异生物素及其代谢物在反刍家畜体组织的分泌与排泄机理

胆汁分泌和尿液排泄是异生物素如芳香族和脂环族化合物排出反刍动物有机体的主要途径.渗透过滤是胆汁分泌的主要机制,离子运输对共轭态异生物素的胆汁分泌具有重要作用,其影响因素主要为代谢物极性、分子量和结构.胆汁分泌促进了异生物素在动物体内持续地进行肠肝循环.肾脏中的分泌排泄过程在肾单位中进行.代谢物的尿液排泄包括3个基本过程:肾小球过滤、肾小管分泌和肾小管再吸收.家畜有机体排出异生物素的其他途径有唾液、乳汁、汗水和气体.家畜对某一特定饲料的采食量以及饲料本身的属性直接影响异生物素经尿液的排泄,以此建立合理的关系模型就可以根据尿液中的排泄量测定或预测家畜的采食量.     

微生态制剂在反刍动物生产上的应用

微生态制剂又称益生素、活菌制剂等,它是在微生态理论指导下,通过特殊工艺应用已知有益微生物制成的一种活菌制剂,在养殖业已经得到应用。文章综述了微生态制剂的概念、分类、在反刍动物中的应用;剖析了不同实验结果出现差异的可能原因,总结了微生态制剂应用中存在的问题及应用前景展望。     

低磷低蛋白日粮添加植酸酶和氨基酸对泌乳母猪粪氮磷排出量的影响

选择3~7胎长白×大白二元杂交母猪45头,随机分为3个组,每个组15头,泌乳期21 d。处理1组的日粮粗蛋白为18%、总磷为0.68%;处理2组的日粮粗蛋白为16.5%、总磷为0.58%;处理3组的日粮粗蛋白为15%、总磷为0.58%;处理2组和处理3组日粮中添加植酸酶。结果表明,日粮蛋白质降低1.5~3个百分点和总磷降低0.1%,对泌乳母猪的采食量和哺乳仔猪日增重无显著影响,母猪泌乳期体重损失显著减少,粪氮和磷的排放量显著减少。     

瘤胃中乳酸的代谢及其调控机制

有关瘤胃酸中毒发生机制研究表明,瘤胃乳酸的累积可能对酸中毒诱导起重要作用,而高精料日粮下瘤胃乳酸累积主要取决于瘤胃乳酸产生菌和乳酸利用菌间的平衡程度。本文综述了瘤胃微生物对乳酸的代谢机制,包括主要乳酸产生菌[溶纤维丁酸弧菌(Butyrivibrio fibrisolvens)、牛链球菌(Streptococcus bovis)、乳酸杆菌(Lactobacillus)]和主要乳酸利用菌[反刍兽新月单胞菌(Selenomonus ruminantium)、埃氏巨型球菌(Megasphaera elsdenii)],并简要概述了酸中毒的调控方法,旨在为反刍动物瘤胃酸中毒的乳酸中毒机制深入解析提供参考。     

微生物发酵粗饲料在反刍动物生产中的应用研究进展

粗饲料是指天然水分含量小于45%,干物质中粗纤维含量大于或等于18%,并以风干物质为饲喂形式的饲料。利用微生物发酵处理粗饲料,可以改变其适口性差、消化率不高等缺点,降低粗饲料中的抗营养因子,改变其微观结构,提高反刍动物消化率及免疫力。文章就粗饲料原料种类、处理方法、微生物发酵粗饲料作用机理、菌种种类、生产工艺贮存方式以及其在反刍动物生产当中的应用等进行综述。     

Effect of vitamin E supplementation of sheep and goats fed diets supplemented with polyunsaturated fatty acids and low in Se

