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1.
本试验旨在研究日粮精粗比对活体外瘤胃发酵和烟酸、烟酰胺合成的影响。以4头装有永久性瘤胃瘘管的成年荷斯坦阉公牛作为瘤胃液供体,选用淀粉、微晶纤维素、酪蛋白3种成分配制成相同粗蛋白质水平(13.5%,DM)和不同精粗比(30:70、50:50、70:30,DM)的3种纯合日粮作为发酵底物。应用人工瘤胃体外产气量法进行培养发酵并测定产气量、挥发酸及发酵液中烟酸、烟酰胺含量的变化。结果表明,提高日粮精粗比可极显著降低发酵液pH、乙酸/丙酸摩尔比、乙酸摩尔比(L,P<0.01),显著降低氨态氮浓度(L,P<0.05),但却极显著增加72 h产气量、总挥发酸浓度、丙酸和丁酸摩尔比(L,P<0.01)。随日粮精粗比的提高,瘤胃发酵液中总烟酸(烟酸+烟酰胺)、烟酰胺浓度在24和48 h均呈线性增加(L,0.050.10)。由此得出,日粮精粗比可改变活体外瘤胃发酵模式和影响瘤胃微生物合成总烟酸和烟酰胺,且随日粮精粗比的上升,瘤胃合成总烟酸、烟酰胺的数量呈线性增加趋势。 相似文献
2.
Origin of abomasum gas in the cows with displaced abomasum 总被引：2，自引：0，他引：2
T Sarashina S Ichijo J Takahashi S Osame 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(2):371-378
The gas composition of the rumen and the abomasum were investigated in 71 cows including 25 cows with displaced abomasum. The ratio of methane (CH4) to CO2 in the abomasum gas was higher than that in the rumen. In the incubated mixtures of fresh rumen fluid, CH4 was detected at a high concentration, while a small amount of CO2 and CH4 was found in incubated mixtures of fresh abomasum fluids. Hence, it was suggested that the gas in the abomasum originated not from the abomasum itself but from the rumen. In cows fed with mixed roughages and concentrates, the rumen CO2:CH4 ratio was higher compared with cows fed with roughages alone. Marked changes in rumen gas composition were presumed to be associated with changes in abomasum gas composition. Consequently, it is possible that feeding a large quantity of concentrates may increase the flow rate of the ingesta through the forestomach, so that the return rate of gas separated from the ingesta in the abomasum to the forestomach may also increase. Therefore, the frequent accumulation of a large amount of gas with concomitant changes in the total volatile fatty acid (VFA) concentration in the abomasum caused abomasal atony and subsequently displaced abomasum. 相似文献
3.
采用体外瘤胃发酵试验结合动态产气实时记录技术,分析了添加植酸酶对瘤胃微生物降解和利用糠麸饲料的功效。试验采集3头健康泌乳期荷斯坦奶牛瘤胃液,以稻糠、玉米麸和麦麸为底物,测定对照组和加酶组(5 U/g植酸酶)发酵72 h的累积产气量、发酵动力学参数和和瘤胃发酵特性指标。结果表明,添加5 U/g植酸酶并不能显著影响稻糠、玉米麸和麦麸的体外干物质消化率、培养液中氨态氮浓度以及发酵的产气量(72 h累积产气量和理论最大产气量)(P>0.050 0),但却能显著降低发酵的产气速率及达到最大产气量1/2时的产气速率(P<0.050 0),显著提高培养液总挥发性脂肪酸浓度(P<0.050 0),总挥发性脂肪酸浓度增幅由高至低依次为麦麸(4.2%)、稻糠(3.3%)和玉米麸(1.7%),除可显著提高异丁酸含量(P<0.050 0)外,对乙酸、丙酸、丁酸等主要挥发性脂肪酸的含量的影响不显著(P>0.050 0)。总之,稻糠、玉米麸和麦麸间体外瘤胃发酵特性存在差异,添加植酸酶可在一定程度上促进瘤胃微生物发酵释放出更多的挥发性脂肪酸,提高瘤胃微生物对饲料中能量物质的发酵利用效率。 相似文献
4.
