Effects of different energy levels in low-protein diet on liver lipid metabolism in the late-phase laying hens through the gut-liver axis

Background The energy/protein imbalance in a low-protein diet induces lipid metabolism disorders in late-phase laying hens.Reducing energy levels in the low-protein diet to adjust the energy-to-protein ratio may improve fat deposition,but this also decreases the laying performance of hens.This study investigated the mechanism by which different energy levels in the low-protein diet influences liver lipid metabolism in late-phase laying hens through the enterohepatic axis to guide feed optimization and nutrition strategies.A total of 288 laying hens were randomly allocated to the normal-energy and normal-protein diet group(positive control:CK)or 1 of 3 groups:lowenergy and low-protein diet(LL),normal-energy and low-protein diet(NL),and high-energy and low-protein diet(HL)groups.The energy-to-protein ratios of the CK,LL,NL,and HL diets were 0.67,0.74,0.77,and 0.80,respectively.Results Compared with the CK group,egg quality deteriorated with increasing energy intake in late-phase laying hens fed low-protein diet.Hens fed LL,NL,and HL diets had significantly higher triglyceride,total cholesterol,acetylCo A carboxylase,and fatty acid synthase levels,but significantly lower hepatic lipase levels compared with the CK group.Liver transcriptome sequencing revealed that genes involved in fatty acid beta-oxidation(ACOX1,HADHA,EHHADH,and ACAA1)were downregulated,whereas genes related to fatty acid synthesis(SCD,FASN,and ACACA)were upregulated in LL group compared with the CK group.Comparison of the cecal microbiome showed that in hens fed an LL diet,Lactobacillus and Desulfovibrio were enriched,whereas riboflavin metabolism was suppressed.Cecal metabolites that were most significantly affected by the LL diet included several vitamins,such as riboflavin(vitamin B2),pantethine(vitamin B5 derivative),pyridoxine(vitamin B6),and 4-pyridoxic acid.Conclusion A lipid metabolism disorder due to deficiencies of vitamin B2 and pantethine originating from the metabolism of the cecal microbiome may be the underlying reason for fat accumulation in the liver of late-phase laying hens fed an LL diet.Based on the present study,we propose that targeting vitamin B2 and pantethine(vitamin B5 derivative)might be an effective strategy for improving lipid metabolism in late-phase laying hens fed a low-protein diet.

Rosemary extract improves egg quality by altering gut barrier function,intestinal microbiota and oviductal gene expressions in late-phase laying hens

Background Rosemary extract(RE)has been reported to exert antioxidant property.However,the application of RE in late-phase laying hens on egg quality,intestinal barrier and microbiota,and oviductal function has not been systematically studied.This study was investigated to detect the potential effects of RE on performance,egg quality,serum parameters,intestinal heath,cecal microbiota and metabolism,and oviductal gene expressions in late-phase laying hens.A total of 21065-week-old“Jing Tint 6”laying hens were randomly allocated into five treatments with six replicates and seven birds per replicate and fed basal diet(CON)or basal diet supplemented with chlortetracycline at 50 mg/kg(CTC)or RE at 50 mg/kg(RE50),100 mg/kg(RE100),and 200 mg/kg(RE200).Results Our results showed that RE200 improved(P<0.05)Haugh unit and n-6/n-3 of egg yolk,serum superoxide dismutase(SOD)compared with CON.No significant differences were observed for Haugh unit and n-6/n-3 of egg yolk among CTC,RE50,RE100 and RE200 groups.Compared with CTC and RE50 groups,RE200 increased serum SOD activity on d 28 and 56.Compared with CON,RE supplementation decreased(P<0.05)total cholesterol(TC)level.CTC,RE100 and RE200 decreased(P<0.05)serum interleukin-6(IL-6)content compared with CON.CTC and RE200 increased jejunal m RNA expression of ZO-1 and Occludin compared with CON.The biomarkers of cecal microbiota and metabolite induced by RE 200,including Firmicutes,Eisenbergiella,Paraprevotella,Papillibacter,and butyrate,were closely associated with Haugh unit,n-6/n-3,SOD,IL-6,and TC.PICRUSt2 analysis indicated that RE altered carbohydrate and amino acid metabolism of cecal microbiota and increased butyrate synthesizing enzymes,including 3-oxoacid Co A-transferase and butyrate-acetoacetate Co A-transferase.Moreover,transcriptomic analysis revealed that RE200 improved gene expressions and functional pathways related to immunity and albumen formation in the oviductal magnum.Conclusions Dietary supplementation with 200 mg/kg RE could increase egg quality of late-phase laying hens via modulating intestinal barrier,cecal microbiota and metabolism,and oviductal function.Overall,RE could be used as a promising feed additive to improve egg quality of laying hens at late stage of production.

