日粮不同NFC/NDF比对奶山羊瘤胃pH值、挥发性脂肪酸及乳酸含量的影响

试验旨在探讨日粮不同非纤维性碳水化合物/中性洗涤纤维比（NFC/NDF）对奶山羊瘤胃发酵参数的影响。选择6只安装有永久性瘤胃瘘管的关中奶山羊作为试验动物,采用自身对照试验法,共分为4组（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种日粮。结果表明,随着日粮NFC/NDF比的提高瘤胃pH值降低,瘤胃pH值下降速率和下降幅度及pH值低于5.2、5.5、5.8、6.0的持续时间随之加快、延长;瘤胃丙酸、丁酸及总挥发性脂肪酸（TVFA）含量随日粮NFC/NDF比提高呈增加趋势,而乙酸含量及乙酸/丙酸则呈降低趋势;血浆乙酸、丙酸、丁酸及TVFA均呈增加趋势。当日粮NFC/NDF比达2.58时,瘤胃pH值在5.2～5.5之间持续时间每日达7h以上,此时瘤胃乳酸含量较低,血浆及瘤胃TVFA含量显著提高（P〈0.05）。结果表明,随着日粮NFC/NDF比的提高,使瘤胃逐渐处于酸性环境,改变了瘤胃发酵模式;瘤胃pH值的下降主要源于瘤胃TVFA增多,而非乳酸;当日粮NFC/NDF比为2.58时,奶山羊发生亚急性瘤胃酸中毒。     

制样方法对粗饲料中NDF和ADF测定值的影响

为探讨高速粉碎机制样对纤维类物质测定的影响,本实验选用小麦秸秆和苜蓿干草为实验样品,用两种方法制样,一种是用碾槽、铁研钵等手工制样,另一种用高速粉碎机制样,粒度控制为全过1mm筛,0.5mm筛上物为80%,然后用尼龙滤袋法和范氏法测定其中的NDF和ADF。实验结果表明,小麦秸秆用范氏法测定的ADF值手工制样的结果极显著高于万能粉碎机制样的测定值,其余各组间差异均不显著,但用碾槽等手工制样的测定结果有高于粉碎机制样测定结果的趋势;苜蓿干草NDF的两种方法的测定值碾槽制样的结果均显著高于粉碎机制样的结果,而ADF用范氏法处理中碾槽制样的结果均显著高于粉碎机制样的结果,尼龙滤袋法处理中碾槽制样的结果与粉碎机制样的结果差异不显著。因此,用高速万能粉碎机制样对粗饲料中NDF和ADF的测定有影响。     

煮沸时间对滤袋法测定青贮玉米NDF和ADF含量的影响

为探明煮沸时间对滤袋法测定青贮玉米的中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量的影响,本研究以Van Soest传统方法所测结果为对照,对煮沸时间30、40、50、60、70、80、90、100、110、120、130min进行优选.结果显示,用滤袋法测定全株玉米青贮和不带穗玉米青贮NDF含量时分别以煮沸110和120min为宜,测定全株玉米青贮和不带穗玉米青贮ADF含量时分别以煮沸60和70 min为宜.可见,用滤袋法测定青贮玉米的NDF、ADF含量时,二者的适宜煮沸时间明显不同.     

