松嫩平原农牧交错区牲畜放牧场的空间转移

研究了松嫩平原农牧交错区牲畜放牧场空间转移动态、不同放牧场对当地畜牧业的贡献率。研究结果表明 :松嫩平原农牧交错区的牲畜放牧场月际变化很大 ,草地、防护林草地和农田在不同阶段是牲畜的主要放牧场 ;牲畜放牧场具有明显的空间转移现象 ,总体趋势为农田 (1～ 3月份 )→草地 (4～ 6月份 )→防护林草地 (7～ 10月份 )→农田 (11～ 12月份 ) ;3种放牧场在不同时期对畜牧业的贡献率变化也很大 ,其变化趋势与放牧场空间转移趋势基本一致 ;草地、防护林草地和农田对松嫩平原农牧交错区畜牧业均起着重要作用 ,贡献率大小分别为农田 (38.8% ) >防护林草地 (31.8% ) >草地 (2 9.4 % )。草地在当地畜牧业中的地位明显下降 ,农田和防护林草地对当地畜牧业的贡献已相当重要。因此 ,应加强松嫩平原农牧交错区防护林草地放牧和农田放牧研究 ,在保护防护林的基础上合理利用防护林草地和杨树叶资源 ,充分利用农田杂草和农田残茬 ,增加可获得性牧草资源 ,促进地区畜牧业发展。     

东北农牧交错区绵羊的自由放养与设计饲养

探讨了在草地自由放养基础上的家畜饲养方式,提出在东北农牧交错区要进行设计饲养。即在利用草地草、农田残茬、林带草和树木落叶自由放养的基础上。按着动物的生长规律设计增重要求,同时利用能量和蛋白质饲料进行补饲,这种日常计划饲养方式有利于草地管理及家畜生产,是我国草地畜牧业的改进发展方向,在东北农牧交错区。当年生羔羊羯羊日粮中若加入20％的豆科牧草,当年体重可以增加40％～65％,即达到52～61kg．这不仅会满足商品畜当年出栏的高标准要求,缩短家畜的存栏期,增进畜牧业效益,同时也必将减轻放牧家畜对草原次年的压力。     

放牧对松嫩平原农牧交错区防护林下草地的影响

针对当前防护林草地已成为松嫩平原农牧交错区牲畜主要放牧场的实际情况,分析了不同放牧强度对防护林草地的影响．结果表明,未放牧防护林草地严重退化,与极度放牧防护林草地最为相似．未放牧和极度放牧均抑制了防护林草地的生长,轻度放牧和中度放牧却促进了防护林草地的生长,草地产量和质量均明显提高,并合理地利用了杨树叶资源．未放牧防护林草地质量指数仅为15．51。属严重退化草地范畴;轻度放牧草地质量指数为86．4,随着放牧强度的增加,草地质量逐渐下降．因此,应提倡轻度放牧、中度放牧,防止未放牧和极度放牧现象出现,促进防护林草地生长,并充分利用杨树叶资源增加畜牧业牧草的来源．     

黄土高原草地畜牧业产业形成与发展的牧草生产力基础

在黄土高原197个区县土地利用方式重新规划的基础上,对黄土高原畜牧业产业形成与发展的牧草生产潜力进行了分析预测。结果表明：规划的牧、林、农、果用地占生产用地的比例分别是草地44％、林地22％、基本农田20％、果园14％;197个区县草地牧草生产、作物秸秆、草田轮作和果园种草预测的总牧草饲料生产潜力达104881028t／a(其中,草地牧草生产潜力约占45％,达47196462．7t／a),可载畜104881028个羊单位／a(其中草地可载畜47196462．7个羊单位／a)。按1999年不变价格计算,黄土高原预测畜牧业总产值将达到5244051万元RMB／a,是1999年畜牧业总产值的5．3倍,超过1999年黄土高原农业总产值14％。农业人口人均预测畜牧业产值大于l000元的区县占59％;小于l000元的区县占41％。此外,预测的农业总产值将达到l147．2234亿元RMB／a,其中畜牧业、果业、林业和农业产值占农业总产值的比重分别是46％、27％、14％和13％。随着畜牧业产业链的逐步建立与完善,产业发展布局的日趋合理,黄土高原畜牧业生产总值将有较大幅度的提高,黄土高原生态环境将有进一步的改善。黄土高原草地畜牧业蕴藏着巨大的发展潜力,有望成为黄土高原优化的生产一生态新产业带建制中的支柱产业。     

黄土高原草地畜牧业产业形成与发展的牧草生产力基础

在黄土高原197个区县土地利用方式重新规划的基础上,对黄土高原畜牧业产业形成与发展的牧草生产潜力进行了分析预测.结果表明:规划的牧、林、农、果用地占生产用地的比例分别是草地44%、林地22%、基本农田20%、果园14%;197个区县草地牧草生产、作物秸秆、草田轮作和果园种草预测的总牧草饲料生产潜力达104 881 028 t/a(其中,草地牧草生产潜力约占45%,达47 196 462.7 t/a),可载畜104 881 028个羊单位/a(其中草地可载畜47 196 462.7个羊单位/a).按1999年不变价格计算,黄土高原预测畜牧业总产值将达到5 244 051万元RMB/a,是1999年畜牧业总产值的5.3倍,超过1999年黄土高原农业总产值14%.农业人口人均预测畜牧业产值大于1 000元的区县占59%;小于1 000元的区县占41%.此外,预测的农业总产值将达到1 147.223 4亿元RMB/a,其中畜牧业、果业、林业和农业产值占农业总产值的比重分别是46%、27%、14%和13%.随着畜牧业产业链的逐步建立与完善,产业发展布局的日趋合理,黄土高原畜牧业生产总值将有较大幅度的提高,黄土高原生态环境将有进一步的改善.黄土高原草地畜牧业蕴藏着巨大的发展潜力,有望成为黄土高原优化的生产-生态新产业带建制中的支柱产业.     

