| Mulberry leaves are rich in nutrients,with physiological functions such as regulating glycolipid metabolism and maintaining immune balance,which can replace some raw materials in the diet of laying hens in production,improve the production performance and egg quality.After the peak egg production period,laying hens are prone to adverse symptoms such as egg production decreased and lipid metabolism disorders.However,the effect and mechanism of mulberry leaves on the lipid metabolism of laying hens in high-fat state are unknown.In this study,the effects of mulberry leaf powder on the production performance and lipid metabolism of high-fat diet-fed laying hens during the late phase of the laying cycle carried outs,and the regulatory mechanism of quercetin in mulberry leaves on chicken fat metabolism was analyzed,which provided a reference for the development and utilization of mulberry resources feed and animal health breeding.Part 1: Effects of high-fat diets on production performance,egg quality and lipid metabolism of laying hensA total of 160 71-week-old laying hens were randomly divided into two groups,namely basal diet group(control group)and high-fat diet group.The pre-experiment was 1 week,and the trial period last 4 weeks.During the test,production performance,egg quality and feed consumption were recorded.At the end of the experiment,physiological and biochemical indicators in blood and live,and internal organ index were measured.The results showed that:(1)Compared with the control group,the laying rate of laying hens in the high-fat diet group significantly reduced(P < 0.05),and there was no significant change in the feed intake and the feed-to-egg production ratio.The yolk color in the high-fat diet group decreased significantly(P < 0.05),and the albumen height and Hauth unit showed a decreasing trend.TG in yolk was significantly increased(P < 0.05),and T-CHO and LDLC showed an increasing trend.(2)TG,T-CHO and LDLC in the blood of laying hens in the high-fat diet group were significantly increased(P < 0.05),and HDLC was elevated but not significant.BUN,γ-GT and AKP were significantly elevated(P<0.05),while CRE,LDH,AST,ALT and GLU all showed an increasing trend but no significant.Inflammation factors IL-2,IL-1β,IL-6 and TNF-α all tended to decrease with no significant between groups.(3)The abdominal fat rate,gizzard index of laying hens in the high-fat diet group were significantly increased(P < 0.05).(4)Anatomical observation of liver showed that the liver was enlarged and yellowish yellow-brown,with a soft and brittle texture.The morphological manifestation is that there are fat vacuoles of different sizes and numbers in hepatocytes,and the structure of the hepatic sinus is not clear;Moreover,the number of fat droplets in the liver in the high-fat diet group increased significantly.TG in the liver was significantly elevated(P < 0.05),and T-CHO,HDLC and LDLC were all elevated but not significant.Part 2: Effect of mulberry leaves powder on the productive performance,egg quality and lipid metabolism in laying hens fed a high-fat dietBased on experiment 1,the basal diet group was randomly divided into: the basal diet group(control group),basal diet + 2.5% mulberry leaf powder group;The high-fat diet group was randomly divided into: high-fat diet group,high-fat diet + 2.5% mulberry leaf powder group.The trial period last 10 weeks.The results showed that:(1)Compared with the control group,the daily consumption,yolk color and eggshell thickness of laying hens with high-fat diet were significantly reduced(P < 0.05),egg weight and TG,T-CHO and HDLC in yolk were significantly increased(P < 0.05).After adding mulberry leaf powder to high-fat diet,the yolk color increased significantly(P < 0.05),and TG,HDLC and LDLC in yolk decreased significantly(P < 0.05).(2)TG,T-CHO,HDLC and LDLC in the blood were significantly increased in high-fat diet group(P < 0.05),and γ-GT,AKP,ALT,AST and GLU were significantly increased(P < 0.05).After adding mulberry leaf powder to high-fat diet,TG,TCHO,HDLC and LDLC in the blood of laying hens were significantly reduced(P < 0.05).The levels of BUN,CRE,γ-GT,AKP,LDH,ALT,AST and GLU were significantly reduced(P < 0.05).(3)The weight,kidney index,abdominal fat rate,number of small yellow follicles and small yellow follicle weight of laying hens fed a high-fat diet were significantly increased(P < 0.05);After adding mulberry leaf powder to high-fat diet,the abdominal fat rate of laying hens were significantly reduced(P < 0.05),the kidney index was significantly increased(P< 0.05),and the other organ index did not change significantly.(4)The liver color of laying hens with continuous feeding of high-fat diets was yellow brown,the size of hepatocytes was different in morphology,the structure of the hepatic sinus was not clear,larger fat vacuoles could be seen,and the number of fat droplets in the liver increased significantly;TG,T-CHO,HDLC and LDLC were significantly increased in the liver(P < 0.05).After adding mulberry leaf powder to the high-fat diet,the liver color was rosy,the hepatocytes were complete in morphology,neatly arranged and dense,the hepatic sinus was clear,and the number of lipid droplets in the liver was significantly reduced.TG,T-CHO,HDLC and LDLC were significantly reduced in the liver(P < 0.05).(5)The expression of m RNA in liver CYP3A5 of laying hens fed with high-fat diet was significantly reduced(P < 0.05);After adding mulberry leaf powder to high-fat diet,the m RNA expression of PPARα and APOB increased significantly(P < 0.05).(6)The metabolome results showed that high-fat diets could cause significant changes in small molecule metabolites in the liver of laying hens(P < 0.05),mainly including lipid metabolism,carbohydrate metabolism,nitrogenous small molecule metabolism,etc.After the addition of mulberry leaf powder to high-fat diet,mulberry leaf powder could cause significant changes in liver lipid metabolites including docosahexaenoic acid,16-glucuronic acid-estriol,and carbohydrate metabolites such as D-(+)-malic acid,Dgossypol sugar,and D-(+)-maltose(P < 0.05).Part 3: Effect and molecular mechanism of quercetin in the flavonoid in mulberry leaves on lipid metabolism in chicken liverIn this experiment,the effects,and regulatory mechanisms of different concentrations of mulberry leave flavonoid of quercetin(10,1000,1000,10 000 ng/m L)on cell viability and lipid metabolism were studied by isolating and culture chicken hepatocytes in vitro.The hepatocytes high-fat model was induced by oleic acid and dexamethasone(OA/DEX).The results showed that:(1)In the high-fat model,the content of lipid droplets and TG in hepatocytes increased significantly(P < 0.05),indicating that the high-fat model was successfully constructed.(2)When 10 000 ng/m L quercetin was added,TG,T-CHO,HDLC and LDLC were significantly reduced(P < 0.05),cell viability was significantly increased(P< 0.05),and IL-2 and IL-6 were significantly reduced(P < 0.05).(3)When 10 000 ng/m L quercetin was added,the m RNA expression of APOB,PPARα,CYP3A5 and SREBP-1 was significantly reduced(P < 0.05).(4)When 10 000 ng/m L quercetin was added,the protein levels of PI3Kp85,PI3Kp110,ERK,p-ERK and SREBP-1 proteins was significantly reduced(P < 0.05).In summary,continuous feeding of high-fat diets can reduce the production performance of laying hens,cause abdominal fat deposition,and increase the content of lipid indexes such as TG in the liver and blood.The addition of mulberry leaf powder to the diet can reduce the content of lipid indexes such as TG in liver and blood,increase the expression of m RNAs related to lipid transport function such as PPARα,and cause changes in small molecule metabolites such as liver lipid metabolism.Quercetin can alleviate OA/DEX induced fat deposition in chicken primary hepatocytes models and may promote lipid metabolism and improve liver function through PI3K/AKT and ERK signaling pathways. |
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