Coated sodium butyrate ameliorates high‑energy and low‑protein diet induced hepatic dysfunction via modulating mitochondrial dynamics, autophagy and apoptosis in laying hens

Background Fatty liver hemorrhagic syndrome(FLHS),a fatty liver disease in laying hens,poses a grave threat to the layer industry,stemming from its ability to trigger an alarming plummet in egg production and usher in acute mortality among laying hens.Increasing evidence suggests that the onset and progression of fatty liver was closely related to mitochondria dysfunction.Sodium butyrate was demonstrated to modulate hepatic lipid metabolism,alle-viate oxidative stress and improve mitochondrial dysfunction in vitro and mice models.Nevertheless,there is limited existing research on coated sodium butyrate(CSB)to prevent FLHS in laying hens,and whether and how CSB exerts the anti-FLHS effect still needs to be explored.In this experiment,the FLHS model was induced by administering a high-energy low-protein(HELP)diet in laying hens.The objective was to investigate the effects of CSB on alleviating FLHS with a focus on the role of CSB in modulating mitochondrial function.Methods A total of 288 healthy 28-week-old Huafeng laying hens were arbitrarily allocated into 4 groups with 6 replicates each,namely,the CON group(normal diet),HELP group(HELP diet),CH500 group(500 mg/kg CSB added to HELP diet)and CH750 group(750 mg/kg CSB added to HELP diet).The duration of the trial encompassed a period of 10 weeks.Results The result revealed that CSB ameliorated the HELP-induced FLHS by improving hepatic steatosis and patho-logical damage,reducing the gene levels of fatty acid synthesis,and promoting the mRNA levels of key enzymes of fatty acid catabolism.CSB reduced oxidative stress induced by the HELP diet,upregulated the activity of GSH-Px and SOD,and decreased the content of MDA and ROS.CSB also mitigated the HELP diet-induced inflammatory response by blocking TNF-α,IL-1β,and F4/80.In addition,dietary CSB supplementation attenuated HELP-induced activation of the mitochondrial unfolded protein response(UPRmt),mitochondrial damage,and decline of ATPase activity.HELP diet decreased the autophagosome formation,and downregulated LC3B but upregulated p62 protein expression,which CSB administration reversed.CSB reduced HELP-induced apoptosis,as indicated by decreases in the Bax/Bcl-2,Caspase-9,Caspase-3,and Cyt C expression levels.Conclusions Dietary CSB could ameliorate HELP diet-induced hepatic dysfunction via modulating mitochondrial dynamics,autophagy,and apoptosis in laying hens.Consequently,CSB,as a feed additive,exhibited the capacity to prevent FLHS by modulating autophagy and lipid metabolism.

Lactiplantibacillus plantarum FRT4 attenuates high-energy low-protein dietinduced fatty liver hemorrhage syndrome in laying hens through regulating gut-liver axis

Background Fatty liver hemorrhage syndrome(FLHS)becomes one of the most major factors resulting in the laying hen death for caged egg production.This study aimed to investigate the therapeutic effects of Lactiplantibacillus plan-tarum(Lp.plantarum)FRT4 on FLHS model in laying hen with a focus on liver lipid metabolism,and gut microbiota.Results The FLHS model of laying hens was established by feeding a high-energy low-protein(HELP)diet,and the treatment groups were fed a HELP diet supplemented with differential proportions of Lp.plantarum FRT4.The results indicated that Lp.plantarum FRT4 increased laying rate,and reduced the liver lipid accumulation by regulating lipid metabolism(lipid synthesis and transport)and improving the gut microbiota composition.Moreover,Lp.plan-tarum FRT4 regulated the liver glycerophospholipid metabolism.Meanwhile,“gut-liver”axis analysis showed that there was a correlation between gut microbiota and lipid metabolites.Conclusions The results indicated that Lp.plantarum FRT4 improved the laying performance and alleviated FLHS in HELP diet-induced laying hens through regulating“gut-liver”axis.Our findings reveal that glycerophospholipid metabolism could be the underlying mechanism for the anti-FLHS effect of Lp.plantarum FRT4 and for future use of Lp.plantarum FRT4 as an excellent additive for the prevention and mitigation of FLHS in laying hens.

Effect of dietary supplementation with discardednutrient medium of Cordyceps militaris on layingperformance and diversity of intestinal flora in laying hens

The aim of the experiment was to explore the feasibility of discarded nutrient medium of Cordyceps militaris as feed in the production of laying hens. 100 g/kg, 200 g/kg, 300 g/kg of discarded nutrient medium of Cordyceps militaris were added to the basal diet of laying hens. The results showed that the optimal addition of discarded nutrient medium of Cordyceps militaris in the diet of laying hens was 10%. According to the results of measuring the conventional indicators of eggs, the weight of eggs produced by laying hens fed with discarded nutrient medium of Cordyceps militaris was higher than that of laying hens fed with ordinary laying hens. The content of interleukin-1(IL-1) in the experimental group was significantly higher than that in the control group, and the concentration of IL-1 increased by 141.5 pg/mL, which indicated that the application of discarded nutrient medium of Cordyceps militaris effectively improved the immunity of laying hens. The high-throughput analysis of the intestinal contents of the two groups of laying hens showed that the microbial population abundance of the intestinal tract of the experimental group was greater than that of control group, and the application of discarded nutrient medium of Cordyceps militaris increased the diversity of bacteria in the intestinal tract of laying hens. In addition, the sensitivity of some pathogenic bacteria in the intestinal tract of chickens to drugs was also increased, thereby reducing the use of antibiotics. The secondary utilization of discarded nutrient medium of Cordyceps militaris has great development and utilization prospects, which provided a scientific reference and basic theoretical basis for the development of discarded nutrient medium of Cordyceps militaris as feed in the production of laying hens.

