能量溢出与储备碳水化合物合成对瘤胃微生物生长效率影响的研究进展

瘤胃微生物将一些ATP用来维持代谢,剩余的ATP用来进行储备碳水化合物合成和能量溢出（进行无效循环并产热）,因此,瘤胃微生物蛋白质合成效率较低。瘤胃原虫贮存的碳水化合物占绝大部分。在一些细菌纯培养实验中发现有能量溢出,最近研究发现在混合瘤胃菌群中也能发生能量溢出。通过精确测定碳水化合物贮存和能量溢出的量,以及二者对微生物生长效率的影响,可以预测微生物蛋白质产量,制定提高瘤胃微生物蛋白质生产效率的措施。综述了瘤胃微生物能量溢出和糖原储备规律方面的研究进展,以期为估测微生物蛋白质合成量,提高饲料蛋白质利用效率提供参考。     

Regulation of lactate metabolism in the rumen

The regulation of lactic acid production, the regulation of lactate fermentation and the role of lactate as intermediate in the rumen metabolism was studied.The pH had a pronounced effect on all three processes and therefore buffer capacity of the rumen contents is also described.Starch gave much less rise to lactic acidosis than soluble sugars, as glucose and fructose. Most bacteria grow faster and therefore produce more lactic acid when amino acids and/or soluble proteins are present in the diet.Activity of LDH (lactate dehydrogenase) of mixed rumen microorganisms is regulated by the NADH/NAD (H) balance and the ATP concentration. About 60% of the LDH in mixed rumen microorganisms is fructose-1, 6-diphosphate independent. Megasphaera elsdenii ferments 60 to 80% of the lactate fermented in the rumen of dairy cattle.Lactate accumulates only when the glycolytic flux (hexose units fermented per unit time per microorganism) is high. During adaptation, the glycolytic flux is increased and lactate may accumulate. After adaptation to a certain diet, the number of microorganisms is changed and the glycolytic flux again is normal and lactate is only a minor intermediate in rumen metabolism.     

Inoculants for ensiling low-dry matter corn crop: a midlactation cow perspective

In many regions, optimum dry matter (DM) content of corn crop pre-ensilage cannot be ensured for management, agronomical and climatic reasons. Under such conditions, corn crops are harvested at low DM, and are easily exposed to unfavourable fermentation pathways and plant spoilage and wastage. Thus, it is a major question for dairy agriculturists whether certain microbial inoculants application to low-DM corn crop pre-ensilage affects silage quality and cow performance. The objective was to determine effects of adding microbial inoculants to low-DM corn crop at ensiling on silage quality, rumen fermentation and milk production of eight Holstein cows fed the treated silages. Whole corn plant was harvested at milk stage of maturity with 204 g DM/kg of fresh crop, cut to a theoretical particle length of 2 cm, filled in 60 t bunker silos, and treated layer by layer with either no inoculant (control), inoculant 'E' (100 000 cfu/g of fresh crop) containing mainly Lactobacillus plantarum, inoculant 'B' (100 000 cfu) containing mainly Pediococcus pentosanus, Lactobacillus plantarum and Propionibacter freudenreichii or a mixture of inoculants 'E' and 'B' (200,000 cfu). Inoculants were mixed with water and sprayed on thin layers of corn chops layer by layer followed by rolling to ensure proper oxygen outage and even microbial distribution throughout the plants. Eight multiparous lactating Holstein cows at 100 ± 20.5 days in milk were used in a replicated 4 × 4 Latin square design with four 20-day periods including 14 days of adaptation and 6 days of sampling. Dietary treatments were mixed rations containing corn silages with or without the inoculants. The basal diet contained 32.9% corn silage, 14.3% alfalfa hay and 52.8% concentrate on a DM basis. Inoculants did not affect silage pH or content of DM, CP, lactate, acetate, ash and total volatile fatty acids (VFA). Applying 'B' to corn crop resulted in higher water soluble carbohydrates (47.7 g/kg vs 29.8 g/kg) and lower neutral detergent fibre (494.1 g/kg vs 464.0 g/kg) compared with control. The combined inoculants increased silage butyrate relative to other treatments. The mixture of 'E + B' and 'B' moderately decreased rumen pH, when compared to 'E'. The 'E + B' increased rumen VFA concentrations relative to 'E' and control silage. Dry matter intake increased when corn crop was ensiled with 'E' than with control and 'E + B', but this had little impact on milk production or its energy concentrations. Milk energy yield tended to decrease when 'B' but not 'E' was applied alone, compared with control and 'E + B'. The estimated proportion of the consumed energy secreted in milk increased when inoculants were applied together compared with when they were used separately. Results suggest positive effects of Lactobacillus plantarum containing inoculant on feed intake, some effects on corn silage water soluble carbohydrates, fibre and butyrate contents, rumen pH and VFA concentrations; but no significant effects on total tract nutrient digestibility or productivity of Holstein cows fed diets with 329 g corn silage/kg of diet DM.     

