饲粮纤维源及粗纤维水平对肉兔营养物质消化率、肠道消化酶活性及盲肠菌群多样性的影响

本试验旨在研究饲粮纤维源及粗纤维(CF)水平对肉兔营养物质消化率、肠道消化酶活性及盲肠菌群多样性的影响。试验采用双因子试验设计,依据等能等氮原则,设2种纤维源(苜蓿草粉、稻壳粉)、3个CF水平(12%、14%、16%),共配制6种试验饲粮。选择144只70~80日龄、平均体重(2 002±77)g的健康伊拉生长肉兔,随机分为6组,每组4个重复,每个重复6只兔,单笼饲养。饲养试验为期4周,饲养试验期末,采用全收粪法进行消化试验,之后进行屠宰,取肠道食糜用于消化酶活性及盲肠菌群多样性的测定。结果表明:1)苜蓿草粉组干物质(DM)、CF、酸性洗涤纤维(ADF)、木质素(ADL)的消化率显著或极显著高于稻壳粉组(P0.05或P0.01),粗蛋白质(CP)消化率则极显著低于稻壳粉组(P0.01);12%CF水平组DM、中性洗涤纤维(NDF)、ADF的消化率显著高于14%CF水平组(P0.05),同时该组能量的消化率及表观消化能(ADE)极显著高于14%、16%CF水平组(P0.01)。2)稻壳粉组十二指肠胰蛋白酶活性极显著高于苜蓿草粉组(P0.01)。与14%、16%CF水平组相比,12%CF水平组的空肠淀粉酶、胰蛋白酶活性及盲肠纤维素酶活性均最低。3)纤维源对盲肠菌群丰富度和香农指数无显著影响(P0.05),但苜蓿草粉组的盲肠菌群均衡指数极显著高于稻壳粉组(P0.01)。CF水平对盲肠菌群丰富度和香农指数有显著影响(P0.05),其中16%CF水平组的数值均为最高。综上所述,在本试验条件下:1)苜蓿草粉组肉兔DM、CF、ADF、ADL的消化率及盲肠菌群均衡指数显著或极显著高于稻壳粉组,但十二指肠胰蛋白酶活性极显著低于稻壳粉组。2)饲粮CF水平为12%时肉兔的ADE和各主要营养物质的消化率最高;CF水平越高,肉兔空肠淀粉酶、胰蛋白酶活性和盲肠纤维素酶活性越高;饲粮CF水平为16%时肉兔盲肠菌群的多样性较高。

Effects of Dietary Fiber Source and Crude Fiber Level on Nutrient Digestibility,Intestinal Digestive Enzyme Activities and Cecal Microbial Diversity of Meat Rabbits

This experiment was conducted to determine the effects of dietary fiber source and crude fiber ( CF) level on nutrient digestibility, intestinal digestive enzyme activities and cecal microbial diversity of meat rabbits. Six diets were formulated according to a two-factor experiment design based on isonitrogenous and isocaloric, one factor was fiber source ( alfalfa hay meal and rice husk meal) , and another was CF level ( 12%, 14% and 16%) . A total of 144 Hyla growing rabbits with the age of 70 to 80 days and average body weight of ( 2 002 ± 77) g were selected and randomly allocated in individual cages for six groups of 4 replicates containing six rab-bits per replicate. The feeding trial lasted for 4 weeks. Digestion experiment was conducted by the method of total fecal collection at the end of feeding trial. Afterwards, rabbits were slaughtered, and intestinal contents were sampled and stored for digestive enzyme activities and cecal microbial diversity determination. The results showed as follows:1) meat rabbits fed diets with the alfalfa hay meal as fiber source had significantly higher dry matter ( DM) , CF, acid detergent fiber ( ADF) and acid detergent lignin ( ADL) digestibility compared with meat rabbits fed diets with the rice husk meal as fiber source ( P<0.05 or P<0.01) , while the crude pro-tein ( CP) digestibility in alfalfa hay meal group was significantly lower than that in rice husk meal group ( P<0.01). The digestibility of DM, neutral detergent fiber (NDF) and ADF of meat rabbits in 12% CF level group was significantly higher than that in 14% CF level group (P<0.05). Moreover, the apparent digestive energy ( ADE) and energy digestibility in 12% CF level group were significantly higher than those in 14% and 16% CF level groups ( P<0.01) . 2) Meat rabbits fed diets with rice husk meal as fiber source had significantly higher duodenal trypsase activity compared with meat rabbits fed diets with alfalfa hay meal as fiber source ( P<0. 01) . Meat rabbits fed diets with 12% CF level had the lowest jejunal amylase activity, jejunal trypsase activi-ty and cecal cellulose activity. 3) There was no significant difference between the 2 fiber sources in cecal flora species richness and Shannon-wiener index were detected ( P>0.05) , but meat rabbits fed diets with alfalfa hay meal as fiber source had the significantly higher cecal flora species evenness than that of meat rabbits fed diets with rice husk meal as fiber source ( P<0.01) . CF level had significant effects on species richness and Shan-non-wiener index of cecal flora ( P<0.05) , and meat rabbits fed 16% CF level diet had the highest values. In this experimental condition, the results demonstrate as follows: 1 ) the digestibility of DM, CF, ADF and ADL and cecal flora species evenness of meat rabbits in alfalfa hay meal group are significantly higher than those in rice husk meal group, but the duodenal trypsase activity is significantly lower than that in rice husk meal group. 2) Meat rabbits fed diets with 12% CF have the highest ADE and main nutrient digestibility, and the higher CF level the higher jejunal amylase activity, jejunal trypsase activity and cecal cellulose activity. Meat rabbits fed diets with 16% CF have the higher cecal microbial diversity.