The effect of intensive and extensive production systems on carcass quality in New Zealand White rabbits

This study aimed to compare the quality of meat (Longissimus thoracis et lumborum—LTL, hind legs—HL) from female and male Californian (CAL) and Flemish Giant Gray (FG) rabbits. The animals were kept outdoor, in a roofed pavilion, in wire mesh cages with a slatted floor and were fed ad libitum a complete pelleted diet. All rabbits were slaughtered at 91 days of age. The meat of CAL rabbits had a higher content of dry matter (p < 0.001), protein (p < 0.001) and unsaturated fatty acids (p = 0.002), higher pH (p < 0.001), and higher taste desirability (p = 0.021) and tenderness (p = 0.046). CAL rabbit meat had also a lower (p < 0.001) water to protein (W/P) ratio, lower (p < 0.001) shear force values, and lower (p = 0.042) taste intensity. The meat of FG rabbits was characterized by lower (p < 0.001) water-holding capacity (WHC). The LTL muscle had a higher content of dry matter (p = 0.003) and protein (p < 0.001), higher L* (lightness) (p = 0.011), b* (yellowness) (p < 0.001), and C* (chroma) (p = 0.010) values, and lower (p = 0.015) WHC. Hind leg muscles had higher (p < 0.001) fat content, a higher (p < 0.001) W/P ratio, and pH (p < 0.001). Sex had no effect (p > 0.05) on the analyzed meat quality attributes, excluding vitamin A content which was higher (p = 0.041) in females. In conclusion, the meat of CAL rabbits slaughtered at 91 days of age can be more mature than the meat of FG rabbits slaughtered at the same age. Furthermore, quality of meat from rabbits of both breeds depends on the anatomical origin of muscles. Further research is needed to identify the possible reasons for the higher vitamin A content of meat from female rabbits which did not differ from the meat of males in terms of other characteristics.

By-products of biofuels production such as rapeseed cake and dried distillers' grains with solubles (DDGS) may constitute valuable feedstuffs for livestock. The objectives of the study were to determine the usability of these components in the feeding of growing rabbits and to assess their impact on physiological changes in the gastrointestinal tract of the animals. Sixty-four rabbits were divided into four feeding groups: Control (5% soyabean meal [SBM] in the diet), R (5% rapeseed cake [RSC]), DDGS (5% wheat DDGS), and R/DDGS (2.5% RSC and 2.5% wheat DDGS). The study included a production experiment, a digestibility-balance experiment and physiological assessment of the functioning of animals' gastrointestinal tract (small intestine, caecum and colon). No statistically significant differences were determined in production results of the rabbits. Digestibility of nutrients and energy and nitrogen retention were the highest in the Control and the lowest in Group DDGS. Group DDGS was characterised by the highest relative weight of small intestine and digesta. In turn, Group R was characterised by the highest degree of caecal digesta hydration and bulking and by the highest pH value and the lowest concentration of VFA in caecum. The activity of selected bacterial enzymes released to the caecal environment was similar in all groups; however, the activity of α-arabinopyranosidase was significantly increased in Groups R and DDGS. Worthy of notice is the enhanced enzymatic activity of colonic microbiota in the R/DDGS group which has a positive effect upon increased utilisation of dietary nutrients compared to the DDGS group. The obtained results indicate that SBM from rabbit diets may be successfully replaced by 5% RSC as well as by 2.5% RSC + 2.5% wheat DDGS.

This study investigated the effect of the BCO2 genotype and the addition of Aztec marigold flower extract to rabbit diets on the expression of BCO1, BCO2, LRAT, and TTPA genes in the liver. The levels of lutein, zeaxanthin, β-carotene, retinol, and α-tocopherol in the liver and blood serum of rabbits, as well as plasma biochemical parameters and serum antioxidant enzyme activities were also determined. Sixty male Termond White growing rabbits were divided into three groups based on their genotype at codon 248 of the BCO2 gene (ins/ins, ins/del and del/del); each group was divided into two subgroups: one subgroup received a standard diet, and the other subgroup was fed a diet supplemented with 6 g/kg of marigold flower extract. The obtained results indicate that the BCO2 genotype may affect the expression levels of BCO1 and BCO2 genes in rabbits. Moreover, the addition of marigold extract to the diet of BCO2 del/del rabbits may increase the expression level of the BCO2 gene. Finally, an increase in the amount of lutein in the diet of rabbits with the BCO2 del/del genotype contributes to its increased accumulation in the liver and blood of animals without compromising their health status or liver function.