饲喂低水平DCAD饲粮同时作为体外发酵底物组合对山羊瘤胃发酵的影响

Effect of Low Level of DCAD Diet as Rumen Fermentation Substrate in vitro on Rumen Fermentation of Goats

试验旨在探讨通过饲喂低水平日粮阴阳离子差(dietary cation-anion difference,DCAD)饲粮并以其作为发酵底物对山羊瘤胃发酵是否会产生负面影响。采用自身对照试验设计,以3只安装永久性瘤胃瘘管的山羊为试验动物,饲粮DCAD水平为高(+121;记为A)和低(-170;记为B),检测瘤胃pH;同时将这2个DCAD水平饲粮作为体外发酵底物(记为C、D),共形成4个饲喂饲粮-发酵底物组合,即A-C、A-D、B-C、B-D,以此进行瘤胃体外发酵试验,检测累积产气量、产气参数、有机物消化率、体外发酵液pH、氨态氮浓度,综合评价低DCAD饲粮在反刍生产实践中的效应。结果显示:饲喂A和B日粮,瘤胃pH差异不显著(P>0.05)。B-D组合在2h时瘤胃体外累积产气量(GP)显著高于A-C、A-D组合(P<0.05),其余4个组合GP没有显著差异(P>0.05)。潜在产气量a+b以B-C、B-D组合较高,显著高于A-C组合(P<0.05)。4个组合间有机物消化率未产生显著差异(P>0.05)。A-C、A-D组合瘤胃体外发酵液pH高于B-C、B-D组合(P<0.05),均处于正常范围。除2、12h外,4个组合对体外发酵液氨态氮浓度在大多数时间点没有产生明显影响,差异不显著(P>0.05)。由此可见,饲喂低DCAD饲粮对山羊瘤胃发酵没有产生明显负面影响,这可为生产实践合理应用低DCAD饲粮提供依据。

This study was conducted to evaluate the effect of varying dietary cation-anion difference（DCAD）on rumen fermentation of goats.Three goats fitted with permanent rumen fistula were used as experimental animals with self-control design.Goats were fed 2DCAD levels at 121（high DCAD level,A）and-170（low DCAD level,B）for rumen fluid pH analysis,meanwhile,rumen fermentation in vitro measurements for control and treatment diets was totally allocated to 4combinations at A-C,A-D,B-C,and BD,respectively;and then was measured for a comprehensive evaluation on varying DCAD on rumen fermentation.Measurements consisted of cumulative gas production and its parameters（a,b,c）,organic matter digestibility,pH,and NH3-N concentration.The results showed that reducing DCAD resulted in slightly decrease on ruminal fluid pH compared with control（P〈0.05）.There was no significant difference（P〉0.05）in gas production for the 4combinations,except for the higher level between B-D and AC and A-D（P〈0.05）.B-C and B-D was observed to have higher a＋b relative to A-C（P〈0.05）.Organic matter digestibility,fermentation fluid pH and NH3-N concentration in vitro were unaffected for the 4combinations（P〉0.05）.It was concluded,from the above results,that reducing DCAD level has limited side effect on rumen fermentation in vitro of goats,therefore,it was safe for application in the practice.