Abstract: 【Objective】 The purpose of this experiment was to investigate the effects of peanut vine,corn,and urea compound extruded feed on the growth performance,rumen fermentation parameters and microbial composition of fattening Hu sheep,and provide a reference for the application of peanut straw compound extruded feed in fattening Hu sheep. 【Method】 A total of 90 Hu sheep with similar weight and good body condition during the fattening period were randomly divided into 3 groups,with 6 replicates in each group and 5 sheep in each replicate.In the diets of the three groups of Hu sheep,the compound expanded feed was used to replace the concentrate in equal amounts,with replacement levels of 0 (control group),10% (group Ⅰ),and 20% (group Ⅱ),respectively.The adaptation period was 15 days,and the main test period was 60 days.At the beginning and end of this experiment,sheep were weighed,feed intake and residual material samples were recorded every day,and blood and rumen juice were collected at the end of this experiment for the determination of growth performance,serum biochemistry,rumen fermentation parameters and microflora. 【Result】 Compared with control group,①The average daily feed intake,average daily weight gain,and final body weight of Hu sheep in groups Ⅰ and Ⅱ were extremely significantly or significantly increased (P＜0.01 or P＜0.05),and the feed-to-gain ratio was significantly decreased (P＜0.05).②The serum urea nitrogen level of Hu sheep in group Ⅱ was significantly increased (P＜0.05).③The concentrations of acetic acid,propionic acid,total volatile fatty acids,and ammonia nitrogen in rumen fluid of Hu sheep in groups Ⅰ and Ⅱ were extremely significantly increased (P＜0.01),and pH was extremely significantly decreased (P＜0.01).The acetic to propionic acid ratio in rumen fluid of Hu sheep in group Ⅱ was significantly decreased (P＜0.05).④The Ace index of rumen microbiota of Hu sheep in group Ⅱ was significantly increased (P＜0.05).Principal coordinate analysis (PCoA) results indicated there was a clear separation of the rumen microbiota among the different groups.⑤At the phylum level,the relative abundance of Bacteroidetes in rumen fluid of Hu sheep in group Ⅱ was significantly increased (P＜0.05),while the relative abundance of Firmicutes was significantly decreased (P＜0.05).⑥At the genus level,the relative abundance of Ruminococcus in rumen fluid of Hu sheep in group Ⅰ was significantly increased (P＜0.05)，and the relative abundance of Prevotella in group Ⅱ was significantly increased (P＜0.05). 【Conclusion】 The composite extruded feed produced by mixing peanut vine,corn and urea as ingredients to replace concentrates could improve the growth performance,promotes rumen fermentation and increases rumen microbial diversity in fattening Hu sheep.

Key words: extruded feed; peanut vine; Hu sheep; growth performance; rumen fermentation; rumen microorganisms