体外产气法评价青海高原反刍家畜常用粗饲料组合效应

采用体外产气法评价青海高原反刍家畜的3种常用粗饲料青贮玉米（Zea mays）秸秆、苜蓿（Medicago sativa）青干草和燕麦（Arrhenatherum elatius）青干草按0∶100、25∶75、50∶50、75∶25和100∶0的比例两两组合时的发酵特性。结果表明,理论最大产气量、48 h产气量分别与中性洗涤可溶物/粗蛋白（NDS/CP）（P＜0.001）、有机物（OM）（P＜0.01）,中性洗涤可溶物（NDS）（P＜0.05）呈正相关关系,分别与酸性洗涤纤维（ADF）（P＜0.001）、中性洗涤纤维（NDF）（P＜0.05）和粗蛋白（CP）（P＜0.05）呈负相关关系;产气速率常数分别与OM（P＜0.001）、NDS（P＜0.001）和NDS/CP（P＜0.01）呈正相关关系,分别与ADF、NDF均呈极显著负相关关系（P＜0.001）;产气延滞时间与ADF（P＜0.01）和NDF（P＜0.05）呈正相关关系,分别与OM（P＜0.01）、NDS（P＜0.05）和NDS/CP（P＜0.05）呈负相关关系,说明了组合牧草体外发酵产气程度主要受非结构性碳水化合物与粗蛋白比例的影响。3种粗饲料两两组合搭配时,青贮玉米秸秆与苜蓿青干草以25∶75比例、青贮玉米秸秆与燕麦青干草以50∶50比例、苜蓿青干草与燕麦青干草以25∶75或50∶50比例组合时较为合适,且随着发酵时间的延长,各组合均呈现组合效应量逐渐减弱的变化趋势。     

体外产气法评价青海高原燕麦青干草与天然牧草组合效应

本研究采用体外产气法评价了青海高原反刍家畜补饲用燕麦青干草分别与藏嵩草、金露梅+珠芽蓼、线叶嵩草3种天然牧草均按0∶100,25∶75,50∶50,75∶25,100∶0的比例两两组合后的发酵产气特性。结果表明,48 h产气量、理论最大产气量与NDS(P＜0.01)呈正相关关系,而与NDF(P＜0.01)、HC(P＜0.01)呈负相关关系;产气速率常数与HC(P＜0.01)呈负相关关系;产气延滞时间与ADF(P＜0.001)、NDF(P＜0.05)呈正相关关系,而与CP(P＜0.01)、NDS(P＜0.05)呈负相关关系。不同牧草组合在发酵12～24 h的正组合效应较高,且随着发酵时间的延长,各组合均呈组合效应量逐渐减弱的变化趋势;且以燕麦青干草作为补饲草进行该地区天然草地反刍家畜的冷季营养补饲时,燕麦青干草分别与藏嵩草、金露梅+珠芽蓼、线叶嵩草草地型牧草均以50∶50比例组合较为合适。因此,做好牧草间的科学搭配组合是提高青海高原天然草地冷季牧草利用率的有效途径之一。     

体外产气法评价蚕豆秸秆与3种作物秸秆营养组合发酵特性

采用体外产气法评价青海高原蚕豆秸秆按不同质量比(0∶100、25∶75、50∶50、75∶25、100∶0)分别于小麦秸秆、青贮玉米秸秆和燕麦青干草两两组合后的发酵产气特性。结果表明:从GP 24h、ME和IVOMD三个产气发酵指标看,农作物秸秆中由高到低的顺序为:青贮玉米秸秆>蚕豆秸秆>小麦秸秆>燕麦青干草,且体外发酵理论最大产气量(A)也呈现类似的变化趋势,而产气延滞时间(Lag)则与之相反。蚕豆秸秆与3种禾本科植物秸秆组合后,产气量均较单一的禾本科植物秸秆有所提高,且随着各组合中蚕豆秸秆质量比增加,产气量也呈现逐渐增大的变化趋势。当蚕豆秸秆与小麦秸秆25∶75或50∶50比例组合,蚕豆秸秆与青贮玉米秸以25∶75比例组合,蚕豆秸秆与燕麦青干草50∶50比例组合时正组合效应最优。因此,科学的组合搭配作物秸秆能有效提高作物秸秆的利用率。     