Multi-omics analysis reveals the molecular regulatory network underlying the prevention of Lactiplantibacillus plantarum against LPS-induced salpingitis in laying hens

Background Salpingitis is one of the common diseases in laying hen production, which greatly decreases the economic outcome of laying hen farming. Lactiplantibacillus plantarum was effective in preventing local or systemic inflammation, however rare studies were reported on its prevention against salpingitis. This study aimed to investigate the preventive molecular regulatory network of microencapsulated Lactiplantibacillus plantarum(MLP) against salpingitis through multi-omics analysis, including microbiome, transcriptome and metabolome analyses.Results The results revealed that supplementation of MLP in diet significantly alleviated the inflammation and atrophy of uterus caused by lipopolysaccharide(LPS) in hens(P < 0.05). The concentrations of plasma IL-2 and IL-10 in hens of MLP-LPS group were higher than those in hens of LPS-stimulation group(CN-LPS group)(P < 0.05). The expression levels of TLR2, MYD88, NF-κB, COX2, and TNF-α were significantly decreased in the hens fed diet supplemented with MLP and suffered with LPS stimulation(MLP-LPS group) compared with those in the hens of CN-LPS group(P < 0.05). Differentially expressed genes(DEGs) induced by MLP were involved in inflammation, reproduction, and calcium ion transport. At the genus level, the MLP supplementation significantly increased the abundance of Phascolarctobacterium, whereas decreased the abundance of Candidatus_Saccharimonas in LPS challenged hens(P < 0.05). The metabolites altered by dietary supplementation with MLP were mainly involved in galactose, uronic acid, histidine, pyruvate and primary bile acid metabolism. Dietary supplementation with MLP inversely regulates LPSinduced differential metabolites such as Lyso PA(24:0/0:0)(P < 0.05).Conclusions In summary, dietary supplementation with microencapsulated Lactiplantibacillus plantarum prevented salpingitis by modulating the abundances of Candidatus_Saccharimonas, Phascolarctobacterium, Ruminococcus_torques_group and Eubacterium_hallii_group while downregulating the levels of plasma metabolites, p-tolyl sulfate, o-cresol and N-acetylhistamine and upregulating S-lactoylglutathione, simultaneously increasing the expressions of CPNE4, CNTN3 and ACAN genes in the uterus, and ultimately inhibiting oviducal inflammation.

Prevotella and succinate treatments altered gut microbiota,increased laying performance,and suppressed hepatic lipid accumulation in laying hens

Background This work aimed to investigate the potential benefits of administering Prevotella and its primary metabolite succinate on performance,hepatic lipid accumulation and gut microbiota in laying hens.Results One hundred and fifty 58-week-old Hyline Brown laying hens,with laying rate below 80%and plasma triglyceride(TG)exceeding 5 mmol/L,were used in this study.The hens were randomly allocated into 5 groups and subjected to one of the following treatments:fed with a basal diet(negative control,NC),oral gavage of 3 mL/hen saline every other day(positive control,PC),gavage of 3 mL/hen Prevotella melaninogenica(10^(7)CFU/mL,PM)or 3 mL/hen Prevotella copri(10^(7)CFU/mL,P.copri)every other day,and basal diet supplemented with 0.25%sodium succinate(Succinate).The results showed that PM and P.copri treatments significantly improved laying rate compared to the PC(P<0.05).The amount of lipid droplet was notably decreased by PM,P.copri,and Succinate treatments at week 4 and decreased by P.copri at week 8(P<0.05).Correspondingly,the plasma TG level in Succinate group was lower than that of PC(P<0.05).Hepatic TG content,however,was not significantly influenced at week 4 and 8(P>0.05).PM treatment increased(P<0.05)the mRNA levels of genes PGC-1βand APB-5B at week 4,and ACC and CPT-1 at week 8.The results indicated enhanced antioxidant activities at week 8,as evidenced by reduced hepatic malondialdehyde(MDA)level and improved antioxidant enzymes activities in PM and Succinate groups(P<0.05).Supplementing with Prevotella or succinate can alter the cecal microbiota.Specifically,the abundance of Prevotella in the Succinate group was significantly higher than that in the other 4 groups at the family and genus levels(P<0.05).Conclusions Oral intake of Prevotella and dietary supplementation of succinate can ameliorate lipid metabolism of laying hens.The beneficial effect of Prevotella is consistent across different species.The finding highlights that succinate,the primary metabolite of Prevotella,represents a more feasible feed additive for alleviating fatty liver in laying hens.