日粮NDF水平对断奶獭兔生长性能和肠道形态的影响

【目的】研究日粮中性洗涤纤维(NDF)水平对断奶獭兔生产性能、肠道形态、盲肠pH值、腹泻率、死亡率和血液碱性磷酸酶(AKP)活性的影响。【方法】将56只体质量相近((432.11±11.17) g)的35 d断奶獭兔,随机分为4组,分别饲喂含质量分数29%,33%,37%和41%NDF的日粮,进行28 d的饲喂试验,于14和28 d测定各组采食量和体质量,计算各组生产性能。饲喂结束后,屠宰并及时采集血液和肠道样品,测定肠道绒毛高度和隐窝深度及血液AKP活性、盲肠pH值、腹泻率、死亡率。【结果】各NDF处理组间的生产性能差异显著(P＜0.05),其中33% NDF组的平均日增质量显著高于37% NDF组和41% NDF组(P＜0.05),料质量比显著低于29% NDF组和41% NDF组(P＜0.05)。日粮NDF水平对十二指肠肠绒毛高度和隐窝深度、空肠肠绒毛高度的影响均不显著(P＞0.05);日粮NDF水平对空肠隐窝深度有显著影响 (P＜0.05),表现为低水平NDF使空肠隐窝加深;日粮NDF水平对回肠肠绒毛高度、隐窝深度和肠绒毛高度/隐窝深度都有显著影响(P＜0.05),表现为41% NDF组的肠绒毛高度和隐窝深度均较其他组高,而肠绒毛高度/隐窝深度值显著低于29% NDF组(P＜0.05)。腹泻率和死亡率随着日粮NDF水平的升高呈降低趋势,AKP活性在各组间无显著差异,盲肠pH值随日粮NDF水平的提高而总体升高,且37% NDF组和41% NDF组盲肠pH显著高于29% NDF组和33% NDF组(P＜0.05)。【结论】高NDF水平日粮可降低断奶獭兔腹泻率,影响其肠道形态,当日粮NDF质量分数为33%时1～2月龄獭兔生产性能最好。     

黄土高原高糖黑麦草的产量和品质预测

为探明黄土高原高糖黑麦草(Lolium perenne)粗蛋白、粗脂肪、中性洗涤纤维、酸性洗涤纤维、粗灰分、可溶性碳水化合物等指标及产草量与其生长时间、株高、分蘖之间的关系,本研究采用田间试验结合预测模型的方法,利用生长时间、株高、分蘖对高糖黑麦草在模拟轮牧和收获干草两种利用方式下的牧草产量及品质进行预测。结果表明,收获干草的Aberavon、Aberstar、Premium和Abermagic黑麦草生长时间、株高和分蘖均与各营养指标显著相关(P0.05);模拟轮牧的Aberavon、Aberstar、Premium和Abermagic黑麦草株高与各营养指标均不相关(P0.05),生长时间、分蘖与粗蛋白、粗灰分之外的其它品质指标均显著相关(P0.05)。利用生长时间、株高、分蘖对4个黑麦草品种的产草量和饲用成分建立一元回归预测和多元回归预测模型,经预测值与实测值对比,预测结果准确度均较高,可为高糖黑麦草在黄土高原栽培和利用提供科学依据。     

Nutritive quality and morphological development under partial shade of some forage species with agroforestry potential

The shade environment produced in agroforestry practices affects the morphology, anatomy and chemical composition of intercropped forages and, therefore, may affect forage quality. During the summer-fall growing season of 1994 and 1995, 30 forage cultivars were grown in 7.6 L (two gallon) pots in full sun, 50%, and 80% shade created by placing shade cloth over a greenhouse frame. Fifteen legumes and grasses that were similar in yield under full sun and shade treatments were selected for quality analysis. With the exception of 'Kobe' lespedeza, D. paniculatum and D. canescens, acid detergent fiber (ADF) was either not affected or was slightly increased by shade. Except for Kobe lespedeza and 'Martin' tall fescue, shade either did not affect or slightly increased the neutral detergent fiber (NDF) of the shade-tolerant forages. Crude protein (CP) percentage increased in most shade-grown forages; however, shade had less effect on CP of legumes than of grasses. Other than Kobe lespedeza, total mass of CP per pot (TCP) was unaffected or increased under 50% shade for all species. Total crude protein of hog peanut, D. esmodium paniculatum and D. canescens was greater under both 50% shade and 80% shade than in full sun. The decrease in ADF of Kobe lespedeza, D. paniculatum and D. canescens under the shade treatments might be associated with maintenance of a higher leaf:stem weight ratio under shade. However, the leaf:stem ratios of the same cultivars grown at different light intensities did not strongly correlate with NDF, CP, and TCP values. In general, on selected species, internodal length and leaf area increased while specific leaf dry weight decreased for plants grown in shade compared to those grown in full sun. The data indicated that forage quality of some species could be enhanced by shade. This revised version was published online in June 2006 with corrections to the Cover Date.     

