不同NFC/NDF比日粮对奶山羊瘤胃pH动态变化的影响

试验采用动态pH连续监测记录系统对瘤胃pH进行24h连续监测,旨在研究不同非纤维性碳水化合物/中性洗涤纤维比(NFC/NDF比)日粮对奶山羊瘤胃pH昼夜动态变化的影响。选用6只安装有永久性瘤胃瘘管的关中奶山羊作为试验动物,采用自身对照试验设计,分为4期,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:瘤胃pH随着日粮NFC/NDF比增加而显著降低(P<0.05),瘤胃pH<5.2、5.5、5.8、6.0的平均持续时间亦随日粮NFC/NDF比增加而延长,分别由Ⅰ期的0、0、2.42h/d和9.40h/d增加到Ⅳ期的0.33、7.50、17.06h/d和20.53h/d;瘤胃pH<5.5、5.8、6.0曲线面积亦逐步加大,分别由Ⅰ期的0、0.21和1.43(pH·h)增加到Ⅳ期的1.09、4.84和8.59(pH·h);而且瘤胃pH下降速率和下降幅度及最低值所持续的时间亦随日粮NFC/NDF比增加而增加。     

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）。     

阉牛不同日粮的纤维消化,瘤胃内VFA对甲烷产生量的影响

装有瘤胃和真胃瘘管的成年阉牛４头，体重（５００±５０）ｋｇ，采用４×４完全拉丁方试验设计，在呼吸代谢室内就不同日粮的纤维消化、瘤胃内ＶＦＡ对甲烷产生量的影响进行了研究。结果表明：（１）可消化中性洗涤纤维（ＤＮＤＦ）和可消化酸性洗涤纤维（ＤＡＤＦ）的甲烷产生量，在不同加工细度羊草之间（７．５ｍｍ，１５ｍｍ，３５ｍｍ和长草）无显著差异（Ｐ＞０．０５）。（２）不同精粗比日粮（０∶１００，２５∶７５，５０∶５０，７５∶２５）的ＮＤＦ或ＡＤＦ降解量（ｋｇ／ｄ）与甲烷产生量呈较高的线性正相关（ｒ＝０．８６８９或ｒ＝０．９７７５），乙酸、丙酸、乙酸＋丙酸产量（ｍｏｌ／ｄ）以及乙酸／丙酸与ＣＨ４产生量（Ｌ／ｄ）之间均存在较高的线性相关（ｒ依次为０．９６９１，－０．９６８３，０．９７８９，０．８８３３）。     

不同NFC/NDF比对奶山羊瘤胃微生物及瘤胃pH值变化的影响

试验研究了在不同非纤维性碳水化合物/中性洗涤纤维（NFC/NDF）比饲粮条件下诱发奶山羊亚急性瘤胃酸中毒（subacute rumen acidosis,SARA）过程中瘤胃微生物区系和瘤胃pH值的变化。该试验选用6只安装了永久性瘤胃瘘管的泌乳期关中奶山羊为试验动物,采用自身对照试验法,共分4期进行,每期10d,依次饲喂NFC/NDF比为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的方法诱导奶山羊发生SARA。结果表明,随着饲粮NFC/NDF比的增大,瘤胃pH值显著降低（P〈0.05）,并且瘤胃pH值下降幅度也随之加快;随着饲粮NFC/NDF比的增加,淀粉分解菌的数量增幅最显著（P〈0.01）;饲粮NFC/NDF比为1.63时,瘤胃细菌总数、乳酸杆菌及坏死梭形杆菌的数量显著增加（P〈0.05）,当该比值为2.58时,埃氏巨型球菌和反刍兽新月单胞菌的数量出现显著增多（P〈0.05）;原虫数量在Ⅳ期降至最低,而牛链球菌的数量在整个试验期并未出现明显的波动。饲粮NFC/NDF比为1.63时,瘤胃内与碳水化合物分解有关的多数细菌的数量明显增加,SARA期时增幅更为明显,而此时原虫数量为最低。     

苜蓿形态学性状与纤维含量的相关性分析

通过田间试验及纤维含量测定,研究苜蓿Medicago sativa主茎长、节间数、节间长等形态学性状与其纤维含量的关系,为在田间选择低纤维苜蓿单株提供有效地优势性状。试验结果表明：苜蓿品种（系）间,各形态学性状、中性洗涤纤维（NDF）和酸性洗涤纤维(ADF)都具有显著性差异(P＜0.05),其性状变异系数依次为节间长(29.91%)＞主枝侧枝数(22.45%)＞主枝茎粗(20.82%)＞分枝数(19.76%)＞节间数(12.57%)＞主茎长(8.87%)＞ADF(4.18%)＞NDF(3.24%),各形态学性状与NDF和ADF相关性分析表明,主茎长与NDF和ADF均呈显著的正相关,主枝侧枝数与ADF也呈显著正相关。其余形态学性状与NDF和ADF不存在显著相关性。     

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.     

日粮中性洗涤纤维水平对生长公牛碳水化合物和蛋白质消化代谢的影响

采用拉丁方试验设计,选择6头12月龄的中国荷斯坦公牛,分别喂给6种不同NDF(中性洗涤纤维)水平的日粮,(NDF在日粮中的比例分别为:30.26%、32.49%、34.74%、36.94%、39.16%、41.39%),以研究NDF对碳水化合物和蛋白质消化代谢的影响。试验表明,NDF水平对日粮ND和ADF(酸性洗涤纤维)的表观消化率有显著影响(P<0.05),日粮NDF和ADF的表观消率随日粮NDF水平的提高而升高,淀粉的消化率受日粮NDF水平的影响下大(P>0.05);NDF水平对日粮氮的利用率有明显影响(P<0.05),过高或过低均不利于氮的沉积;NDF对日粮能量的表观消化率有显著影响(P<0.05),日粮能量表观消化率随NDF水平的提高而下降。     

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。     

The agronomic performance and nutritional content of oat and barley varieties grown in a northern maritime environment depends on variety and growing conditions

Warmer temperatures and increasing interest in high provenance food and drink products are creating new opportunities for cereal growing in northern Europe. Nevertheless, cultivation of oats and barley in these areas for malting and milling remains a challenge, primarily because of the weather, and there are few reports of their nutritional content from this region. In this study, trials in Orkney compared agronomic characteristics and nutritional content of recommended UK oat and barley varieties with Scandinavian varieties over three years. For a subset of varieties, nutritional content was compared with samples cultivated in more southerly sites. For Orkney, barley was considered a more suitable crop than oats because varieties matured earlier. In both crops, Scandinavian varieties matured earlier than UK varieties and some produced comparable yields. The range of values for macronutrients and minerals in oats and barley in Orkney were similar to those reported previously for other locations, but there were some significant differences attributable to variety and year. Compared with grain samples from more southerly locations, oats in Orkney had a significantly lower β-glucan and higher sodium content. The lower β-glucan may have resulted from higher rainfall and lower temperatures during the months of grain filling and maturation.