An international study on the importance of androstenone and skatole for boar taint: levels of androstenone and skatole by country and season

Fat samples from 43,13 entire males taken from six European countries were measured for androstenone and skatole using rapid ELISA and colourimetric methods, respectively. The samples were collected during summer (replicate 1) and during the following winter period (replicate 2). A sub-population of over 400 samples was further measured for androstenone and skatole using laboratory methods. For skatole, there were only small differences between rapid and laboratory measurements; therefore, the rapid measurements were used throughout. Rapid measurements of androstenone could not be used because of large differences with the laboratory measurements in replicate 2. Therefore, the rapid values of androstenone for the whole population were corrected based on the laboratory ELISA measurements. Mean skatole concentration differed between replicates, but there was no overall difference for androstenone. Significant country by replicate interactions were observed for both androstenone and skatole. Skatole levels were higher in replicate 1 than replicate 2 for the United Kingdom (0.15 vs. 0.11 μg/g), Sweden (0.13 vs. 0.10 μg/g) and the Netherlands (0.19 vs. 0.16 μg/g), whereas they did not differ between replicates for the other countries (Denmark, France and Spain). Androstenone levels were higher in replicate 2 than replicate 1 only for the Netherlands (0.69 vs. 0.86 μg/g), while the reverse was found in the United Kingdom (0.91 vs. 0.72 μg/g). Overall, the correlation coefficient between androstenone and skatole was 0.30. Apart from the interaction between countries and replicates, various countries within replicates differed for mean androstenone and skatole concentrations due to the different frequency distributions for both. Overall, the United Kingdom (0.81 and 0.54 μg/g), France (0.80 and 0.53 μg/g) and the Netherlands (0.79 and 0.53 μg/g) had the lowest mean and median concentrations for androstenone, whereas Sweden (1.22 and 0.82 μg/g) and Spain (1.27 and 0.85 μg/g) had the highest. The lowest mean concentration for skatole was found in Denmark (0.10 μg/g), while it was highest in the Netherlands (0.17 μg/g) and Spain (0.17 μg/g). Androstenone and skatole concentrations increased with increasing carcass weight and decreased with increasing lean meat percentage. However, the correlation coefficients were very low; about 0.10 for carcass weight and −0.15 for lean meat percentage. Overall, more than 60% of the entire males had androstenone levels above 0.5 μg/g and about 30% had levels above 1.0 μg/g. For skatole, 15% of the entire males had levels above 0.2 μg/g and more than 10% had levels above 0.25 μg/g, but there was a large variation between countries. In the Netherlands and Spain, about 20% of the entire males had skatole levels above 0.25 μg/g, while this was lower than 2% in Denmark.