Effective population size and inbreeding depression on litter size in rabbits. A case study

The purpose of this study is to use demographic and litter size data on four Spanish maternal lines of rabbits (A, V, H and LP), as a case study, in order to: (i) estimate the effective population size of the lines, as a measure of the rate of increase of inbreeding, and (ii) study whether the inbreeding effect on litter size traits depends on the pattern of its accumulation over time. The lines are being selected for litter size at weaning and are kept closed at the same selection nucleus under the same selection and management programme. The study considered 47 794 l and a pedigree of 14 622 animals. Some practices in mating and selection management allow an increase of the inbreeding coefficient lower than 0.01 per generation in these lines of around 25 males and 125 females. Their effective population size (Ne) was around 57.3, showing that the effect of selection, increasing the inbreeding, was counterbalanced by the management practices, intended to reduce the rate of inbreeding increase. The inbreeding of each individual was broken down into three components: old, intermediate and new inbreeding. The coefficients of regression of the old, intermediate and new inbreeding on total born (TB), number born alive (NBA) and number weaned (NW) per litter showed a decreasing trend from positive to negative values. Regression coefficients significantly different from zero were those for the old inbreeding on TB (6.79 ± 2.37) and NBA (5.92 ± 2.37). The contrast between the coefficients of regression between the old and new inbreeding were significant for the three litter size traits: 7.57 ± 1.72 for TB; 6.66 ± 1.73 for NBA and 5.13 ± 1.67 for NW. These results have been interpreted as the combined action of purging unfavourable genes and artificial selection favoured by the inbreeding throughout the generations of selection.     

Accounting for unknown foster dams in the genetic evaluation of embryo transfer progeny

Animals born by embryo transfer (ET) are usually not included in the genetic evaluation of beef cattle for preweaning growth if the recipient dam is unknown. This is primarily to avoid potential bias in the estimation of the unknown age of dam. We present a method that allows including records of calves with unknown age of dam. Assumptions are as follows: (i) foster cows belong to the same breed being evaluated, (ii) there is no correlation between the breeding value (BV) of the calf and the maternal BV of the recipient cow, and (iii) cows of all ages are used as recipients. We examine the issue of bias for the fixed level of unknown age of dam (AOD) and propose an estimator of the effect based on classical measurement error theory (MEM) and a Bayesian approach. Using stochastic simulation under random mating or selection, the MEM estimating equations were compared with BLUP in two situations as follows: (i) full information (FI); (ii) missing AOD information on some dams. Predictions of breeding value (PBV) from the FI situation had the smallest empirical average bias followed by PBV obtained without taking measurement error into account. In turn, MEM displayed the highest bias, although the differences were small. On the other hand, MEM showed the smallest MSEP, for either random mating or selection, followed by FI, whereas ignoring measurement error produced the largest MSEP. As a consequence from the smallest MSEP with a relatively small bias, empirical accuracies of PBV were larger for MEM than those for full information, which in turn showed larger accuracies than the situation ignoring measurement error. It is concluded that MEM equations are a useful alternative for analysing weaning weight data when recipient cows are unknown, as it mitigates the effects of bias in AOD by decreasing MSEP.     

RNA-Seq技术在瘤胃微生物研究中的应用进展

反刍动物瘤胃内多种多样的微生物组成一个复杂的微生态系统,它们在瘤胃内物质消化过程中发挥重要作用。RNA-Seq技术的出现为反刍动物瘤胃微生物的研究提供了前所未有的机遇。本文主要从新一代高通量测序技术出发,阐述RNA-Seq技术在瘤胃微生物代谢酶特性、瘤胃微生物的多样性、瘤胃微生物新功能基因方面的应用,以期为瘤胃微生物的研究提供参考。     

湖南小溪国家级自然保护区生态旅游资源的SWOT分析

对湖南小溪国家级自然保护区进行了生态旅游资源的SWOT分析,其优势是:良好的原始次森林和高品位的自然资源、森林浴的理想场所、优秀独特的人文资源、丰富的植物基因库存.但是可进入性差、知名度低、接待设施及能力较差.周边存在张家界国家森林公园和栖凤湖风景区的竞争威胁.分析了发展机会.     

总结经验 再接再厉 努力提升森林资源连续清查水平

森林资源连续清查是依法监测全国森林资源消长和生态状况变化的林业基础性工作,其成果是制定和调整经济社会发展规划和林业生态建设方针政策的重要依据。我国已经完成六次全国森林资源连续清查,积累的许多经验值得总结,更要适应生态建设的需要,进一步加以保持和发扬,并提升到新的水平。     

浙江省国家重点保护野生植物就地保护的研究

对浙江省国家重点保护野生植物就地保护现状及评价进行了研究。目前浙江省已有8个省级以上野生植物和森林生态系统类型自然保护区(点),就地保护国家重点保护植物达38种,占浙江省国家重点保护野生植物总种数(50种)的76%;初步提出了合理调整和布局自然保护区,大力发展自然保护小区、自然保护点和禁伐区,就地保护和其它手段相结合等保护措施。     

大老岭国家森林公园生态旅游的开发与管理

分析了大老岭国家森林公园的自然地理概况、人文经济、景观生态和旅游资源,探讨了其景观生态与旅游开发之间的关系,并提出了生态旅游开发与管理的相关方案:根据生态管理的科学规律设计生态化景观结构,合理布局景观生态功能区,制定合理的生态旅游容量。     

抗战时期沦陷区文化的特点--奴化思想教育

抗战时期,日本帝国主义为了使文化为侵华战争服务,在沦陷区实施的奴化思想教育,是一种具有欺骗性、侵略性、组织性和高度的垄断性等特点的文化现象.奴化思想教育不仅在精神上摧残中国人民的民族意识,而且在物质上对我国教育硬件设施进行损坏.其实质是日本"兴亚院"文化部进行的一场"教育一体化"的政治阴谋,是一种思想渗透和文化侵略,这种侵略比其政治、经济、军事上的侵略更为疯狂、残暴.     

湖南省西南部蝶类资源研究

用采集和饲养相结合的方法收集到湘西南蝴蝶标本293种和亚种，分属11科148属。首次发现湖南新记录143种。一批世界精品蝶，中国珍蝶和在湘西南有分布而全世界仅有1－5种的属。次次列出我省珍稀蝶39种。对湘西南蝶类分布区系及特点进行了详尽分析，同时提出了保护，利用蝶类资源的建议。     

排他性法院管辖协议公约谈判与我国植物新品种权保护

在对我国和国际植物新品种权保护制度进行介绍的前提下,从植物新品种权保护角度出发,对海牙《排他性法院管辖协议公约》谈判中涉及的知识产权案件管辖权问题进行了分析,对我国在谈判中应采取的立场提出了独到见解。通过与国际植物新品种权保护制度的对比,指出我国植物新品种保护制度的不足,并提出完善建议。