草鱼鱼种对胆碱需要量的研究

用不含胆碱的饲料饲养草鱼鱼种，草鱼鱼种生长减慢，饲料效率降低，肝脏脂肪浸润，血浆总脂，甘油三脂，胆固醇和磷脂含量降低，随着饲料中胆碱含量的添加，草鱼生长和饲料效率改善，肝脏脂肪含量降低，血浆总脂、甘油三脂、胆固醇，磷脂含量回升。当饲料中胆碱添加量达到０．３％以上时，草鱼生长率最高，肝脏脂肪含量，血浆总脂、甘油三脂，胆固醇，磷脂与摄食天然饲料（浮萍）的草鱼基本相同。在本研究条件下，建议草鱼鱼种饲料中     

Sorghum grain yield,forage biomass production and revenue as affected by intercropping time

Sorghum is an excellent alternative to other grains in poor soil where corn does not develop very well, as well as in regions with warm and dry winters. Intercropping sorghum [Sorghum bicolor (L.) Moench] with forage crops, such as palisade grass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] or guinea grass (Panicum maximum Jacq.), provides large amounts of biomass for use as straw in no-tillage systems or as pasture. However, it is important to determine the appropriate time at which these forage crops have to be sown into sorghum systems to avoid reductions in both sorghum and forage production and to maximize the revenue of the cropping system. This study, conducted for three growing seasons at Botucatu in the State of São Paulo in Brazil, evaluated how nutrient concentration, yield components, sorghum grain yield, revenue, and forage crop dry matter production were affected by the timing of forage intercropping. The experimental design was a randomized complete block design. Intercropping systems were not found to cause reductions in the nutrient concentration in sorghum plants. The number of panicles per unit area of sorghum alone (133,600), intercropped sorghum and palisade grass (133,300) and intercropped sorghum and guinea grass (134,300) corresponded to sorghum grain yields of 5439, 5436 and 5566 kg ha⁻¹, respectively. However, the number of panicles per unit area of intercropped sorghum and palisade grass (144,700) and intercropped sorghum and guinea grass (145,000) with topdressing of fertilizers for the sorghum resulted in the highest sorghum grain yields (6238 and 6127 kg ha⁻¹ for intercropping with palisade grass and guinea grass, respectively). Forage production (8112, 10,972 and 13,193 Mg ha⁻¹ for the first, second and third cuts, respectively) was highest when sorghum and guinea grass were intercropped. The timing of intercropping is an important factor in sorghum grain yield and forage production. Palisade grass or guinea grass must be intercropped with sorghum with topdressing fertilization to achieve the highest sorghum grain yield, but this significantly reduces the forage production. Intercropping sorghum with guinea grass sown simultaneously yielded the highest revenue per ha (€ 1074.4), which was 2.4 times greater than the revenue achieved by sowing sorghum only.     

光皮树与香茅草林草间作对其生长的影响

对光皮树-香茅草林草间作模式下光皮树与香茅草的生长量变化进行了分析,结果表明：间作模式下,光皮树树高、胸径、枝下高及平均冠幅面积均比对照有所增加,其中光皮树胸径的变化最大,其最大增幅达到了8%左右;香茅草平均单株生物量比对照增加了0.154 g左右;光皮树各指标的生长量变化与香茅草各指标生物量的变化有显著的相关。光皮树与香茅草间作能促进光皮树及香茅草的生长,不存在＂他感＂现象,依存度较高。     

Prospects for genomic selection in forage plant species

Genomic selection (GS) is a powerful method for exploitation of DNA sequence polymorphisms in breeding improvement, through the prediction of breeding values based on all markers distributed genome‐wide. Forage grasses and legumes provide important targets for GS implementation, as many key traits are difficult or expensive to assess, and are measured late in the breeding cycle. Generic attributes of forage breeding programmes are described, along with status of genomic resources for a representative species group (ryegrasses). Two schemes for implementing GS in ryegrass breeding are described. The first requires relatively little modification of current schemes, but could lead to significant reductions in operating cost. The second scheme would allow two rounds of selection for key agronomic traits within a time period previously required for a single round, potentially leading to doubling of genetic gain rate, but requires a purpose‐designed reference population. In both schemes, the limited extent of linkage disequilibrium (LD), which is the major challenge for GS implementation in ryegrass breeding, is addressed. The strategies also incorporate recent advances in DNA sequencing technology to minimize costs.     

