康奈尔净碳水化合物-蛋白质体系预测小肠可消化粗蛋白质含量

本试验旨在建立奶牛饲料的康奈尔净碳水化合物-蛋白质体系(Cornell net carbohydrate and protein system,CNCPS)预测小肠可消化粗蛋白质(uCP)含量的数学模型.采用CNCPS体系对13种饲料蛋白质组分进行划分,采用移动尼龙袋法测定13种饲料小肠uCP含量,试验动物为3头带有永久性瘤胃瘘管和十二指肠瘘管的荷斯坦奶牛,采用单因素试验设计.结果表明:1)豆粕、棉籽粕、菜籽粕、葵花籽粕、芝麻粕、玉米胚芽粕、米糠、米糠饼、米糠粕、大麦、麦麸、玉米和玉米麸质饲料的uCP含量分别为390.32、321.90、297.21、230.50、388.62、177.49、85.53、116.78、134.74、80.47、128.26、70.28和66.65g/kg.2)所有试验饲料实测uCP含量与CNCPS各蛋白质组分含量的回归方程为:uCP=-4.11+6.48PA+7.73PB1+5.72PB2+8.26PB3+5.11PC(R2=0.9972,P＜0.01);蛋白质饲料实测uCP含量与CNCPS各蛋白质组分含量的回归方程为:uCP=12.79+5.47PA+7.04PB1+9.74PB2+8.14PB3(R2=0.9987,P＜0.01);能量饲料实测uCP含量与CNCPS各蛋白质组分含量的回归方程为:uCP=14.80+8.55PA+6.27PB2+17.64PB3(R2=0.9874,P＜0.01).3)蛋白质饲料、能量饲料及所有试验饲料的实测uCP含量与CNCPS各蛋白质组分含量的相关系数均高于0.95,蛋白质饲料实测uCP含量与CNCPS各蛋白质组分含量的相关系数高于能量饲料.结果提示,利用CNCPS体系划分的各蛋白质组分含量预测饲料uCP含量是可行的,且预测蛋白质饲料的uCP含量比预测能量饲料的uCP含量更准确.     

奶牛常用饲料康奈尔净碳水化合物-蛋白质体系中含氮化合物组分含量与可利用氨基酸含量之间的关系

为了预测奶牛常用饲料中可利用氨基酸(u AA)的含量,本试验采集了21个奶牛饲料原料样品,测定了饲料样品的粗蛋白质(CP)、粗脂肪(EE)、粗灰分(ash)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、可溶性粗蛋白质(SCP)、非蛋白氮(NPN)、中性洗涤剂不溶粗蛋白质(NDIP)、酸性洗涤剂不溶粗蛋白质(ADIP)含量,并根据康奈尔净碳水化合物-蛋白质体系(CNCPS)对饲料含氮化合物组分的划分方法,计算出饲料样品的含氮化合物组分非蛋白氮(PA)、快速降解真蛋白质(PB1)、中速降解真蛋白质(PB2)、慢速降解真蛋白质(PB3)和不可利用蛋白质(PC)的含量,测定了饲料的氨基酸含量,同时利用饲料氨基酸含量与u AA含量之间的关系估测出饲料的u AA含量。结果表明,奶牛常用饲料的CNCPS含氮化合物组分(PA、PB1、PB2、PB3、PC)含量(%DM)与u AA、可利用蛋氨酸(utilizable methionine,u Met)、可利用赖氨酸(utilizable lysine,u Lys)、可利用亮氨酸(utilizable leucine,u Leu)含量(%DM)存在显著的相关关系,回归方程如下:u AA=0.171PA+0.134PB1+0.364PB2+0.370PB3+0.148PC+7.785,R2=0.99,P0.01;u M et=0.019PA-0.031PB1+0.024PB2+0.078PB3-0.004PC-0.071,R2=0.93,P0.01;u Lys=-0.045PA-0.020PB1+0.072PB2+0.038PB3-0.011PC+0.780,R2=0.92,P0.01;u Leu=0.071PA+0.033PB1+0.093PB2+0.189PB3+0.003PC+0.006,R2=0.94,P0.01。结果显示,根据CNCPS含氮化合物组分和本试验所建立的方程,可以准确地预测奶牛饲料的u AA、u M et、u Lys和u Leu含量。     

Development of an in vitro incubation technique for the estimation of the utilizable crude protein (uCP) in feeds for cattle.

