Effect of Silybum marianum herb on the productive performance, carcass traits and meat quality of growing rabbits

The present study aimed to test the effect of a dietary supplementation with Silybum marianum (SM), an herbaceous Mediterranean plant traditionally used to treat liver and gastrointestinal diseases and with antioxidant properties, on the productive performance, carcass traits and meat quality of growing rabbits. With this purpose, at weaning (5 weeks of age), a total of 144 Pannon Large rabbits were allocated to three experimental groups. The control group (C, n=51) was fed with a basal diet, whereas the other groups received the basal diet supplemented with SM herbal powder at two concentrations: 5 g/kg (SM1, n=48) and 10 g/kg (SM2, n=45). Rabbits were housed in wire-mesh cages (3 rabbits/cage) and fed ad libitum throughout the experiment. Productive performance and mortality were recorded weekly. Rabbits were slaughtered at 11 weeks of age, carcasses were dissected, and hind leg (HL) and Longissimus thoracis et lumborum (LTL) meat were analysed for meat quality (oxidative status, pHu and L*, a*, b* colour) traits. In addition, a sensory analysis on the LTL meat was carried out by a trained panel. Mortality was significantly reduced in SM treatments compared to C group from week 6-7 (10.4 and 11.1 vs. 17.7%, for SM1, SM2 and C groups, respectively; P<0.05), and in SM2 compared to C and SM1 considering the whole productive cycle (5-11 weeks). The dietary inclusion of SM did not affect carcass traits and did not change neither colour nor oxidative status of LTL muscle. Differently, SM diet increased pHu of LTL muscle (5.98 vs. 6.03 vs. 6.10 in C, SM1 and SM2, respectively; P<0.05). The sensory traits of LTL meat were affected by SM dietary inclusion: a higher herbaceous odour was observed in SM2 compared to C and SM1 (P<0.001) treatments, whereas rabbit odour followed an opposite trend with C receiving a higher score compared to SM1 and SM2 (P<0.05). Panellists also perceived a stronger rabbit flavour in C than in SM1 and SM2 meat (2.40 vs. 1.90 and 1.70, P<0.05; P<0.001). Silybum marianum seems to be a promising natural feed additive to improve the health condition of growing rabbits. Differently, the antioxidant activity of Silybum marianum was not confirmed when considering fresh meat of rabbits supplemented with the inclusion levels of the present experiment. The dietary supplementation with Silybum marianum changed then sensory characteristics of rabbit loin thus, in the future, consumer acceptability should be also carefully assessed.