Decreased eggshell strength caused by impairment of uterine calcium transport coincide with higher bone minerals and quality in aged laying hens

Background Deteriorations in eggshell and bone quality are major challenges in aged laying hens.This study compared the differences of eggshell quality,bone parameters and their correlations as well as uterine physiologi-cal characteristics and the bone remodeling processes of hens laying eggs of different eggshell breaking strength to explore the mechanism of eggshell and bone quality reduction and their interaction.A total of 24074-week-old Hy-line Brown laying hens were selected and allocated to a high(HBS,44.83±1.31 N)or low(LBS,24.43±0.57 N)eggshell breaking strength group.Results A decreased thickness,weight and weight ratio of eggshells were observed in the LBS,accompanied with ultrastructural deterioration and total Ca reduction.Bone quality was negatively correlated with eggshell quality,marked with enhanced structures and increased components in the LBS.In the LBS,the mammillary knobs and effective layer grew slowly.At the initiation stage of eggshell calcification,a total of 130 differentially expressed genes(DEGs,122 upregulated and 8 downregulated)were identified in the uterus of hens in the LBS relative to those in the HBS.These DEGs were relevant to apoptosis due to the cellular Ca overload.Higher values of p62 protein level,caspase-8 activity,Bax protein expression and lower values of Bcl protein expression and Bcl/Bax ratio were seen in the LBS.TUNEL assay and hematoxylin-eosin staining showed a significant increase in TUNEL-positive cells and tissue damages in the uterus of the LBS.Although few DEGs were identified at the growth stage,similar uterine tissue damages were also observed in the LBS.The expressions of runt-related transcription factor 2 and osteocal-cin were upregulated in humeri of the LBS.Enlarged diameter and more structural damages of endocortical bones and decreased ash were observed in femurs of the HBS.Conclusion The lower eggshell breaking strength may be attributed to a declined Ca transport due to uterine tissue damages,which could affect eggshell calcification and lead to a weak ultrastructure.Impaired uterine Ca transport may result in reduced femoral bone resorption and increased humeral bone formation to maintain a higher mineral and bone quality in the LBS.

Dietary supplementation of Macleaya cordata extract and Bacillus in combination improve laying performance by regulating reproductive hormones,intestinal microbiota and barrier function of laying hens

Background:This study aimed to investigate whether the combination of Macleaya cordata extract(MCE)and Bacil-lus could improve the laying performance and health of laying hens better.Methods:A total of 36029-week-old Jingbai laying hens were randomly divided into 4 treatments:control group(basal diet),MCE group(basal diet+MCE),Probiotics Bacillus Compound(PBC)group(basal diet+compound Bacil-lus),MCE+PBC group(basal diet+MCE+compound Bacillus).The feeding experiment lasted for 42 d.Results:The results showed that the laying rate and the average daily egg mass in the MCE+PBC group were significantly higher than those in the control group(P<0.05)and better than the MCE and PBC group.Combina-tion of MCE and Bacillus significantly increased the content of follicle-stimulating hormone(FSH)in the serum and up-regulated the expression of related hormone receptor gene(estrogen receptor-β,FSHR and luteinizing hormone/choriogonadotropin receptor)in the ovary of laying hens(P<0.05).In the MCE+PBC group,the mRNA expressions of zonula occluden-1,Occludin and mucin-2 in jejunum was increased and the intestinal epithelial barrier detected by transmission electron microscopy was enhanced compared with the control group(P<0.05).In addition,compared with the control group,combination of MCE and Bacillus significantly increased the total antioxidant capacity and catalase activity(P<0.05),and down-regulated the mRNA expressions of inflammation-related genes(interleukin-1βand tumor necrosis factor-α)as well as apoptosis-related genes(Caspase 3,Caspase 8 and P53)(P<0.05).The concen-tration of acetic acid and butyric acid in the cecum content of laying hens in the MCE+PBC group was significantly increased compared with the control group(P<0.05).Conclusions:Collectively,dietary supplementation of 600μg/kg MCE and 5×108 CFU/kg compound Bacillus can improve laying performance by improving microbiota to enhance antioxidant capacity and intestinal barrier,regulate reproductive hormones and the concentration of cecal short-chain fatty acids of laying hens,and the combined effect of MCE and Bacillus is better than that of single supplementation.