An in vitro incubation technique based on the first stage of the in vitro digestion technique published by Tilley and Terry (1963) was developed to estimate the utilizable crude protein (uCP) of single feeds and feed mixtures as non ammonia-N after 24 h of incubation. The results of 25 feed samples showed that there was a significant relationship between the uCP values calculated by regression based on in vivo data sets (Y, CP [g.kg-1 DM]) and those measured by the in vitro incubation technique (X, CP [g.kg-1 DM], 24 h incubation): y = 0.85x + 18.0, r2 = 0.84, P < or = 0.001. It was concluded that it can be possible to determine the uCP value of single feeds or feed mixtures by this in vitro incubation technique and to estimate the uCP value of feeds by this regression equation.     

利用体外产气法和CNCPS法对不同生育期虉草营养价值的评价研究

为了评定不同生育期虉草的营养价值,分析体外产气法和CNCPS法两种营养评价方法的相关性。采用体外产气法测定抽穗期、开花期、灌浆期、乳熟期4个生育期虉草的体外发酵产气量、发酵参数(a、b、c)、DM消化率、NDF和ADF降解率,用康奈尔净碳水化合物和蛋白质体系(cornell net carbohydrate and protein system,CNCPS)分析方法测定相应组分,评价其营养价值,并比较研究两种方法评价结果的相关性。结果表明,体外发酵至72 h结束,累计总产气量和产气参数a以开花期最高(122.68 和4.46 mL),显著高于各组(P<0.05),且从抽穗期、灌浆期、乳熟期有降低的趋势;抽穗期和开花期的DM消化率、NDF和ADF降解率分别显著高于灌浆期和乳熟期(P<0.05)。随着虉草生育期的延长,CP和SOLP呈递减趋势,即抽穗期和开花期显著高于灌浆期和乳熟期(P<0.05);NDF、ADF和ADL呈递增趋势,但NDFIP、ADFIP呈递减趋势。灌浆期和乳熟期的CHO含量显著高于抽穗期和开花期(P<0.05),而CA和CNSC含量则相反,且CC含量同样以灌浆期与乳熟期较高;蛋白质组分中,PA与CA及CC与PC组分呈现同样的趋势。虉草CNSC、CA、CB₁、CB₂、PA、PB₃组分含量与不同时间点产气量呈显著或极显著的相关性(P<0.05或P<0.01)。因此,开花期虉草营养价值最高,其次为抽穗期、灌浆期和乳熟期,产气法和CNCPS评价牧草具有相关性,用体外产气量估测牧草CNCPS组分是可行的。     

用CNCPS评定反刍动物几种常用精料营养价值的研究

[目的]为了验证CNCPS评定方法的可靠性.[方法]分别从黑龙江省的大庆、哈尔滨、双鸭山、佳木斯、牡丹江、集贤和五常等地采集反刍动物常用精饲料样品19种, 应用康奈尔净碳水化合物-蛋白质体系(CNCPS)提出的碳水化合物和蛋白质分类方法, 分别测定了饲料的粗蛋白质(CP)、非蛋白氮(NPN)、可溶性粗蛋白(SCP)、酸性洗涤不溶粗蛋白(ADFIP)和中性洗涤不溶粗蛋白(NDFIP)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)、木质素和淀粉.并根据CNCPS提出的计算方法计算了饲料粗蛋白质中的非蛋白氮(PA)、快速降解蛋白质(PB1)、结合蛋白质(PC)、中度降解蛋白质(PB2)、慢速降解蛋白质(PB3)和碳水化合物中的不可利用纤维(CC)、可利用纤维(CB2)、果胶(CB1)和糖类(CA).[结果]通过CNCPS饲料评定技术可对反刍动物常用精饲料营养价值分析评定.[结论]说明CNCPS可广泛用于对刍动物饲料营养价值的评定.     

