Effect Of Dietary Energy Level On Growth Performance, Metabolism Of Nitrogen And Energy And Caecum Fermentation Of Rex Rabbits

The experiment was conducted to investigate the affects with one factor at five dietaryenergy levels on the growth performance, metabolism of nitrogen and energy, activity ofsmall intestine digestive enzyme, fur and meat quality, the interior environment andmicroecology of caecum on Rex Rabbits. The total test was divided into two stages: fromweaning to3-month old,and from3to5-month old. The dietary energy of five groups wereDE9.46,9.97,10.46,10.94and11.43MJ/kg. Except the energy, other nutrientcompositions in the five diets were identical.(1) Two hundred weaned Rex Rabbits (similar BW) were randomly divided into5treatments (40replicates per treatment,1rabbit per replicate). The trial lasted7days foradaptation, and53days for test, respectively. The results showed that: DE levelssignificantly effected the daily feed intake (ADI)(P<0.01), feed gain (F/G)(P<0.05) and thefeed efficiency of10.46MJ/kg group was better than other treatments. As the increasing DElevels, the nitrogen intake (IN) and fecal nitrogen (FN) were significantly reduced(P<0.01,P<0.05). DE/GE and ME/GE were also effected by DE levels (P<0.05), and reached to themaximum in10.46MJ/kg treatment. DE levels could alter the insulin concentration (P<0.05)and HDL-C content in blood serum (P<0.01). The amylase concentration in the smallintestine was significantly increased with the increasing DE level. NH3-N concentration(P<0.01) and propionic acid ratio of caecum (P<0.05)were increased in high DE levels, butthe acetic acid ratio and acetic acid to propionic acid ratio had the contrary tendency(P<0.01, P<0.05). As the increasing DE level, the similarity coefficients of9.46MJ/kg withother groups were decreacing gradually.The bands of the microorganism reached themaximun in the10.46MJ/kg and10.94MJ/kg group. The increasing DE level maked thebacterial community in the intestinal tract more complicate, and a sharp reducing with thecontinue increasing DE level. The fur length, width, area and the weight were notsignificantly effected by the increasing DE level. In conclusion, the appropriate DE levelwas10.46MJ/kg for weaning to3-month old Rex rabbits．(2)1803-month-old Rex rabbits (similar BW) were randomly divided into5 treatments (36replicates per treatment,1rabbit per replicate). The trial lasted7days foradaptation, and53days for test, respectively. The results indicated that: DE levelssignificantly effected the daily gain (ADG)(P<0.05), and ADG increased firstly and thendecreased with the increasing DE level. Finally it reached to the maximum in10.46MJ/kgtreatment. As the increasing DE levels, the fecal nitrogen (FN) was significantly effected(P<0.01), also with the apparent digestible nitrogen efficiency and digestible nitrogenutilization ratio (P<0.05). DE level significantly effected the fecal energy (FE), digestibleenergy (DE), metalbolism energy (ME)(P<0.05), DE/GE and ME/GE (P<0.01), and DE/GEand ME/GE reached to the maximum in10.94MJ/kg treatment. DE levels could alter thelow density lipoprotein (LDL) levels in blood serum (P<0.05), and the glucagon (GC)concentration (P<.0001), insulin concentration in blood serum and the trypsin activity in thesmall intestine was significantly effected (P<0.05).The pH value of the meat wassignificantly effected by the increasing DE level (P<0.05), no significant affects with thedrip loss, tenderness, lightness value, redness value and yellowness value (P>0.05).Increasing DE level significantly effected the fur length (P<0.05) and weight (P<0.01), andthe length had a tendency of increasing firstly and then down with the maximum in the10.94MJ/kg group. The pH value and NH3-N concentration of caecum were significantlyincreased with the increasing DE level (P<0.05). In the similarity coefficients of bacterial inthe caecum content,10.94MJ/kg and11.43MJ/kg groups’ reached the maximum with64.6%,9.46MJ/kg group and10.94MJ/kg group’s reached the minimum with25.1%. Thebands of10.46MJ/kg and10.94MJ/kg group were more than the others. In conclusion, theappropriate DE level was10.94MJ/kg for3to5-month old Rex rabbits．...