In different experiments, the nutritive value of maize silage associated with urea was compared with that of the same forage associated with soybean meal. The ammonia concentration in the rumen fluid was measured with two dry cows fitted with a permanent rumen cannula. Urea gave rise to much higher NH3 concentrations compared with soybean meal. The duodenal N flow was measured with two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus. Adding increasing amounts of either of the two N supplements to the maize silage showed that they were equivalent with low N intakes. However, clearly more N reached the intestine with soybean meal than with urea when the N intake increased. With 33 cows in the second part of lactation, the substitution of soybean meal for urea decreased the urinary N loss. At the same time, it significantly increased the mammary protein secretion and the milk production. The increase of the dietary metabolizable energy density noted under these feeding conditions corresponded to about two thirds of the increase of the milk production. Milk composition was only slightly affected. 相似文献
5.
用体外产气法评价精粗饲料的组合效应 总被引：1，自引：0，他引：1
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,利用体外产气法,通过产气量、干物质(DM)、有机物(OM)和中性洗涤纤维(NDF)的降解率、挥发性脂肪酸(VFA)产量这五个指标的测定,评价精粗比(玉米:稻草)为0∶100、20∶80、30∶70、50∶50、100∶0的五种饲料组合的营养价值及组合效应。结果表明,随着体外培养时间的延长,各精粗比日粮体外累积产气量及DM、OM、NDF降解率、TVFA产量均呈上升趋势;随着精料水平的提高,累积产气量不断升高,DM和OM的降解率均呈上升趋势,NDF降解率下降,乙酸含量减少,丙酸含量增加。精粗比为30:70的混合日粮多项组合效应值最高,组合效应最好。 相似文献
6.
本试验通过体外培养法,研究在不同精粗比饲粮中添加维生素B12对体外瘤胃发酵和微生物酶活力的影响。试验采用3×3双因子试验设计,即3个底物精粗比(玉米∶羊草=35∶65、50∶50和65∶35)和3个维生素B12添加量(0、40和90 ng/mL)。体外试验用瘤胃液取自3只安装有永久性瘤胃瘘管的湖羊。体外培养24 h后测定体外瘤胃发酵参数和微生物酶活力。结果显示:1)随着底物精粗比和维生素B12添加量的提高,体外培养24 h的产气量、潜在产气量和有机物消化率极显著地增加(P<0.01),且维生素B12添加量与上述指标存在线性剂量效应(P<0.01)。2)当底物精粗比为50∶50和65∶35时,添加维生素B12显著提高了发酵液中氨态氮、微生物蛋白、总挥发性脂肪酸、乙酸和丙酸浓度(P<0.05),但对丁酸浓度和乙酸/丙酸无显著影响(P>0.05)。3)当底物精粗比为35∶65和50∶50时,添加40 ng/mL维生素B12使发酵液中羧甲基纤维素酶、木聚糖酶活力显著提高(P<0.05);当精粗比为65∶35时,添加90 ng/mL维生素B12使发酵液中羧甲基纤维素酶、木聚糖酶活力显著提高(P<0.05)。结果提示,底物精粗比和维生素B12添加量影响体外瘤胃发酵。添加维生素B12可增加瘤胃微生物酶的活力,从而提高有机物消化率以及微生物蛋白和总挥发性脂肪酸的产量。当底物精粗比(玉米∶羊草)较高(50∶50和65∶35)时,维生素B12的添加效果更明显,并且具有剂量依赖效应。 相似文献
7.
8.
Rumen fluid samples from a cow were withdrawn manually from the feed mat (solid phase) or the liquid phase below this mat and incubated in vitro with wheat straw, sorghum hay and a concentrate mixture. From the inoculum and several samples collected during in vitro incubation RNA was extracted to assess microbial population size and structure. RNA content recovered from the solid phase rumen fluid was significantly higher than from the liquid phase. The composition of the microbial population in the solid phase material was characterised by a high proportion of Ruminococci. Neither the proportion of other cell wall degrading organisms (Fibrobacter and Chytridiomycetes) nor the Eukarya and Archaea populations differed between the two sampling sites. Gas production was higher when substrates were incubated with solid phase than with liquid phase rumen fluid regardless of sampling time. However, the higher level of gas production was not accompanied by a corresponding increase in true digestibility. The RNA probes showed that during in vitro incubation with liquid phase rumen fluid, the eukaryotic population was inactive no matter which substrate was used and the activity of methanogens (Archaea) was lower than with solid phase rumen fluid. The population pattern of the cell wall degrading organisms was influenced mainly by the substrate fermented, and to a smaller extent by the inoculum used for in vitro fermentation. 相似文献
9.