Chronic heat stress induces renal fibrosis and mitochondrial dysfunction in laying hens

Background Heat stress in laying hens negatively affects egg production and shell quality by disrupting the homeo-stasis of plasma calcium and phosphorus levels.Although the kidney plays an important role in calcium and phos-phorus homeostasis,evidence regarding the effect of heat stress on renal injury in laying hens is yet to be elucidated.Therefore,the aim of this study was to evaluate the effects of chronic heat stress on renal damage in hens during laying periods.Methods A total of 16 white-leghorn laying hens(32 weeks old)were randomly assigned to two groups(n=8).One group was exposed to chronic heat stress(33°C for 4 weeks),whereas the other group was maintained at 24°C.Results Chronic heat exposure significantly increased plasma creatinine and decreased plasma albumin levels(P<0.05).Heat exposure also increased renal fibrosis and the transcription levels of fibrosis-related genes(COLA1A1,αSMA,and TGF-β)in the kidney.These results suggest that renal failure and fibrosis were induced by chronic heat exposure in laying hens.In addition,chronic heat exposure decreased ATP levels and mitochondrial DNA copy number(mtDNA-CN)in renal tissue,suggesting that renal mitochondrial dysfunction occurs under conditions of heat stress.Damaged mitochondria leak mtDNAs into the cytosol and mtDNA leakage may activate the cyclic GMP-AMP synthase(cGAS)stimulator of interferon genes(STING)signaling pathway.Our results showed that chronic heat exposure activated the cGAS-STING pathway as indicated by increased expression of MDA5,STING,IRF7,MAVS,and NF-κB levels.Furthermore,the expression of pro-inflammatory cytokines(IL-12)and chemokines(CCL4 and CCL20)was upregulated in heat-stressed hens.Conclusions These results suggest that chronic heat exposure induces renal fibrosis and mitochondrial damage in laying hens.Mitochondrial damage by heat stress may activate the mtDNA-cGAS-STING signaling and cause subse-quent inflammation,which contributes to the progression of renal fibrosis and dysfunction.

Adjusting phosphate feeding regimen according to daily rhythm increases eggshell quality via enhancing medullary bone remodeling in laying hens

Background Body phosphorus metabolism exhibits a circadian rhythm over the 24-h daily cycle.The egg laying behavior makes laying hens a very special model for investigating phosphorus circadian rhythms.There is lack of information about the impact of adjusting phosphate feeding regimen according to daily rhythm on the phosphorus homeostasis and bone remodeling of laying hens.Methods and results Two experiments were conducted.In Exp.1,Hy-Line Brown laying hens(n=45)were sampled according the oviposition cycle(at 0,6,12,and 18 h post-oviposition,and at the next oviposition,respectively;n=9 at each time point).Diurnal rhythms of body calcium/phosphorus ingestions and excretions,serum calcium/phosphorus levels,oviduct uterus calcium transporter expressions,and medullary bone(MB)remodeling were illustrated.In Exp.2,two diets with different phosphorus levels(0.32%and 0.14%non-phytate phosphorus(NPP),respectively)were alternately presented to the laying hens.Briefly,four phosphorus feeding regimens in total(each included 6 replicates of 5 hens):(1)fed 0.32%NPP at both 09:00 and 17:00;(2)fed 0.32%NPP at 09:00 and 0.14%NPP at 17:00;(3)fed 0.14%NPP at 09:00 and 0.32%NPP at 17:00;(4)fed 0.14%NPP at both 09:00 and 17:00.As a result,the regimen fed 0.14%NPP at 09:00 and 0.32%NPP at 17:00,which was designed to strengthen intrinsic phosphate circadian rhythms according to the findings in Exp.1,enhanced(P<0.05)MB remodeling(indicated by histological images,serum markers and bone mineralization gene expressions),elevated(P<0.05)oviduct uterus calcium transportation(indicated by transient receptor potential vanilloid 6 protein expression),and subsequently increased(P<0.05)eggshell thickness,eggshell strength,egg specific gravity and eggshell index in laying hens.Conclusions These results underscore the importance of manipulating the sequence of daily phosphorus ingestion,instead of simply controlling dietary phosphate concentrations,in modifying the bone remodeling process.Body phosphorus rhythms will need to be maintained during the daily eggshell calcification cycle.

