Studies On Ascophyllum Nodosum And Its Extracts Allievating On Rumen Acidosis Of Hu Sheep Induced By Feeding High-concentrate Diet

With the expansion and intensification of modern livestock production in China,many small and medium-hold farms tend to feed large amounts of cereal starch-based highconcentrate rations in order to improve production efficiency,which can improve animal production efficiency but also easily lead to a rapid decrease in rumen fluid pH value in ruminants and eventually cause sub-acute ruminal acidosis(SARA)based nutritional metabolic diseases.It is also likely to lead to a decrease in the pH value of the rumen fluid in ruminants and eventually to the development of nutritional and metabolic diseases,mainly subacute ruminal acidosis(SARA).Seaweeds and their extracts are rich in bioactive substances,which have biological functions such as immunomodulation,antioxidant,antiviral and anti-cardiovascular diseases.The aim of this study is to investigate the effects of seaweeds and their extracts on growth efficiency,rumen fermentation,rumen microbiota and blood biochemistry and immunity of Hu sheep when added to high concentrate rations,and to provide a theoretical basis for the practical application of seaweeds and their extracts in ruminant production.Trial 1.In vitro study comparing the effects of Ascophyllum nodosum,Sargassum fusiforme and Fucoidan on rumen fermentation parameters in Hu sheep under high concentrate dietThe aim of this experiment was to investigate the effect of adding different proportions of the seaweed extract Fucoidan,two seaweeds with high Fucoidan content,Ascophyllum nodosum and Sargassum fusiforme on the in vitro fermentation parameters of a high concentrate diet,and clarify their optimal proportion which could relieve rumen acidosis.The experiment used in vitro batch culture to study five supplemental levels[0%(as control),1.0%,1.5%,2.0%,2.5%,dry matter basis]of Fucoidan(FUC0,FUC1,FUC2,FUC3,FUC4)、[0%(as control),1.0%,2.0%,3.0%,4.0%,dry matter basis]of Ascophyllum nodosum(ASC0,ASC1,ASC2,ASC3,ASC4)and Sargassum fusiforme(SAR0,SAR1,SAR2,SAR3,SAR4)when the concentration to forage ratio was 70:30.The pH value,ammonia nitrogen(NH3-N),microbial protein(MCP),lactic acid and volatile fatty acid(VFA)contents of the fermentation broth under different treatment conditions were determined at 6,9,12 and 24 hours.The results showed that:1)Fermentation broth pH value of FUC3,FUC4,ASC3,ASC4 and SAR3 addition groups were significantly higher than their respective control groups at all time points of fermentation(P<0.05);2)Fermentation broth NH3-N concentration of FUC3,FUC4,ASC3 and SAR3 addition groups were significantly lower than their respective control groups at 12 h of fermentation(P<0.05),and MCP concentration was 24 h of fermentation was significantly higher(P<0.05);3)At 24 h of fermentation,the lactic acid concentration of fermentation broth in the FUC2,FUC3 and FUC4 addition groups was significantly lower than that in FUC0(P<0.05);the lactic acid concentration of fermentation broth in each of the FUC2 and FUC4 addition groups was significantly lower than that in the respective control groups(P<0.05).4)Compared with the respective control groups,at 24 h of fermentation,the fermentation broth A/P ratio was significantly higher in the FUC4 and SAR3 groups and in each of the FUC4 groups(P<0.05),and the propionic acid ratio was significantly lower(P<0.05).The fermentation broth A/P ratio was significantly higher(P<0.05)and the propionic acid ratio was significantly lower(P<0.05).5)Compared to FUC0,the relative contents of M.esdenii,S.ruminantinm and P.ruminicola in FUC3 and FUC4 groups were significantly increased(P<0.05),while the relative contents of S.bovis and R.mylophilus were significantly decreased(P<0.05).Compared with ASCO group,the relative contents of M.esdenii and S.ruminantinm were significantly increased in ASC3 and ASC4 groups,while the relative contents of S.bovis were not significantly changed in ASC3 and ASC4 groups(P>0.05).Compared with the SAR0 group,the relative contents of M.esdenii,B.fibrisolvens and R.amylophilus in each addition group were significantly decreased(P<0.05),while the relative contents of S.bovis were significantly increased(P<0.05).In conclusion,under the conditions of this experiment,the optimal addition ratio of fucoidin was 2.5%and the addition of Ascophyllum nodosum or Sargassum fusiforme can effectively alleviate the decrease of pH value,reduce the concentration of lactic acid,increase the acetate to propionate ratio,and improve the rumen fermentation pattern,which has the potential to alleviate rumen acidosis.Under the conditions of this experiment,the optimal added 3.0%ofAscophyllum nodosum and Sargassum fusiorme were to relieve ruminal acidosis effectively and Ascophyllum nodosum had the best effect.Trial 2.Effects of high concentrate diet supplemented with