Abstract: 【Objective】 The effects of different doses of Zanthoxylum bungeanum essential oil (EOZB) on the production performance and gastrointestinal tissue structure of Small-tail Han sheep (STH) were measured and analyzed in this study,in order to provide a theoretical reference for the application of EOZB in ruminants.【Method】 Twenty 3-month-old STH with similar initial body weight were randomly divided into four groups:control group (CON) and experimental groups Ⅰ,Ⅱ and Ⅲ.The control group was fed the basal diet,while experimental groups Ⅰ,Ⅱ and Ⅲ were supplemented with 5,10 and 15 mL/kg of EOZB in the basal diet.The test period was 52 d.At the end of the test,all test sheep were slaughtered and gastrointestinal tissue samples were collected from 10 sites (rumen,reticulum,omasum,abomasum,duodenum,jejunum,ileum,cecum,colon and rectum).The effect of EOZB on the gastrointestinal tract organization of STH was systematically evaluated by production performance and gastrointestinal papilla length,papilla width,submucosal thickness,muscle thickness,intrinsic membrane thickness,stratum corneum thickness,villus length,villus width,crypt depth and other indicators.【Result】 ①EOZB could improve the productive performance of STH. Compared with the control group, the average daily gain, dry matter intake and F/G of EOZB10 group were significantly increased, and significantly higher than the other two test groups (P＜0.05). ②EOZB could promote the development of stomach on STH. Compared with the control group, the thickness of ruminal submucosa and muscularis increased significantly (P＜0.05), the thickness of corneum decreased significantly (P＜0.05), the length and width of reticulum and omasum papillae increased significantly (P＜0.05), the thickness of omasum submucosa, muscularis and lamina propria increased significantly (P＜0.05), and the thickness of abomasum mucosa and submucosa increased significantly (P＜0.05). In the three test groups, the above indexes in EOZB10 group were also higher than those in the other two groups (except for the thickness of rumen muscle layer, the width of reticulum papilla and the thickness of abomasum submucosa), and some indexes reached significant levels (P＜0.05). ③EOZB could promote small intestine development in STH. Compared with the control group, duodenal villus length, muscular layer thickness, jejunal villus width, recess depth and muscular layer thickness in EOZB10 group increased significantly (P＜0.05), and ileal villus length, villus width and villus length/recess depth increased significantly (P＜0.05). In the three test groups, the length and width of ileal villus in EOZB10 group were significantly higher than those in the other two groups (P＜0.05). ④EOZB could promote the development of large intestine in STH. Compared with the control group, the rectum muscular layer thickness and colon mucosal layer thickness in EOZB10 group were significantly increased (P＜0.05). In the three test groups, the rectum muscular layer thickness in EOZB10 group was significantly lower than that in EOZB15 group, and the colon muscular layer thickness and mucosal layer thickness were significantly lower than those in EOZB15 group, but significantly higher than those in EOZB5 group (P＜0.05). 【Conclusion】 Adding EOZB to the diet could improve the production performance and promote the development of gastrointestinal tissue structure in STH,under the conditions of this test,10 mL/kg of EOZB was the most effective.

Key words: Zanthoxylum bungeanum essential oil; Small-tail Han sheep; gastrointestinal tract tissue structure