Soya saponin improves egg-laying performance and immune function of laying hens

Background:Soya saponin(SS),an active compound in soybean meals,has been widely studied in the medical field.However,it was considered as an anti-nutritional factor in poultry diets.The objective of this experiment was to measure the effects of dietary SS using three dietary treatments on egg-laying performance and immune function of laying hens.Birds were fed a low soybean meal basal diet(CON),a low-SS diet(50 SS)containing 50mg/kg SS,or a high-SS diet(500 SS)containing 500 mg/kg SS for 10 weeks.At the end of the 5th and 10th week of the trial,samples were collected for analysis.Results:Results showed that with 50 mg/kg SS supplementation,the egg production rate,feed conversion ratio(FCR),and eggshell quality tended to be improved.Serum follicle stimulating hormone(FSH)and Interleukin-4(IL-4)levels were also elevated as well as the peripheral blood LPS stimulation index,the proportion of B lymphocytes,and antibody titer of bovine serum albumin(BSA).We also found that mRNA levels of follicle stimulating hormone receptor(FSHR)in ovarian,nuclear transcription factor kappa B(NF-κB),Transforming growth factor(TGF-β)and interferonγ(IFN-γ)in spleen were up-regulated at the end of the trial.Additionally,dietary 50 mg/kg SS improved the ileal flora via up-regulating the relative abundance of Lactobacillus,Romboutsia and Lactobacillus delbrueckii.Although the immune related indicators were improved with 500 mg/kg SS supplemented,it seemed to have a negative influence on the laying-performance.Specifically,serum alanine aminotransferase(ALT),alkaline phosphatase(ALP),and the ratio of IFN-γto IL-4 were increased in the 500 SS group at the end of the trial.The m RNA levels of gonadotropin releasing hormone 1(GnRH1)in Hypothalamus,the estrogen related receptor(ERR)in ovaries were downregulated as well as the egg production rate during the trial with 500 mg/kg SS supplemented.Conclusions:The egg production performance was improved by dietary supplemented with 50 mg/kg SS via increasing ovarian FSHR transcription level and serum estrogen level.A beneficial shift in intestinal microflora was recorded,and the immune function of laying hens was also improved with 50 mg/kg SS supplementation.Surprisingly,the long-term supplementation of 500 mg/kg SS exerted a negative impact on the laying performance and physiological functions of the liver of laying hens.

Effect of dietary nonphytate phosphorus on laying performance and small intestinal epithelial phosphate transporter expression in Dwarf pink-shell laying hens

This study examined the effects of various levels of dietary nonphytate phosphorus on laying performance and the expression patterns of phosphorus metabolism related genes in Dwarf pink-shell Jaying hens. A total of 405 28-week-old Dwarf pink-shell laying hens were fed the same corn-soybean basal meals but containing 0.20%, 0.25%, 0.30%, 0.35% or 0.40% nonphytate phosphorus. The results showed that feed intake, egg production, and average egg weights were quadratically correlated with dietary nonphytate phosphorus content （P 〈 0.05）, and the highest egg production, feed intake and average egg weights were achieved when dietary nonphytate phosphorus was at 0.3% （P 〈 0.05）. mRNA expression of intestinal sodium phosphorus co-transporter linearly decreased when dietary nonphytate phosphorus increased, mRNA and protein expression of intestinal calbindin and vitamin D receptor correlated quadratically with dietary nonphytate phosphorus, and the highest expression was found when dietary available phosphorus was at 0.2,5% to 0.3%. In conclusion, the ideal phosphorus requirement for Dwarf pink-shell layer hens is estimated to be 0.3% in a corn-soybean diet. With this level of phosphorus supplementation, calbindin and vitamin D receptor reached their highest expression.

Application of Several Additives Instead of Antibiotics in the Production of Laying Hens

[ Objective ] The test was conducted to study the effect of three different additives instead of antibiotics in the production of laying hens. [ Method ] Basal diets in four test groups were added with 0. 015 % oxytetracycline, 0. 01% microecological preparation, 0.2% fulvic acid, and 0. 1% Chinese herbal medi- cine extract respectively, and laying hens in control group were fed with basal diets. Effect of four different additives on performance and egg quality were studied under the temperature of 28.6℃. [ Result] The average egg-laying rate and feed-egg ratio in groups 2, 3 and 4 were significantly better than those in control group and group 1 （P 〈 0.05 ）. The contents of fat and cholesterol in eggs in groups 2, 3 and 4 were lower than those in control group and group 1. And the fat content of eggs in group 4 was 13.42% lower than that in control group, the difference was significant （ P 〈 0.05 ）. The protein contents in groups 2, 3 and 4 were signifi- cantly higher than those in control group and group 1 （P 〈 0.05 ）. [Condusion ] Microecological preparation, fulvic acid and Chinese herbal medicine extract could replace antibiotics to be applied in the production of laying hens.

Effects of dietary phosphorous supplementation on laying performance,egg quality,bone health and immune responses of laying hens challenged with Escherichia coli lipopolysaccharide