体外产气法评价青海高原补饲草料与天然草地牧草组合效应

采用体外产气法评价了青海高原反刍家畜补饲用燕麦草(Arrhenatherum elatius(Linn.)Pressl)、老芒麦草(Elymus sibiricus L.)和精补料分别按质量比0:100,25:75,50:50,75:25,100:0的比例与藏嵩草(Kobresia tibetica Maxim.)草地型冷季牧草两两组合后的发酵产气特性。结果表明:补饲草料与藏嵩草草地型冷季牧草组合能有效提高单一藏嵩草的消化率;燕麦草和老芒麦草与藏嵩草草地型冷季牧草均以25:75比例组合时较为合适,精补料与藏嵩草草地型冷季牧草以50:50比例组合时较为合适,且各饲草料组合的正组合效应大部分在发酵12～24h时较高,体外发酵48h后其组合效应有下降趋势。研究结果将为该地区草地放牧家畜的营养平衡补饲提供科学依据。     

用体外产气法评价不同粗饲料与相同精料间的组合效应

以3头安装有永久性瘤胃瘘管的荷斯坦奶牛作为供体动物,应用体外批次培养法,利用多项指标综合指数(MFAEI),通过测定pH值、72h的累积产气量、有机物质降解率、微生物蛋白(MCP)及挥发性脂肪酸(VFA)产量,研究了粗-精料间的组合效应。试验结果表明,在不同粗料混合以后与同一精料(55:45)搭配产生了明显的正组合效应。当羊草、玉米青贮、草木樨分别以50%的比例替代玉米秸秆时,相对于100%的玉米秸秆来说,以玉米秸+草木樨+精料(27.5:27.5:45)组(MFAEI:1.199)和玉米秸+羊草+精料(27.5:27.5:45)组(MFAEI:1.032)这两组组合效应值较大,而玉米秸+玉米青贮+精料(27.5:27.5:45)组组合效应值(MFAEI:0.997)较小。以玉米秸+草木樨+精料组混合日粮多项组合效应值最高,组合效应最好。说明粗饲料组合后通过营养素间的互补,提高了日粮的整体发酵水平。     

用体外产气法评价双低菜籽饼与藏嵩草的组合效应

 采用体外产气法评价了青海高原反刍家畜补饲用双低菜籽饼按质量比为0∶100、25∶75、50∶50、75∶25、100∶0的比例与藏嵩草草地型冷季牧草组合的发酵产气特性。结果表明,双低菜籽饼与藏嵩草草地型冷季牧草组合能有效提高单一藏嵩草的体内消化率,且以25∶75比例组合时较为合适;双低菜籽饼与藏嵩草的正组合效应值在发酵12~24 h时较高,并呈现随发酵时间的延长而减小的变化趋势。     

青海省农牧交错区牦牛12种常用粗饲料营养参数的测定

本研究结合常规营养成分分析和体外发酵产气技术,主要测定了青海省农牧交错区的农作物秸秆(小麦秸秆、豌豆秸秆、蚕豆秸秆、油菜秸秆及马铃薯秸秆)、优质补饲饲草(青贮玉米秸、苜蓿青干草、燕麦青干草)和天然草地型(线叶嵩草、高山柳+黑褐苔草、金露梅—珠芽蓼及藏嵩草)冷季牧草等牦牛12种常用粗饲料的常规营养成分及体外发酵产气参数等营养评价指标,结果表明,5种农作物秸秆除豌豆秸秆和蚕豆秸秆的粗蛋白质含量分别为8.5%、9.75%,其余秸秆均低于8%,有机物质消化率在40%～65%,代谢能在4.0～9.0MJ/kg;4种天然草地型冷季牧草的粗蛋白质均低于8%,有机物质消化率在48%～70%,代谢能在6.0MJ/kg～10.0MJ/kg的范围内;3种优质补饲饲草苜蓿青干草、燕麦青干草和青贮玉米秸的粗蛋白质含量分别为11.36%、8.79%、5.25%,有机物质消化率在42%～70%,代谢能在5.0～11.0MJ/kg。     