牦牛暖季放牧对牧草消化率的影响

通过垂穗披碱草-星星草混播草地连续3个放牧季的牦牛放牧试验,对不同放牧强度下牧草的消化率进行了研究。结果表明：放牧强度对牦牛所食牧草中酸性洗涤纤维消化率的影响极显著（P〈0．01）,对粗纤维消化率的影响显著（P〈0．05）,而对所食牧草中的总能、粗蛋白、粗灰分和中性洗涤纤维的影响不显著（P〉0．05）;放牧时间对中性和酸性洗涤纤维的影响极显著（P〈0．01）,而对牧草总能、粗蛋白、粗纤维和粗灰分的影响不显著（P〉0．05）。尽管牦牛的采食量均随放牧强度的增加而减小,但牦牛对采食牧草各营养成分的消化率并未出现规律性变化。     

三江源高寒草地牧草营养时空分布

草地的产草量和牧草品质影响着草地载畜量和草食动物的营养状况、生命活动及生产性能。以三江源及其周边地区的天然草地不同生长期（返青期,盛草期,枯黄期）牧草为对象,分析草地产草量及牧草品质的时空格局。结果显示：从整个区域看,草地生产力、可食牧草产量以及粗蛋白产量(Crude Protein, CP)分布均具有较明显的地域差异性,三者的高值区大多分布在三江源东部及南部的高寒草甸区,三者的低值区主要在三江源中部和西部的草甸及高寒草原区;大部分地区总生产力和可食牧草产量盛草期显著高于枯黄期,枯黄期显著高于返青期。粗蛋白产量在大部分地区呈现出盛草期显著高于返青期和枯黄期,返青期和枯黄期差异不明显,少数地区返青期显著高于盛草期和枯黄期,盛草期显著高于枯黄期（如：可可西里）;CP含量及产量在三江源区空间上的分布,均为南部地区高于北部地区,东部农牧交错区高于西部无人区;所有区域CP含量的返青期为最高,枯黄期为最低,而其他养分含量在不同区域的季节波动并不一致;盛草期牧草CP含量随海拔升高先增加后减小,粗灰分随着海拔升高而显著增加,中性洗涤纤维、酸性洗涤纤维和酸性洗涤木质素含量随着海拔升高呈降低趋势。结论：三江源及周边地区牧草生产力、可食牧草产量以及CP产量较高,可食性较好;三江源多数地区高寒草地牧草营养质量相对较好,牧草在返青期营养价值最高（蛋白高,纤维低）,到盛草期,牧草产量及营养物质输出量达到最高峰,进入枯黄期的牧草营养质量低劣,此时应进行补饲,以提高家畜生产性能。三江源区可利用草地主要集中在东部、南部和东南部,该区牧草品质较高、利用潜力（粗蛋白产量）较大,可适度利用开发。     

国家种质多年生牧草圃

国家种质多年生牧草圃是国家唯一的无性繁殖和多年生牧草保存圃,承担着牧草种质资源的保存和繁殖更新任务,挂靠在中国农业科学院草原研究所。设在中国农科院草原研究所农牧交错试验示范基     

苏南丘陵地区土地持续利用模式的建立

对苏南丘陵地区农田生物结构及功能的研究表明,在荒丘荒坡上建立林地、茶园、果园人工草地及新辟鱼塘以形成农牧渔复合农业生态系统．提出土地持续利用的单元模式;丘岗坡地─—林茶果草立体利用,冲田地─—粮、饲、经、肥、作物合理布局,养殖业—猪、禽、奶牛、鱼全面发展．资源利用─—种养加工业配套成龙．在粮食稳产基础上,农林牧副渔收入增长２．３倍,农用土地收入及人均农业收入均增长２．７倍．     

北方农牧交错带土地利用类型对土壤养分分布的影响

对北方农牧交错带多伦县5种土地利用类型进行118个土壤样点分析表明,农田土壤养分含量最低,草地含量处中等,林地含量最高.分别对4种不同土地利用类型在4种＞15.坡的小流域进行布点采样,研究不同土地利用结构对土壤有机质、速效磷、速效氮和全氮的影响.结果表明,在垂直方向上,由坡底到坡中到坡顶,对应的耕地-草地-林地土壤养分要比对应草地-林地-耕地这一土地利用类型中土壤营养元素含量高出1倍左右,说明此种土地利用类型具有较好的土壤养分保持能力,从而优化出最适合当地的土地利用类型,为改善生态环境、提高当地经济效益提供科学依据.     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan