纤维素酶添加量与中性洗涤纤维体外降解率的关系

通过体外降解方法测定添加纤维素酶在玉米-豆粕-麸皮、玉米-豆粕-DDGS、玉米-豆粕-杂粕型饲粮中对饲料中性洗涤纤维(NDF)降解率的影响.结果表明:添加纤维素酶可以显著提高中性洗涤纤维的降解率;饲粮中不同NDF含量与纤维素酶添加量及NDF降解率之间存在极显著的二元二次回归关系,当纤维素酶添加量为3000IU.kg-1时,NDF降解率达到最高,相对于不加酶组,玉米-豆粕-麸皮型饲粮的NDF降解率提高5.6%,玉米-豆粕-DDGS的NDF降解率提高3.7%,玉米-豆粕-杂粕型的NDF降解率提高3.16%.     

微贮对秸秆的瘤胃DM和NDF降解率的影响

试验采用３个重复对比设计,将玉米、小麦和稻草秸秆的微贮样与原样放置在永久瘘管牛体内,分别在６,１２,２４,３６,４８和７２ｈ时间点取出样本进行ＤＭ（干物质）和（ＮＤＦ（中性洗涤纤维）降解率试验测定分析,结果表明：秸秆处理样在各个时间点的ＤＭ和ＮＤＦ瞬间降解率和有效降解率均极显著优于原样（Ｐ〈０．０１）,而玉米秸秆原样和处理样ＤＭ降解率均显著高于小麦和稻草（Ｐ〈０．０１）。     

傅立叶近红外快速预测菜籽粕的中、酸性洗涤纤维的研究

为了快速测定菜籽粕中的中、酸性洗涤纤维,对73个不同地区的菜籽粕样品进行了傅立叶近红外光谱扫描以及中、酸性洗涤纤维的化学测定,根据光谱与化学值利用偏最小二乘法建立傅立叶近红外的预测模型,并对模型进行评价。结果表明,NDF和ADF的决定系数分别为97.03和95.57,矫正标准差分别为0.95和1.17。模型的准确度较好,外部检验后真值与化学值接近,说明该模型适合快速预测菜籽粕的中、酸性洗涤纤维的含量。     

Use of fibrolytic enzymes additives to enhance in vitro ruminal fermentation of corn silage

Two experiments were conducted to evaluate the effect of four enzyme additives on ruminal fermentation of corn silage using a 48 h batch culture in vitro assay with buffer and ruminal fluid. Experiment 1 (Exp. 1) and Experiment 2 (Exp. 2) were conducted as completely randomized designs each with two runs and four replicates. The enzyme additives (E1, E2, E3, and E4) were commercial products that provided a range in endoglucanase, exoglucanase, and xylanase activities. For both xylanase (birch wood and oat spelt substrate) and endoglucanase (carboxymethylcellulose substrate), the enzyme products (per ml) were ranked E4>E1>E2>E3. In Exp. 1, the four enzymes were added at 0, 2, 4, and 8 μl/g of corn silage dry matter (DM), whereas in Exp. 2 enzymes were added at 0, 0.5, 1, 2, and 4 μl/g DM. Gas production (GP) was measured at 3, 6, 12, 18, 24, and 48 h after incubation. Disappearance of DM (DMD), neutral detergent fiber (NDFD), and acid detergent fiber (ADFD), and volatile fatty acid concentrations (VFA; total and individual molar proportions) were determined after 24 and 48 h. In Exp. 1, E1 and E2 had higher NDFD and ADFD at 24 and 48 h of incubation (P<0.001) compared with E3 and E4. Increasing dose rate increased NDFD and ADFD for all enzymes (except ADFD for E4 at 48 h), with the optimum dose rate dependant on the enzyme additive (dose×enzyme; P<0.01). There were some treatment effects on DMD and total GP at 24 and 48 h, but these responses were not consistent with responses in NDFD and ADFD. Experiment 2 was conducted to confirm the effects and optimum dose rate of each enzyme additive. In Exp. 2, DMD was not affected by enzyme after 24 and 48 h incubation. There were no enzyme×dose interactions for DMD, NDFD, or ADFD after 24 or 48 h of incubation (except for ADFD at 48 h). After 24 h, DMD, NDFD, and ADFD increased linearly with increasing dose (P<0.05); after 48 h DMD increased linearly, whereas NDFD increased quadratically with increasing enzyme dose (P<0.05). The ADFD increased linearly after 48 h for E3 and E4, but after 48 h ADFD increased quadratically for E1 and E2. Total GP was consistently lowest for E4 at both incubation times (P<0.05). There were no enzyme×dose interactions (P>0.05) for any of the fermentation variables at either 24 or 48 h of incubation in Exp. 2. There were differences amongst the additives for total VFA at 24 and 48 h (P≤0.05); increasing enzyme dose decreased total VFA after 24 h but increased total VFA at 48 h, such that all doses were higher than the control (P<0.001). Overall, the enzyme additives increased NDFD and ADFD of corn silage in vitro; however, E1 and E2 were more effective than E3 or E4. Responses to increasing dose of enzyme were generally linear or curvilinear, and the optimum dose rate differed amongst the products evaluated. Evaluation of the enzymes at 24 and 48 h generally led to the same ranking of the additives, and the degradation of NDF and ADF was more useful in differentiating the enzymes compared with DM and total GP.     