幼龄反刍动物瘤胃微生物的定植过程与调控措施

反刍动物是畜牧业中的重要支柱，研究瘤胃微生物在幼龄反刍动物上的定植过程，并利用其中的定植规律采取科学的早期调控措施，以此提高反刍动物的生产效率，对于维持畜牧业高效、健康、可持续发展具有重要意义。瘤胃微生物的定植过程伴随着幼龄反刍动物瘤胃的发育和饮食结构的巨大变化。在幼龄反刍动物哺乳时，瘤胃由于食管沟反射的存在而不发挥功能，发育缓慢，此时只有部分功能菌群逐渐定植；随着日龄的增长，幼龄反刍动物大量摄入固体饲料，瘤胃在固体饲料的刺激下迅速发育直至成熟，此时大量菌群定植，瘤胃发酵逐渐活跃，且优势菌及其丰度与前期相比发生较大变化。同时，大量瘤胃发酵产物的积累又进一步刺激了瘤胃的发育。反刍动物在幼龄阶段经历了从非反刍到反刍的生理过渡，是其最敏感和可塑性最强的时期，可以在此阶段对反刍动物瘤胃微生物采取人工调控措施，以保证机体的健康和后续生长发育。作者综述了反刍动物瘤胃早期发育过程、瘤胃内微生物的种类、来源及其在幼龄反刍动物瘤胃中的定植过程，阐明瘤胃微生物在反刍动物消化代谢、生产性能以及畜体健康方面的重要功能，并归纳了常用的瘤胃微生物调控技术，从而为生产中对幼龄反刍动物的饲养管理、营养调控提供参考。     

Effect of donor animals and their diet on in vitro nutrient degradation and microbial protein synthesis using grass and corn silages

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.     

发酵时间对苜蓿青贮品质和微生物群落的影响

以紫花苜蓿(Medicagosativa L.)为原料,于初花期刈割,分别在发酵2d、3d、5d、7d、15d和30d开袋取样,研究苜蓿青贮营养品质、发酵品质及微生物多样性.结果表明,在青贮第1? 7d,随着青贮时间的延长,其干物质耗损的速率较快.在发酵前期,乳球菌属(Lactococcus)和肠球菌属(Enteroc...     

不同水平的青贮饲料对饲喂稻草秸秆奶牛瘤胃微生物数量和微生物蛋白合成的影响

本试验的目的是确定饲粮中青贮银合欢添加水平对奶牛瘤胃微生物种群、氮平衡和微生物蛋白合成的影响。试验采用4×4拉丁方设计,选择12头初始体重为163±16 kg、带有瘤胃瘘管的奶牛,随机分为4个组,每组3个重复,每个重复1头牛。基础日粮以100%的水稻秸秆为原料,处理组分别用30%、60%和100%的青贮银合欢替代水稻秸秆,奶牛自由采食水稻秸秆和青贮银合欢,每天按照体重的0.2%补充浓缩料。结果表明,用60%青贮银合欢替代水稻秸秆组奶牛瘤胃微生物群,尤其是纤维素分解菌、蛋白分解菌和厌氧真菌的数量显著增加(P<0.05),各组对淀粉分解菌群无显著影响(P>0.05)。原生动物种群数量随日粮青贮银合欢添加水平的增加呈线性下降(P<0.05)(P<0.05)。此外,氮平衡和微生物蛋白合成均随着日粮青贮银合欢添加水平的升高而升高(P<0.05),其中以60%青贮银合欢组最高。结论:在本试验基础上,用60%青贮银合欢替代水稻秸秆可以显著提高奶牛体内的微生物数量和微生物蛋白的合成。     