Gehrke M 《Polish journal of veterinary sciences》2005,8(3):201-207
This study was carried out in order to determine the influence of nitrogen excess in rumen and deficit of digestible organic matter in a feed ration for dairy cows on hypomagnesaemia at the beginning of green forage feeding. The balance of nitrogen and energy metabolism in rumen was determined using the rules of evaluation of the nutritional value of fodder (PDI system) according to the Institut National de la Recherche Agronomique (INRA), taking into consideration a potential protein synthesis from nitrogen by microorganisms in rumen (MPRN) and microbial protein synthesized from digestible organic matter (MP(RE)). It was found that an increase in the amount of rumen degradable protein (RDP) and MPRN-MPRE balance leads to a significant increase of urea nitrogen in serum (p < 0.05). An increase of total MPRN-MPRE balance in rumen results in a decrease of Mg concentration in serum. It has been demonstrated that in cows fed green forage at the end of spring (2nd half of May to 1st half of June) when the MPRN-MPRE balance is not higher than 187 g, adding 7 g or 25 g of MgO/cow/day to the same extent successfully prevents hypomagnesaemia. 相似文献
10.
试验选用新培育的品种天农青饲Ⅰ号饲用高粱原料,研究其在泌乳奶牛瘤胃内的能量养分消化代谢。选用2头健康泌乳奶牛,试验原料为天农青饲Ⅰ号品种的2种不同栽培处理的样品（A、B）,分别测定风干全株穗天农青饲Ⅰ号高粱A组和天农青饲Ⅰ号高粱B组奶牛瘤胃内9个时间点(0、2、4、8、12、24、36、48和72 h)的能量降解率。结果表明,品种高粱A原料能量值为11.22 MJ/kg,泌乳奶牛的瘤胃能量降解率为59.41％;品种高粱B的原料能量值为15.38 MJ/kg,泌乳奶牛瘤胃能量降解率为62.69%。试验品种高粱的栽培技术及其物理化学特性,影响泌乳奶牛的瘤胃能量降解率。 相似文献
11.
Calabrò S Moniello G Piccolo V Bovera F Infascelli F Tudisco R Cutrignelli MI 《Journal of animal physiology and animal nutrition》2008,92(3):356-362
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. 相似文献
12.
研究柴胡皂苷(SSA)对体外发酵指标及发酵液中菌群变化的影响。采用完全随机试验设计,在0.5 g全混合日粮(TMR)中分别添加0,0.125,0.25和0.5 mg的SSA,通过AGRS-III微生物发酵微量产气自动记录仪在39℃条件下进行48 h体外发酵,并通过实时定量PCR(RT-PCR)检测发酵液中菌群相对含量的变化。结果表明,0.25 g/kg的SSA提高了干物质降解率(DMD,P=0.08)和总产气量(GP,P<0.05),并提高了发酵液中挥发酸(VFA)的含量(P<0.05),而0.5和1.0 g/kg的SSA对GP和DMD没有显著的影响,但是提高了乙酸和TVFA的含量(P<0.05)。SSA提高了白色瘤胃球菌和牛链球菌的相对含量(P<0.05);但降低了短普雷沃氏菌和噬淀粉瘤胃杆菌的相对含量(P<0.05)。因此,SSA提高了体外GP和VFA浓度,并改变发酵液中细菌的含量,这表明SSA有利于调控微生物体外发酵参数。 相似文献
13.