奶牛中性洗涤纤维营养研究进展

本文对奶牛中性洗涤纤维(NDF)和物理有效中性洗涤纤维(peNDF)营养调控进行了较全面的综述。日粮中NDF能够通过影响奶牛采食、咀嚼和反刍,调节瘤胃中有机酸、pH和微生物的数量等途径对瘤胃发酵进行调控;peNDF的营养调控作用也主要体现在奶牛的采食和消化过程中。日粮中适宜浓度的NDF和peNDF是维持奶牛健康和生产性能的重要因素。     

日粮不同NDF水平对山羊内源氮流量的影响

以装有瘤胃、十二指肠、回肠瘘管的山羊为试验动物。采用拉丁方试验设计,探讨4种NDF水平分别为40.70%、38.37%、34.28%、30.36%的日粮对山羊十二指肠、回肠内源氮流量的影响。结果表明:在该试验条件下,日粮NDF水平在30%～40%范围时,十二指肠、回肠内源氮流量差异不显著(P>0.05)     

肉牛日粮补锌对粗料纤维和玉米有机物瘤胃降解的影响

为研究肉牛日粮补饲无机锌对粗料纤维和玉米有机物对瘤胃降解的影响,选用4头装有永久性瘤胃瘘管的西门塔尔杂交肉牛,采用4×4拉丁方设计,以瘤胃尼龙袋法测定日粮补饲锌(源于硫酸锌,分别补饲0、25、50和100 mg Zn/kgDM)对稻草纤维性物质和玉米有机物(OM)瘤胃降解率的影响.结果表明,对照组(0补饲)、25 mg Zn/kgDM、50 mg Zn/kgDM、100 mg Zn/kgDM处理组的稻草中性洗涤纤维(NDF)降解率分别为16.32%、17.43%、20.32%和25.31%,50、100 mg Zn/kgDM处理组的稻草NDF降解率明显高于对照组;对照组、25 mg Zn/kgDM、50 mg Zn/kgDM和100 mg Zn/kgDM处理组的玉米OM降解率分别为46.41%、46.89%、50.16%和48.49%,50 mg Zn/kgDM处理组的玉米OM降解率也明显高于对照组.肉牛日粮补饲锌(源于硫酸锌)明显影响瘤胃稻草NDF和玉米OM降解率,日粮补饲50 mg Zn/kgDM可明显提高稻草NDF和玉米OM的降解率.     

饲粮不同NFC/NDF对奶山羊瘤胃溶纤维丁酸弧菌、牛链球菌及埃氏巨型球菌含量变化的影响

试验旨在探讨在饲粮不同非纤维性碳水化合物/中性洗涤纤维条件下,奶山羊发生亚急性瘤胃酸中毒（subacute rumen acidosis,SARA）过程中瘤胃溶纤维丁酸弧菌、牛链球菌及埃氏巨型球菌数量的变化。选用6只安装有永久性瘤胃瘘管的泌乳期关中奶山羊为试验动物,采用动物自身前后对照法,试验分4期进行,每期10d,依次饲喂NFC/NDF比分别为1.02（Ⅰ期）、1.24（Ⅱ期）、1.63（Ⅲ期）、2.58（Ⅳ期）的4种饲粮,以逐渐增加饲粮精料含量的方式诱导奶山羊发生SARA,并采用实时定量PCR技术对瘤胃内溶纤维丁酸弧菌、牛链球菌及埃氏巨型球菌的数量变化进行定量分析。结果表明：①随着饲粮NFC/NDF比的逐步升高,溶纤维丁酸弧菌和埃氏巨型球菌的数量均增加,但当饲粮NFC/NDF比升至2.58时,与其他试验期相比,埃氏巨型球菌的数量极显著增加（P〈0.01）,而溶纤维丁酸弧菌的数量却极显著降低（P〈0.01）;②牛链球菌的数量随着饲粮NFC/NDF比的逐步增加呈显著下降趋势（P〈0.05）,但到第Ⅳ期又恢复到第Ⅰ期的数量。结果提示,当奶山羊发生SARA时,瘤胃牛链球菌的数量无明显变化,对低pH值敏感的溶纤维丁酸弧菌数量急剧下降,而耐酸性的埃氏巨型球菌数量表现为大幅增加。     

玉米秸秆DNF与ADF含量变化规律的研究

为了弄清不同品种、不同收获时间玉米秸秆营养成分变化情况，应用范氏洗涤纤维分析方法对10个品种、四个收获时期玉米秸秆中NDF、ADF含量进行了测定。结果表明：品种不同，四期秸杆中NDF和ADF含量平均值变化范围分别是62.4%～70.62%和38.31%～41.93%；收获时期不同，10个品种秸秆中NDF和ADF含量平均值变化范围分别是64.14%～70.48%和37.22%～43.55%。     

Neutral detergent fiber increases endogenous ileal losses but has no effect on ileal digestibility of amino acids in growing pigs

Two experiments were conducted to determine the effect of neutral detergent fiber (NDF) on endogenous amino acids and protein ileal losses; and also apparent ileal digestibility (AID), and standardized ileal digestibility (SID) of amino acids and crude protein. Sixteen barrows were fed four protein‐free diets containing graded NDF levels in Experiment 1. NDF was a mixture of sugarcane bagasse and corn leaves (SBCL). Twenty‐four barrows were fed diets with soybean protein concentrate (SPC) or casein as protein sources and SBCL or corncobs (CC) as NDF sources in Experiment 2. In Experiment 1, a linear increase (P < 0.05) in endogenous amino acid and protein ileal losses was observed with increased NDF levels, except for arginine, histidine, methionine and proline. In Experiment 2, protein (P < 0.001) and NDF (P < 0.01) sources significantly affected AID of dry matter, which was higher in casein diets (71.7%) and CC diets (70.7%). Protein and NDF sources significantly affected (P < 0.05) SID of crude protein, which was higher in casein diets (92.8%) and CC diets (92.7%). NDF source had no effect (P > 0.05) on SID of amino acids. Overall, this study showed that NDF increased endogenous amino acid and protein ileal losses, but did not affect ileal digestibility of amino acids.