Ascophyllum nodosum on performance,ruminal fermentation parameters and ruminal microbial community structure in Hu sheepThirty-two male Hu sheep with similar body condition and initial body weight of 26±1.5 kg were randomly divided into 4 groups(n=8):control group(CON group),high concentrate group(HC group),control+Ascophyllum nodosum group(CAS group)and high concentrate+Ascophyllum nodosum group(HAS group).On the first day of the feeding period,the sheep were weighed before the morning feed to determine the initial weight of the test sheep;on the last day of the feeding period,the sheep were weighed before the morning feed to determine the final weight of the test sheep;after the start of the feeding period,the feed residues are taken out from the feeding trough before feeding each day,and the amount of the feed residues is measured and recorded,to determine the average daily feed intake(ADFI)and feed-weight ratio(F/G).On the last day of the feeding period,before morning feeding and 3,6 and 9 h after feeding,30 mL of rumen fluid was collected through an oral sampler inserted in the oesophagus,partly for rumen fermentation indicators:pH value,volatile fatty acid concentration,lactic acid and NH3-N measurements,and partly for flora structure analysis.The results showed that:1)End weight of HC and HAS groups were higher than CON and CAS groups(P<0.05);end weight of HAS group was higher than HC group(P<0.05).The ADG of the HC and HAS groups were higher than CON and CAS groups(P<0.05);the F/G was lower(P<0.05).2)The mean pH value of HAS group was higher than that of HC group(P<0.05);compared with the CON and CAS groups,the percentage of acetic acid and A/P were lower of the HC and HAS groups(P<0.05),the proportion of propionic acid and lactic acid concentration were higher of the HC and CAS groups(P<0.05).3)Relative abundance of Firmicutes and Actinobacteria of the HC and HAS groups were higher than the CON and CAS groups(P<0.05).The relative abundance of Firmicutes and Actinobacteria the HAS group were lower(P<0.05).The relative abundance of Bacteroidetes and Proteobacteria in the HC group was lower than that of CON,CAS and HAS groups(P<0.05).4)The relative abundance of Prevotella in HC group was lower than that in CON,CAS and HAS groups(P<0.05);Compared with CON group,the relative abundance of Prevotella in CAS group was increased(P<0.05).The relative abundance of Selenomonas of HC group was higher than that of other treatment groups(P<0.05).Compared to the CON group,Rikenellaceae_RC9_gut_group,F082_unclassified,Bacteroidales_RF16_group_unclassified,and Prevotellaceae_UCG-003 of the HC group was decreased(P<0.05).The relative abundances of F082_unclassified,Prevotellaceae_UCG-003,and Muribaculaceae_unclassified in the HAS group were higher than HC group(P<0.05).In conclusion,high concentrate diet supplemented with Ascophyllum nodosum can effectively improve the ruminal fermentation pattern as well as the ruminal microflora structure.Trial 3.Effect of adding Ascophyllum nodosum to high concentrate diet on blood biochemical,inflammatory reaction and antioxidant indexes of Hu sheep fed high concentrate dietOn the last day of the experiment,the experimental sheep were subjected to fasting jugular vein blood collection.The blood samples were left at room temperature for 30 min,and then centrifuged at 3000 R/min for 10 min in a 4℃ low-temperature centrifuge to prepare serum samples,used for the determination of follow-up indicators.The results showed as follows:1)The concentration of aspartate transaminase in HC group was higher than CON group and CAS group(P<0.05),the concentration of creatinine in HC group washigher than other groups(P<0.05).2)The concentrations of LPS and LBP in HC and HAS groups were higher than CON and CAS groups(P<0.05).LPS and LBP concentrations of the HAS group were reduced(P<0.05).The concentration of HP in HC and HAS groups was higher than CON and CAS groups(P<0.05).The concentrations of SAA,TLR-4,IL-6 and TNF-α in the HC and HAS groups were higher(P<0.05).Compared with the HC group,the HAS group had significant reductions in SAA,TLR-4,IL-6 and TNF-α concentrations(P<0.05).The HAS group had higher levels of IL-4 and IL-10 than HC group(P<0.05).3)The concentration of MDA in HC group and HAS group was higher than CON group and CAS group(P<0.05).The MDA concentration of HAS group were reduced than HC group(P<0.05).The concentration of GSH-Px in HC and HAS groups was significantly lower than that in CON and CAS groups(P<0.05).Compared with the HC group,the HAS group had a significant increase in GSH-Px concentration(P<0.05).The concentrations of T-SOD and T-AOC in the HC and HAS groups were significantly lower than those in the CON and CAS groups(P<0.05).In conclusion,the supplementation of Ascophyllum nodosum could help to regulate the inflammatory response and enhance the antioxidant capacity of animals fed a high-concentrate diet.