| The goose liver has a high capacity for synthesis and storage of fatty acids.Goose fatty liver is a well-known delicacy with high nutritional value and special health care effects,and it is favored by consumers worldwide.Lipids play an important role in dietary formulas and provide the body with high levels of energy and essential fatty acids,especially the health benefits of polyunsaturated fatty acids(PUFAs)have received much attention.A lot of studies were developed to improve the contents of liver PUFAs and by changing the percentage composition of fatty acids in diet.However,the regulation mechanism is complicated and has not been illuminated.Besides,few comprehensive articles related to fatty liver performance,molecular regulation and gut microbiota were reported.In this study,different fats(tallow,fish oil,goose fat and rapeseed oil)and a feed additives,Jumpstar,were add to basal diets to study their effects on growth performance,fat deposition,serum parameters and liver fatty acid composition of Landes geese.In addition,the effects of them on intestinal morphology and microbiota were carried out.Meanwhile,Digital Gene Expression(DGE),quantitative real-time PCR(q-RT-PCR)were applied to explore the pathways how the liver fatty acids is regulated and detect candidate genes related to PUFAs and cholesterol,preliminarily clarified the molecular mechanisms that dietary PUFAs improve the n-3 PUFAs in goose fatty liver.1.Effects of different supplemental oils and hydrated sodium calcium aluminosilicate on serum parameters in overfed Landes geeseA flock of one hundred twenty 70-day-old healthy Landes geese(3.0±0.05 kg)was selected and randomly divided into 6 groups with 4 repeats and each repeat had 5 geese.The geese were overfed with the corn basal diet with the addition of either 2%goose fat(GF),fish oil(FO),rapeseed oil(RO),or beef tallow(BT)and 0.3%HSCAS through a 27-d period,with a 7 d pre-overfeeding period.The control group was ad libitum access to the corn basal diet(control I).As to determine effect of the hydrated sodium calcium aluminosilicate(Improved HSCAS,Jumpstar),the GF group was used as positive control(control II).The results showed that the addition of FO reduced the serum total triglycerides(TG),low density lipoproteins(LDL)and very low density lipoproteins(VLDL),and that of RO reduced LDL compared with the GF group(P<0.05).The serum total cholesterol(TC)in RO group was significantly lower than those in the BT group(P<0.05).Serum high density lipoproteins(HDL)levels in the BT group were significantly higher than those in the GF group(P<0.05).The levels of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)tend to be lower in the BT,FO and RO groups than in the GF group(P>0.05).Compared with the control I group,serum TC,TG,VLDL,cholinesterase,lipoprotein lipase,AST,ALT,IgA,IgM,and IgG levels in the HSCAS treatment group all significantly increased(P<0.05)after 20 days of overfeeding.Compared with the control II group,the IgA were higher in HACAS group after 20 days’overfeeding(P<0.05).HSCAS treatment also led to higher cholinesterase,VLDL and decreased lipase,ALT(P>0.05),and decreased AST levels than those in the Control II group(P<0.05).It is concluded that dietary supplementation with FO or RO leads to decrease serum lipids and HSCAS treatment improved serum parameters in overfed Landes geese,which could enhance the health status of these geese.2.Effects of different supplemental oils and HSCAS on fatty liver,fat deposition and liver fatty acid composition of overfed Landes geeseThe goal of this study was to determine the effect of different oils and HSCAS on fat deposition,growth performance,and the effect of four source of supplemental oils on liver fatty acid composition of overfed Landes geese.The results showed that the liver weight of the RO and BT groups was higher than that of the FO group,and the relative liver weight of BT was significantly higher than that of the GF group(P<0.05).The live and eviscerated weight of the RO and GF groups were significantly higher than those of the BT and FO group(P<0.05).The FO had lower content of total saturated fatty acids(SFA),and higher content of unsaturated fatty acids(UFA)C16:1,C17:I,C18:1,C18:2,C18:3,C20:1,C20:4,C20:5,C22:1,C22:5,C22:6,C24:1 and total UFA(P<0.05)than did the GF group.RO reduced the content of total SFA,and increased the content of UFA C16:1,C18:1,C18:2,C20:2,C22:1 and