| The purposes of this research wereto evaluate if there were some relationships between OBCFA(odd-and branched-chain fatty acids)originated from rumen and milk fat and the corresponding data of ruminal fermentation parameters,microbial populations and bases contents which used to mark microbial protein in rumen and duodenal and to investigate the changes of different dietary ratios of forage and concentrate(F:C)and lactation stages of ruminal and milk odd-and branched-chain fatty acids(OBCFA)profiles,and ruminal fermentation parameters,microbial populations and bases contents which came from rumen and duodenal.The main goal of this study was to investigate the potentiality of using OBCFA(originated from rumen or milk fat)as microbial marker in ruminants.Experiment 1.Effect of dietary F:C ratio on ruminal OBCFA contents,fermentation pattern,microbial populations and bases contents,and duodenal metabolism parametersThe experimental design was a 3×3 Latin square.Three rumen-and duodenal-fistulated dry Holstein cows were fed three rations with different dietary F:C ratios(F:C;30:70,50:50,and 70:30).The rumen and duodenal samples were collected every two hours over 3 consecutive days of each sampling period.The parameters were determined including profiles of OBCFA in rumen solid phase(SAB)and liquid phase(LAB),rumen fermentation parameters,bacterial populations as well as bases contents,and duodenal metabolism parameters and bases contents.The results showed that the concentrations of each volatile fatty acids(VFA)were significantly increased(P< 0.05),as the F:C ratio increased.The molar proportions of acetate were highest for the cows fed the ration with F:C = 70:30(P< 0.05),and the isoacids molar proportions were highest for those fed ration with F:C = 50:50 and lowest in the group of F:C = 70:30(P< 0.05).For the cows fed diet with F:C = 70:30,the populations of Ruminococcus Flavefaciens were higher than the other groups(P< 0.05).The dietary F:C ratios significantly influenced the contents of bases with the exception of cytosine and bases/N in the rumen.The contents of uracil were highest for the cows fed ration with F:C = 50:50,but guanine and adenine contents were highest in the group of F:C = 30:70.With the dietary increased,the contents of ruminal OBCFA were significantly changed except the contents of anteiso C15:0.The contents of C15:0 were highest in the group of F:C = 50:50,but other OBCFA were highest in F:C = 70:30 group.In duodenal flow,the concentrations of VFA were highest for the cows fed ratios with F:C = 70:30,but lowest for those fed ration with F:C = 50:50(P< 0.05).The contents of cytosine,uracil and adenine were increased as the dietary F:C ratios raised before feeding.Experiment 2.Changesof ruminal fermentation pattern,microbial populations and bases contents and ruminal and milk OBCFA contents in different lactation stagesNine lactating Holstein dairy cows with similar body weight and parity(parity =1)were selected in this study.Three cows with similar milk production in early(or middle or late)lactation period were then selected.The rumen and milk samples were collected over 3 consecutive days of each cow and ruminal and milk OBCFA profiles,ruminal fermentation parameters,bacterial populations and bases contents were measured.The results showed that the proportions of VFA and p H were significantly changed with the different lactation stages(P< 0.05).As well as,the lactation stages significantly affected the populations of Ruminococcus Albus and Streptococcus Bovis,as well as the contents of cytosine,total bases and Pyrimidine(P< 0.05).Lactation stages significantly affected ruminal and milk OBCFA profiles(P< 0.05).The concentrations of OBCFA with the exception of C11:0 and C15:0 were significantly different between in milk and rumen(P< 0.05).The concentrations of anteiso-fatty acids in milk was higher than that in rumen,and the contents of linear odd-chain fatty acids were higher than branched-chain fatty acids both in milk and rumen.Experiment 3 Correlations between milk and ruminal OBCFA profiles and ruminal fermentation pattern,mocrobial populations,bases and and duodenal metabolism parametersUsing the data obtained from Experiment 1 and Experiment 2,to determine whether relationships exist between the contents of ruminal(or milk)OBCFA and the ruminal fermentation parameters,bacterial populations and bases contents,and duodenal VFA and basescontents.The results showed thatruminal OBCFA contents were positively correlated with the molar proportion of acetate,however,negatively related to the other VFA proportions(P< 0.05).As well as,the OBCFA concentrations were positively associated with NH3-N contents,but negatively related to p H value in rumen(P< 0.05).The concentrations of ruminal C11:0 and C13:0 were significantly positively related to cellulolytic bacterial populations(P< 0.05),but negatively correlated with amylolytic bacterial populations(P< 0.05).And the ruminal bacterial populations were significantly related to the contents of C15:0 and odd-chain fatty acids in rumen(P< 0.05).In addition,the concentrations of C11:0,C13:0 and total branched-chain fatty acids were positively correlated with the ruminal bases contents(P< 0.05),but ruminal C15:0 contents and C15:0/C17:0 were negatively associated with the amounts of ruminal bases contents(P< 0.01).The ruminal contents of C15:0 and C15:0+C17:0 were positively related to the molar proportions of duodenal acetate,however,negatively correlated with the other VFA and NH3-N contents(P< 0.05).The ruminal C15:0/C17:0 was positively correlated with the proportions of acetate and p H value(P< 0.05),but negatively related to other VFAcontentsin duodenum(P< 0.05).The duodenal flow bases contents were positively linked with ruminal C11:0 and iso C17:0 contents(P< 0.05),but negatively related to C15:0/C17:0 and iso C15:0/iso C17:0(P< 0.05).There were significant relationships existed between the concentrations of C11:0,iso C15:0,anteiso C15:0,C15:0 and anteiso C17:0 in rumen and milk(P< 0.05).The contents of total OBCFA in milk was positively related to acetate molar proportion,but negatively correlated with isoacids(P< 0.05).As well as,the contents of iso C15:0 and anteiso C15:0 was negatively related to ruminal NH3-N contents(P< 0.05).The populations of Ruminococcus albus,Ruminococcus flavefacients and Eubacterium ruminantium were significantly related to milk C13:0 contents(P< 0.05).There was a significant relationship between milk iso C17:0 and ruminal microbial protein contents(P< 0.05).The ratio of adenine to N was negatively related to milk OBCFA(P< 0.05),but positively associated with iso C15:0/isoC17:0(P< 0.05).Above all,it had the following conclusions:(1)The ruminal OBCFA contents,fermentation pattern,microbial populations and bases contents were significantly affected by the dietary F: C ratios.(2)Milk lactation stages significantly affected both milk and rumen OBCFA profile.In addition,the ruminal fermentation pattern was significantly influenced by milk lactation stages.(3)The OBCFA which originated from both rumen and milk were significantly correlated with ruminal fermentation parameters,ruminal bacterial populations and bases contents.The ruminal OBCFA contents were significantly related to duodenal VFA and bases contents. |
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