| The content of dietary carbohydrate is the key factor in regulation rumen fermentationand high productivity in ruminant. The subacute rumianl acidosis (SARA) is a commondigestive disorder in ruminant production, which threatens the health and the productivity indairy industry. Both dietary fiber and NFC can affect ruminal pH, but the SARA models inprevious studies cannot avoid the confounding effect of different DMI and forage toconcentrate ratio between the treatments. In addition, the recommended carbohydrate contentdata (peNDF and RDS) by a single experiment is limited, and need to combine related studiesto optimize their supplementation. In the present study, we intended to adopt pared-fed designand replacement method to development the SARA models and compared their differences inrumen fermentation parameters, microflora, and biomarkers to and found biomarker duringthe SARA challenge. We also use Meta-analysis method that combination related experimentsto quantitativeoptimized the dietary peNDF content and CBI for dairy cows.1. The objective of this experiment was to characterize the relationship among rumenfermentation variables, milk fatty acid (FA) profile, and dietary physically effective neutraldetergent fiber (peNDF) content in a study that controlled for the potential confoundingeffects of dissimilar DMI among treatments. Ten multiparous Xinong Saanen dairy goats weredivided into2groups with2ruminally cannulated goats per group. Goats in each group wereassigned to1of2dietary treatments (high peNDF and low peNDF) according to a2×2crossover design, with21d for adaption diets and9d for sample collection in each period.The peNDF content of alfalfa hay (proportion of NDF retained on an8.0mm screen) was42.1%for the high peNDF and14.5%for the low peNDF group. Reducing dietary peNDFcontent had no effect on DMI and milk production and composition. Milk energy efficiencyincreased with low dietary peNDF. Duration of pH below5.60was longer for goats fed thelow peNDF ration compared with the high peNDF ration. Reducing dietary peNDF increasedrumen total VFA (114.6vs.95.1mM) and decreased chewing time (404vs.673min/d). Therelative abundance of Fibrobacter succinogenes and Ruminococcus flavefaciens increasedwith reduce dietary peNDF. Reducing dietary peNDF decreased the proportion of iso C14:0,iso C15:0and trans-11C18:1in milk fat. This study demonstrated that low dietary peNDF in dairy goats increases rumen VFA, reduces chewing time and is correlated to the amount of F.succinogenes and R. flavefaciens.2. This study investigated the effects of dietary physical effective NDF (peNDF, g/kg ofDM) to rumen degradable starch (RDS, g/kg of DM) ratios (CBI) on the risk of sub-acuteruminal acidosis (SARA), bacterial density, and rumen content fatty acid (FA) composition indairy goats. Six ruminally cannulated dairy goats were assigned to3treatments in a repeated3×3Latin square design. Treatment diets consisted of three CBI levels:1.81,1.43, and1.21,which were achieved by replacing dietary corn with wheat (0,175, and350g/kg of DM). Thetime and the area with a ruminal pH below5.8or below5.6(from1.20to3.05h/d, and fromlinearly increased when the dietary CBI was reduced. With the reducing of dietary CBI, themolar ratio of acetate decreased, whereas that of propionate increased. Reducing the dietaryCBI caused a linear decrease in the rumen concentrations of iso C14:0, iso C15:0, and isoC17:0. The relative abundance of Ruminococcus flavefacienswere decreased with decreasingdietary CBI. These results suggested that the odd and branched FA content of the rumen mightbe used to determine the fluctuation of the ruminal pH and of the bacterial population. Inaddition, the recommended dietary CBI for dairy goats was1.43.3. This study investigated the effects of a wheat induced sub-acute ruminal acidosis(SARA) challenge on rumen bacterial populations and in situdegradability of NDF, starch andcrude protein of feeds. Four multiparous dairy goats fitted with ruminal canula were assignedto a2×2crossover design (28d treatment periods