Effects of Supplementation of a Grass Silage and Barley Diet with Urea,Rapeseed Meal and Heat-moisture-treated Rapeseed Cake on Omasal Digesta Flow and Milk Production in Lactating Dairy Cows

Four multiparous dairy cows, fitted with rumen and duodenal cannulas, were fed grass silage and one of four concentrates of barley (B), barley+urea (BU), barley+solvent-extracted rapeseed meal (BRM) or barley+heat-moisture-treated rapeseed cake (BRC). Despite marginal N deficiencies for the control diet (B), BU did not affect milk yield, ruminal fibre digestion or omasal total non-ammonia-N (NAN) or microbial NAN flow. In contrast, BRM and BRC diets significantly increased milk and milk protein yields and omasal dietary NAN flows. Effects of rapeseed meal (RSM) and rapeseed cake (RSC) on milk yield and omasal NAN flow were similar. The diets had no effect on rumen microbial protein synthesis. In general, non-protein N and soluble true protein comprised 0.20 of omasal total NAN flow, for all diets. Supplementary AAT from rapeseed feeds appeared to escape from the rumen as insoluble feed particles.     

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation

Nitrogenous emissions from ruminant livestock production are of increasing public concern and, together with methane, contribute to environmental pollution. The main cause of nitrogen-(N)-containing emissions is the inadequate provision of N to ruminants, leading to an excess of ammonia in the rumen, which is subsequently excreted. Depending on the size and molecular structure, various bacterial, protozoal and fungal species are involved in the ruminal breakdown of nitrogenous compounds(NC). Decelerating ruminal NC degradation by controlling the abundance and activity of proteolytic and deaminating microorganisms, but without reducing cellulolytic processes, is a promising strategy to decrease N emissions along with increasing N utilization by ruminants. Different dietary options, including among others the treatment of feedstuffs with heat or the application of diverse feed additives, as well as vaccination against rumen microorganisms or their enzymes have been evaluated. Thereby, reduced productions of microbial metabolites, e.g. ammonia, and increased microbial N flows give evidence for an improved N retention. However, linkage between these findings and alterations in the rumen microbiota composition, particularly NC-degrading microbes, remains sparse and contradictory findings confound the exact evaluation of these manipulating strategies, thus emphasizing the need for comprehensive research. The demand for increased sustainability in ruminant livestock production requests to apply attention to microbial N utilization efficiency and this will require a better understanding of underlying metabolic processes as well as composition and interactions of ruminal NC-degrading microorganisms.     

Theoretical turnover rate of the rumen liquid fraction in dairy cows and its relationship to feed intake,rumen fermentation,and milk production

Ruminant animals are able to convert plant materials (grain and the human‐indigestible portion of carbohydrates) to milk and meat. In this conversion, most of the plant materials are digested by rumen fermentation and are changed to short‐chain fatty acids, microbial cells, and methane, which is released into the atmosphere. The relationships among feed, rumen fermentation, and milk production are poorly understood. Here we report a novel indicator of characteristics of rumen fermentation, theoretical turnover rate (TTOR) of the rumen liquid fraction. The TTOR was calculated from the presumed rumen volume (PRV) which is estimated by dividing the methane yield by the methane concentration of rumen fluid. The formula for the TTOR is: TTOR = PRV/body weight^0.75. Our present analyses confirm that the TTOR as an indicator is capable of connecting feed, rumen fermentation, and milk production, because dry matter intake/TTOR showed a strong correlation with milk yield/TTOR. In addition, the TTOR may be related to ruminal pH, as we observed that the ruminal pH decreased as the TTOR increased. We propose that the TTOR is a factor characterizing rumen fermentation and a good indicator of the productivity of ruminants and dysbiosis of the rumen microbiome.     

