Effect Of Rosemary Extract On Production Performance,Egg Quality,and Intestinal Health Of Late-Phase Laying Hens

Objectives:(1)Extraction of antioxidant active ingredients from a new variety of rosemary‘Kexuan 2~#’cultivated by the Institute of Botany,Chinese Academy of Sciences,to obtain rosemary extract(RE),and quantitative analysis of the antioxidant active ingredients contained in RE using high-performance liquid chromatography(HPLC).(2)To investigate the effects of RE on the production performance,egg quality,redox balance,immune status,intestinal microorganisms,and short-chain fatty acids of late-phase laying hens,to investigate the feasibility of adding RE to diets to improve the production performance and egg quality of laying hen and to provide a theoretical basis for the application of RE in animal production.Methods:(1)Preparation of RE and quantification of antioxidant components:Ethanol was used as the solvent to extract the active ingredients from rosemary leaves,and the antioxidant active ingredients in the extract were quantified by high-performance liquid chromatography(HPLC).(2)Feeding trail on laying hens:210 65-week-old commercial laying hens of‘Jing Fen No.6’were randomly divided into 5 groups,with 6 replicates in each group.The test period was 8 weeks.The test treatments were:1.basic diet(CON);2.basic diet+50 mg/kg of Chlortetracycline Premix(AGP);3.basic diet+50 mg/kg of rosemary extract(RE50);4.basic diet+100 mg/kg of rosemary extract(RE100);5.basic diet+200 mg/kg of rosemary extract(RE200).The plasma biochemistry,antioxidant performance,immune status,cecum microorganisms,cecum short-chain fatty acids,production performance,and egg quality of the hens were measured.Results:The ethanolic extract obtained from rosemary leaves contained 13.85%Carnosic acid and 13.20%Carnosol.No significant differences in production performance were observed in all treatments in the feeding trials(P>0.05).Relative to CON,egg production rates increased by 7.44%and 5.10%in RE100 and RE200 treatments,respectively,and feed-to-egg ratios(FCR)decreased by 8.50%and 9.72%,respectively,slightly better than the AGP treatment.The results of egg quality analysis showed that high doses of RE were beneficial in increasing eggshell thickness and egg Haugh units(P<0.05),and RE at all concentrations reduced the pentadecanoic acid(C15:0)content of yolk(P<0.05),medium to high doses of RE increased the yolk stearic acid(C18:0)and oleic acid(C18:1 n9c)content(P<0.05),high doses of RE decreased the ratio of n-6/n-3 in egg yolk(P<0.05),and AGP treatment had no significant effect on the content of various fatty acids in egg yolk.The high dose of RE was beneficial to increase the activity of SOD in plasma and CAT and GSH-Px in the intestinal mucosa of laying hens(P<0.05)decreasing the levels of IL-6 and total cholesterol in plasma(P<0.05).The analysis of intestinal flora showed that the structure of the cecum flora of RE200-treated hens produced significant differences compared to CON(P<0.05),with a significant increase in the relative abundance of Eisenbergiella,Papillibacter,and Paraprevotella in the cecum(P<0.05),unclassified＿f＿Spirochaetaceae,and Bacteroides abundance were significantly decreased(P<0.05),and AGP treatment significantly reduced the relative abundance of Bacteroides in the cecum of laying hens.Low and medium doses of RE significantly increased isobutyric acid content in the cecum of laying hens(P<0.05),and AGP and RE200 treatments significantly increased butyric acid content in the cecum of laying hens(P<0.05).Conclusion:‘Kexuan 2~#’rosemary has a high content of antioxidant active ingredients,which is an excellent new variety suitable for the food industry,cosmetics,and medicine.Both antibiotic and RE treatments improved egg production and feed efficiency of late-phase laying hens to some extent,but the effects of both 200 mg/kg and 100 mg/kg of RE were slightly better than those of antibiotic treatment.The antioxidant performance and immune status of laying hens were significantly enhanced by the addition of 200 mg/kg of RE to the feed,while the antibiotic treatment did not have a significant effect on the antioxidant performance and immune status of laying hens.RE at 200 mg/kg significantly increased the relative abundance of Eisenbergiella,Paraprevotella,and Papillibacter populations in the cecum of laying hens,which facilitate the metabolism of protein substances,fiber,and starch,and decreased the relative abundance of the potentially pathogenic bacteria Bacteroides and unclassified＿f＿Spirochaetaceae.Dietary supplementation of RE is beneficial to the metabolic function of laying hens and reduces the intestinal stress caused by pathogenic bacteria.The addition of 200 mg/kg of RE to the feed is most effective for the overall consideration of performance,egg quality and health status of the hens.