Vitamin E (VitE) and selenium (Se) are an essential part of the antioxidative functions of metabolism. There are situations of low supply of both micronutrients. As VitE is involved in ruminal biohydrogenation of polyunsaturated fatty acids (PUFA) and their protection against oxidation in metabolism, diets supplemented with PUFA may challenge VitE to an extent making recommended supplies insufficient. Twelve goats and sheep each were fed a diet supplemented with PUFA and characterised by low Se and limited VitE contents during the last 2 months of gestation and the first 2 months of lactation. The basal diet consisted of hay and concentrate. Six goats and sheep received extra VitE, while the control groups received no extra VitE. Blood and milk samples were taken. In addition, liver, heart muscle and spleen samples were obtained from the offspring after slaughtering at an age of 8 weeks. No significant changes were observed in serum Se and VitE. A significant increase in serum VitE concentrations between 2 and 4 weeks postpartum (pp) was evident in the supplemented kids. In 4, 6 and 8 weeks pp, the serum concentrations of VitE in the supplemented kids were significantly higher compared to the unsupplemented group. In the kids, VitE was higher in liver of the supplemented groups. There were no significant differences in response to extra VitE between sheep and goat. The kids responded to serum VitE different from that of lambs, as a significant difference was observed between supplemented and unsupplemented animals in the goat kids, but not the lambs. In conclusion, goats and sheep have to be viewed differently and may not be considered alike relating to VitE/Se metabolism and requirements, especially in young animals.     

反刍动物瘤胃内乳酸代谢与瘤胃酸中毒调控的研究进展

乳酸是反刍动物瘤胃内重要的中间代谢产物,在饲喂高精料的反刍动物瘤胃内乳酸累积过多可能会加速瘤胃酸中毒的进程。本文综述了瘤胃内乳酸代谢机制和影响因素,以及提高乳酸利用和添加硫胺素等预防瘤胃酸中毒的几种方式,旨在系统地总结反刍动物瘤胃内乳酸代谢机制,为瘤胃酸中毒的调控提供理论支撑。     

经密码子优化的小反刍兽疫病毒H蛋白在昆虫细胞中的表达

小反刍兽疫病毒（peste des petits ruminants virus,PPRV）属于副黏病毒科、麻疹病毒属成员。本实验室已经证明,该病毒的囊膜糖蛋白H蛋白在未经密码子优化条件下难以在昆虫细胞中表达。本研究首先对其密码子进行优化,然后构建了在昆虫细胞中表达该蛋白的重组杆状病毒。经Western-blot和间接免疫荧光试验表明,该重组杆状病毒在昆虫细胞中能够表达H蛋白,但表达量相对较低。     

瘤胃微生态种群对宿主动物氮源物质的调节作用研究

瘤胃微生物如细菌、原虫以及纤毛虫等的研究一直是反刍动物研究的重要方面。它们不仅可以对饲料纤维、淀粉进行降解,日粮蛋白质也是它们的发酵底物之一,此外,内源性的含氮物质和日粮中添加的氮源物质都可被它们代谢利用。在瘤胃微生物产生的各种降解酶的作用下,饲料养分被逐级降解进行转化,但它们的作用机理及相互作用尚不完全清楚,一直是反刍动物营养研究的重点。为此,文章对瘤胃微生物对宿主动物氮源物质的作用及其需求作一介绍,以便为深入研究作一参考。     

Formation of peste des petits ruminants spikeless virus-like particles by co-expression of M and N proteins in insect cells

Peste des petits ruminants virus (PPRV) has a non-segmented negative sense RNA genome and is classified within the Morbillivirus genus of the Paramyxoviridae. Using the Bac-to-Bac® baculovirus expression system, we constructed recombinant baculoviruses that were able to co-express the PPRV matrix and nucleocapsid proteins in insect cells under the control of the polyhedron and p10 promoters, respectively. The results showed that although both structural proteins were expressed at a relatively low level, the interaction between them caused the formation of virus-like particles (VLPs) by viewing of transmission electron microscopy. The VLPs morphologically resembled authentic PPRVs but lacked spikes protruding from the particulate surfaces. Interestingly, the diameter of PPRV VLPs ranged from 100 to 150 nm, far less than the mean diameter (400–500 nm) of parental virions.     