玉米DDGS作为反刍动物能量或蛋白饲料原料的营养价值

为准确评价不同来源的DDGS作为反刍动物饲料的营养价值,研究采用美国康奈尔大学净碳水化合物和净蛋白质体系(CNCPS)的原理和方法,测定和分析了8种不同来源的玉米干酒糟及其可溶物(DDGS)的营养价值及营养特性,并且把DDGS和当地的玉米、豆粕的营养价值进行了比较。经测定,8种DDGS常规营养成分(占干物质%)的平均数为:粗蛋白(28.28±2.56)%,粗脂肪(11.01±1.03)%,碳水化合物CHO(56.10±5.65)%,NDF(45.06±4.24)%,ADF(18.94±1.52)%,木质素(3.67±0.35)%。在蛋白组分中,PA、PB1、PB2、PB3和PC分别占粗蛋白的(5.67±0.27)%、(4.9±0.51)%、(22.89±2.39)%、(49.8±4.77)%和(16.68±2.61)%,其中,PA、PC的含量变化大,变异系数分别为8.8%和16.7%。在碳水化合物组分中,CA、CB1、CB2和CC分别占CHO的(25.74±0.82)%、(13.74±3.14)%、(44.76±4.49)%和(15.76±1.23)%。作为能量饲料和玉米相比,DDGS的载能物质主要是脂肪和可消化纤维,所估计的产奶净能低于玉米(6.56MJ/kg比7.73MJ/kg)。作为蛋白质饲料和豆粕相比,DDGS中主要的蛋白质组分是慢速降解蛋白(PB3),且能为小肠提供多于豆粕的过瘤胃蛋白(96.50g/kg比62.57g/kg)。上述结果表明,不同来源或不同生产工艺产生的DDGS营养价值差异较大,可溶性蛋白的含量和酸性洗涤不溶蛋白质含量的变化是引起DDGS营养价值变化的主要原因。因此,改善玉米DDGS的加工工艺,准确测定DDGS蛋白质组分和碳水化合物组分的含量是科学利用DDGS饲料产品的必要条件。     

江西几种奶牛常用饲料的多体系营养价值评定

分别用Weende、Van Soest与CNCPS体系分析了稻草、苜蓿、玉米秸秆、豆腐渣与啤酒糟的营养成分,并计算了这5种饲料的相对值(RFV)与分级指数(GI)以及碳水化合物与蛋白质组分,旨在为各体系在江西奶牛业的合理应用提供基础理论数据。同时指出,Weende与Van Soest体系是奶牛饲料营养价值评定的基础,应根据需要选择综合评定指数或是CNCPS体系。     

Effects of heat treatment on protein feeds evaluated in vitro by the method of estimating utilisable crude protein at the duodenum

The effect of heat treatment on the protein value of field beans, lupins and peas was studied using an in vitro method. Protein feeds were subjected to heat treatment for 30, 60 and 90 min in forced air oven at 120, 140 and 160 °C and in autoclave at 105, 120 and 135 °C. The heat‐treated protein feeds were incubated in buffered rumen fluid together with grass silage and barley in complete isonitrogenous diets. The gas production (GP) was recorded continuously, and ammonia‐N (NH₃‐N) concentrations were determined during the in vitro incubation at 8, 24 and 48 h and used to determine the utilisable crude protein (uCP) at the duodenum at 16 h of incubation (uCP₁₆). Heat treatments decreased the concentration of soluble crude protein and increased neutral detergent insoluble CP (NDICP) in all protein feeds compared to untreated. Inclusion of protein feeds to basal diet showed no increase in the uCP₁₆ in untreated field bean diet and only a small numerical increase in the uCP₁₆ concentrations from 160 g/kg dry matter (DM) to 166 and 172 g/kg DM in untreated lupine and pea diets, respectively, indicating high degradability of untreated feeds. Increasing the time and temperature of the heat treatment linearly increased the uCP₁₆ concentrations in field bean and pea diets, but not in lupin diets. Autoclave treatment was more effective in decreasing uCP₁₆ than oven treatment despite the lower temperatures used. However, the combination of highest temperatures and treatment time in autoclave increased acid detergent insoluble CP (ADICP) concentrations in protein feeds, indicating protein damage and decreased intestinal digestibility. Determining in vitro uCP and ADICP shows to be a promising method for evaluating protein value in heat‐treated animal feeds.     

