共查询到20条相似文献，搜索用时 593 毫秒
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奶牛体型主要性状的主成分分析 总被引：6，自引：0，他引：6
奶牛体型的线性评定方法是本世纪80年代在奶牛遗传改良中出现的一项新技术。奶牛体型线性评定的主要性状有15项,次要性状有14项之多,由此得到的数据资料累计起来就十分可观。如何时这些原始资料统计分析处理,从中提取出有价值的信息显得很重要。本文拟对奶牛体型线性评定的15个主要性状进行主成分分析处理,推导如何将这些性状转化为较少的指标,这些新指标既彼此互不相关、又能综合反映原来多个性状的信息,是原来多个信息的线性组合。从而利用这些较少的新指标就可方便地进行其他的统计分析。一、材料与方法数据取自于奶牛体型线性评定课题组五年中评定的北京市2649头成乳牛资料。评定的15个主要性 相似文献
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浅谈奶牛线性外貌评分法 总被引：2，自引：0，他引：2
奶牛线性外貌鉴定是近年发展起来的一种新的奶牛外貌评定技术。现将评分方法简明介绍如下。一、什么是奶牛线性外貌评分法线性评分法是根据奶牛的生物学特点进行的功能型外貌评分法。它将那些在经济上和生产性能上有重要作用并可通过遗传改进的外貌性状,用直线度量各性状表现的全过程,最后根据被评定奶牛各性状的实际表现状况进行评点给分。 相似文献
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奶牛体型线性评定,是对奶牛体况进行无偏见评定的一种方法（储明星等,1996）.1986年,师守堃等将线性鉴定技术引入我国,并于1987年提出了将线性评分转化为功能评定,计算部位评分和整体评分.1995年中国奶牛协会颁发了《中国荷斯坦牛体型线性鉴定实施方案（试行）》.本文将主要按体躯容积、乳用特性、一般外貌、泌乳系统四大特征性状分15个重点性状进行评定分析. 相似文献
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江苏省奶牛体型性状的表型参数测定 总被引：1，自引：0，他引：1
江苏省奶牛体型性状的表型参数测定江苏农学院牧医系（杨州２２５００１）王杏龙，杨章平，徐允令线性度量的体型评定是本世纪８０年代首先在奶牛中发展起来的新技术新方法。线性评定的依据是体型性状的生物学特点，大部分评定的性状均可数量化度量，缩小了不同鉴定人员间... 相似文献
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奶牛体型线性评定总分的快速计算法荆福林，关长顺（辽宁省抚顺牧工商联合公司奶牛场１１３１２３）奶牛体型线性评定技术是本世纪八十年代在奶牛业中发展起来的新方法，它具有依据奶牛体型性状的生物学特点，对每一性状进行评定。采用该种方法对奶牛进行体型评定，评定的... 相似文献
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奶牛体型线性性状与其成年奶当量的关系 总被引：1，自引：0，他引：1
体型线性性状评定做为奶牛育种工作的一项重要内容，在生产中已经开展起来。事实上，人们进行奶牛体型外貌线性评定的主要目的之一在于通过评定预测其产奶能力。因此，深入研究奶牛和各线性性状与其成年奶当量之间的关系，就显得很有必要。我们现通过对奶牛各线性性状与其成年奶当量的关系进行统计分析，以期从中找出影响奶牛奶当量的主要性状，为提高牛群产奶水平并在更大范围内进行有效的选种选育提供理论依据。１材料和方法１．１数据来源１．１．１５８６头荷斯坦奶牛的正常生产记录。各个体不同胎次的产奶量均校正为３０５天产奶量后进… 相似文献
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奶牛线性外貌评定的数据计算系列软件 总被引：4，自引：0，他引：4
奶牛线性外貌评定的数据计算系列软件黑龙江省家畜繁育指导站（哈尔滨１５００６０）葛星明，李洪铎，李贵范奶牛线性外貌评定方法，是当今世界各国普遍应用的方法。奶牛线性外貌评定的数据，一般需进行三个方面的处理。即由各性状的线性评分计算功能分、部位及整体评分；... 相似文献
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奶牛体型性状之间关系的研究进展 总被引：3，自引：0，他引：3
1 前言 奶牛体型性状线性分析的概念是1976年提出的。美国农业部和荷斯坦奶牛协会为合理解决奶牛育种工作中的体型评定问题,从1977年开始委托一些大学的专家经数年研究并与体型描述评定进行比较后,于1980年提出了奶牛体型线性评定方法。1983年正式应用于美国荷斯坦 相似文献
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奶牛体型线性评定数据的应用 总被引：1，自引：0，他引：1
奶牛体型线性评定数据的应用北京农业大学动物科技学院（１０００９４）储明星，师守奶牛体型性状线性分析的概念是１９７６年提出的，美国农业部和荷斯坦奶牛协会为合理解决奶牛育种工作中的体型评定问题，从１９７７年开始委托一些大学的专家经数年研究并与体型描述评定... 相似文献
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M.A. Kristula D.T. Galligan C.R. Curtis R.C. Bartholomew 《Preventive veterinary medicine》1992,14(3-4):251-258
This study evaluated the accuracy of a Dairy Herd Improvement Association test compared with bacterial culture to report the prevalence of chronic intramammary infections in dairy cattle. The Association classification considers a cow to have a chronic intramammary infection when her linear score is 4 or greater for more than one test in a lactation. The threshold level of linear score 6 minimized the sum of the misclassification errors. The Association test was not sensitive or specific enough compared with bacterial culture to classify individual cows accurately. 相似文献
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H. G. Allore D. J. Wilson H. N. Erb P. A. Oltenacu 《Preventive veterinary medicine》1998,33(1-4):11-29