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。     

Use of plants in novel approaches for control of gastrointestinal helminths in livestock with emphasis on small ruminants

Helminth infections are a major cause for reduced productivity in livestock, particularly those owned by the poor worldwide. Phytomedicine has been used for eons by farmers and traditional healers to treat parasitism and improve performance of livestock, and many modern commercial medicines are derived from plants. However, scientific evidence on the anti-parasitic efficacy of most plant products is limited, regardless of their wide ethnoveterinary usage. Scientific validation of the anti-parasitic effects and possible side-effects of plant products in ruminants is necessary prior to their adoption as a novel method for parasite control. A variety of methods has been explored to validate the anthelmintic properties of such plant remedies, both in vivo and in vitro. In vitro assays are useful as pre-screens of activity and are mainly performed with the free-living rather than parasitic stages of nematodes. Concentrations of potentially active substances used in vitro do not always correspond to in vivo bioavailability. Therefore, in vitro assays should always be accompanied by in vivo studies when used to validate the anthelmintic properties of plant remedies. In vivo controlled studies have shown that plant remedies have in most instances resulted in reductions in the level of parasitism much lower than those observed with anthelmintic drugs. Whether it is necessary or not to achieve very high efficacy in order for plant remedies to have a role in the control of parasitism depends on the determination of biologically important levels of reduction of parasitism and it will be required prior to the wide-scale use of plant products for parasite control. Similarly, standardisation of validation studies in reference to the numbers of animals required for in vivo studies to measure direct anthelmintic effects of a plant needs to be established. Although in many cases the active compounds in the herbal remedies have not been fully identified, plant enzymes, such as cysteine proteinases, or secondary metabolites, such as alkaloids, glycosides and tannins have shown dose-dependent anti-parasitic properties. However, as some of the active compounds may also have anti-nutritional effects, such as reduced food intake and performance, it is essential to validate the anti-parasitic effects of plant products in relation to their potential anti-nutritional and other side effects. A concerted effort on isolation, development, and validation of the effects of these herbal remedies will have to be undertaken before their wider acceptance.     

蛋白质水平和氨基酸模型对蛋鸡生产性能及氮磷利用与排泄的影响

本试验研究了按理想蛋白氨基酸模式配制日粮对蛋鸡生产性能及营养素氮和磷利用与排泄的影响。试验结果表明:试验组比对照组的产蛋率、产蛋量、蛋重及饲料转化率均有所提高,但差异不显著(P>0.05);而氮和磷的表观利用率分别提高了6.46%和9.31%,差异显著(P<0.05);氮排泄量降低了11.93%,差异显著(P<0.05);总磷排泄量降低了2.20%,差异不显著(P<0.05)。结果表明,按理想蛋白氨基酸模式配制日粮,通过合理的营养调控技术,可以降低蛋鸡氮磷排泄量。     

ORIGINAL ARTICLE: Effects of supplementing rice straw with Leucaena (Leucaena leucocephala) and Madras thorn (Pithecellobium dulce) foliages on digestibility,microbial N supply and nitrogen balance of growing goats

A total of 12 crossbred (Boer × Anglo‐Nubian) goats were chosen from a commercial farm on the basis of similar body weight (25.0 ± 3.1 kg). The goats were housed in individual pens and allowed 3 weeks to adapt to experimental conditions. The goats were randomly allocated to three treatments in a 3 × 3 Latin square experiment (replicated four times). Within each period, each goat was given rice straw as roughage plus the respective treatment diet. The diets were iso‐nitrogenous and iso‐energetic containing cassava pulp, molasses, urea and commercial mineral and vitamin mix. The experimental treatments were (i) soybean meal (SBM), (ii) partial substitution of SBM with Leucaena (Leucaena leucocephala) foliage and (iii) partial substitution of SBM with Madras thorn (Pithecellobium dulce) foliage. Nutrient intakes, ruminal characteristics (pH, ammonia nitrogen and volatile fatty acids), nitrogen balances, plasma urea nitrogen and microbial N supply were not significantly different among treatments. The results of this study indicate that protein foliages from locally grown shrubs and trees can substitute imported feedstuff concentrates (e.g. SBM) as protein supplement for goat production.     