total UFA(P<0.05).Supplemental BT increased the content of C18:3,C20:1,C22:5,C22:6 and total polyunsaturated fatty acids(PUFA)(P<0.05).Compared with the Control I group,liver weight,relative liver weight,abdominal fat weight,and intestinal fat weight in the HSCAS treatment group all significantly increased(P<0.05)after 20 days of overfeeding.Compared with the Control II group,the relative liver weight was higher in HACAS group after 20 days’ overfeeding(P<0.05).It is concluded that dietary supplementation with RO or BT leads to better goose fatty liver performance.Both RO and FO can increase the liver PUFA without obvious effects on growth performance.BT supplementation increases production of fatty liver,but reduces fat deposition and growth performance.HSCAS treatment had a beneficial effect on fat deposition and fatty liver production.3.Digital gene-expression profiling analysis of the fatty liver of Landes geese fed different supplemental oilsA digital gene expression(DGE)profiling analysis of goose fatty livers based on RNA transcriptome sequencing was employed to screen the different expressed genes(DEGs)in 2%goose fat group(GF)and 2%rapeseed oil group(RO).Nine samples of liver total mRNAs were extracted,reverse transcripted,and sequenced respectively.DGE libraries were constructed from the three groups(three samples each group),and generated over 12 million clean reads per library,50.1%-56.7%of them were mapped to the goose reference genome.A total of 1290 and 1419 DEGs were identified in GF and RO,respectively,compared to C.Compared to GF,there were 124 up-regulated and 129 down-regulated DEGs in the fatty liver of RO.Of which,many DEGs code for proteins involved in the lipid metabolic process,including solute carrier family(SLC2A2,SLC2A5,and SLC5A9),all of which were up-regulated;cytochrome P450 family(CYP450 1A4,CYP450 2K1,and CYP4502C19),all of which were down-regulated;ELOVL fatty acid elongase family(ELOVL1,ELOVL2,and ELOVL3);and the ATP-binding cassette(ABC)transporters family(ABCA1,ABCB4,ABCC2,ABCG5,and ABCG8).And some DGEs involved in fatty acid biosynthesis such as SCD1,ACACA,and ACSBG2 also regulated by RO supplementation.The DGEs have pro-and anti-apoptosis roles,including caspase-7 and BCL2A1 which were up-regulated and TNFRSF17 and GAS2L3,which were down-regulated.Some oxidative stress-related genes such as PEX11A,SOD1,DAO,CRAT,and CROT,were all down-regulated.In addition,genes/proteins associated with steroid and steroid hormone biosynthesis were altered in RO,suggesting that the fatty liver of goose fed different oils undertakes both an oxidation function and hormone-related metabolic function.In conclusions,these data suggest that RO supplementation reduces liver lipid oxidation and improves lipogenesis.These findings provide new insights into the molecular mechanisms involved in fatty liver formation and provide valuable resources for analysing mechanisms underlying the effects of oils from different sources on the goose fatty liver.4.Effects of different supplemental oils and HSCAS on the liver and intestine morphology of overfed geeseIn the present study,the effect of different oils and HSCAS on morphology among 3 intestinal sections(duodenum,jejunum,and ileum)and liver tissues of overfed Landes geese were evaluated.Geese were randomly divided into control and treatment groups,fed with basal diet and overfed with basal diet added 2%goose fat,beef tallow,fish oil or rapeseed oil as well as 0.3%HSCAS for 27 days,respectively,with a 7 days pre-overfeeding period.Histological staining was applied to examine the morphology of intestines.The results showed that,in the oil-treated groups,the cell density in FO group was significantly higher than that in the BT and RO groups(P<0.05).The average cell area in the BT and GF group was higher than that in the fish oil and rapeseed oil group(P<0.05).Compared with goose fat group,dietary supplementation with beef tallow significantly reduced the VH and VH/CD in duodenum,jejunum and ileum(P<0.05).Fish oil treatment significantly reduced the VH in duodenum,and VH,CD in jejunum(P<0.05).Rapeseed oil had no significant effects on the other intestinal sections(P>0.05).The hepatocellular area of HSCAS was higher than that of the Control Ⅰ group(P<0.05),but was lower than that of the control Ⅱ group(P<0.05),and the cell integrity was better showed by H.E staining.The villus height and villus height/crypt