Comparison of production systems for efficient use of indigenous pig breeds in developing countries

Conserving pig genetic resources and improving their productivity is important to increase returns over investment in developing countries. The purebred, first‐cross, rotational cross and backcross matings representing production systems based on pig breeds indigenous to the country and exotic pig breeds were investigated. The number of pigs in the nucleus and commercial herds necessary to produce a defined quantity of pork was considered. The amount of heterosis between the indigenous and exotic breeds, superiority in meat production, and degree of inferiority in reproductive performance of the exotic breed compared with that of the indigenous breed were investigated. The number of breeding pigs in the whole system was in the following order: pure breeding (PB) > first‐cross (F1) > rotational cross (RC) > backcross (BC) systems. The number of breeding pigs in the nucleus herds of the RC and BC systems was smaller than that in the nucleus herds of the PB and F1 systems. The degree of inferiority in reproductive performance of the exotic breed compared with that of the indigenous breed affected the efficiency of the production system.     

深化草业经济体制改革实行草原有偿承包制度

实行草原有偿承包制度,是草业经济体制改革的重要突破。本文在总结草原有偿承包制度产生与发展过程的基础上,阐明草原有偿承包制度的基本内容,阐述了建立草原有偿承包制度之理论、法律、现实和实践根据及其在草地畜牧业经济建设中的重大意义。     

乙脑病毒PrME基因在杆状病毒表达系统中的表达

本试验将乙型脑炎病毒（ＪＥＶ）的ＰｒＭ／Ｅ基因的ＨｉｎｄⅢ－ＢｇｌⅡ片段（２．１ｋｂ）插入到杆状病毒载体ｐＡｃＵＷ３１的ＢａｍＨＩ位点,使外源基因置于多角体蛋白启动予下游,构建成转移载体ｐＡｃＵＷ３１ＪＥ,以Ｌｉｐｏｆｅｃｔｉｎ作为共转染试剂,将纯化的ｐＡｃＵＷ３１ＪＥ与Ｂｓｕ３６Ｉ线性化的杆状病毒ＡｃＭＮＰＶ．ＬａｃＺＤＮＡ共转染昆虫ｓｆ９经病毒蚀斑纯化技术和Ｘ－ｇａｌ与中性红双重染色技术,随机     

云南肉牛生产体系建设

本文根据云南省肉牛生产现状和特点,对云南省肉牛生产体系建设作了全面论述。     

春季休牧对草原和家畜生产力的影响

从4月上旬到6月下旬,在内蒙古锡林郭勒典型草原,进行春季休牧试验,对休牧和非休牧的草原进行生产力监测.结果表明:春季休牧可以有效地保护草原生态环境,经过两个月休牧后,草原植被状况明显改善;休牧期间采用低投入维持性饲养,可以显著降低饲养成本.并对休牧措施的生态效益、生产实践可行性和经济合理性进行综合讨论和评价.     

优质肉鸡繁育体系的效益评估

近十多年来，我国优质肉鸡的生产方兴未艾，许多育种公司和科研院所不断推出新品系。为充分发挥新品系的遗传潜力，探求优质肉鸡最佳的繁育生产模式具有重要意义。由于不同的品系及其杂种后代在不同的性状上各有优缺点，很难用生产性能进行直接比较，而适合用育种规划的方法通过经济学指标进行评价。系统分析通过把生产系统抽象概念化并用数学手段模型化的方法，     

Characterization of Interstitial Cells of Cajal in Bowel of Cattle (Bos taurus)

Interstitial cells of Cajal (ICC) have been described in the gastrointestinal tract of different mammals including humans, horses, pigs, rats, dogs, mice and guinea-pigs. In the present study, ICC were identified in the jejunum of Bos taurus using polyclonal anti-c-Kit antibodies in immunohistochemical assays. Vimentin and desmin intermediate filaments were also determined using monoclonal antibodies. ICC were found in the tunica muscularis either in a palisade distribution pattern between the outer longitudinal and the inner circular layers (ICC-MP) or freely distributed in clusters in the longitudinal layer (ICC-LM). Morphometric studies determined that ICC have a fusiform shape presenting cytoplasmic prolongations. ICC were positive to c-Kit and vimentin antigens but negative to desmin. We have observed and described for the first time the presence of ICC in a ruminant. As observed in the aforementioned mammals, bovine ICC were associated with the myenteric plexus. Nevertheless, the presence of widespread ICC in the longitudinal muscular layer of the jejunum differs from previously described studies of other mammals.     

高校勤工助学应从体力型转向智力型

在国家建立的资助经济困难学生的奖、贷、助、补、减政策体系中，勤工助学具有独特的地位和作用。随着社会的发展，体力型勤工助学已经越来越不能满足贫困学生的需要。要想完全发挥勤工助学的作用，必须将勤工助学从体力型转向智力型。     

论股权分置改革中的分类表决制度

分类表决制度是我国证券市场的一大制度革新。随着我国股权分置改革的全面推进，分类表决制度也发挥着越来越重要的作用，它赋予流通股股东更多自我保护的权益，对股权分置改革起到有力的推动作用；同时，它也存在着不容忽视的局限性。文中通过具体分析，提出一些建议以供参考。     

建立青藏高原草地乳用牦牛生态系统的思路

牦牛是青藏高原的特有家畜之一,不同的草地类型形成了不同的生活生态型,并针对牦牛乳的品质和开发潜力,提出了用黑白花奶牛冻精与母牦牛杂交提高牦牛的产乳性能,特别是采用野牦牛冻精改良母牦牛生产性能的途径.草地乳用牦牛生态系统的建立,一是要遵循牦牛逐水草而牧季节转场的习性;二是为牦牛过冬贮备充足的饲草料;三是建棚圈、实现冷季家畜的舍饲和持续增膘;四是把野牦牛的保护纳入家牦牛生产的范围,使这一系统更富有自然和谐和可持续发展的活力.