Absorption Patterns Of Essential Oil In The Digestive Tract Of Broilers And Its Effect On Growth Performance And Intestinal Health

Essential oil(EO)is a kind of natural compound with special aroma and color present in plants which has been widely used in food,medicine and other fields.It has reported that EO has a wide range of physiological and pharmacological effects including better growth-promoting and antioxidant function.The current study was conducted to explore the absorption patterns of EO in the digestive tract of broilers,and evaluate its effect on the growth performance and intestinal health in broilers.This study will facilitate the application of EO in the poultry nutrition and feed industry.Exp.1 The absorption patterns of different essential oils components in digestive tract of broilersThe experiment used a single factorial arrangement in order to investigate the absorption regularity of different components of EO(thymol,carvacrol,cinnamaldehyde,eugenol,menthol,citral)in the digestive tract of broilers in a 5-d experiment.A total of 190 AA broilers of 21 days of age were randomly divided into 5 groups with six replicates of seven chicks except F1 group(no replicates,7 broilers in total),including a negative control diet without additives(F1 group),and basal diet supplemented with 500mg/kg cinnamaldehyde+500 mg/kg thymol(F2 group),500 mg/kg carvacrol+500 mg/kg eugenol(F3 group),500 mg/kg menthol(F4 group),500 mg/kg citral(F5 group).Pre after 3 days of feeding,the broilers were fasted at 18:00 on the 24th day and slaughtered on the 25th day for the chyme collection of digestive tracts(sac,stomach,duodenum,jejunum,ileum,cecum)of broliers,and waiting to tested the absorption rate of the six EO components.Results showed that:(1)During the 3d pre-feeding period,the feed intake of broilers in each experimental group was slightly decreased,of which F4(menthol)and F5(citral)were the lowest two groups;(2)Six EO components were mainly absorbed in the anterior segment of the digestive tract(the sac,stomach and duodenum).Among them,the absorption rate in the sac is 49% to 75%;after the chyme enters the stomach,the absorption rate of the essential oil is 73% to 94%;the rest of the essential oil can be completely absorbed after the chyme passes through the duodenum;Exp.2 Effects of essential oils on growth performance,immune function and intestinal health of broilersThe experiment used a single factorial arrangement to evaluate the growth performance,antioxidant capacity,immune regulation,and intestinal health of EO in broilers in a 42-d experiment.A total of five hundred one-day-old Arbor Acres(AA)broilers with good health and closely weight were randomly assigned to five groups with ten replicates of 10 chicks,including a negative control diet without additives(control),and basal diet supplemented with 50,100,200 and 400 mg/kg of EO.A total of 42 days during the trial period,divided into early(1-21d)and late(22-42d).And digestive test was performed on the 36th day and slaughtered on the 21st and 42d for sample collection.Results showed that:(1)There had no significant effects on average daily gain,average daily feed intake and feed-to-weight ratio of broilers among the treatment groups(P>0.05);The digestibility of dry matter,energy,crude fat,and crude protein of every treatment group increased significantly higher than the control group(P<0.01);(2)Dietary supplementation of 200 mg/kg EO significantly increased serum TSOD activity in 21-day-old and serum IgG concentration in 42-day-old of broilers(P<0.05);(3)The sIgA concentration in the jejunum and ileum of every treatment group at the age of 21 days was significantly higher than that of the control group(P<0.05);there was no significant difference in viscera index(thymus index,spleen index,Bursa’s index)among the treatment groups(P>0.05);(4)Dietary supplementation of 100 mg/kg EO significantly reduced jejunal crypt depth in 21-day-old and 42-day-old broilers,and significantly increased ileal villus height in 42-day-old broilers(P<0.05);(5)The activity of sucrase in the ileum mucosa of the EO50 group,EO100 group,and the EO200 group at the age of 21 days was significantly higher when compared with the control group(P<0.01),and the sucrase activity of the ileum mucosa of the EO100 group at the age of 42 days was higher than that of the control group(P<0.01);(6)Dietary supplementation of 100 mg/kg EO significantly up-regulated the relative expression levels of critical genes,including Occludin,ZO-1,SGLT1,GLUT2,SLC38 A,SLC79A and FATP4 in the jejunum and ileum mucosa of 21-day-old broilers(P<0.05);and significantly up-regulated the relative expression levels of critical genes which including ZO-1,SGLT1,GLUT2,SLC79A,FATP4 in the jejunum mucosa and ZO-1,GLUT2,SLC38 A,SLC79A,FATP4 in the ileum mucosa of 42-day-old broilers(P<0.05).In summary,this study initially revealed the absorption patterns of the main EO components in the digestive tract of broilers and found that EO is mainly absorbed in the anterior segment of the digestive tract;Dietary supplementation of EO had no significant effect on the performance of broilers,but it can improve the digestibility of some nutrients,significantly improve the antioxidant capacity and immune function,and significantly improve the intestinal health of broilers.