提高母羊双羔多胎率有技术

提高母羊双羔多胎率,是提高养羊经济效益,增加产仔数和扩大羊毛、羊肉、羊奶及羊绒等产品的一项重要技术措施.而影响母羊双羔多胎的生产因素主要有以下几点:一是母羊的年龄与胎次;二是遗传力;三是羊的品种;四是营养等因素.为此,笔者根据近年来国内外的一些先进技术,现将提高母羊双羔多胎率的几点做法介绍如下:

An Improved Adaptive Multi-way Principal Component Analysis for Monitoring Streptomycin Fermentation Process

Multi-way principal component analysis (MPCA) had been successfully applied to monitoring the batch and semi-batch process in most chemical industry. An improved MPCA approach, step-by-step adaptive MPCA (SAMPCA), using the process variable trajectories to monitoring the batch process is presented in this paper. It does not need to estimate or fill in the unknown part of the process variable trajectory deviation from the current time until the end. The approach is based on a MPCA method that processes the data in a sequential and adaptive manner. The adaptive rate is easily controlled through a forgetting factor that controls the weight of past data in a summation. This algorithm is used to evaluate the industrial streptomycin fermentation process data and is compared with the traditional MPCA. The results show that the method is more advantageous than MPCA, especially when monitoring multi-stage batch process where the latent vector structure can change at several points during the batch.

Perinatal and early life risk factors for inflammatory bowel disease

AIM:To investigate associations between perinatal risk factors and subsequent inflammatory bowel disease (IBD) in children and young adults.METHODS:Record linked abstracts of birth registrations,maternity,day case and inpatient admissions in a defined population of southern England.Investigation of 20 perinatal factors relating to the maternity or the birth:maternal age,Crohn's disease (CD) or ulcerative colitis (UC) in the mother,maternal social class,marital status,smoking in pregnancy,ABO blood group and rhesus status,pre-eclampsia,parity,the infant's presentation at birth,caesarean delivery,forceps delivery,sex,number of babies delivered,gestational age,birthweight,head circumference,breastfeeding and Apgar scores at one and five minutes.RESULTS:Maternity records were present for 180 children who subsequently developed IBD.Univariate analysis showed increased risks of CD among children of mothers with CD (P=0.011,based on two cases of CD in both mother and child) and children of mothers who smoked during pregnancy.Multivariate analysis confirmed increased risks of CD among children of mothers who smoked (odds ratio=2.04,95% CI=1.06-3.92) and for older mothers aged 35+ years (4.81,2.32-9.98).Multivariate analysis showed that there were no significant associations between CD and 17 other perinatal risk factors investigated.It also showed that,for UC,there were no significant associations with the perinatal factors studied.CONCLUSION:This study shows an association between CD in mother and child;and elevated risks of CD in children of older mothers and of mothers who smoked.

Genetic Analysis of Yield and Yield Components Based on the Three Controlled Hybrid Populations in the Robusta Coffee （Coffea canephora Pierre）

Genetic analysis of yield and yield components were carried out on three parental clones of Coffea canephora Pierre and their controlled hybrid progenies. There is a possibility to estimate coffee yield capabilities in simply via the easier measuring traits of yield components since significant correlation between them were detected. We found that among parental show very few significantly differences of all observed characters and even not found between the overall mean of the descendants and their donor parents, whereas some particular descendants show higher values rather than their donor parent in one or more characters. Increased value between the best parent to the best descendent were detected varies from zero to 102%. This situation suggests the difficulty to find out the optimum yield in a single plant by accumulating all of yield components that actually can increase 143% to 278% from actual to potential yields. In addition, observed characters among population were also actually found highly varies from 159% in out-turn in population B to 28,333% in number of productive branch among population A. Low heritability （h2） that generally found in quantitative traits due to polygenic control was present in our studies in almost all characters observed. Therefore, selection for actual high yielding through conventional breeding will not efficient, and more convincing the power of selection using molecular markers to assist for cumulate additive effects in a single genotypes that resulted of high yielding in the future.

Effects of nutrient profiles and light regime on the production of exopolysaccharide by Porphyridium cruentum

In order to increase the yield of polysaccharides from Porphyridium cruentum and the cell biomass, we investigated several important cultural conditions such as nutrient-salts, light irradiance as well as growth conditions in the flat plate photobioreacturs （FPPBR） with different light-path. We have found that the optimal （OCM II ） was a superior medium for extracellular polysaccharide production than the f/2 and Koch medium, and the polysaccharide production with OCM II was increased by 1.79 times and 1.62 times compared with that of f/2 and Koch medium; the yields of polysaccharides were also improved by optimizing the light intensity and irradiation length Furthermore, we significantly enhanced the yields of both the biomass and extracellular polysaccharidc using a small light-path photobioreactor, and about 2.1 times increase of polysaccharide production was observed in FPPBR-30 than in FPPBR-100. Overall, the process for polysaccharides production was improved and this would facilitate further studies on such polysaccharidcs such as their antiviral and antitumor activities.

