Effect Of Dietary Theabrownin Supplementation On Production Performance,Egg Quality,Hepatic Lipid Metabolism And Ovarian Function In Laying Hens

Theabrownin（TB）,a rich and active substance in Pu’er tea,is known to have the functions of regulating lipid metabolism,intestinal flora balance and antioxidation in humans and model animal（mice and rats）,but the research on poultry is scarce.This trial was aimed to explore the effect of dietary TB supplementation on production performance,egg quality,intestinal health,lipid metabolism and ovarian function in laying hens,and find appropriate dosage of TB in the basal diet of layers.One factor design was used in this experiment.In total,160 Lohman laying hens,25 weeks old and weight as well as laying rate were similar,were randomly allocated to 4 treatment groups,namely the control group（basal diet+0 mg/kg TB）,TB1 group（basal diet+100 mg/kg TB）,TB2 group（basal diet+200 mg/kg TB）,and TB4 group（basal diet+400 mg/kg TB）,respectively.For each treatment（n=40）,there were 10 replicates of 4birds each that were raised in a single cage.The entire experimental time was 12 weeks.Result:（1）The addition of 100mg/kg TB in basal diet significantly increased laying rate during 9-12 weeks,egg wight during 5-8 weeks as well as 1-12 weeks and decreased the ratio of feed to egg during 1-12 weeks（P<0.05）.The average egg weight of 1-12weeks showed quadratic change,which first increased and then decreased.(P _Quadratic<0.05).（2）The addition of TB in basal diet significantly enhanced the albumen height（P<0.05）and Haugh unit（P<0.01）at the 8th and 12th weeks（the albumen height as well as Haugh unit at 8th week and the albumen height at 12th week were increased linearly）,meanwhile,linearly enhanced the DPPH free radical scavenging ability and reduced the concentration of Malondialdehyde（MDA）(P _Linear<0.01)in egg yolk.At the same time,the addition of TB linearly enhanced the reducing power of yolk and albumen(P _Linear<0.01),and linearly heightened the total anti-oxidant capacity（T-AOC）of yolk(P _Linear<0.01)and albumen(P _Linear<0.05).After storage of 21 days,the albumen height and Haugh unit in TB treatment were higher significantly compared to CONT group,and linear correlation(P _Linear<0.01).（3）Compared with CONT group,the concentration of Cysteine（Cys）in hydrolyzed amino acids of egg yolk was linearly decreased(P _Linear<0.01).At the same time,the concentration of Methionine（Met）and Histidine（His）in hydrolyzed amino acids of egg yolk in TB2 and TB4 groups were linearly increased(P _Linear<0.01).The concentration of Cysteine（Cys）in free amino acids of egg yolk was linearly increased(P _Linear<0.01).The concentration of Tryptophan（Trp）in free amino acids of egg yolk in TB1,TB2 and TB4 groups was linearly increased(P _Linear<0.01).Dietary TB supplementation significantly increased the concentration of vitamin A andα-tocopherol in egg yolk,andα-tocopherol showed quadratic change of increased first and then decreased(P _Quadratic<0.01).At the results of free amino acids in albumen,Compared with CONT group,the concentration of Cysteine（Cys）and Tryptophan（Trp）of TB4 group were significantly increased,and the increase of Cys is linear(P _Linear<0.01),the concentration of Tyrosine（Tyr）of TB2 and TB4 group was linearly increased and the concentration of Valine（Val）and Histidine（His）in TB1,TB2 and TB4 groups were significantly increased,the increase of Val is linear(P _Linear<0.05).（4）Compared with CONT group,the m RNA expression of zonula occludens-1（ZO-1）,Claudin-1 and Mucin-2 of TB1 and TB2 groups in jejunum were up-regulated（P<0.05）.The addition of TB in basal diet significantly down-regulated the m RNA expression of Interleukin-1β（IL-1β）（P<0.05）,Interleukin-6（IL-6）（P<0.01）and Tumor necrosis factor alpha（TNF-α）（P<0.05）in jejunum.In the meantime,the concentration of IL-6 was reduced by TB intervention（P<0.05）.（5）Dietary TB supplementation significantly decreased the concentration of low-density lipoprotein cholesterol（LDL-C）,total cholesterol（TC）and total triglyceride（TG）in serum（P<0.05）.The addition of TB linearly increased the concentration of total protein（TP）in serum（P<0.05）.Compared with CONT group,the addition of TB significantly reduced the concentration of TG as well as TC and lipid droplet optical density in liver（P<0.01）.At the same time,addition of TB significantly decreased the hepatic m RNA expression of key enzymes of lipid synthesis pathway Acetyl-Co A carboxylation（ACC）（P<0.05）,increased the hepatic m RNA expression of cholesterol decomposition key enzyme CYP8B1（P<0.01）.（6）Dietary TB linearly enhanced the concentration of serotonin（5-HT）(P _Linear<0.01),follicle-stimulating hormone（FSH）(P _Linear<0.01)and estradiol（E2）(P _Linear<0.05)in serum,compared to CONT group.Meanwhile,the addition of TB linearly increased the concentration of anti-mullerian hormone（AMH）(P _Linear<0.05)and melatonin（MT）(P _Linear<0.01)in serum.The addition of TB linearly increased the activity of glutathione（GSH）in ovary(P _Linear<0.05).Addition of TB linearly increased the activity of superoxide dismutase（SOD）as well as catalase（CAT）,and linearly reduced the activity of 8-hydroxy-2 deoxyguanosine（8-OHDG）in magnum(P _Linear<0.01).The activity of GSH in magnum linearly enhanced(P _Linear<0.01).Dietary TB linearly reduced the concentration of MDA in magnum(P _Linear<0.01).Dietary TB significantly up-regulated the expression of anti-apoptotic gene B-cell lymphonma-2（Bcl-2）in ovary（P<0.05）.In the meantime,dietary TB significantly up-regulated the expression of antioxidative gene nuclear factor-E2 related factor 2（Nrf2）,heme oxygenase-1（HO-1）and NAD（P）H:quinone oxidoreductase 1（NQO1）in magnum（P<0.01）.The expression of Bcl-2 associated X protein（Bax）of TB4 group in magnum was significantly down-regulated compared to CONT group（P<0.05）.The expression of anti-apoptotic gene Bcl-2 of TB1,TB2 and TB4 groups in magnum was significantly up-regulated compared to CONT group（P<0.05）.The results of this experiment manifested that TB elevated the production performance and egg quality by ameliorating intestinal,lipid metabolism and ovarian function.Meanwhile,the effect of improving Albumen quality is related to Nrf2 signal pathway.In this study,based on the egg laying rate,egg weight and feed conversation ratio,it is recommended that the most suitable dosage for laying hens in peak period is100 mg/kg;Based on the Haugh unit and Albumen height,it is recommended that the appropriate addition amount for laying hens in peak period is 100-400 mg/kg;After comprehensive consideration,the recommended dosage is 100 mg/kg.