| The source and structural composition of fatty acids are important factors that affect the quality of pet food and pet health.The fatty acid composition of hemp oil,especially the proportion of essential fatty acids,is more in line with animal metabolism and has a higher potential for functional development.In this study,we aimed to explore the effects of adding different levels of hemp seed oil to the diet on nutrient digestion,intestinal microorganisms,biochemical blood indexes,antioxidant capacity,and metabolomics of dogs.Specifically,this study designed 25 female Teddy dogs aged 1-2 years in good health and similar weight(4.75kg±l.34kg)as observed samples.All data were collected randomly divided into 5 groups with 5 replicates in each group.The dogs were fed a full-price diet with 0(group A),0.5%(group B),1%(group C),2%(group D)and 4%(group E)of hemp seed oil.The entire experimental period consisted of a 15 days of pre-feeding period and 30 days of regular feeding period.The main study results were discussed as follows:(1)Nutrient digestibility analysis revealed that the addition of different levels of hemp seed oil to the diets had no significant effect(P>0.05)on dry matter(DM),crude protein(CP),and crude fat(EE);the addition of hemp seed oil had no significant effect(P>0.05)on dog fecal score.(2)The analysis of fecal microorganisms by 16s rRNA high-throughput sequencing technology revealed that the dominant phyla in feces were mainly Firmicutes,Fusobacteria,Proteobacteria,Actinobacteria,and Bacteroidetes.Among them,the Firmicutes accounted for the highest proportion,at 77.49%～89.51%.At the genus level,the dominant genera were mainly Peptoclostridium,Allobaculum,Peptococcus,Blautia;And alpha diversity index analysised the difference between groups was not significant(P>0.05).(3)Blood biochemical analysis revealed that the addition of hemp seed oil significantly increased the levels of Immunoglobulin M(IgM),Interferon-r(γ-IFN),Total protein(TP),Albumin(ALB),Thyroxine 4(T4),Triiodothyronine 3(T3)and Adrenocorticotropic hormone(ACTH)in the serum(P<0.05),with the highest TP and T3 levels in group C The highest levels of TP and T3 were found in group C,reaching 69.54 g/L and 1.67 nmol/L,respectively;the highest levels of IgM,γIFN and T4 were found in group D,reaching 1.52 g/L,31.78 ng/L and 36.75 nmol/L,respectively;the highest levels of ALB and ACTH were found in group E,reaching 40.38 g/L and 11.41 ppg/ml,respectively;which significantly reduced Triglycerides(TG)and Low-density lipoprotein cholesterol(LDL-C)levels(P<0.05),with the lowest TG level of 0.47 mmol/L in group C and the lowest LDL-C level of 0.26 mmol/L in group D.Serum Immunoglobulin G(IgG),Immunoglobulin E(IgE),Complement 4(C4),Globulin(GLB),Total cholesterol(TC),and blood Glucose(GLU)levels were not significantly different between groups(P>0.05).(4)From the analysis of antioxidant capacity,the addition of hemp seed oil increased Superoxide dismutase(SOD)significantly and decreased Minimum descent altitude(MDA)(P<0.05).Specifically,the highest SOD activity of 33.02 U/mL in group E and the lowest MDA content of 3.28 nmol/ml in group D.The differences between Total antioxidant capacity(T-AOC)and Catalase(CAT)groups were not significant(P>0.05).(5)The liquid chromatography-tandem mass spectrometry(LC-MS/MS)technique was used to detect metabolites in the blood of each group of dogs.The results showed that 440 metabolites were detected in the blood of dogs.Specifically,the observed data classified into 33 general categories,including mainly amino acids and their metabolites,organic acids and their derivatives,nucleotides and their metabolites,oxidized lipids,lipids,and other fatty acids.Annotation of the detected differential metabolites using the KEGG database and pathway enrichment analysis presented the primary differential metabolites.Specifically,the difference involved leukotriene B4,thromboxane B2,prostaglandin D2,2-’deoxyguanosine 5’-monophosphate,adenosine,goose deoxycholic acid,ubiquinone,taurocholic acid,adenosine-3’-phosphate,vitamin D3,α-linolenic acid/octadecatrienoic acid(cis-9,12,15),gamma-linolenic acid(C18:3),prostaglandin E2,and 20hydroxy-5Z,8Z,11Z,and 14Z-eicosatetraenoic acid.The main metabolic pathways involved in these differential metabolites are purine metabolism,arachidonic acid metabolism,biosynthesis of bile acids,oxidative phosphorylation,biosynthesis of unsaturated fatty acids,and rheumatoid arthritis.The addition of hemp seed oil to the diet significantly affects the content and type of metabolites in the blood.In summary,the addition of hemp seed oil to the diet had no significant effect on the digestibility of nutrients and intestinal microorganisms in dogs.However,it can significantly improve test dogs’ immunity,promotes lipid metabolism,improve antioxidant capacity,and the content and types of beneficial metabolites in the blood will be significantly higher and more when the amount added was 1%～2%appropriate. |
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