Background: Phosphorus is an essential nutrient to maintain poultry health and performance. The objective of this study was to evaluate the effect of dietary phosphorus levels on egg production, egg quality, bone health, immune responses of laying hens challenged with Escherichia coli lipopolysaccharide.Methods: Three hundred laying hens at 28 wk were randomly divided into 2 dietary treatments with 10 replicates of 15 birds. The wheat-soybean based diets contained either 0.12% or 0.4% non-phytate phosphorus(NPP). At 32 wk of age, all the birds of each dietary treatment were injected into the abdomen with 1.5 mg/kg body weight(BW) of either LPS or saline once a day at 24-h intervals for continuous 9 d. The performance of laying hens was evaluated for 9 d. The eggs after the fifth injection were collected to value the egg quality. Three hours after the first injection, blood was collected to measure serum metabolite and immune response associated parameters.Three hours after the fifth injection, the hens were euthanized to obtain tibia, cecal tonsils and jejunum.Results: Compared with saline-injected hens, LPS-injected hens had lower feed intake and egg production(P < 0.05).Eggshell thickness, strength, albumin height and Haugh unit were significantly increased in LPS-injected hens compared with saline-injected hens(P < 0.05). Furthermore, laying hens challenged with LPS had lower villious height/crypt depth ration than those received saline. Serum calcium, phosphorus and SOD activities significantly decreased in the LPS-injected hens compared with the control(P < 0.05). LPS up-regulated expression of IL-1β, IL-6 and IL-10 in cecum, and serum concentration of MDA, IL-1β and IL-6(P < 0.05), whereas 0.40% dietary non-phytate phosphorus supplementation significantly increased(P < 0.05) villi height/crypt depth ratio, decreased(P < 0.05) serum MDA and IFN-γ concentration compared with the 0.12% non-phytate phosphorus group.Conclusion: In summary, this study demonstrates that 0.40% dietary non-phytate phosphorus supplementation significantly increased calcium and phosphorus levels of eggshell, increased villi height/crypt depth ratio, decreased serum MDA and IFN-γ concentration compared with the 0.12% non-phytate phosphorus groups. The results indicate that high level of dietary non-phytate phosphorus exerts a potential effect in alleviating systemic inflammation of LPSchallenged laying hens.

The Effect of Different Levels of Sesame Oil on Productive Performance, Egg Yolk and Blood Serum Lipid Profile in Laying Hens

Addition of sesame oil into layer diets has been proved to enrich the proportion of polyunsatu-rated fatty acids in animal’s products. In this study, the effects of different levels of sesame oil in the diets on the performance, egg yolk and blood serum lipid profile of Isa Brown laying hens were investigated. A total of 96 layers were assigned into 4 groups to receive either 1 of 4 different diets contained 0.0%, 1.5%, 3.0% and 4.5% sesame oil, respectively. Sample of 12 eggs obtained from each groups were assessed for egg quality. The egg yolk fatty acid profile was determined with gas chromatography. Results revealed that the higher levels of sesame oil in the diet decreased egg production, egg weight, and egg yolk color except feed conversion ratio. In addition, supplementation of sesame oil increased the flow index of the eggs and the Haugh unite. The egg yolk lipid profile was not significantly different in the sesame oil fed groups, whereas, compare to control, it decreased the level of cholesterol. The blood serum lipid profile decreased in the sesame oil groups compare to control group. Meanwhile, monoacildigliserol also decreased in the sesame addition groups. In parallel with increasing levels of sesame oil, monounsaturated fatty acid (oleic acid) in the egg yolks significantly increased compared to the control (37.00%, 42.89%, 42.20% and 43.48%, respectively). It can be implied that sesame oil supplementation into the laying hens diet is necessary to produce monounsaturated fatty acid (MUFA) enriched eggs.

Effect of Quercetin on Egg Quality and Components in Laying Hens of Different Weeks

This trial was conducted to evaluate the effect of quercetin on egg quality and components in laying hens of different weeks. A total of 240 healthy Hessian laying hens at 29, 39-week-old with similar body weight and laying rate were randomly divided into four groups with six replicates of 10 each replicate, respectively. The treatments were fed with basal diet supplemented with 0, 0.2, 0.4 and 0.6 g-kg-1 quercetin for 8 weeks. The results showed that compared with the control, broken or soft shell rate significantly decreased at 0.2 and 0.4 g.kg-1 quercetin and eggshell thickness significantly increased at 0.4 g.kg-1 quercetin （P〈0.01） in laying hens at 39-47 weeks old; yolk protein significantly decreased at 0.6 g kg-1 quercetin （P〈0.05） in laying hens at 29-37 weeks old; while yolk protein significantly increased at three quercetin treatments in laying hens at 39-47 weeks old; yolk cholesterol significantly decreased by quercetin in laying hens at 29-37 weeks old （P〈0.05）; yolk total phospholipids significantly increased at 0.4 and 0.6 g kg-1 quercetin （P〈0.01） and yolk cholesterol significantly decreased at 0.6 g kg-1 quercetin （P〈0.05） in laying hens at 39-47 weeks old. In a word, quercetin affected egg quality and components to some extents in laying hens of different weeks, the older the hens became, the better improvement they would be. The optimum level of quercetin was 0.4 g kg-1 in the basal diet.

