Oregano, rosemary and vitamin E dietary supplementation in growing rabbits: Effect on growth performance, carcass traits, bone development and meat chemical composition

Abstract

The study aimed to evaluate the effect of dietary supplementation with different natural additives (aqueous extracts) on the performance of growing rabbits, the nutritional composition and oxidative stability of their meat and on their hind leg bone traits. For this experiment, 200 New Zealand White rabbits weaned at 30 days of age were randomly allocated into five dietary groups (n=40 rabbits/group) until 80 days of age, when they were sacrificed. Dietary groups were: S (standard diet with no supplementation), E (standard diet+150ppm vitamin E positive control), O (standard diet+0.2% oregano, Origanum vulgare, aqueous extract), R (standard diet+0.2% rosemary, Rosmarinus officinalis, aqueous extract) and OR (standard diet+0.1% oregano extract+0.1% rosemary extract). An additional 50ppm vitamin E was added to each diet. Rabbits in the O and OR groups showed the highest final live weight and carcass weight (P<0.001). Oregano supplemented animals also had the best feed conversion ratio. Longissimus dorsi (LD) meat of E and R rabbits had higher protein content compared to O and OR (P<0.001) which had a higher moisture content than E rabbits (P<0.005). All dietary treatments improved the oxidative stability of the LD meat compared to the S group. Treatments O and E were the most effective in delaying the lipid oxidation of LD meat, followed by the OR and R diets (P<0.005). No significant differences among groups in composition of the hind leg meat (HL) were observed. The O rabbits had a higher bone weight (P<0.05) than E animals and this difference was mainly ascribable to femur weight (P<0.01). In conclusion, the study showed that supplementation with 0.2% oregano can have a positive effect on productive performance and meat quality of rabbits.