收刈时间对不同品种玉米秸秆营养成分和干物质降解率的影响

大田试验种植4个早中熟玉米品种,包括农大108、高油298、冀丰58、郑单958,在生长期的92 d、96 d、100 d和104 d收刈秸秆,研究收刈时间对秸秆营养物质含量和干物质降解率的影响,试验结果表明,收刈时间明显影响玉米秸秆的粗蛋白质、纤维性物质含量,所选种的玉米品种秸秆蛋白质含量和干物质降解率在100 d达到峰值.     

Effect of dietary fiber on methane production in Chinese Lantang gilts

The objective of this study was to determine the effect of dietary fiber on methane (CH₄) production in pigs using the Chinese native Lantang gilts as study model. The study consisted of two experiments. In the first, 12 Lantang gilts (58.7±0.37 kg), individually housed in open-circuit respiration chambers were randomly divided into two groups (six replicates per dietary group) and fed either with low fiber diet [LFD; neutral detergent fiber (NDF)=201.5 g/kg] or high fiber diet (HFD; NDF=329.7 g/kg). Wheat bran was the main source of fiber for the LFD while ground rice hull (mixture of rice bran and rice hull) was used in the HFD. Results of the study showed that gilts fed LFD recorded higher (P<0.05) digestibility coefficients for dry matter (DM), total organic carbon (TOC), acid detergent fiber (ADF) and cellulose than those in the HFD. However, digestibility coefficient for NDF did not differ between treatments but that for hemicellulose was higher for HDF than for LDF. Because of the higher NDF and hemicellulose contents in the diet, pigs in the HFD recorded higher (P<0.05) amount of digested NDF (126.1 vs. 83.6 g/d) and hemicellulose (38.7 vs. 11.9 g/d) than those fed LFD. The higher amount of digested NDF and hemicellulose recorded for the HFD treatment was inconsistent with the lower (P<0.01) daily CH₄ production from gilts fed the HFD compared to that fed LFD (2.46 vs. 3.90 L/pig). To better explain for the unexpected higher CH₄ production from pigs fed LFD, an in vitro fermentation study was conducted using a factorial design comprised of two inocula (collected from low fiber and high fiber diets) and eight substrates (LFD, HFD, wheat bran, ground rice hull and their respective NDF residues). Results of the in vitro trial seems to suggest that the low CH₄ production from the HFD animals was primarily the results of low fermentation rates of HFD and the ground rice hull. However, the calculated CH₄ productions based on the molar percentage of volatile fatty acids (VFA) in both, in vivo and in vitro experiments reaffirmed the in vivo result, that is, CH₄ production from pigs fed HFD was lower than that fed LFD. Although there is a lack of scientific data from this study to fully explain for the unexpected lower CH₄ production from pigs fed the HFD, our results seems to suggest that quantity of digested fiber (including NDF) was not the sole factor affecting enteric CH₄ production in pigs.     

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.     

Effects of rice straw particle size on digesta particle size distribution,nitrogen metabolism,blood biochemical parameters,microbial amino acid composition and intestinal amino acid digestibility in goats

Effects of rice straw particle size and physically effective neutral detergent fiber (peNDF) on particle size distribution of different digestive tract, nitrogen (N) metabolism, blood biochemical parameters, microbial amino acid (AA) composition and intestinal AA digestibility in goats were investigated. A 4 × 4 Latin square design was employed using four mature Liuyang black goats fitted with permanent ruminal, duodenal, and terminal ileal fistulae. During each of the four periods, goats were offered one of four diets that were similar in chemical composition, but varied in particle sizes and peNDF through alteration of the theoretical cut length of rice straw (10, 20, 40 and 80 mm, respectively). Dietary peNDF contents of four diets were 17.4, 20.9, 22.5 and 25.4%, respectively. Results showed that increasing particle size of rice straw and dietary peNDF significantly affected the particle size distributions of digesta in rumen, duodenum and ileum, except feces. However, increasing particle size of rice straw and peNDF did not affected N metabolism in goats, except the increased apparent N digestibility in rumen and large intestine, and the decreased apparent N digestibility in small intestine. Furthermore, increasing particle size of rice straw and peNDF showed little influence on the profile of blood biochemical parameters, microbial AA composition and intestinal AA digestibility in goats.