Effect of hop (Humulus lupulus) supplementation on performance, oxidative stress, and oxidative stability of broiler chicken meat

Chickens in different housing systems are often exposed to oxidative stress, which can lead to impaired health along with reduced performance and quality of meat. The aim of this study was to examine the effect of hop supplementation to polyunsaturated fatty acid (PUFA) rich feed mixtures on performance, oxidative stress in vivo, and oxidative stability of broiler meat. A total of 84 male broilers (Ross 308) were caged in floor cages and randomly divided into 3 groups of 28 birds each with 4 replicate pens for each group. All groups received a high PUFA diet containing 7.5% linseed oil that was either un-supplemented (CONT) or supplemented with 0.9 g of hops/kg of feed (HOPS_0. 9) or 3.6 g of hops/kg of feed (HOPS_3. 6). Oxidative stress in vivo was studied by measuring lymphocyte DNA damage, malondialdehyde (MDA) in plasma and breast muscle, and antioxidant capacity of lipid- (ACL) and water-soluble compounds (ACW) in the blood. The oxidative stability of meat was studied by measuring MDA and vitamin E in raw and refrigerated as well as deep-frozen breast meat. Hop supplementation in the highest concentration reduced performance. A higher level of supplementation (3.6 g hops/kg) induced MDA formation in plasma, decreased lymphocyte DNA fragmentation, and reduced ACL in comparison to the CONT group. In fresh meat, the concentration of MDA was higher in the HOPS_3. 6 group, but statistical differences between the groups of stored meat were not found. The concentrations of vitamin E, gamma-tocopherol, were statistically lower in both experimental groups in comparison to CONT in fresh and stored meat. In conclusion, the results of the study showed detrimental effects of hops (especially at 3.6 g/kg) supplementation on performance and on some in vivo parameters of oxidative stress, while on the other hand, the rate of fragmentation of lymphocyte DNA was reduced. A negative effect of hop supplementation was observed primarily on the oxidative stability of raw meat.