This trial was conducted to investigate the effect of different kind of fiber and different adding levels on growth performance,fecal nitrogen metabolism,fecal fiber content,serum bio-chemical index,the gastrointestinal structure and cecal microflora of broilers,in order to provide theoretical basis for the rational utilization of fiber in broilers'diet.Three hundred and sixty one-day-old healthy Shengze"901"male broilers with similar body weight(47.07±0.26 g)were ran-domly allotted into 6 groups with 6 replicates per group and 10 broilers per replicate.The broil-ers were randomly subjected to one of the following 6 treatments for 42 days with 2 periods:con-trol group(T6 group)fed the basal diet,the addition groups were fed a basal diet supplemented with 1.5 kg·t-1 fiber sample 1(T1 group),2.5 kg·t-1 fiber sample 1(T2 group),150 g·t-1 fiber sample 2(T3 group),2 kg·t-1 fiber sample 3(T4 group)and 3 kg·t-1 fiber sample 3(group T5),respectively.The results showed as follows:compared with T6 group,1)The average daily feed intake(ADFI)for 22-42 d and the feed/gain(F/G)for 1-42 d in T2 group were significantly increased by 5.04％and 3.07％(P＜0.05)respectively,the F/G for 22-42 d and 1-42 d in T3 group were significantly increased by 4.16％and 3.68％(P＜0.05)respective-ly,and average body weight(ABW)for 21 d and 42 d,average daily gain(ADG)for 1-21 d and 1-42 d and ADFI for 22-42 d in T5 group were increased significantly by 6.26％and 4.93％,6.70％and 5.02％and 4.87％(P＜0.05)respectively;2)The nitrogen intake and retention(NI and NR)at 21 d in group T1,the nitrogen retention rate(NRR)at 21 d in group T4,the NRR at 21 d in group T5 and the NR at 42 d were significantly increased by 11.24％and 16.77％,6.18％,7.65％and 9.95％,respectively(P＜0.05).Fecal nitrogen content in T5 group at 21 d was significantly decrease d by 6.87％(P＜0.05);3)Urea nitrogen(UN)and total antioxidant capacity(T-AOC)at 42 d in T1 group were significantly increased by 333.33％and 57.14％(P＜0.05)respectively,UR at 21 and 42 d in T2 group were significantly increased by 375.00％and 466.67％respectively,and malondialdehyde(MDA)at 21 d was significantly decreased by 17.69％(P＜0.05).In T3 group,UR at 21 and 42 d was significantly increased by 350.00％and 233.33％respectively,MDA at 21 d was significantly decreased by 15.58％,total protein(TP)and low density lipoprotein(LDL)at 42 d were significantly decreased by 15.34％and 20.00％respectively,and alanine aminotransferase(ALT)was significantly increased by 102.70％(P＜0.05).At 42 d,glucose content in T4 group was significantly increased by 35.36％(P＜0.05),and albumin(ALB),triglyceride(TG)and MDA at 21 d in T5 group were significantly decreased by 10.79％,25.45％and 33.60％,respectively.At 42 d,high density lipoprotein(HDL)and ALT were significantly increased by 25.32％and 62.16％,respectively(P＜0.05);4)At 42 d,the ileum length(IL)in T1 group,the jejunum weight(JW)and IL in T2 group,the jejunum length(JL)and IL in T3 group and IL in T5 group were significantly in-creased by 5.04％,13.71％and 19.26％,19.38％and 21.84％and 23.18％,respectively(P＜0.05);5)The villus height(VH)of ileum in T3 group was significantly decreased by 29.20％(P＜0.05)at 42 d,the crypt depth(CD)of duodenum and jejunum in T5 group were significant-ly increased by 116.67％and 73.33％,respectively,and the VH/CD of duodenum was signifi-cantly decreased by 48.02％(P＜0.05).6)Alpha and Beta diversity analysis showed that cae-cum microflora has obvious difference between each group.The type and quantity of microbes OTU for 21 d was increased.Bacteroides fragilis A and Alistipes finegoldii in genus of Bacte-roides and Allstilpes were the most abundant and were the dominant genera.Bacteroides and Bacteroides fragilis A were the highest richness at 21 days,and Allstilpes and Alistipes finegol-dii were the highest richness at 42 days.It mainly played a functional role in carbohydrate metab-olism and amino acid metabolism,and transport and replication and repair by KEGG pathway a-nalysis.In conclusion,dietary fiber supplementation can promote intestinal development,im-prove and stabilize intestinal microflora,improve nutrient utilization,and thus increase daily gain and feed intake of broilers.Under the conditions of this experiment,adding 3 kg·t-1 Muzhiqian product has the best effect.
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