Adaptive changes in microbial synthesis and nitrogen balance with progressing dietary feeding periods in sheep fed diets differing in their ruminal degradation synchronicity between nitrogen and organic matter

Two diets differing in their degrees of ruminal degradation synchronicity between nitrogen (N) and organic matter (OM) were fed to six adult rams at a maintenance level for three months in a two‐way layout design combining a randomized block design. Adaptive changes in microbial N (MBN) supply and N balance were investigated for both diets. The in situ rumen degradation parameters of OM and N were determined for four feeds and subsequently were used to formulate the two diets to have different ruminal degradation synchronicity and to be identical with metabolizable energy (ME), metabolizable protein (MP) and ruminally degradable N concentrations. The animals were divided into two groups and fed asynchronous (ASYNC) or synchronous (SYNC) diet, respectively. On days 30, 60 and 90 of each feeding period, a five‐day metabolism trial was carried out. Animals consumed their diets thoroughly and did not show marked body weight change during the observation. The apparent digestibility of OM and N did not differ significantly between the diets throughout the periods. The MBN supply was significantly greater for ASYNC than that for SYNC (P < 0.01) and was greater on days 60 and 90 than that on day 30 (P < 0.05). Neither diets nor periods had a significant effect on the efficiency of MBN synthesis. There was a significant period effect on N retention (P < 0.05) together with tendency of diet × period interactions (P = 0.1). There was no significant dietary effect. An improvement in N retention with advancing feeding period was observed for both diets. The plasma urea concentration decreased with feeding period (P < 0.01) and there was a concomitant decrease in urinary N excretion. Plasma glucose concentration tended to increase (P = 0.07). The results suggest that lengthening feeding duration from 30 days might have caused ameliorative changes in the utilization of ME and MP, and may have improved microbe synthesis irrespective of the degradation synchronicity.     

菌渣对黑麦草根际微生物群落的影响

为了探讨菌渣对黑麦草(Lolium perenne)根际土壤微生物群落结构的影响,测定了添加不同量菌渣后黑麦草根际土壤的磷脂脂肪酸(phospholipid fatty acids,PLFAs),比较分析了不同处理下黑麦草根际土壤微生物PLFAs组成、相对含量和微生物群落结构的差异。结果表明,施用菌渣后,黑麦草植株根际土壤微生物磷脂脂肪酸生物标记种类和总量均高于对照组。进一步分析表明,菌渣处理可以改变黑麦草根际土壤微生物种群结构,有利于根际土壤中细菌、真菌和放线菌的生长。同时,采用菌渣处理黑麦草后,其根际土壤微生物群落的Simpson、Shannon-Wiener和Pielou指数均得以提高,表明菌渣可以增加黑麦草根际土壤中微生物群落多样性,推测其可以改善根际土壤质量。     

Relation of soya bean meal level to the concentration of plasma free amino acids and body growth in white rats

Amino acid (AA) levels in plasma and body growth were determined in rats (n20) fed diets with different soya bean meal levels. Free AA in plasma was determined by reversed-phase high-pressure liquid chromatography. We have used four levels of protein diets like 8%, 15%, 23% and 35% in this trial. Rats which were fed the low-protein (8%) diet with low percentage of soya bean meal were found to be growth-retarded. The body weight gain of high protein group (35%) was lower than that of the 23% groups. In the rats fed with the low-soya bean meal diet, some nonessential AA (NEAA) in plasma like asparagine, aspartic acid, cysteine, glutamic acid and serine increased, whereas the essential AA (EAA), with the exception of arginine, methionine and valine decreased. Here, plasma EAA-to-NEAA ratios were not correlated to growth and experimental diet. We hypothesize that AA metabolism is associated to changes in growth in rats on different protein intake. This study has showed the sensitivity of body mass gain, feed intake, feed conversion rate of rats to four levels of protein in the diet under controlled experimental conditions.