Influence Of Rumen Microbial Reshaping On Feed Intake And Feeding Behavior Of Holstein Cows During The Late Perinatal Period

In this study,four experiments were conducted to explore the effects of different lactation periods on dairy cows DMI,eating frequency,metabolism and bacterial community in the rumen and rectum;effects of rumen microbial reshaping during the late Perinatal Period on DMI,eating frequency,and bacterial community in the rumen and rectum of dairy cows;and prediction and regulation mechanism of bacteria OTUs abundance on DMI and eating frequency of dairy cows.Trial 1 was to research the effects of different lactation periods on DMI,eating frequency,organic metabolism of dairy cows.Using Roughage Intake Control System(RIC)and GC-TOF/MS analysis system,20 healthy second pregnant cows with simillar body weight,body condition score and expected date of parturition were selected to determine the DMI,eating frequency and serum metabolome on the 7th day(the late Perinatal Period)and the 50th day(the Peak Period of Lactation)of postpartum dairy cows.The results showed that 7th day cows DMI(12.322 kg/d)and eating frequency(50.560/d)was significantly lower than that of the 50th day DMI(22.132 kg/d)and eating frequency(63.152 times/d),which indicated that appetite of dairy cows on the 7th day obviously less than the50th day(P<0.01);there was a very significant difference in metabolisms of 7 d and 50 d(P = 0.002),the 50th d metabolism was more vigorous than the 7th d(FDR<0.05),Maybe,due to the stress of delivery,conversion of diet,environment change and immunity and inflammation during the late perinatal periods,the appetite,intake behavior and metabolism of dairy cows were evidently inhibited.Trial 2 was conducted to assess the effects of different lactation periods on bacterial community inthe rumen and rectum of dairy cows.Based on 16S rRNA gene,the objective of the experiment,test animals and design the same as trial 1,was to sequence macrogenome high throughput of the bacterial community in the rumen and rectu1 of the postpartum cows on the 7th/and 50th d.The results showed that alpha diversity of bacterial community in the rumen of the postpartum cows on the 7th U obviously lower than the 50th d(P<0.01),but there’s no significant difference in the rectum(P>0.05);bacterial community constructure and distribution of core bacterial comlunity in the rumen and rectum of the 7th d postpartum cows were remarkablely different to the 50th d(P<0.01).The relative abundance of dominant bacteria was significantly different(P<0.05),but there’s no clear distinction in the core bacterial flora abundance(P>0.05).Therefore,to draw a conclusion,there is inherent core bacterial fauna in the rumen and rectum of dairy cows,some of which species and distributions vary with diet,physiological period and environmental change,nevertheless,the abundance of the core bacteria community always stays stable,maybe,on account of changes in bacterial community constructure which make appetite,intake behavior and metabolism of postpartum dairy cows inhibited.The objective of trial 3 was to study the influence of reshaping of rumen microbe in postpartum cows on DMI,eating frequencey and bacterial community constructure in rumen and rectum.10 healthy pregnant cows in 2nd parity,with similar body weighll body condition score,and permanent rumen fistula,were divided randomly into control group(CON,n = 5)and microbial transplantation group(MT,n = 5),to measure intake and eating frequency of cows in two groups in 1-28 days after delivery by RIC,based on 16S rR/NA gene,and to sequence metagenomic high-throughput of bacterial community in rumen and rectum of periparturient dairy cow.The results showed that:DMI and the eating frequency of group MT were significantly more than that of group CON(P<0.01),about 3.752 kg/d-head and 12.129 times/d-head,respectively;the principal coordinate analysis indicated that the ecological structure of bacteria community in the rumen fluid and feces of CON and MT was gradually close to that of donor group,and the MT was more closer than that of CON;compared with the donor group,there were no significant differences in the maturity of the bacterial communities in the rumen fluid and feces of the CON and MT in the early perinatal period(P>0.05),however,the relative maturity of MT in the late perinatal period was significantly higher than that of CON(P<0.05);the bacterial community in the rumen and rectum of CON cows in the late perinatal period was significantly different from that of MT in phylum and genus taxonomic level(P<0.01 or 0.05).Hence,after the rumen microorganism reshaping in the late perinatal period,the ecological structure and relative maturity of microorganisms in the rumen and rectum are fast approaching that of the peak lactation cows,which illustrates that transplanting the rumen liquid of the peak lactation cows into the post-perinatal dairy cows successfully reshapes their microbial community,improves the micro-ecological constructure of rumen and rectum of dairy cows effectively in the late perinatal period,and enhances the cow’s appetite,makes its ingestion more active,thus improves their organism metabolism,which is conducive to the health of dairy cows in this stage.Using the same experimental animals and design as trial 3,trial 4 studied regulation mechanism of DMI and eating frequency influenced by abundance of OTU in rumen and rectum of the late perinatal cows.The results showed that:in postpartum dairy cows foregut(rumen),the predictive rates of bacteria OTU abundance to DMI and eating frequency were 69.88%and 54.08%respectively,but in hindgut(rectum)were 68.91%and 55.23%;(2)in forgut of the late perinatal cows,the mechanism that bacterial communities regulated DMI and intake frequency as following:DMI had a positive correlation with the abundance of 28 bacterial OTUs in the rumen,and had a negative correction with that of 29 bacterial OTUs(P<0.05);the eating frequency also had a positive correlation with that of 18 bacteria OTUs in the rumen,and a negative correlation with that of 7 bacteria OTUs(P<0.05);DMI and intake frequency increased or decreased significantly with the increase or decrease of OTU25,OTU665 and OTU779 abundance at the same time,but had a negative correction with that of OTU739,OTU612,OTU3340,OTU2889 and OTU622(P<0.05).in hindgut of the late perinatal cows,the mechanism that bacterial community regulated DMI and intake frequency as following:DMI clearly had a positive correlation with the abundance of 5 bacterial OTUs in the rectum(P<0.05),the eating frequency also had a positive correlation with the abundance of 6 bacterial OTUs in the rectum,and had an obvious negative correction with that of 10 bacterial OTUs(P<0.05);The possible route that bacterial community in foregut(rumen)and hindgut(rectum)of late perinatal cow regulated DMI and the eating frequency was microbial-brain-secreting cell axis.Hence,this study directly confirms that intestinal microorganism can regulate feed intake and eating frequency of dairy cows,which is an important part of the regulation mechanism of ruminant feed intake,such regulation mechanism of intestinal microorganisms can better explain the causes of the decrease of feed intake and eating frequency of cows during the late perinatal period than the theory of physical and chemical regulation.It’s a necessary supplement to the regulation theory of feed intake of ruminant.