Effect of high dietary digestible fibre content on the fatty acid composition of two muscles in fattening rabbits

The effect of a high (260 g DF/kg DM) vs. a low (180 g DF/kg DM) dietary digestible fibre level on the intramuscular fatty acid composition of Longissimus lumborum and Biceps femoris was investigated in 24 fattening rabbits, allotted in two groups: low digestible fibre (LDF) and high digestible fibre (HDF). The animals were slaughtered at 2.77 kg and muscles were excised from the carcasses after chilling at 4 °C for 24 h. Muscle fatness and saturated fatty acids were not affected by the dietary digestible fibre, whereas monounsaturated fatty acids were lower (p < 0.01) in HDF rabbits. An increase in the polyunsaturated fatty acids (p < 0.05) observed for the HDF rabbits was attributed to its higher linoleic acid percentage (+ 1.2%). Microbial origin, namely odd-numbered (ONFA) and branched-chain (BCFA) fatty acids were higher (p < 0.001) in both muscles by the high dietary digestible fibre content. Muscles in the HDF rabbits differed significantly in fatty acid composition and enzyme indices due to fatness mostly, but no significant interactions with the dietary digestible fibre were observed. Microbial origin fatty acids were different (p < 0.001) between muscles independently of fatness. However, branched relative to odd-numbered fatty acids appeared to be distributed in the fatter Biceps muscle at a higher degree, as suggested by the lower (p < 0.001) ONFA:BCFA ratio. Data adjustment for fatness showed that differences in fatty acid profile between muscles might be related to factors other than fatness. Considering the biological significance of branched-chain fatty acids the extent to which the influence of dietary digestible fibre occurs in different muscles of rabbit carcass, should be further investigated.