Relationship between carcass weight, adipose tissue androstenone level and expression of the hepatic 3β-hydroxysteroid dehydrogenase in entire commercial pigs

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3β-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3β-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3β-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3β-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3β-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3β-HSD expression is under the control of sex hormones.