Abstract:

The experiment was conducted to investigate the effects of energy levels on growth performance, nutrient metabolism, biochemical parameters and caecum fermentation of Rex Rabbits from weaning to 3monthold. Two hundred weaned Rex Rabbits (similar BW ) were randomly divided into 5 treatments (40 replicates per treatment, 1 rabbit per replicate): feeding diets containing DE 9.46, 9.97, 10.46, 10.94 and 11.43 MJ·kg-1, respectively. The trial lasted for 7 days for adaptation, and 53 days for test, respectively. By animal breeding experiment, digestibility experiment and slaughtering experiment, indexes were determined. The results showed that, the daily feed intake (ADI) (P<0.01), feed gain (F/G) (P<0.05) were decreased with the increase of DE levels, and the feed efficiency of 10.46 MJ·kg-1 group was better than that of other treatments. As the increasing DE levels, the nitrogen intake (IN) and fecal nitrogen (FN) were significantly reduced (P<0.01 or P<0.05). DE/GE and ME/GE were also affected by DE levels (P<0.05), and DE/GE and ME/GE reached to the maximum in 10.46 MJ·kg-1 treatment. DE levels could affect the insulin concentration in blood serum (P<0.05). NH3N concentration and propionic acid ratio of caecum were increased (P<0.01 or P<0.05) in high DE levels, but the acetic acid percentage and acetic acid to propionic acid percentage had the contrary tendency(P<0.01 or P<0.05). In conclusion, the suitable DE level was 10.46 MJ·kg-1 for Rex Rabbits from weaning to 3monthold.