Effects of Yeast Chromium Combined with Probiotics on Laying Performance,Intestinal Microflora and Digestive Enzyme Activities of Laying Hens in Summer

[ Objective] To study the effects of yeast chromium combined with probiotics on laying performance, intestinal microflora and digestive enzyme activities of laying hens. [ Method] A total of 432 healthy 40-week-old Roman brown laying hens were randomly divided into nine groups. Laying hens in control group were fed with basal diet, laying hens in test groups were fed with basal diet combining with different levels of yeast chromium （0,400,600 μg/kg） or probiotics （0,400,800 mg/kg）. [ Result] Yeast chromium, probiotics or yeast chromium combined with probiotics adding into feeds could significantly increased the laying rate （ P 〈 0.05 ） and significantly reduced feed-egg rate （ P 〈 0.05 ）. Joint use of yeast chromium and probiotics had significant interaction effects on laying rate and feed conversion rate（P 〈 0. 05）. Adding of yeast chromium combined with probiotics in diets could significantly increased the amount of Lactobacillus and Bifidobacterium （P 〈0.05 ） in ileum and cecum of laying hens, and significantly reduced the amount of Escherichia coli and Salmonella （P 〈0.05 ） , in addition, the activity of total protease, lipase and amylase in duodenal contents were significantly increased （ P 〈 0.05 ）. Joint use of yeast chromium and probioties had sig- nificant interaction effects on the activity of total protease, lipase and amylase in laying hens duodenal contents （ P 〈 0.05 ）. [ Conclusion ] Joint adding of 600μg/kg yeast chromium and 800 mg/kg probiotics in diets in summer had best effects on laying performance, intestinal microflora and digestive enzyme activities of laying hens.

Effects of Exposure to Lead and Cadmium on the Oxidative Damage of Livers in Laying Hens

[Objective] To detect the effects of exposure to lead and cadmium on the oxidative damage of livers in laying hens. [Methods] One hundred and twenty 40-week-old Hyline brown hens were randomly divided into four groups. 100 mg / L Pb and / or 50 mg / L Cd was added into the drinking water for eight weeks. [Results] Compared with control group,AST and ALT activities in Pb group enhanced; but there were no significant differences. AST and ALT activities in Cd group and( Pb + Cd) group significantly or extremely significantly increased( P 【 0. 05 or P 【 0. 01). SOD activity,GSH- Px activity and GSH content in( Pb + Cd) group,Cd group and Pb group were significantly or extremely significantly lower than those in control group( P 【0. 05 or P 【0. 01). Among them,( Pb + Cd) group showed the greatest reduction( P 【0. 01). MDA contents in the three groups were significantly higher than that of control group; and( Pb +Cd) group was significantly higher than Pb group and Cd group. Cu,Fe and Zn contents in three groups were higher than those in control group in different degrees( P 【0. 05 or P 【0. 01). Se contents in Cd group and( Pb + Cd) group were significantly lower than that in control group( P 【0. 01). Residue contents in livers in Pb group and Cd group were significantly greater than that in control group; while residue content in( Pb + Cd) group was significantly higher than those in Pb group and Cd group. Ultrastructure showed that there were symptoms of mitochondrial swelling and fractured cristae in liver cells of laying hens after the exposure to Cd and Pb. In( Pb + Cd) group,these symptoms were even greater. [Conclusion] Oxidative damage and disturbance of trace element metabolism were one of the mechanisms for hepatotocity in laying hens induced by Pb and Cd,and synergistic effect lied in the coadministration.

Effects of Compound Acidifier and Probiotics on Production Performance,Blood Biochemical Indexes,Antioxidant Indexes and Salmonella Infection of Laying Hens

This study evaluated the effects of compound acidifier and probiotics on production performance, blood biochemical indexes, antioxidant indexes and Salmonella infection of laying hens. A total of 600 50-week-old healthy laying hens with similar laying rate were randomly assigned to four groups, 10 repeats each group, and each repeat contained 15 chickens. The laying hens in control group were fed a basal diet, and in the other three experimental groups were fed basal di- ets supplemented with 300 g/t probiotics, 0. 1% compound acidifier in the drinking water every other day, and 300 g/t probiotics ＋ 0.1% compound aeidifier in the drinking water every other day, respectively. After the feeding of 16 weeks, a total of 60 laying hens from control group were divided into four treatments as the same above for a 13-day long Salmonella challenge （1.3×10^8 CFU） trial. The results were shown as follows： no significant effects were observed on production performance, hemoglobin content, the superoxide dismutase activity and total antioxidant capacity of reproductive organ in compound acidifier and probiotics groups （ P 〉 0.05 ）. Dirty egg rate was significantly decreased in compound acidifier group, probiotics group and combination group of both （P 〈 0.05 ）. Compared with the control group, white blood cell count in probiotics group was significantly decreased （P 〈0.05 ）, and the immunoglobulin content in probiotics group tended to be increased （P = 0.061 ）. The malondialdehyde （MDA） content in oviduct isthmus of hens in compound acidifier group and combination group was significantly decreased compared with the control group （ P 〈 0.05 ）. The Salmonella positive rate in oviduct of hens in compound acidifier group was significantly decreased at the 7th and 14^th days （ P 〈0.05 ）, but that in probiotics group and combination group was not significantly different compared with control group （ P 〉 0.05 ）. In conclusion, compound acidifier and probiotics can improve health status of laying hens through decreasing the dirty egg rate and increasing antioxidant capacity and immunity of them, thus reducing Salmonella infection of body and eggs.