多组学技术在奶牛瘤胃微生物与宿主互作机制中的研究进展

对于反刍动物而言,瘤胃对宿主的新陈代谢、机体免疫调节具有重要的意义。作为瘤胃内强大而丰富的群落,瘤胃微生物结构紊乱不仅会导致生产性能下降,还会引发机体全身炎症反应。近年来,多组学技术分析瘤胃微生物与宿主的关系及其调控机制已逐渐受到研究者的关注。本文从瘤胃微生物的影响因素、多组学技术在瘤胃微生物中的应用及瘤胃微生物紊乱对宿主的影响等多方面进行综述,以通过调节瘤胃微生物来提高奶牛生产性能、增强机体免疫力以及预防疾病等新的视角为奶牛养殖者提供参考。     

单宁酸和乳酸菌对紫花苜蓿青贮品质和体外瘤胃发酵的影响

为评价单宁酸和乳酸菌单独以及组合添加对紫花苜蓿（Medicago sativa L.）青贮品质和体外瘤胃发酵的影响,本试验以晾晒至含水量约为55%的初花期紫花苜蓿为青贮原料,设无添加剂为对照组（CK）,单宁酸（Tannic acid,TC）、乳酸菌（Lactic acid bacteria,L）和单宁酸+乳酸菌（Tannic acid+Lactic acid bacteria,TL）为添加剂处理组。青贮60 d后开袋取样,测定相关指标。结果表明：添加剂处理组均显著降低了青贮饲料的pH值、乙酸和非蛋白氮含量（P<0.05）,干物质和真蛋白含量显著增加（P<0.05）;添加剂处理组均能促进瘤胃丙酸生成,提高微生物蛋白产量（P<0.05）;与TC处理组相比,TL处理组能够减轻TC处理组对青贮饲料干物质降解的抑制作用。综上,单宁酸和乳酸菌组合添加对紫花苜蓿青贮饲料品质的调控作用效果最好。     

不同粗饲料组合混合日粮对奶牛泌乳性能的影响

本试验通过给奶牛饲喂不同粗饲料组合的TMR日粮,探讨日粮中不同粗饲料组合对奶牛泌乳性能的影响.结果表明,日粮鲜重的精粗比从30∶70提高到40∶60后,奶牛的干物质采食量有显著地增加（P＜0.05）.随着精料比例增加,其能量水平、蛋白含量和乳蛋白率增加.同时,蛋白含量和产奶量都有所提高.在试验二组中用青贮代替了全贮,提高了奶牛的采食量和泌乳性能.说明,奶牛全混合日粮（TMR）可以提高日粮养分表观消化率、产奶量和改善乳蛋白质水平.青贮饲料的蛋白质的降解和利用更容易被瘤胃微生物降解和吸收,从而提高奶牛的泌乳性能,取得较高的经济效益.     

Rumen fermentation and degradability in buffalo and cattle using the in vitro gas production technique

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.     

Effect of feeding frequency on fermentation pattern and microbial activity in the bovine rumen.

The influence of the feeding frequency on the fermentation in the bovine rumen was investigated by a single reversal trial with restricted supply of feed. The study comprised 6 rumen-fistulated dairy heifers fed a complete diet, low in crude fibre, at 2 frequencies. The effect of the treatment was assessed by the parameters: Concentration of microbial metabolites, total counts of microorganism, concentration of adenosine triphosphate (ATP), and fermentative activity in the rumen.Frequent feeding compared to feeding twice daily resulted in marked reduction of the diurnal variation in the concentration of ruminai metabolites without significant influence on the daily means of total VFA and pH, but the molar composition of the VFA mixture and the production rate of VFA were highly affected. The implications of these observations for improved feed utilization to milk production and fattening are discussed.Pronounced increment of the concentration of ATP was found by frequent feeding, but the total counts of microorganisms were found almost unaffected. Since the rate of fermentation was highly correlated with the concentration of ATP, the ATP pool may be an indicator of the fermentative activity of rumen microorganisms.     

