Effects Of Dietary Fiber Source And Level On Pellet Quality, Digestive Physiology And Cecal Microflora Of Meat Rabbits

The purpose of this experiment was to study the effects of dietary fiber source and level on pellet quality, growth performance and cecal microliora of meat rabbits. The experiment was carried out using two factor factorial design. Six experimental diets were formulated with two fiber sources (alfalfa hay meal and rice husk meal,respectively) and three crude fiber (CF) levels (12%,14% and 16%, respectively) under the isoenergetic and isonitrogenous conditions, and the proportions of alfalfa hay meal and rice husk meal were 24.5%,31.5%, 37.5% and 14.0%,17.5%,22.0%, The pellet quality was determined. In the meantime, a total of 144 Ira growing meat rabbits aged 70 to 80 days were randomly distributed into 6 groups, and each group contained 4 replicates and each replicate consisting of 6 rabbits (3 males and 3 females) used in feeding trial.The pre trial period lasted for 1week, and trial period lasted for 4 weeks. Total feces were collected for digestibility determination at the end of feeding trial. Afterwards,4 rabbits per group (1 rabbit from each replicate) were randomly selected, slaughtered and sampled, the related indicators were determined.The results were showed as follows:(1) The pellet length, bulk density and hardness which from rice husk meal diet were significantly higher than those from alfalfa hay meal (P<0.05), however, the percent fines of pellet from alfalfa hay meal diet was significantly higher than that from rice husk meal (P<0.01).The higher CF levels the higher pellet hardness, and the lower percent fines in alfalfa hay meal diet.(2) The 16% CF level diet with the alfalfa hay meal group had the highest average daily gain (ADG),average daily feed intake (ADFI) and the lowest feed/gain (F/G), and significant effects were not observed for ADG, ADFI and F/G of rabbits fed the diets with rice husk meal of different CF levels (P>0.05). The pH24h, shear force and cooking loss of rabbit meat were not significantly affected by dietary fiber source and CF level (P>0.05), but drip loss of rabbit meat was significantly affected by dietary fiber source (P<0.05).(3) Rabbits fed diets with the alfalfa meals as fiber source had significantly higher digestibility of dry matter(DM)(P<0.05), CF, acid detergent fiber(ADF) and acid detergent lignin(ADL) in comparison with the rice husk meals groups(P<0.01). The digestibility of DM, neutral detergent fiber(NDF) and ADF in rabbits fed 12% CF diet were higher than that of 14% CF diet(P<0.05). Moreover, apparent digestive energy (ADE) and energy apparent digestibility were higher than that of 14% and 16% CF diet (P<0.01). The dietary fiber source and CF level had no significant effects on the relative length of the stomach, duodenum, Jejunum ileum and cecum (P>0.05).The dietary fiber source and CF level had no significant effects on the relative weight of the stomach, duodenum and cecum(P>0.05), except the relative weight of jejunum ileum from rice husk meal was significantly higher than that from alfalfa hay meal (P<0.01). Rabbits fed diets with rice husk meals as fiber source had significantly higher duodenum trypsase activity in comparison with the alfalfa meals (P<0.01). Rabbits fed diets with 12% CF level had the lowest jejunum amylase activity, jejunum trypsase activity (P<0.05), and concentration of cecum cellulose (P<0.01). The villus height of duodenum from alfalfa hay meal group was significantly higher than that from rice husk meal group (P<0.05), the 16% CF level diet with the alfalfa hay meal group had the highest villus height and ratio of villus height to crypt depth, significantly higher than the other groups (P<0.05), but the dietary fiber source and CF level had no significant effects on crypt depth of the duodenum (P>0.05).(4) There was no significant difference between dietary source in cecal flora species richness and shannon-wiener index were detected (P>0.05), but rabbits fed diets with alfalfa meals as fiber source had the significantly higher flora species evenness than that with rice husk (P<0.01). Species richness and shannon-wiener index in the cecal digesta of rabbits fed 16%CF diet were increased significantly than that of 12% and 14% CF diet(P<0.05), particularly promoted bacteroides proliferation in that of rabbits fed diets with rice husk.In summary, diet with rice husk meals as fiber source, and the higher CF levels had the higher pellet hardness; the rabbits fed the 16% CF diet with the alfalfa meals(37.5%) have the best growth performance; and when the diet with rice husk meals as fiber source, the best proportion is 22%(16%CF diet).