J. Boguhn T. Zuber M. Rodehutscord 《Journal of animal physiology and animal nutrition》2013,97(3):547-557
Two nonlactating cows and two wether sheep, all fitted with a permanent cannula into the rumen, were fed either hay plus concentrate, grass silage or corn silage to study the effect of the donor animal and its diet on in vitro fermentation and microbial protein synthesis. Rumen inoculum was obtained before the morning feeding. Grass silage or corn silage was incubated in a semi‐continuous rumen simulation system for 14 days. Four replicated vessels were used per treatment. Degradation of crude nutrients and detergent fibre fractions as well as microbial protein synthesis and the production of volatile fatty acids were studied. Additionally, total gas and methane production was measured with a standard in vitro gas test. Gas production and methane concentration was higher when the inoculum used was from sheep than that from cows. The donor animal also affected the degradation of organic matter and ether extract as well as the amount of propionate and butyrate, and the acetate‐to‐propionate ratio. The effect of the diet fed to the donor animal on fermentation was much greater than the effect of the donor animal itself. Feeding hay plus concentrate resulted in higher gas production and degradation of acid detergent fibre, but in lower degradation of ether extract and reduced microbial protein synthesis. Additionally, the pattern of volatile fatty acids changed significantly when the diet of the donor animals was hay plus concentrate or one of the silages. These results show that in vitro fermentation and microbial protein synthesis is different when based on inoculum from either cattle or sheep. The diet fed to the donor animal is more important than the animal species and is probably mediated by an adjusted microbial activity. With regard to standardized feed evaluations, these results further support the need to harmonize in vitro approaches used in different laboratories. 相似文献
14.
高粗料日粮中添加脂肪对奶年血液代谢产物瘤胃发酵和干物质消化率影响的研究 总被引：2，自引：0，他引：2
对50头泌乳中期的奶牛进行为期6周的饲养试验，研究高粗料高脂肪日粮对奶牛血液代谢产物、瘤胃发酵和干物质消化率的影响。试验设有10个重复，每个重复5头奶牛，每头奶牛给定一种日粮。试验用日粮为：对照日粮（日粮1）和试验日粮（高粗料75％高脂肪7．5％，日粮2；高粗料，中等水平脂肪5．0％，日粮3；中等水平粗料65％，高水平脂肪，日粮4；中等水平粗料和脂肪，日粮5；或者对照日粮中含有50％粗料和2．0％脂肪）。这些日粮含氮量相同（CP17．7％）。粗饲料由20苜蓿干草、40％苜蓿半干青贮和40％青贮玉米组成。所用脂肪由80％瘤胃 保护脂肪和20％黄色油脂组成。试验结果表明：试验组和对照组的血糖浓度差异不显著；试验组的血浆非酯化脂肪酸（NEFA）高于对照组。而奶牛采食日粮的粗饲料和脂肪水平不同，其NEFA差异不显著；对照组、试验组与粗饲料和脂肪水平不同的日粮的瘤胃PH、瘤胃VFA浓度和干物质消化率差异不显著。 相似文献
15.
Krizsan SJ Nyholm L Nousiainen J Südekum KH Huhtanen P 《Journal of animal science》2012,90(9):3162-3173
The objective of this study was to compare the application of different in vitro and in situ methods in empirical and mechanistic predictions of in vivo OM digestibility (OMD) and their associations to near-infrared reflectance spectroscopy spectra for a variety of forages. Apparent in vivo OMD of silages made from alfalfa (n = 2), corn (n = 9), corn stover (n = 2), grass (n = 11), whole crops of wheat and barley (n = 8) and red clover (n = 7), and fresh alfalfa (n = 1), grass hays (n = 5), and wheat straws (n = 5) had previously been determined in sheep. Concentrations of indigestible NDF (iNDF) in all forage samples were determined by a 288-h ruminal in situ incubation. Gas production of isolated forage NDF was measured by in vitro incubations for 72 h. In vitro pepsin-cellulase OM solubility (OMS) of the forages was determined by a 2-step gravimetric digestion method. Samples were also subjected to a 2-step determination of in vitro OMD based on buffered rumen fluid and pepsin. Further, rumen fluid digestible OM was determined from a single 96-h incubation at 38°C. Digestibility of OM from the in situ and the in vitro incubations was calculated according to published empirical equations, which were either forage specific or general (1 equation for all forages) within method. Indigestible NDF was also used in a mechanistic model to predict OMD. Predictions of OMD were evaluated by residual analysis using the GLM procedure in SAS. In vitro OMS in a general prediction equation of OMD did not display a significant forage-type effect on the residuals (observed - predicted OMD; P = 0.10). Predictions of OMD within forage types were consistent between iNDF and the 2-step in vitro method based on rumen fluid. Root mean square error of OMD was least (0.032) when the prediction was based on a general forage equation of OMS. However, regenerating a simple regression for iNDF by omitting alfalfa and wheat straw reduced the root mean square error of OMD to 0.025. Indigestible NDF in a general forage equation predicted OMD without any bias (P ≥ 0.16), and root mean square error of prediction was smallest among all methods when alfalfa and wheat straw samples were excluded. Our study suggests that compared with the in vitro laboratory methods, iNDF used in forage-specific equations will improve overall predictions of forage in vivo OMD. The in vitro and in situ methods performed equally well in calibrations of iNDF or OMD by near-infrared reflectance spectroscopy. 相似文献
16.