In situ and in vitro evaluation of crude protein degradation and utilisable crude protein content of barley,rye and triticale grains for ruminants

Rations for dairy cows are comprised of high proportions of cereal grains. Thus, despite their low crude protein (CP) content, grains can contribute considerably to the CP intake of dairy cows. This study was conducted to describe and compare ruminal CP degradation of a broad range of barley, rye and triticale genotypes in situ and in vitro and different methods to estimate the utilisable CP at the duodenum (uCP). Twenty samples each of rye, barley and triticale were incubated in situ and in vitro. Exponential regression analyses were used to estimate in situ degradation parameters. Further, the effective degradability (ED), ruminal undegraded CP (UDP) and uCP for ruminal passage rates of 5% and 8% per hr were estimated. The uCP was estimated in vitro and based on two different approaches using in situ UDP data and estimates of microbial synthesised protein (based on fermented organic matter [fOM] or equations of the Gesellschaft für Ernährungsphysiologie). The degradation rate declined from rye (43% per hr) to triticale (27% per hr) to barley (20% per hr), and it exhibited remarkable variation between the genotypes of a single species. The maximal degradable CP fraction also differed between the species, but was overall very high (94%–99%). The lowest washout fraction (26%) and the highest variation in ED (77%–86% and 69%–80% for a passage rate of 5% and 8% per hr, respectively) were found in barley. The in situ uCP content (estimated using fOM) was lower for barley than for rye and triticale at ruminal passage rates of 5% and 8% per hr (barley: 157 g/kg DM at both passage rates; rye and triticale: 168 (at 5% per hr) and 169 (at 8% per hr) g/kg DM). In vitro estimations of uCP did not differ between the grain species and uCP estimated according to GfE was higher for triticale than for barley and rye, which did not differ. The low variation within a single grain species and the weak correlations between ruminal CP degradation and nutrient concentrations suggested that differentiation of ED and uCP between the genotypes of a single grain species is not necessary.     

辽宁绒山羊常用饲料营养价值评定

采集辽宁绒山羊常用饲料17种23个样品,应用康奈尔净碳水化合物-蛋白体系(CNCPS)提出的原理和方法对饲料营养价值进行评价。测定饲料原料常规营养成分以及非蛋白氮(NPN)、可溶性蛋白(SCP)、酸性洗涤不溶蛋白(ADFIP)、中性洗涤不溶蛋白(NDFIP)及酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)、木质素(LIGNIN)和淀粉,并对饲料原料的蛋白质和碳水化合物进行分类分析。结果表明:粗饲料可溶性蛋白质主要是NPN,真蛋白含量少,3种蛋白质饲料可溶蛋白主要是真蛋白,NPN含量少;所采集灌木类饲料纤维含量尤其是慢速降解细胞壁成分含量低,可快速降解糖类和可利用蛋白质含量高,质量优于秸秆和干草等其他粗饲料;棉粕的不可消化纤维和不可消化蛋白质含量高,可消化利用性较差。豆皮的蛋白质含量较低,主要是慢速降解纤维成分占绝大多数。     

江西省几种奶牛常用饲料的多体系营养价值评定

分别用Weende、Van Soest体系与CNCPS分析了稻草、苜蓿、玉米秸秆、豆腐渣与啤酒糟的营养成分,并计算了这5种饲料的相对值（RFV）与分级指数（GI）以及碳水化合物与蛋白质组分,旨在为各体系在江西奶牛业的合理应用提供基础理论数据。同时指出,Weende与Van Soest体系是奶牛饲料营养价值评定的基础,应根据需要选择综合评定指数还是CNCPS。     

发酵湿玉米纤维饲料和几种常用粗饲料营养价值分析

试验旨在运用康奈尔净碳水化合物—蛋白质体系(CNCPS)和NRC模型分析比较发酵湿玉米纤维饲料(FWCGF)、湿玉米纤维饲料(WCGF)、苜蓿和青贮玉米(CS)的营养价值,预测FWCGF替代或部分替代反刍动物常用粗饲料的可行性.从黑龙江省不同牧场采集饲料样品,测出4种原料的常规营养成分,然后利用CNCPS模型剖分4种原...     