体外产气法评估荞麦秸秆、油菜、苜蓿干草和玉米青贮的组合效应

试验拟采用体外培养技术,通过将荞麦秸秆、油菜、苜蓿干草和青贮玉米进行不同比例的组合搭配,在体外进行培养试验。通过检测多项发酵指标,用以评估这几种粗饲料的组合效应。组合比例(%)为油菜20青贮80,荞麦20苜蓿80,荞麦40苜蓿60,油菜20苜蓿80,油菜40苜蓿60,荞麦20青贮80。每种组合3个重复,采用体外发酵技术,评估每种组合发酵0、3、6、12、24 h的产气量、pH值、干物质消化率、氨态氮浓度、挥发性脂肪酸(VFA)、微生物蛋白(MCP)和甲烷含量,计算不同组合的单项组合效应指数(SFAEI)和多项组合效应指数(MFAEI)。结果显示,各组挥发性脂肪酸的含量随着体外培养时间的增长均呈上升的趋势,油菜20苜蓿80组挥发性脂肪酸总浓度最大。油菜20青贮80平均消化率达到了37.19%,其组合效应综合指数也最高。干物质消化率和产气量最高的为油菜20青贮80组,最小油菜20苜蓿80。各组NH_3-N浓度并无规律性变化。油菜20青贮80组甲烷排放量最低。荞麦20苜蓿80组的微生物蛋白浓度最高。各试验组pH值维持在5.57～5.93,随着培养时间增加略有下降。以MFAEI对各项指标进行评定时发现,油菜20青贮80组合效应值最高,荞麦20苜蓿80组次之。     

利用体外产气法评价玉米秸秆黄贮与甜菜块根组合效应

为探讨玉米(Zea mays)秸秆黄贮与甜菜(Beta vulgaris)块根的体外发酵组合效应,本研究将玉米秸秆黄贮与甜菜块根以100:0(T1)、80:20(T2)、60:40(T3)、50:50(T4)、40:60(T5)、20:80(T6)、0:100(T7)的比例进行组合,利用体外瘤胃发酵技术,分析其养分降解率、发酵参数及总产气量,以评价组合效应的功效.结果表明:1)随着甜菜块根比例的增加,干物质消化率(dry matter degradability,DMD)、中性洗涤纤维消化率(neutral detergent fiber degradability,NDFD)、酸性洗涤纤维消化率(acid detergent fiberdegradability,ADFD)先升高后降低,且组合后的养分降解率均高于单一原料养分降解率.2)随甜菜块根比例的增加,发酵液pH逐渐降低,T1组pH显著高于其他组(P<0.001),T3、T6组NH3-N浓度显著低于其他组(P=0.003).当甜菜块根比例为40％时,总挥发性脂肪酸(total volatile fatty acids,TVFAs)和各挥发性脂肪酸浓度最高,当甜菜块根比例大于40％时,其浓度又呈现降低趋势,T3、T4、T5组乙酸/丙酸值显著高于其他组(P<0.001).3)发酵时间对总产气量有显著影响(P<0.001),且时间和处理具有显著互作效应(P=0.006),总产气量随发酵时间的延长逐渐升高,随着甜菜块根比例的增加,呈现先升高后降低趋势.发酵4、8、12 h,T3组总产气量显著高于T1、T6、T7组(P<0.004),发酵24、48 h,T4组总产气量均显著高于T6、T7组(P<0.008).4)不同比例的单项组合效应值各有差异,但是从综合组合效应值来看,结果为T3>T5>T4>T2>T6.因此,玉米秸秆黄贮与甜菜块根的最优组合为60:40.     

