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Tannins are considered anti-nutritive substances because they precipitate proteins, inhibit digestive enzymes and affect the utilisation of vitamins and minerals. They can also alter feed palatability and hence feed intake and performance. Still, certain tannins show positive properties as antimicrobial, antihelmintic or antioxidant. Sweet chestnut wood extract (SCWE), mainly hydrolysable tannins, showed reducing oxidative stress in pigs and poultry. Hydrolysable tannins in pigs inhibit protein fermentation in the colon and reduce intestinal production of skatole, a boar taint compound. Therefore, their supplementation is likely to affect carcass and meat quality. The aim of the present trial was to study the potential impact on carcass and meat quality of supplementing diets for pigs with SCWE, in particular on oxidative stability and fatty acid composition. Entire (non-castrated) male pigs (n = 24) were assigned to treatment groups within litter and offered one of 4 finisher diets fed ad libitum basis: T0 (control), T1, T2 or T3, supplemented with 0, 1, 2 or 3% of commercially available SCWE, respectively.
The highest SCWE supplementation reduced carcass fat deposition and water holding capacity of meat (higher thawing loss). In fresh meat, SCWE supplementation increased lipid (malondialdehyde) and protein oxidation (carbonyl groups in myofibril isolates). Regarding the fat tissue, SCWE supplementation increased the proportion of polyunsaturated fatty acids. According to the results of the present study, there is an indication that supplementation with hydrolysable tannins reduces carcass fat deposition, leading also to a higher percentage of PUFA in fat tissue.
The results referring to the quality of the meat, indicate that supplementation SCWE produces an increase in the markers of oxidation of lipids and proteins together with a lower water retention capacity in fresh meat and suggest an increase of the pro-oxidative potential.
Rezar, V., Salobir, J., Levart, A., Tomažin, U., Škrlep, M., Lukač, N. B., & Čandek-Potokar, M. (2017). Supplementing entire male pig diet with hydrolysable tannins: Effect on carcass traits, meat quality and oxidative stability. Meat science, 133, 95-102. https://doi.org/10.1016/j.meatsci.2017.06.012