AC and 3.924 ± 0.586 μg/mL (P = 0.004) for biochar at the end of recovery. Moreover, concentrations of androstenone in the fat at the end of treatment and recovery were similar between AC and biochar treatments. These findings demonstrate that biochar can decrease fat androstenone concentrations in some mature boars, with comparable efficacy to that of AC. However, additional work is needed to identify biomarkers associated with positive treatment responses so that biochar can be provided in a targeted manner to boars that will respond favorably.