Plasma skatole and androstenone levels in entire male pigs and relationship between boar taint compounds, sex steroids and thyroxine at various ages

The objectives of the study were to investigate the age-associated variations of plasma skatole and androstenone levels and their relationship to testosterone, estrone sulphate and thyroxine in plasma from entire male pigs. Effect of photoperiod on boar taint compounds in plasma was also investigated. In total, 47 uncastrated crossbred male pigs, siblings from 13 litters, were divided into three groups: Control group (natural photoperiod), Spring/Summer group (artificial spring conditions) and Autumn/Winter group (artificial autumn conditions). Blood samples were collected every 2 weeks at the average age from 8 weeks until slaughter at the age of 20-24 weeks. Neither skatole nor androstenone levels in plasma were affected by photoperiod. Skatole concentrations in plasma varied with age and were high at the age of 8 - 10 weeks. The early increase of skatole levels related to no other investigated compounds. At the older age, skatole levels in plasma were positively correlated to androstenone (r = 0.30; 20 weeks of age), testosterone and estrone sulphate levels (r = 0.43 and 0.54, respectively; 22 weeks of age) and negatively to thyroxine levels (r = - 0.44; 22 weeks of age, and r = - 0.72; 24 weeks of age). Plasma androstenone levels were positively correlated to levels of testosterone and estrone sulphate from approximately 14 to 24 weeks of age, not at younger age, with correlation coefficients ranging from 0.34 to 0.79. Negative correlations between androstenone and thyroxine levels in plasma were found at the ages of 16, 18 and 20 weeks (r = - 0.42, - 0.35 and - 0.30, respectively). Skatole and androstenone levels in fat at slaughter, 20-24 weeks of age, were highly correlated (r = 0.68; P<0.001). (C) 2003 Elsevier B.V. All rights reserved.