Assessment of the effect of grape seed cake inclusion in the diet of healthy fattening‐finishing pigs
Wine by‐products including grape pomace (peels, seeds and stems) or grape seed cake are considered special source of such secondary metabolites due to their high levels of polyphenolic compounds, especially anthocyanins, flavonoids and phenolic acids or others (linoleic‐ω‐6 fatty acid, fibres, etc.). Many of these compounds have been shown to exert a broad range of beneficial effects on health in humans and rodent models (Cho et al., 2013; Gessner, Ringseis, & Eder, 2016; Torres et al., 2002).
In contrast, in farm animals, the effects of dietary inclusion of grape waste and its capacity to modulate important physiological responses (e.g., inflammation, oxidative stress) by their bioactive compounds have been scarcely investigated so far (Gessner et al., 2013). However, studies carried out until now revealed the capacity of polyphenols from grape to act as powerful antioxidants against lipid peroxidation with improvement of meat quality and gut health (Gessner et al., 2016). For example, Santos et al. (2014) showed that the inclusion of grape residue in the diet of lactating cows could contribute to the prevention of oxidation of milk fatty acids and could improve the general health of cows. Furthermore, feeding cows with diets containing dried or ensiled grape marc was associated with enhanced concentration of polyunsaturated fatty acids in milk, a decrease of 20% methane emission and changes in the ruminal bacterial communities (Moate et al., 2014). In experiments with chicken, dietary grape pomace reduced the lipid oxidation of meat and increased α‐tocopherol concentration in the liver (Goni et al., 2007). Administration of grape seed procyanidins to weaned piglets had beneficial effects on diarrhoea incidence, immune and antioxidant response (Hao et al., 2015; Sehm, Treutter, Lindermayer, Meyer, & Pfaffl, 2011). The addition of grape extract or fermented grape pomace in the diet of finishing pigs improved the animal's performance and resulted in an increase in the total polyunsaturated fatty acids in the subcutaneous fat, low lipid oxidation and high colour stability of meat (Garrido, Auqui, Martí, & Linares, 2011; Yan & Kim, 2011). But, the effects of grape compounds with respect to their anti‐inflammatory and antioxidative defence response have been less investigated in this category of farm animals. Therefore, the effect of 5% dietary inclusion of a grape waste (seed cake) in fattening‐finishing pigs was assessed in the study described herein by measuring the performance and health status as well as several specific markers of inflammation and antioxidative status in plasma and liver as the most important site of xenobiotic biotransformation (Cui, Yang, Lu, Chen, & Zhao, 2014) and immune homeostasis (Mbimba et al., 2012; Park, Choi, Eom, & Choi, 2013; Pistol et al., 2014). Fattening pig was also regarded as an experimental model for human nutrition in this study, due to the high degree of similarity between pig and human for digestive anatomy and physiology (Soucek, Zuber, Anzenbacherova, Anzenbacher, & Guengerich, 2001).