Nutrient profile and availability of co-products from bioethanol processing

Bioethanol production in North America has led to the production of considerable quantities of different co‐products. Variation in nutrient profiles as well as nutrient availability among these co‐products may lead to the formulation of imbalanced diets that may adversely affect animal performance. This study aimed to compare three types of dried distiller’s grains with solubles [100% wheat DDGS (WDDGS); DDGS blend1 (BDDGS1, corn to wheat ratio 30:70); DDGS blend2 (BDDGS2, corn to wheat ratio 50:50)] and their different batches within DDGS type with regard to: (i) protein and carbohydrate sub‐fractions based on Cornell Net Carbohydrate and Protein System (CNCPS); (ii) calculated energy values; and (iii) rumen degradation of dry matter (DDM), organic matter (DOM), crude protein (DCP), neutral detergent fibre (DNDF) and starch (Dstarch) at 36 and 72 h of ruminal incubations. Wheat DDGS had a lower intermediately (PB2, 136.4 vs. 187.4 g/kg DM) and a higher slowly degradable true protein (PB3, 142.2 vs.105.3 g/kg DM) than BDDGS1, but similar to those of BDDGS2. Sugar (CA4) was higher, whereas starch (PB1) and digestible fibre (PB3) were lower in WDDGS than in BDDGS1 and BDDGS2. All carbohydrate sub‐fractions determined differed significantly between the two batches of BDDGS2. The BDDGS2 had the highest calculated energy values (TDN, DE_3×, ME_3×, NEL_3×, NE_m and NE_g) among the three DDGS types. The energy values were slightly different between the batches of the three DDGS types. At all incubation times, wheat DDGS had a significantly higher (p < 0.05) DDM, DOM, DCP and DNDF than both DDGS blends. Differences were observed between different batches within DDGS types with regard to in situ rumen degradation of DM, OM, CP, NDF and starch. In conclusion, differences were observed in protein and carbohydrate sub‐fractions and in situ ruminal degradation of DM, OM, CP, NDF and starch among the three DDGS types and different batches within DDGS type. This indicates that the nutrients supplied to ruminants may not only differ among different types of DDGS but it may also differ among different batches within DDGS type.     

不同氮源对反刍动物饲料可利用粗蛋白的影响

本试验应用体外培养技术研究了不同氮源对反刍动物饲料可利用粗蛋白(utilizable crude protein,uCP)的影响,以及不同氮源在培养发酵过程中降解损失的情况。将4种氮源,即尿素、赖氨酸、蛋氨酸和酪蛋白水解物,分别添加到肉牛的典型基础日粮中(粗蛋白,CP14.1%),配制成4种日粮,并使各日粮的粗蛋白水平相近(约20%),作为试验日粮。以未添加氮源的基础日粮作为对照日粮。应用Zhao和Lebzien(2002)的体外培养法测定了4种试验日粮和对照日粮的uCP。结果表明,添加尿素、赖氨酸、蛋氨酸和酪蛋白水解物,均能够有效地提高基础日粮的uCP(P<0.05)。在这4种氮源中,赖氨酸提高uCP的效果最好。在培养发酵过程中,尿素、赖氨酸、蛋氨酸和酪蛋白水解物的氨态氮损失分别占粗蛋白质的72.9%、22.8%、55.2%和70.3%。     

Calculation of utilizable crude protein at the duodenum of cattle by two different approaches.

The duodenal flow of utilizable crude protein (crude protein minus endogenous protein) in cows was estimated using dietary parameters, first by multiple regression and secondly by the addition of microbial protein and undegraded feed protein. These estimates were compared with 327 results from experiments conducted with fistulated cows in Braunschweig-V?lkenrode and Rostock-Dummerstorf. The regressions and the measurements for microbial protein synthesis as well as feed protein degradation and organic matter fermentation in the rumen were based on the same experimental data set. The prediction of utilizable crude protein (uCP) at the duodenum by regression with digested organic matter (kg DOM) and undegraded feed protein (g UDP) as predicting variables, was more accurate than the value given by microbial protein synthesis and rumen protein degradability. The regression model [g uCP = [188.5-(116.5 (UDP/CP))] DOM + 1.03 UDP] had the highest coefficient of determination (r2 = 0.91) and the lowest coefficient of variation (cv = 8.6); indicating the model's superiority over the other method of estimation.     

