Effects Of Probiotic Fermented Feed On Production Performance,Egg Quality And Lipid Metabolism Of Laying Hens

When laying hens enter the laying period,their metabolism is in the most vigorous state,and their resistance is relatively weak,which makes them vulnerable to stimulation from various stress factors.For commodity laying hens,if improper feeding peak in egg production management,will shorten the preserved egg production peak time,and the body’s physiological function and metabolic will gradually degenerate,to feed in the absorption of nutrients decreased significantly,easily lead to fat in the liver tissue deposition rate too fast,fat deposition quantity increased,after the accumulation to a certain extent,fatty liver syndrome is seen,As a result,the performance and egg quality decreased significantly,which caused serious economic losses to laying hens.In order to solve the problem of healthy breeding of laying hens,it is consistent with the trend that antibiotics as drug additives are gradually banned in the feed of laying hens during laying period.Therefore,green and safe probiotic fermented feed has become a research hotspot.In order to evaluate the effects of different levels of probiotic fermented feeds on production performance,egg quality and lipid metabolism of laying hens.In this experiment,corn,soybean meal and bran were used as substrates to prepare fermented feed with compound probiotics.A total of 360 layers(Jingfen No.6,23-wk-age)assigned to 4 dietary treatments(6 replicates/treatment and 15 birds/replicate).The control group was provided with the basal diet,while the experimental groups were provided with 4%,6% and 8% probiotics fermented mixed feed,respectively.The pre-experimental period lasted for two weeks and the experimental period lasted for 25 weeks.Nutritional composition,performance,egg quality,serum physiological and biochemical indexes and egg cholesterol content of probiotics fermented feed were determined,and the possible molecular mechanism of the regulation of lipid metabolism of laying hens by probiotics fermented feed was preliminarily revealed based on liver transcriptome analysis.The following main findings were obtained:1.Adding 6% probiotic fermented mixed feed significantly promoted the laying hens’ egg production rate and average egg weight(P<0.05),which had no significantly effects on average daily feed intake and feed egg ratio(P>0.05).Compared with control group,the addition of probiotics fermentation feed in the diet had no significantly effects on eggshell strength,protein height,huff unit and eggshell thickness(P>0.05).whereas yolk color of the probiotic fermented feed with 6% addition was significantly higher than that of control group(P<0.05).2.The contents of triglycerides and cholesterol in egg yolk were remarkably decreased(P<0.05).Compared with the group,the triglyceride and total cholesterol levels in serum of laying hens added with 6% probiotic fermented feed decreased by 30% and 16%,respectively.3.Through liver transcriptome sequencing,the regulatory mechanisms affecting the differential expression of genes related to lipid metabolism in laying hens were explored at the molecular level.A total of 518 differentially expressed genes were screened out in the control group and the experimental group.Compared with the control group,258 differentially expressed genes were up-regulated and 260 differentially expressed genes were down-regulated.The GO function enrichment analysis of differentially expressed genes revealed 32 significantly enriched functions(P<);Among them,21 were enriched in biological processes(BP),10 in cellular components(CC),1 in molecular function(MF),and 8in GO were mainly related to lipid metabolism-related metabolic processes such as cholesterol metabolism,sterol biosynesis and triglyceride.The genes with the highest differential expression were LPL and HMGCR.Enrichment analysis of differentially expressed gene KEGG pathways revealed that there were 4 significantly enriched KEGG signaling pathways,3 of which were related to lipid metabolism in the liver of laying hens.Conclusions:(1)Probiotic fermented feed can improve the nutritional value of feed ingredients,increase the content of crude protein,reduce the content of crude fiber,which can effectively improve the production performance and egg quality of laying hens,can be in a certain extent,regulate lipid metabolism of laying hens,laying hens lowering of blood lipid levels and the lipid content of eggs,prevent fat metabolism disorder in laying hens.According to the comprehensive evaluation,the optimal supplemental amount of probiotics fermented feed was 6%.(2)6% probiotics fermented feed affects liver lipid metabolism by up-regulating or down-regulating the expression of genes related to lipid metabolism,and finally regulates the performance of laying hens.