Hydrolysable tannin fed to entire male pigs affects intestinal production, tissue deposition and hepatic clearance of skatole

• Hydrolysable tannin-rich wood extract (1%, 2% or 3%) was supplemented to entire male pigs.
• Decreased feed intake and salivary gland adaptation were noted when the 3% supplement was fed.
• Hydrolysable tannins lowered intestinal skatole production.
• CYP2E1, CYP2A19 were stimulated and found to be inversely proportional to fat skatole levels.
• Tannin supplementation may reduce boar taint, but the optimal dose remains to be determined.

The effect of adding hydrolysable tannins to the diet of fattening boars was studied. Performance, reproductive organ weights, salivary gland morphology, boar taint compounds and skatole metabolism were evaluated. At 123 days of age and 52 ± 6 kg liveweight, 24 Landrace × Large White boars were assigned within a litter to four treatment groups: control (T0 fed mixture with 13.2 MJ/kg, 17.5% crude proteins) and three experimental diets for which the T0 diet was supplemented with 1%, 2% and 3% of hydrolysable tannin-rich extract (T1, T2 and T3, respectively). Pigs were kept individually with ad libitum access to feed and water and slaughtered at 193 days of age and 122 ± 10 kg liveweight.Adding hydrolysable tannins to the diet had no negative effect on growth performance at 1% and 2%, whereas the 3% inclusion reduced feed intake and resulted in an adaptive response of the salivary glands (particularly parotid gland hypertrophy). Relative to T0, fat tissue skatole concentration was increased in the T1 group, but was similar in T2 and T3. Across treatments tissue skatole concentrations were proportional to the activity of hepatic CYP450. The results indicate the potential of tannin supplementation to reduce boar taint although further investigations are needed in order to establishing optimal dosage.