Digestion studies in captive Hippopotamidae: a group of large ungulates with an unusually low metabolic rate

We performed intake and digestibility studies in four common (Hippopotamus amphibius) and four pygmy (Hexaprotodon liberiensis) hippos from two zoological institutions, using acid detergent lignin as an internal marker for the quantification of faecal output. In the case of one pygmy hippo, where total faecal collection was also possible, there was no distinct difference between the two methods of faecal output quantification. Two animals from each species were tested on a conventional zoo diet of hay and concentrates (diet HC) and on hay only (diet H). The other two animals received fresh grass at two different levels of intake (diets G1 and G2). Dry matter (DM) intake was higher on HC than on H or G diets, and averaged 37 +/- 11 for common and 35 +/- 14 g/kg(0.75) for pygmy hippos. There were no species differences in the average digestibility (aD) coefficients. Non-dietary faecal nitrogen averaged 65 +/- 4% of total faecal nitrogen, aD of crude protein (CP) averaged 67 +/- 9% and true protein digestibility 89 +/- 3%. Average digestibility of DM and crude fibre averaged 54 +/- 11% and 45 +/- 17%, respectively. In comparison with ruminants, hippos generally achieve lower aD for DM, organic matter and fibre parameters, but equal or higher aD CP coefficients. This is most likely due to the absence of significant fermentative activity in the hindgut and the corresponding low metabolic faecal nitrogen losses. Digestible energy intake was higher on HC than on H or G diets and averaged 0.30 +/- 0.11 MJ/kg(0.75) metabolic body mass. This value is extremely low for ungulates, supporting earlier suspicions that hippos have particularly low metabolic rates, and explains the proneness of this species to obesity in captivity when fed energy-dense pelleted feeds.     

不同热处理DDGS中CNCPS组分与糠氨酸含量的相关性研究

本试验旨在利用康奈尔净碳水化合物-蛋白质体系（CNCPS）的原理和方法评定不同程度热处理玉米乙醇糟（DDGS）的营养价值，并探究CNCPS组分及其瘤胃降解特性和小肠消化率与美拉德反应中间产物糠氨酸之间的相关性，为饲料营养价值的评定提供新的研究方法和思路。本试验将湿DDGS进行不同温度（110、120、130℃）、不同时间（0.5、1.0、1.5 h）的烘干处理，采用常规化学分析方法并结合CNCPS和AMTS-Cattle数据库对蛋白质各组分的瘤胃降解特性和小肠消化特性进行估测，同时采用高效液相色谱法测定糠氨酸的含量，进而探求CNCPS各组分瘤胃降解特性和小肠消化率与糠氨酸含量之间的相关性并建立回归方程。结果显示：①不同程度热处理的DDGS之间，糠氨酸含量、蛋白质组分、瘤胃可降解蛋白质组分、瘤胃不可降解蛋白质组分、小肠可消化蛋白质组分均存在显著差异（P<0.05）。②糠氨酸与蛋白质PA2、PB1、PB2和PC组分，瘤胃可降解蛋白RDPB2组分，瘤胃不可降解蛋白RUPB2、RUPC和TRUP组分，小肠消化蛋白IDGPB2组分间均存在显著相关性（P<0.05），并可通过回归建立预测方程。综合试验结果，经过不同程度热处理的DDGS的蛋白质组分和糠氨酸含量存在显著相关性，可以利用糠氨酸含量对不同程度热处理DDGS的蛋白质组分的瘤胃降解特性和小肠消化率进行估测。     

In vitro fermentation characteristics and effective utilisable crude protein in leaves and green pods of Moringa stenopetala and Moringa oleifera cultivated at low and mid‐altitudes

