Relatedness between numerically small Dutch Red dairy cattle populations and possibilities for multibreed genomic prediction

Red dairy breeds are a valuable cultural and historical asset, and often a source of unique genetic diversity. However, they have difficulties competing with other, more productive, dairy breeds. Improving competitiveness of Red dairy breeds, by accelerating their genetic improvement using genomic selection, may be a promising strategy to secure their long-term future. For many Red dairy breeds, establishing a sufficiently large breed-specific reference population for genomic prediction is often not possible, but may be overcome by adding individuals from another breed. Relatedness between breeds strongly decides the benefit of adding another breed to the reference population. To prioritize among available breeds, the effective number of chromosome segments (M_e) can be used as an indicator of relatedness between individuals from different breeds. The M_e is also an important parameter in determining the accuracy of genomic prediction. The M_e can be estimated both within a population and between 2 populations or breeds, as the reciprocal of the variance of genomic relationships. We investigated relatedness between 6 Dutch Red cattle breeds, Groningen White Headed (GWH), Dutch Friesian (DF), Meuse-Rhine-Yssel (MRY), Dutch Belted (DB), Deep Red (DR), and Improved Red (IR), focusing primarily on the M_e, to predict which of those breeds may benefit from including reference animals of the other breeds. All of these breeds, except MRY, are under high risk of extinction. Our results indicated high variability of M_e, especially between M_e ranging from ～3,500 to ～17,400, indicating different levels of relatedness between the breeds. Two clusters are especially important, one formed by MRY, DR, and IR, and the other comprising DF and DB. Although relatedness between breeds within each of these 2 clusters is high, across-breed genomic prediction is still limited by the current number of genotyped individuals, which for many breeds is low. However, adding MRY individuals would increase the reference population of DR substantially. We estimated that between 11 and 133 individuals from other breeds are needed to achieve accuracy of genomic prediction equivalent to using one additional individual from the same breed. Given the variation in size of the breeds in this study, the benefit of a multibreed reference population is expected to be lower for larger breeds than for the smaller ones.     

两类联图中保Wiener指数的树

Wiener指数是指一个连通图中所有顶点之间的距离之和.给定一个连通图G,若存在G中一个子树T,使得W(G)=W(T),则称T为G的一个保Wiener指数的树.利用图论中Wiener指数的计算方法和不定方程的求解方法,证明了满足特定条件的两类联图中均具有无穷多个保Wiener指数的子树.     

压电换能器在串并联谐振频率附近的特性研究

研究了压电换能器在串、并联谐振频率附近工作时的特性.采用等效电路变换的方法,推导出了换能器在串联、并联谐振频率附近时,串联、并联匹配电感参数以及有功电阻的表达式.结果表明电感匹配可以提高有效机电耦合系数.     

BAM网络在车型识别中的应用

设计了一种采用双向联想记忆网络 (BAM) ,仅以车型的轮廓曲线序列作为特征参数 ,能在高速公路不停车收费系统中 ,按照高速公路收费标准对不同车型进行分类的系统 .训练时 ,选择合适的权矩阵 ,把相应的参数训练成网络的稳定状态 ;识别时 ,输入用于区分车型的曲线序列 ,通过对车辆图像进行预处理及图像分析即可利用BAM神经网络识别出车辆的类型 .     

罗汉果有效成分提取的研究进展

综述了罗汉果主要化学成分的类别、成分分析;简要介绍了罗汉果所含主要成分的药理和保健作用;着重对其有效成分的各种先进的提取技术作了综合性的分析研究。为罗汉果的深度研究开发和资源合理利用提供必要的依据。     

Monitoring of black tea fermentation process using electronic nose

Black tea fermentation is essentially an oxidation process. After the plucked tea leaves are treated by series of processes called withering (removal of moisture by air flow), pre-conditioning and CTC (essentially maceration and cutting of leaves), the leaves are subjected to the process of fermentation by exposing them to air by laying the cut tea leaves on floor, trough or moving conveyor under controlled temperature, humidity and air-flow conditions. During this process, the leaves change colour from green to coppery brown and the grassy smell gets transformed to floral smell. It is critical that the leaves be allowed to ferment only up to the desired limit and both under and over fermentation result in deteriorated quality of black tea. Out of the two detectable parameters (colour and smell), smell is very important since a strong, very specific fragrance emanates from the leaves once leaves are optimally fermented. A new electronic nose-based approach for monitoring of tea aroma during fermentation is proposed. Two methods namely the 2-Norm method (2NM) and the Mahalanobis distance method (MDM) were tested and the results were correlated with the results of colorimetric tests and human expert evaluation.     