Reflux of bile acids from the duodenum into the rumen of cows with a reduced intestinal passage 总被引：1，自引：0，他引：1
The purpose of this study was to find out whether the concentration of bile acids in the rumen of healthy cows differs from that of cows with a reduced gastrointestinal passage. The investigations were performed on 277 heifers and cows of the Swiss Braunvieh, Simmental and Swiss Holstein breeds. Forty of these had traumatic reticuloperitonitis, 30 had right or left abomasal displacement, 14 had an ileus of the duodenum, 36 had an ileus of the jejunum and 54 had a caecal dilatation. The other 103 animals had disorders which did not affect the digestive system and were used as controls. The mean (+/- se) bile acid concentration in the rumen fluid of the control animals was 1.0 +/- 0.30 mumol/litre. The bile acid concentrations in the rumen fluid of the cows with a duodenal or jejunal ileus were significantly higher than those of the other groups, demonstrating that bile acids may reflux from the duodenum into the rumen of cows with an ileus in the small intestine. 相似文献
17.
Váradyová Z Baran M Siroka P Styriaková I 《Berliner und Münchener tier?rztliche Wochenschrift》2003,116(7-8):317-321
The objective of the present experiment was to determine the effects of addition of silicate minerals, zeolite (Z), bentonite (B), kaolin (K), granite (G) on the rumen fermentation parameters, total gas, methane, total and individual volatile fatty acids (VFA) and hydrogen recovery in rumen fluid inoculum from sheep. Different materials (0.25 g) meadow hay (MH), wheat straw (WS), barley (BA) and amorphous cellulose (AC) were used as substrates. Silicate minerals (0.1 g) were added to the fermentation bottles containing substrates and rumen fluid inoculum and incubated for 72 h in vitro. The gas production technique simulates fermentation in the rumen was used to determine fermentation parameters. The total gas production was significantly higher compared to control for MH plus B (MHB), MH plus G (MHG), WS plus Z (WSZ), WS plus B (WSB), WS plus K (WSK), WS plus G (WSG), AC plus B (ACB), AC plus G (ACG), BA plus Z (BAZ), BA plus B (BAB), BA plus K (BAK), BA plus granite (BAG). Significant differences of the methane production were found between the controls, WSG, BAB and BAK. The total VFA concentration was increased in ACG (83.1 mM). The acetate: propionate (A:P) ratio of the control and additives ranged between 3.1 and 3.6 for MH, 2.7 and 3.5 for WS, 1.6 and 1.8 for AC and 2.3 and 2.9 for BA. It was concluded that the silicate minerals had no appreciable effect on the methane production, however, they support the microbial metabolism by influencing (bentonite, granite) and slightly influencing (zeolite, kaolin) the rumen fermentation. 相似文献
18.