This study was conducted to assess the in vitro nutrient digestibility and utilisation of leaves and green pods of two Moringa species in supplementing the feed of ruminant animals during the dry season. Samples were analysed for proximate nutrients using official methods. The metabolisable energy (ME), organic matter digestibility (OMD) and effective utilisable crude protein (uCP) were estimated using the Hohenheim in vitro gas test method. Gas volume in Moringa stenopetala leaves and green pods was generally higher than those of Moringa oleifera. Gas volume for leaves was similar between low and mid‐altitudes but was higher for green pods at mid‐altitude. M. stenopetala leaves contained significantly higher ME (9.8 MJ/kg DM) and OMD (75%) than those of M. oleifera. Similarly, M. stenopetala green pods had higher ME and OMD values than those of M. oleifera. For green pods, the ME and OMD values were significantly higher at mid‐altitude than those at low altitude although these values for leaves were similar between both altitudes. Moringa oleifera leaves had higher effective uCP than those of M. stenopetala. Nevertheless, the effective uCP was higher for green pods of M. stenopetala than those of M. oleifera. The effective uCP for leaves cultivated at mid‐altitude was slightly higher than those at low altitude. This study suggested that leaves and green pods could be used as alternative energy and protein supplements for tropical ruminants, particularly during dry periods. It was further concluded that leaves were generally better in nutrient compositions and in vitro nutrient digestibility characteristics than green pods.     

Ruminal protein degradation and protein value of feeds

The relationship between dry matter (DM) degradation and crude protein (CP) degradation in the dairy cow's rumen was determined with a view to defining the protein value of feeds for ruminants. The nylon bag technique was applied for these studies. For all the feeds investigate (green fodder and preserves from cocks-foot, ryegrass, alfalfa/grass and meadow grass, as well as alfalfa, extracted soybean meal) a significantly positive relationship was found to exist between the levels of DM and CP degradation (r = 0.73 to 1.0). The regression coefficient b1 (CP degradation as regressor) was found to average 0.87. The positive relationship between DM degradation and CP degradation implies that microbial protein amount and unfermented feed protein at the duodenum are negatively correlated. Model calculations show that, on account of the compensation between microbial protein and feed protein at the duodenum, in feeds with a CP concentration below 200 g/kg DM, the extent of ruminal protein degradation does not exert a marked influence on duodenal protein passage. The partial calculation of the duodenal protein supply on the basis of undegraded feed protein and microbial protein, as practiced in the new models of protein evaluation, leads to systematic errors unless the relationship between DM degradation and CP degradation is considered.     

Evaluation of the fermentation dynamics of soluble crude protein from three protein sources in continuous culture fermenters

Eight dual-flow continuous culture fermenters (1.03 +/- 0.05 L) were used to assess differences in microbial degradation of the soluble CP fraction of canola meal (CMSCP), soybean meal (SBMSCP), and fish meal (FMSCP) using a completely randomized design with two 9-d experimental periods and a solution of tryptone as a control treatment (control). All fermenters received the same basal diet (58% ground corn, 40% canary grass hay, 0.4% vitamin-mineral premix, 1% CaCO(3), 0.6% salt on a DM basis) in 8 equal portions daily. During sampling on the last 3 d of each period, 90-mL doses containing soluble CP were infused into the fermenters 30 min after the beginning of the first and last feedings of the day. The total amount of soluble CP supplied by the infusions of FMSCP, CMSCP, and SBMSCP was 3.2 g/d, representing 24% of the daily dietary CP intake. Infusion of FMSCP resulted in the greatest (P < 0.05) NH(3)-N concentration (4.6 +/- 0.40 mg/dL) compared with the other treatments (0.5 +/- 0.40 mg/dL). Microbial N flow (g/d) from the fermenters was also greatest (P < 0.05) with FMSCP (1.42 +/- 0.062) compared with the other soluble CP fractions (1.08 +/- 0.062). The efficiency of microbial protein synthesis tended to be lowest with the control diet, and the efficiency of N utilization was lowest with FMSCP treatment. These results indicate that N was limiting microbial growth in the control diet, and there was more rumen-available N with the FMSCP diet compared with the other dietary treatments. The extent of degradation of the soluble CP fraction from fish meal, soybean meal, and canola meal was determined to be 99, 30, and 37% of soluble CP, respectively. These results indicate that the soluble CP fraction is not 100% degraded in all feeds and that assuming a high degradation extent of the soluble CP fraction from soybean meal and canola meal may result in an underestimation of the supply of undegradable protein from these protein sources.