植物精油对反刍动物瘤胃蛋白质代谢的影响

随着抗生素作为饲料添加剂被禁用,寻求能够改善瘤胃代谢从而提高饲料效率和动物生产性能的抗生素替代品一直是研究热点。植物精油被认为是代替饲料中抗生素的有效产品之一,它能够通过抑制某些微生物的生长发育来改善瘤胃发酵。本文就近几年来植物精油对瘤胃蛋白质代谢及其对反刍动物生产性能的影响作一综述。     

植物次生代谢产物调控反刍动物瘤胃发酵及甲烷产生的研究进展

论文主要阐述了植物次级代谢产物的种类,及其对反刍动物瘤胃微生物（原虫、真菌、细菌）的影响,进一步综述了其对瘤胃发酵参数（瘤胃液pH、氨态氮的浓度、挥发性脂肪酸浓度）、瘤胃微生物蛋白的合成及甲烷产量的影响.     

尿液嘌呤衍生物法估测瘤胃微生物蛋白质产量及其评价

近年来,以尿液嘌呤衍生物为标记物估测流入十二指肠瘤胃微生物蛋白质产量的非损害(non-inva-sive)方法得到较快发展。该方法的依据是反刍动物尿液中嘌呤衍生物主要来源于瘤胃内微生物体嘌呤的降解,尿液嘌呤衍生物与瘤胃微生物产量成正比。该方法的主要优点是不需要瘘管动物,但对瘤胃微生物蛋白质产量的估测值较十二指肠嘌呤法和15N法估测值低。许多研究者提出了不同的估算公式,适用于牛或羊的估算公式是不同的。     

芳香族和脂环族化合物在反刍家畜消化道中的释放代谢机制

芳香族和脂环族化合物(异生物素)在反刍动物体内的消化代谢水平主要取决于瘤胃的消化代谢能力,而这种能力是由瘤胃微生物决定的;瘤胃微生物在厌氧环境下具有降解芳香族异生物素的潜力,咀嚼有助于植物细胞壁脂化酚酸及其内容物的酚化合物的释放,释放后的代谢物大部分在瘤胃内被微生物代谢;瘤胃微生物糖酶的作用,使与细胞壁结合的酚酸以可溶性酯-糖单元的形式从牧草中释放出来,在肠道内微生物水解活动可引起植物中自然存在的结合态酚酸释放成游离态;细胞壁酯化的p-香豆酸含量与体内细胞壁消化率、体外干物质消化率和半体内瘤胃纤维降解率呈显著负相关,草本植物的木质素含量与细胞壁降解率也常为负相关;异生物素对动物和微生物具有毒害作用,但在瘤胃的厌氧微生物作用下,通过水解、还原、取代和脱羧等反应,异生物素发生生物转化和矿化,其还原代谢产物的毒性远低于其前体物.芳香族化合物在反刍家畜消化道中的释放代谢机制的研究,为其代谢物在尿液中的排泄含量作为反刍动物采食量的预测指标的可行性和机理从代谢水平上奠定基础.     

甲酸处理对苜蓿青贮品质及瘤胃降解率的影响

为研究添加剂甲酸对紫花苜蓿(Medicago sativa L.)青贮品质、有氧暴露后微生物数量以及瘤胃降解特性的影响,分别在新鲜紫花苜蓿中添加0(CK),4(FA1),6(FA2),8 mL·kg^-1(FA3)甲酸后,室温青贮60 d。通过隶属函数法比较青贮品质,筛选出青贮效果最佳的处理,测定其有氧暴露后微生物数量及瘤胃降解率。结果表明：与CK组相比,添加不同水平甲酸均能显著提高紫花苜蓿干物质(Dry matter, DM)、粗蛋白(Crude protein, CP)、可溶性碳水化合物及乳酸含量(P<0.05),显著降低中性洗涤纤维(Neutral detergent fiber, NDF)及酸性洗涤纤维(Acid detergent fiber, ADF)、pH值、氨态氮比总氮(P<0.05)。通过隶属函数法筛选出FA2处理总隶属度最高。FA2组在有氧暴露后第0～6天的pH值、酵母菌和好氧菌计数显著低于CK组(P<0.05)。瘤胃降解特性中,FA2组DM,CP,NDF及ADF有效降解率较CK组显著提高(P<0.05)。综上,添加6 m...