Effect of dietary starch level and source on growth performance, caecal fermentation and meat quality in rabbits

To evaluate the effects of starch level and source on growth performance, caecal fermentation, and carcass and meat quality, six diets were formulated including different percentage of barley (B) or corn (C) or equal proportions of the two cereals (BC) to obtain moderate (M) or high (H) starch levels, and fed to 96 rabbits from 35 d of age until slaughter (73 d). Within starch level, B and C diets presented similar chemical composition and nutritive value while starch digestibility was higher in B diets. The starch source did not affect growth performance and meat quality and showed weak effects on caecal fermentation, apart from a higher proportion of valerate in rabbits fed diets C (P<0.05). According to cereal inclusion rate, M diets were lower in starch (17.0 vs 20.6% DM) and digestible energy concentration (12.1 vs 12.6 MJ/kg DM) and higher in fibre concentration (ADL: 4.7 vs 3.9% DM) than H diets. The starch level affected growth performance: H diets stimulated weight gain (41.7 vs 43.5 g/d; P<0.05) and improved feed conversion (P<0.001) in comparison with M diets but did not affect health status or caecal fermentation. High-starch diets also increased dressing percentage (60.9 vs 61.5%; P<0.05), and cooking losses and share press force of meat.