A tropical grass resource for pasture improvement and landscape management: Themeda triandra Forssk

Themeda triandra Forssk. is one of the most widespread grasses in the dry to mesic prairie ecosystems of Africa, Asia and Australia. It is of particular interest due to its high value as a forage species for wildlife and livestock, and its potential use in landscaping practices. In this review we have collated information from the many studies that have been devoted to this species since the 1960s to provide information about the species' distribution, taxonomy, morphology, ploidy and reproduction, and to describe its vegetation and germination and their relationship with the most important ecological aspects of its preferred habitats. Agronomic aspects are considered in detail, with particular focus on the role of T. triandra as a forage species and the relative importance of grazing, fire and rainfall regimes for its management. We also explore how this species can help with the rehabilitation of degraded areas, soil and water conservation, countering exotic species invasion and landscaping in general. We conclude with a brief discussion of the as yet unresolved taxonomic relationship between the African species T. triandra and the Australian species Themeda australis.     

Nitrogen uptake and leaching loss of thirteen temperate grass species under high N loading

The intensification of grazed pasture systems in New Zealand has resulted in increased nitrate () leaching and associated significant reductions in water quality, resulting from high N loading in the cow urine patch. A glasshouse soil column experiment was conducted at Lincoln University examining the N uptake capacities and leaching losses of sixteen commercial and ‘weed’ pasture grasses, comprising thirteen species. Three dairy cow urine N treatments (N loading rates) were applied in May 2010: 0 (N0), 300 (N300) and 700 (N700) kg N ha^?1. Grass was harvested at 21‐d intervals, leachates collected to quantify N leaching losses and root mass measured. Shoot yield, root mass, N uptake and N leaching loss varied significantly between species (P < 0·001) and were strongly driven by N loading rate. The highest yielding species at N700 were Lolium multiflorum ‘Feast 2’ and ‘Tama’ (782 and 743 g DM m^?2), while Festuca arundinacea ‘Flecha’ and Lolium perenne ‘Alto' were lowest yielding (375 and 419 g DM m^?2). Plant N uptake and root mass followed a similar trend, and only moderate increases in total plant N uptake were observed for most species when urine N application rate was increased from N300 to N700. N leaching loss was highest at N700 for F. arundinacea ‘Flecha’ (378 kg N ha^?1) and lowest for L. multiflorum ‘Feast 2’ and ‘Tama’ (134 and 130 kg N ha^?1). Strong negative linear relationships were observed between N leaching loss, plant N uptake and root mass. The results indicate that species such as L. multiflorum may play a critical role in reducing pasture N leaching losses, while traditionally sown L. perenne, and also F. arundinacea, may be less suitable.     

投喂不同饲草的草鱼主养池塘中鱼类的生长和效益比较

在湖南省岳阳洞庭黄龙水产养殖股份有限公司生态养殖基地的鱼池中,分别投喂桂牧1号草、美国矮象草、苎麻3种饲草,研究草鱼主养池塘中鱼类的生长及效益。150 d的养殖试验结果表明：桂牧1号草组的草鱼增重率、特定增长率均显著高于美国矮象草组、苎麻组(P <0.05),其中苎麻组的草鱼增重率、特定增长率又显著高于美国矮象草组(P <0.05);各试验组中,鲢鱼和青鱼的增重率、特定增长率差异均无统计学意义(P >0.05),但美国矮象草组中的鳙鱼增重率、特定增长率显著高于其他2组(P <0.05);桂牧1号草组鲢鱼成活率显著高于美国矮象草组、苎麻组(P <0.05),其中苎麻组又显著高于美国矮象草组(P <0.05),各试验组中的草鱼、鳙鱼、青鱼成活率差异均无统计学意义(P >0.05);投喂桂牧1号池塘中的鱼类总产量及效益最高,分别为934.25 g/m2、26 967.75元/hm2。综合分析,投喂桂牧1号池塘中的鱼类生长良好,且养殖效益最高。     

