| Effect of different NDF levels but equal CF levels on growth performance, nutrition utilization,immunology and caecum fermentation were investigated on New Zealand White rabbit. The total feeding course was divided into two stages.The earlier stage was from weaning to 2- month old and the later satge was from 2-month old to 3-month old. Then these results were compared between two kinds of stage.In exp.1,80 weaning to 2-month old New Zealand rabbit were randomly assigned to each of the 5 dietary groups,each group have 16 rabbits.Nutrient content of five kinds of experimental diets is resemble except NDF levels (24%,27%,30%,33%,36%). The result were followed : dietary NDF levels had significently influence on ADG,feed conversion rate(p<0.05),ADG and feed conversion rate were all curvilinear ,ADG accended first with the improvement of NDF levels ,then descended. feed conversion rate adverse.ADG in 30% NDF treatment was highest but feed conversion rate was lowest.which was 31.52g/d and 3.23:1 respectively.Dietary NDF levels had not significently influence on feed intake(p>0.05),but the feed intake was rising. Dietary NDF levels had significently influence on nutrient digestibilities and Nitrogen Utilazition(p<0.05)and CF(p<0.01), nutrient digestibilities except NDF were descend with the improvement of NDF levels.Dietary fiber levels had significently influence on caecum growth(p<0.05),the propotion of caecum in the body weight was ascended .thymus indices and spleen indices were all ascended, 36%NDF group was highest, they were 2.41g/kg and 0.71g/kg.36%NDF groups have no significently difference(p>0.05).caecum pH was ascended,but had no significently difference(p>0.05),NH3-N concentration was ascended also,24%,27% NDF groups had significently difference with 36% NDF group(p>0.05).The total VFA concentration was ascended,24%NDF group had significently difference with 36% NDF group(p>0.05),they were 28.64mmol/g和51.92mmol/g.The molar propotion of acetic acid content were increased and propionate,butyrate descended.The activity of cellulose enzyme was extreme significent(p<0.01),was from 13.79u/g to 58.68u/g.Dietary fibre is important to children rabbit,the laxness rate in 24% and 27% NDF groups were higher than 30%,33%,36% NDF groups in the experiment.In a word,the diet of 30%-33% NDF was suited to weaning to 2 month-old NZ rabbit.Exp.2 was continurous with exp.1,the groups and diets were originally. Experiment would end in 3-month old rabbit.The result were followed :The graph was similitude of growth with exp.1, dietary NDF levels had significently influence on ADG,feed conversion rate(p<0.05),ADG and feed conversion rate were all curvilinear ,ADG accended first with the improvement of NDF levels ,then descended. feed conversion rate adverse.ADG in 30% NDF treatment was highest but feed conversion rate was lowest.which was 30.09g/d and 4.27:1 respectively.Dietary NDF levels had not significently influence on feed intake(p>0.05),but the feed intake was rising.The growth performance in exp.2 compared with exp.1:ADG was decreased,FI and feed conversion rate were Dietary NDF levels had significently influence on nutrient digestibilities and Nitrogen Utilazition(p<0.05)and extreme signifiently influence in CF(p<0.01), nutrient digestibilities except NDF were descend with the increaed. improvement of NDF levels. Nutrient digestibilities in exp.2 were descended than in exp.1.The slaughter had no significently difference(p>0.05),it were descended with the improvement of NDF levels. the propotion of caecum in the body weight was ascended ,it's weight were increased but the propotion were not variety.thymus indices and spleen indices were all ascended, 36%NDF group was highest, they were 2.22g/kg and 0.76g/kg.36%NDF groups have no significently difference(p>0.05),the value were increased than in 2-month old rabbits. caecum pH was ascended,but had no significently difference(p>0.05),pH were lower than 2-month old.NH3-N concentration was ascended also,24%NDF group had significently difference wit...
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