The Highest and Best Use of Agricultural Land in a Multifunctional Land Market, Evidence from South Africa

Agricultural land has conventionally been perceived primarily as a production factor. For this reason the highest and best use （HBU） of such land was considered to be agricultural production for income purposes. The transition towards a multifunctional agricultural land market, where alternative uses--such as for lifestyle purposes--is evident, has challenged this view. Lifestyle buyers of farms often focus on a variety of characteristics of agricultural land which are not necessarily related to income but usually more intangible and subjective, which pose a measurement problem for valuers. The continued use of familiar traditional farming characteristics when valuing agricultural properties where lifestyle motivations are present, and the exclusion of less measurable characteristics, means that the market sales comparison method cannot be executed accurately. This study used a mixed methods research strategy to determine whether valuers use characteristics mainly related to agricultural production as HBU in valuations of agricultural properties bought for lifestyle purposes, and to identify the value attributes of farms that attract lifestyle buyers （and whether these differ from production oriented buyers）. This was done in an intensive and extensive agricultural area within the Western Cape Province of South Africa. Results indicate that valuers use familiar production related characteristics when valuing farms bought for lifestyle purposes, while lifestyle and production oriented buyers also interpret the value attributes of agricultural properties differently. For this reason a multiple perspective approach to agricultural land valuations where the HBU is uncertain is proposed.

Analysis of the contribution of multiple factors to the recent decrease in discharge and sediment yield in the Yellow River Basin, China

The Yellow River basin is well known for its high sediment yield. However, this sediment yield has clearly decreased since the 1980 s, especially after the year 2000. The annual average sediment yield was 1.2 billion tons before 2000, but has significantly decreased to 0.3 billion tons over the last 10 years. Changes in discharge and sediment yield for the Yellow River have attracted the attention of both the Central Government and local communities. This study aimed to identify the individual contributions of changes in precipitation and human activities(e.g. water conservancy projects, terracing, silt dams, socio-economic and needs, and soil and water conservation measures) to the decrease in discharge and sediment yield of the Yellow River. The study used both improved the hydrological method and the soil and water conservation method. The study focused on discharge analysis for the upper reaches and the investigation of sediments for the middle reaches of the river. The results showed that discharge and sediment yield have both presented significant decreasing trends over the past 50 years. Precipitation showed an insignificant decreasing trend over the same period. The annual average discharge decreased by 5.68 billion m3 above Lanzhou reach of the Yellow River from 2000 to 2012; human activities(e.g. socio-economic water use) contributed 43.4% of the total reduction, whereas natural factors(e.g. evaporation from lakes, wetlands and reservoirs) accounted for 56.6%. The decrease in annual discharge and sediment yield of the section between Hekouzhen station and Tongguan station were 12.4 billion m3 and 1.24 billion tons, respectively. Human activities contributed 76.5% and 72.2% of the total reduction in discharge and sediment yield, respectively, and were therefore the dominant factors in the changes in discharge and sediment yield of the Yellow River.

Role of cyclic AMP signaling in the production and function of the incretin hormone glucagon-like peptide-1

Pancreatic cells express the proglucagon gene （ gcg ） and thereby produce the peptide hormone glucagon , which stimulates hepa tic glucose production and thereby increases blood glucose levels. The same gcg gene is also expressed in the intesti nal endocrine L cells and certain neural cells in the brain. In the gut, gcg expression leads to the production of glucagon-like peptide-1 （GLP-1）. This incretin hormone stimulates insulin secretion when blood glucose, level is high. In addition, GLP-1 stimulates pancreatic cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells.

Neutrinos,supernovae,and the origin of the heavy elements

Stars of～8-100 M_⊙end their lives as core-collapse supernovae(SNe). In the process they emit a powerful burst of neutrinos,produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for SN progenitors results in diverse neutrino signals, explosion energies, and nucleosynthesis products. A major mechanism to produce nuclei heavier than iron is rapid neutron capture, or the r process. This process may be connected to SNe in several ways. A brief review is presented on current understanding of neutrino emission, explosion, and nucleosynthesis of SNe.