空气等离子体处理涤纶非织造布的研究

 针对涤纶纤维的表面能较低导致其吸湿性差的现状,采用空气等离子体对涤纶非织造布进行处理。通过实验得出了处理时间、功率以及放电间隙这3 个参数对涤纶非织造布吸湿性的影响。结果表明:该方法能显著改变涤纶非织造布的润湿性;随着功率的不断增大,吸湿量增加到一定峰值后有少许的减少;随着处理时间的延长,吸湿量持续增加;放电间隙为1 mm时,可以获得较为理想且均匀的等离子体,可对非织造布进行均匀的处理。     

Effects of alfalfa particle size and specific gravity on chewing activity, digestibility, and performance of Holstein dairy cows

Two experiments were carried out to test the effects of alfalfa particle size and functional specific gravity (FSG) on chewing activity, digestibility, rumen kinetics, and production of lactating dairy cows fed corn silage based rations. In experiment 1, water-holding capacity (WHC), insoluble dry matter, hydration rate, and FSG changes were determined in alfalfa hay (varying in particle size) and corn silage. Reduction of particle size increased bulk density, FSG, and the rate of hydration, and decreased WHC of alfalfa. In experiment 2, 9 midlactation Holstein dairy cows fed total mixed rations containing 3 sizes of alfalfa hay (with geometric mean 7.83, 4.04, and 1.14 mm) were used in a replicated 3 x 3 Latin square design. The diets contained 20, 20, 35, 7, 7.5, 10, 0.3, 0.1, and 0.1% of DM alfalfa, corn silage, barley, soybean meal, beet pulp, wheat bran, dicalcium phosphate, vitamin premix, and salt, respectively. The geometric means (GM) of rations were 3.34, 2.47, and 1.66 mm in long, medium, and fine alfalfa treatments, respectively. Reduction of particle size increased daily NDF intake (kg), but decreased the proportion of physically effective factor (pef) and physically effective NDF (peNDF) in the ingested rations. Reduction of particle size increased the FSG of rations and intake of DM but reduced digestibility of NDF and ash. Reduction of particle size decreased ruminal mean retention time (RMRT), but increased the ruminal particulate passage rate. Milk and FCM yield were not affected by treatments. The rumen pH, total chewing activity, rumination, eating time, and milk fat were reduced as particle size decreased, but milk protein increased. This study showed that reduction of forage particle size increased bulk density, FSG, and hydration rate of alfalfa and was the most influential factor affecting DMI, milk composition, and chewing behavior. Reduction of forage particle size had minimal impact on digestibility and milk production.     

QuEChERS-气相色谱法测定牛奶中24 种有机氯及菊酯类农药残留

建立QuEChERS快速净化结合气相色谱法测定牛奶中24 种有机氯及菊酯类农药残留的分析方法。样品经乙腈提取,QuEChERS法净化,气相色谱-电子捕获检测器分析,外标法定量。结果表明,待测物质在5～250 μg/L范围内线性关系良好,相关系数大于0.99,检出限为0.06～0.30 μg/kg,样品加标平均回收率为85.5%～111.2%,相对标准偏差为3.2%～10.8%。该方法简单、准确、高效,可用于牛奶样品中有机氯及菊酯类农药残留的快速筛查和定量检测。     

不同孵化期的鸡胚蛋营养和功效成分研究

鸡胚蛋在孵化期间,鸡胚的不断生长发育,蛋体内的各种营养物质,在酶的作用下,进行一系列的物质代谢。研究表明,对人体有利的物质在增加,如蛋白质、氨基酸增加1%以上,牛磺酸增加近20倍,无机盐中的钙增加6倍多,磷增加80%,铁增加40%,维生素A增加1倍,维生素B1增加3倍,维生素E增加100倍,具有抗菌作用的溶菌酶活性增加1倍,必需脂肪酸中的亚油酸增加1倍。而对人体不利的脂肪含量下降50%,胆固醇下降5.5倍,这对人体营养保健和防病治病有着重要作用。