Effect of dietary hop extracts and humic substances on the growth performance, carcass yield, blood biochemistry parameters, and meat quality of rabbits

This study aimed to evaluate the effects of hop extract in the form of xanthohumol (XA) and humic substances (HS) supplementation in the rabbit diet on growth performance, carcass traits, blood biochemical parameters, and the qualitative and sensory properties of rabbit meat. Experimental material consisted of 60 Big Light Silver × Chinchilla Giant crossbred rabbits, randomly assigned to three dietary groups. Experimental groups, XA and HS, were fed pellets enriched with 1.0% XA or 1.0% HS, respectively, for 63 days during the fattening period. Control group (C), consisting of rabbits that received a basal diet without supplements. In the XA group, the higher final live weight and carcass weight were recorded at the end of the fattening period, along with increased protein content and collagen-free muscle protein (BEFFE) in the leg and loin muscles, compared to the control group. In contrast, the HS-supplemented group exhibited the lower final live weight and carcass weight, along with reduced fat content in the leg and loin muscles, as reflected in lower blood cholesterol levels. Additionally, elevated blood serum calcium and phosphorus levels were observed in the HS group. Higher values of colourimetric parameters L* and h* (lightness and hue angle) were recorded in the leg meat of the XA group compared to the control group. Moreover, the results demonstrated that supplementation with 1.0% XA was more effective in delaying lipid oxidation in meat compared to the control group on the 7th day of refrigerated storage. In conclusion, the primary benefit of supplementing rabbit diets with 1% xanthohumol is improved growth performance, positively influenced by increased protein content, reduced fat content, and enhanced oxidative stability of the meat.