体外发酵产气技术在饲料营养价值评定中的应用

体外产气技术是反刍动物饲料营养价值评定中常用的方法之一。文章比较了体内法、瘤胃尼龙袋法和体外法在反刍动物营养价值评定中的特点,并着重从体外产气技术的技术细节、测定装置和应用范围进行了全面的论述,为该技术的标准化和自动化提供参考。     

玉米芯与苜蓿、精料配比对饲粮组合效应的影响

为了探讨玉米芯与苜蓿、精料间不同配比对饲粮组合效应(associative effects, AE)的影响。采用体外产气法测定在精粗比40∶60和30∶70时,精料∶玉米芯∶苜蓿分别为40∶60∶0、40∶45∶15、40∶30∶30、40∶15∶45、40∶0∶60和30∶70∶0、30∶55∶15、30∶40∶30、30∶25∶45、30∶10∶60、30∶0∶70时各饲料组合及各种单独原料分别培养2,4,6,9,12,24,36,48 h的产气量(gas production, GP),培养结束后的上清液及残渣用以测定pH、挥发性脂肪酸(volatile fatty acids,VFA)、氨态氮(NH_3-N)、干物质降解率(dry matter digestibility, DMD)和有机物降解率(organic matter digestibility, OMD),并通过各组合的加权估算值计算出各指标的单项组合效应指数(single factor AE indexes, SFAEI)和综合组合效应指数(multiple-factors AE index, MFAEI)。结果表明:当精粗比为40∶60和30∶70时,玉米芯比例为30、15和10、25、40、55的组在GP、DMD、OMD、NH_3-N、TVFA上显著高于其他组,且有较高的SFAEI (P<0.05,P<0.01),30和10组的MFAEI极显著高于其他各组(P<0.01)。结论:当精料∶玉米芯∶苜蓿为40∶30∶30、30∶10∶60时,饲粮的综合组合效应值最大。     

Chemical composition, in vitro digestibility and gas production of straws from different varieties and accessions of chickpea

Chemical composition, in vitro digestibility and gas production of straw from four different varieties of Kabuli chickpea (Cicer arietinum) were studied. Kinetics of fermentation of straws from 19 different accessions of chickpea was also evaluated using gas production technique. Significant difference (p < 0.05) was observed in the yield of straw [from 1041 to 1174 kg dry matter (DM)/ha] from different varieties. The proportion of seed/straw from different varieties varied from 0.61 to 0.93. Crude protein, neutral detergent fibre and acid detergent fibre content of straw ranged from 28.1 to 35.8, 598.6 to 645.4 and 459.2 to 473.4 g/kg DM respectively. Organic matter digestibility was different (p < 0.05) among varieties and varied from 471.4 to 535.5 g/kg DM. Potential gas production (A), the rate constants (c and d) and lag times of straws from different chickpea varieties were not different (p > 0.05). However, the rate constants (c and d) and lag times were different (p < 0.05) among accessions. Potential gas production (A) differed (p < 0.05) approximately twofold among different accessions. The results emphasized that in any evaluation of chickpea varieties or accessions, where straw of this legume seed is used as an animal feed, not only seed yield but also yield and quality of straw should be taken into consideration.     

Prediction of rabbit caecal fermentation characteristics from faeces by in vitro gas production technique: roughages

To find equations able to estimate the fermentation characteristics of the caecum from that of faeces, caecal content and faeces of 10 hybrid Hyla rabbits were used as inocula for an in vitro gas production trial. About 1 g of 12 roughages, 11 hays (ryegrass, alfalfa, sulla, oat, vetch, sulla-lolium, vetch-oat, sulla-oat, clover, ryegrass-clover, sulla-vetch-oat) and a wheat straw, was weighed, in triplicate per inoculum, in 120-ml flasks; 75 ml of anaerobic medium and 4 ml of reducing solution were added and the flasks were placed at 39 degrees C. Caecal content and faeces were diluted respectively 1:2 (CI) and 1:8 (FI) with anaerobic medium and were introduced into their respective flasks (10 ml). Gas production was recorded 20 times at 2-24 h intervals throughout fermentation (120 h). The fermentation characteristics (i.e. degraded organic matter, OMd; potential gas production, A; maximum fermentation rate, R(max); volatile fatty acid, VFA; ammonia, NH(3)) were studied by inocula and substrates. The two inocula did not differ in OMd but CI produced significantly higher gas (A, 213.1 vs. 199.4 ml/g, respectively, for CI and FI, p < 0.01) in less time (R(max), 3.08 vs. 2.24 ml/h, respectively, for CI and FI, p < 0.01). CI also produced higher levels of total VFA (57.86 vs. 46.70 mmol/g OM, respectively, for CI and FI, p < 0.01) and showed a higher branched chain proportion (0.023 vs. 0.018, respectively, for CI and FI, p < 0.01). For some parameters (as OMd pH and propionate) the equations for the estimation of caecal fermentation characteristics from that of faeces were accurate (R(2) > 0.8828) and reliable (CV < 10.78%) suggesting that faeces can be successfully used for the estimation of these parameters.     