晾晒、添加物及不同温度对象草青贮发酵品质和微生物的影响

华南地区气候潮湿多雨,象草收获时水分含量高,单独青贮发酵品质较差。通过晾晒（水分含量由83.19%降至75.11%）、添加10%玉米粉或2%蔗糖,探究象草在不同温度（20、30和40 ℃）下青贮的发酵特性和微生物组成。研究结果表明：温度对象草各处理的青贮饲料的发酵品质有显著影响。晾晒后原材料的水溶性碳水化合物含量显著降低,青贮后发酵品质变差,尤其在30 ℃,pH达到5.85,乳酸含量只有1.56% DM,乙酸含量为2.10% DM,NH₃-N含量高达25.09% TN。对照和添加物处理的青贮饲料均随青贮温度升高,乙酸含量增加。晾晒后在20和30 ℃时青贮,产气量显著高于40 ℃或未晾晒处理。此外,象草青贮前的细菌多样性较丰富,青贮后主要是肠杆菌属和乳球菌属,尤其是20 ℃青贮的相对丰度较高,且晾晒处理在20和30 ℃青贮肠球菌属的相对丰度高于40 ℃。因此,在华南地区,象草原料中添加玉米粉或蔗糖可以降低环境温度对象草青贮发酵品质的不良影响,阴湿条件下晾晒未发挥积极效果。     

农林院校与基层农技推广机构的合作动向——基于行政驱动视角的分析

农林院校与基层农技推广机构是新型农技推广服务体系的重要主体,两者之间的有效合作可以有效整合农技推广力量和显著改善农技推广服务能力.从合作动力视角切入,分析现阶段我国农林院校与基层农技推广机构在农技推广服务体系中的合作动向,指出“行政驱动”是其典型特征.在“行政驱动”作用下,农林院校与基层农技推广机构之间的合作存在合作形成的初始条件不充分、合作发展受限、合作关系质量不能有效评价等问题,需要强化主体利益激励,助力双方合作创新,重视对合作过程和结果控制,以实现农林院校与基层农技推广机构合作的优化.     

高效氯氰菊酯对草鱼血清和脾脏酸性磷酸酶活性的影响

研究了暴露在不同浓度高效氯氰菊酯下草鱼(Ctenopharyngodon idellas)血清和脾脏中酸性磷酸酶(ACP)的活性变化.将高效氯氰菊酯浓度设5组,包括1个对照组(0μg/L)和4个处理组(0.5、1.0、3.0、5.0μg/L),每组分别于暴露1、5、12d时取样,测定血清和脾脏ACP的活性.结果显示,暴露1d时,血清ACP活性各处理组显著下降;脾脏ACP活性0.5μg/L组和1.0μg/L组显著升高,3.0μg/L组和5.0μg/L组显著下降.暴露5d时,血清ACP活性1.0μg/L组显著上升,3.0μg/L组和5.0μg/L组显著下降;脾脏ACP活性1.0、3.0和5.0μg/L组显著下降.暴露12d时,血清ACP活性1.0、3.0和5.0μg/L组显著下降;脾脏ACP活性各处理组均显著下降.ACP活性的变化反映了高效氯氰菊酯能够影响鱼体的代谢平衡,对鱼体具有毒害作用;同时,血清和脾脏的ACP活性对高效氯氰菊酯早期污染的敏感性可以作为监测水体中此类化学品污染的一个特异性标志物.