depth of jejunum in HSCAS were also higher than those in the Control Ⅰ(P<0.05).Compared with the Control Ⅱ group,HACAS treatment reduced the crypt depth of jejunum(P<0.05).The results indicated that the hepatocytes in the BT and GF groups were larger than FO group and had more fat deposition.Of the intestinal sections,the ileum is the primary site for digestion and absorption in Landes geese,as this section exhibited optimal morphology.In conclusion,dietary supplementation with 2%beef tallow compromised intestinal morphology as a whole,in contrast,fish oil and rapeseed oil addition had a good effect.HSCAS treatment had a beneficial effect intestinal morphology in overfed Landes geese,which could enhance the digestion and absorption of nutrients,and had a good hepatocyte morphology,thereby promoting the fatty liver production of these geese.5.The effect of hydrated sodium calcium aluminosilicate on the composition of the intestinal microbiota in overfed Landes geeseThe goal of this study was to determine the effect of different oils and HSCAS on microbiota in ileum and cecum of overfed Landes geese.The treatment groups and experimental process were the same with the fourth experiment.16S rDNA V4 region sequencing was applied to examine the microbiota of intestines.The Clean Tags obtained from 16S rDNA V4 region sequencing were divided into 3,891 OTUs and 412 genera were obtained.The number of operational taxonomic units(OTUs)obtained was low in the ileum,which were more abundant in the cecum than in ileum.In ileum,the highest number of OTUs was in rapeseed oil group,and the least in fish oil group.As respect to cecum,the OTUs were high in goose fat and beef tallow group,which was least in fish oil group.Alpha diversity analysis indicated that the microbiotic diversity occurred in the ileum was lower than that of the cecum.And rapeseed oil significantly reduced the diversity of the ileum microbiota,while fish oil increased the the diversity of the cecum microbiota,which were reduced by beef tallow,goose fat and rapeseed oil supplementation.Taxa of Lactobacillus,Streptococcus,Escherichia,Bilophila wadsworthia,Faecalibacterium and Megamonas were chosen for further analysis on the results of linear discriminant analysis coupled with effect size(LEfSe).Cecum contained the large number of microorganisms that participate in fermentation.HSCAS supplementation increased the relative abundance of Lactobacillus,and decreased the relative abundance of Actinobacillus in the ileum and the relative abundance of Erysipelotrichi,Bacteroides and Escherichia in the ceca.Bacterial richness indicators were also increased in samples from ileum and ceca after HSCAS supplementation.In conclusion,dietary supplementation with 2%beef tallow reduced the richness and diversity of the microbiota as a whole,in contrast,fish oil and rapeseed oil addition had a good effect,as the increase of beneficial bacteria relative abundance in them.Dietary HSCAS supplementation had a beneficial effect on the intestinal microbiota composition of Landes geese during the overfeeding.It increased beneficial bacteria and reduced the harmful bacteria relative abundance,which promoted the liver performance in overfed geese.This study comprehensively examined the effects of dietary fats on digestive system,fatty liver performance and lipid metabolism of Landes geese.The results showed that dietary supplementation with RO or BT leads to better goose fatty liver performance.Both RO and FO can increase the liver PUFA and reduced serum lipids.2%GF and 2%RO had beneficial effects on intestinal morphology and microbiota.The mechanisms of reducing serum cholesterol and increasing PUFAs between 2%GF and 2%RO were different in liver lipid oxidation,steroid and steroid hormone biosynthesis and the synthesis of polyunsaturated fatty acids.HSCAS supplementation had a beneficial effect on fatty liver production,intestinal development,and serum parameters,and improved the intestinal microbiota composition of overfed Landes geese,which could enhance the health status of these geese.In the future,the flavor assessment of goose liver and cell-level experiments are needed perform to verify the effects of different fatty acids.The effects of different oil sources in the goose breeding industry need to be further evaluated in terms of nutritional values and economic costs. |
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