Evaluation of associative effects on ruminal digestion kinetics between pasture and grains using in vitro gas production method

In vitro gas production (GP) method was used to investigate associative effects on ruminal digestion when grains (corn or barley) were supplemented to spring pasture and autumn pasture. Pasture (75%) was incubated with 25% corn or barley and gas production was monitored up to 96 h. After incubation, the residues were used to determine dry matter and organic matter digestibility (DMD and OMD). Gas production parameters were analyzed by applying a single exponential equation. Organic matter effective degradability (OMED) was determined from GP parameters and OMD. The positive associative effects on the rate of GP, DMD, OMD and OMED were observed when spring pasture was incubated with corn. However, similar effects were not observed in a barley mixture. However, for autumn pasture, both corn and barley mixtures showed positive associative effects on rate of GP, OMD and OMED. The results of this study indicated that supplementation of corn would be better than barley for spring pasture with high water‐soluble carbohydrate contents, whereas both grain supplementations were effective to obtain positive associative effects on the rate of GP and OMED for autumn pasture with high cell wall content.     

Rumen fermentation and degradability in buffalo and cattle using the in vitro gas production technique

An in vitro trial was conducted to investigate the effect of different inoculum sources (buffalo vs. cattle) on rumen fermentation and degradability. Incubations were carried out using rumen fluid obtained from buffalo or cattle fed the same diet [60% grass hay and 40% concentrate; 18 kg dry matter (DM)/day]. The fermentation kinetics of eight feeds commonly used in ruminant nutrition (alfalfa hay, barley meal, beet pulp, corn meal and silage, ryegrass hay and silage and soya bean meal s.e.) were studied with the in vitro gas production technique and rumen fermentation parameters (substrate disappearance, pH and volatile fatty acids production) were determined after 120 h of incubation. The linear relationship indicates that the microbial metabolic pathways of the two inocula for all the substrates were qualitatively similar, albeit often quantitatively different. In this in vitro study, a significant influence of rumen inoculum (buffalo vs. cow) on fermentation and degradability of the examined substrates was found. The differences in buffalo and cattle rumen fermentation can be explained with a different microbial activity of the two ruminant species, because of different amount of microbial population or microbial population constituted by different species of bacteria and protozoa.     

Comparison of the dietary fiber digestibility and fermentability of feedstuffs determined by conventional methods and in vitro gas production technique in pigs

Abstract

This study evaluated the accuracy of an in vitro 2-step method combined with an in vitro gas production technique (2+IVGPT) for the estimation of dietary fiber (DF) digestibility coefficient and fermentability of feedstuffs in the large intestine of growing pigs. Digestibility coefficients of corn, wheat, soybean meal, and wheat bran, estimated by the in vitro methods, including the 2-step, 3-step, 2+IVGPT, and in vivo were compared. The fermentation characteristics of feedstuffs were also determined through the 2+IVGPT. The results showed that the in vivo DF digestibility coefficient of wheat bran was 0.39, which was similar to the result estimated by the 2+IVGPT (0.40). In regard to the fermentation characteristics, the lowest maximum rate of gas production (R_max) was obtained for wheat bran (11.0 ml h^?1). To conclude, in vivo total tract digestibility of DF in the fibrous feedstuff (e.g. wheat bran) could be accurately estimated by the 2+IVGPT.