separated by a7d washout interval). Thetreatment diets consisted of two levels of cracked wheat:0(Control, corn based concentrate)and35%(diet-induced SARA, wheat based concentrate). Results showed that diet with35%wheat decreased ruminal pH (6.21vs.5.98), and increased the duration and area of ruminalpH below5.6and induced SARA. Compared with the control group, the SARA challengedecreases the relative abundance of Fibrobacter succinogenes (-59.3%) and Ruminococcusflavefaciens (-68.4%), while it increased Succinimonas amylolytica (198.1%) andRuminobacter amylophilus (125.2%). The SARA challenge decreased24h and48h DM andNDF degradabilities of corn silage. The SARA challenge reduced in situ12h degradabilitiesof DM and CP of soybean meal and extruded soybean. These results indicated that thecracked wheat induced SARA challenge reduced degradation values of NDF in roughages aswell as the nitrogen of soybean meal (-19.8%) and extruded soy (-18.9%), but this challengeincreased the starch degradability in corn, which due to the increased amylolytic bacteria anddecreased cellulolytic bacteria in rumen.4. The objective to the present study was to modeling the regression relationship amongdietary peNDF content (peNDF1.18and peNDF8.0), ruminal pH, DMI, milk fat content and feed efficency to optimize the dietary peNDF content which ensure rumen health and highproductivity. In the present sutdy,27peered reviewed studies were adopted in the database.The results showed that dietary peNDF1.18and peNDF8.0showed strong relationship withruminal pH, milk fat and feed efficiency. And diets content18.8%peNDF8.0would resultrelative high DMI (22.4%). To ensure ruminal pH over6.16, the peNDF1.18, peNDF8.0, CBI1.18and CBI8.0should be higher than27.59%,12.83%,1.42, and0.73, respectively. And to keepmilk fat higher than3.2%, the peNDF1.18, peNDF8.0, CBI1.18and CBI8.0should be higher than23.60%,12.31%,1.08, and0.70. In the present study, the Meta analysis can give theregression relationship of dietary peNDF and CBI to ruminal pH, milk fat content, and feedefficiency and DMI parameters. The optimized dietary peNDF and CBI based on multipleindicators that ensure the health and high productivity, the dietary peNDF and peNDF shouldbe in the range of27.59-35.62%and12.83-18.80%, respectively.5. The objective of the present study indent to optimize the dietary forage NDF (FNDF)and rumen degradation starch (RDS) content and ratios by using meta-analysis in lactatingdairy cow. This study collected39peered review manuscripts, which were related to dietaryFNDF or RDS content on rumen health and milk performance in dairy cow. In this study, weuse FNDF to RDS ratio (CBIR) or the difference (CBID) as carbohydrate balance indexes (CBI)to evaluate their regression relationship to the ruminal pH, fermentation characteristics, milkfat and feed efficiency. The results suggested that the CBIRand CBIDshowed strong linear orquadratic relationship with the dependent variables. Dietary CBIRand CBIDabove1.28or1.09kg/d can minimize the risk of subacute ruminal acidosis, respectively. To obtainappropriate feed efficiency (≥1.5), milk fat (≥3.5%) and acetate to propionate ratio (2.2~3:1)in dairy cow, the CBIDand CBIRshould be in the range of0.42~0.99kg/d and0.93~1.30,respectively. In this study, the appropriate CBIDand CBIRranges were calculated based onmeta-analysis.In the present study, decreasing dietary roughage length and increasing dietary RDSreduced ruminal pH and increased risk of SARA. The fermentation type, microflora andbacteria were different between the two models of SARA. And the bacteria fatty acid canreflect the fluctuation of ruminal predominant cellulolytic and amylolytic bacteria. In addition,to ensure ruminal health and high productivity of dairy cow, we use meta-analysis method tooptimize the carbohydrate nutrition, and obtained the appropriate dietary peNDF1.18,peNDF8.0and CBI. This study provided theoretical basis to prevent the SARA and ensure animal healthand high productivity. |
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