在底物精粗比为6∶4的条件下,在底物中添加不同剂量[使发酵液中植物精油的浓度分别为0(对照)、50、100、200和400 mg/L]的丁子香酚、D-柠烯、茴香脑、肉桂醛、百里香酚或香芹酚,通过体外产气法比较研究不同植物精油对体外瘤胃发酵和甲烷(CH4)产量的影响。每种植物精油的每个剂量设3个重复。体外模拟瘤胃发酵培养24 h,测定产气量和气体中的CH4含量以及发酵液的p H、挥发性脂肪酸(VFA)和氨态氮(NH3-N)浓度。结果表明:1)除百里香酚外,添加各种植物精油对体外发酵液p H均无显著影响(P0.05)。2)添加丁子香酚、D-柠烯、茴香脑和肉桂醛对体外发酵液总VFA浓度没有显著影响(P0.05),但总VFA浓度随百里香酚和香芹酚浓度的增加呈二次曲线变化(PQ0.01)。与对照组相比,添加400 mg/L百里香酚和香芹酚显著降低体外发酵液总VFA浓度(P0.01)。D-柠烯、茴香脑、百里香酚和香芹酚的添加改变了各VFA占总VFA的摩尔百分比。与对照组相比,添加50 mg/L D-柠烯和茴香脑使乙酸比例显著增加(P0.05),丙酸比例显著降低(P0.05);而添加400 mg/L D-柠烯和茴香脑则使乙酸比例显著下降(P0.05),丙酸和丁酸比例显著上升(P0.05)。百里香酚和香芹酚的添加对乙酸比例没有产生显著影响(P0.05),与对照组相比,400 mg/L百里香酚和香芹酚使丙酸比例显著下降(P0.05)。3)添加茴香脑、百里香酚和香芹酚显著影响体外发酵液NH3-N浓度(P0.05),与对照组相比,400 mg/L百里香酚和香芹酚显著降低NH3-N浓度(P0.05)。4)添加D-柠烯、茴香脑、肉桂醛对体外发酵24 h产气量没有显著影响(P0.05)。与对照组相比,各浓度的百里香酚和香芹酚均显著降低体外发酵24 h产气量(P0.05),且产气量随百里香酚和香芹酚浓度的增加呈二次曲线变化(PQ0.01)。5)添加D-柠烯、茴香脑和肉桂醛对体外发酵24 h CH4产量没有显著影响(P0.05)。与对照组相比,50和100 mg/L的丁子香酚显著增加体外发酵24 h CH4产量(P0.05),而400 mg/L的百里香酚和香芹酚体外发酵24 h CH4产量分别降低84.7%(P0.05)和73.9%(P0.05)。综合以上试验结果可知,不同植物精油对体外瘤胃发酵和CH4产量的影响结果不同,且与添加剂量有关。其中,低剂量的百里香酚和香芹酚促进体外瘤胃发酵,而高剂量的百里香酚和香芹酚抑制体外瘤胃发酵且显著降低24 h CH4产量。 相似文献
19.
Herbage intake and ruminal digestion of dairy cows grazed on perennial ryegrass pasture either in the morning or evening 
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下载免费PDF全文 This study aimed to clarify diurnal fluctuations of herbage intake, ruminal fermentation of herbage carbohydrates and proteins, and digesta particulate weight in the rumen of grazing dairy cows. Six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture either in the morning (04.00 to 08.00 hours) or the evening (16.00 to 20.00 hours). Cows grazed in the evening spent more time (P < 0.01) and consumed more herbage (P < 0.01) compared with cows grazed in the morning. Higher (P < 0.05) daily mean concentrations of total volatile fatty acid, propionate and n‐butyrate in rumen fluid were observed for cows grazed in the evening compared with cows grazed in the morning. Although cows grazed in the evening ingested more crude protein compared with cows grazed in the morning, no significant difference in NH3‐N concentration in rumen fluid was observed between them. The ratio of purine‐derivative concentration to creatinine concentrations was higher (P < 0.01) in the urine of cows grazed in the evening than in cows grazed in the morning. These results clearly indicated that evening grazing was advantageous for dairy cows compared with morning grazing, in terms of ruminal fermentable energy intake and nitrogen utilization efficiency. 相似文献
20.
Mechanical maceration of alfalfa 总被引：2，自引：0，他引：2
Maceration is an intensive forage-conditioning process that can increase field drying rates by as much as 300%. Because maceration shreds the forage and reduces its rigidity, improvements in bulk density, silage compaction, and ensiling characteristics have been observed. Macerating forage also increases the surface area available for microbial attachment in the rumen, thereby increasing forage digestibility and animal performance. Feeding trials with sheep have shown increases in DMI of 5 to 31% and increases in DM digestibility of from 14 to 16 percentage units. Lactation studies have demonstrated increases in milk production and BW gain for lactating Holstein cows; however, there is a consistent decrease in milk fat percentage when dairy cattle are fed macerated forage. In vitro studies have shown that maceration decreases lag time associated with NDF digestion and increases rate of NDF digestion. In situ digestibility studies have shown that maceration increases the size of the instantly soluble DM pool and decreases lag time associated with NDF digestion, but it may not consistently alter the rate or extent of DM and NDF digestion. 相似文献