The data for this cross-sectional retrospective study are from surveys of 65 dairy-cattle herds in central New York, USA sampled between February, 1993 and March, 1995. The objective was to identify probability distributions of logarithmically transformed somatic-cell counts (linear score) for use in a simulation model of mastitis and milk quality. Probability density functions were estimated using maximum-likelihood estimators for the linear score of individual-cow compositemilk samples culture negative and culture positive for the pathogens Streptococcus agalactiae, Streptococcus non-agalactiae, Staphylococcus aureus, and coagulase-negative staphylococci for the complete dataset and by bulk-tank somatic-cell count group (< 500 000, ≥ 500 000 SCC/ml). Based on the rankings of three goodness-of-fit tests (Anderson-Darling, Kolmogorov-Smirnov and x2), the Weibull distribution (among the three top-ranking distributions for 14 out of 15 cases) may be used to model the individual-cow linear-score response by culture-result-specific bulk-tank somatic-cell count group. A β distribution was among the three top-ranking distributions for nine out of 15 culture-result-specific bulk-tank somatic-cell count groups and has a logical relationship to linear score because it is defined on a fixed interval. On the other hand, the normal distribution had a poorer fit than the Weibull and at least two other distributions for all culture negative and coagulase-negative staphylococci samples. We do not assume that the underlying biological processes are fully explained by either Weibull or β distribution—but modelling the linear score for the above culture results with these distributions provided an adequate fit to the survey data, reduced the need for two-sided truncation that open intervals needed, and had errors that did not appear to be systematically positive or negative. 相似文献
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Body weight, heart girth and condition score were monitored in 75 Boran cows over an eight-month period. Condition score was highly correlated with both weight and heart girth when these variables were measured at the end of the dry season. Over the whole period the correlation coefficient between weight and condition score was r = 0.76 and the relationship was linear. When the data were broken down by lactation status the correlation between condition score and weight of lactating cows was lower but was improved by adjusting for differences in cow weight. Heart girth and condition score over the whole period were linearly related as was heart girth and weight. A change of one point in a nine-score system was equivalent to a change of about 24 kg. 相似文献
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Haslam SM Knowles TG Brown SN Wilkins LJ Kestin SC Warriss PD Nicol CJ 《British poultry science》2007,48(3):264-275
1. Standardised data on flock husbandry were recorded on 149 broiler farms during the 4 d prior to slaughter. 2. Birds were examined at the slaughterhouse for contact dermatitis lesions. Foot pad dermatitis score (FPDS) and hock burn score (HBS) were measured on five point scales. Carcase rejection data were also collected. 3. The mean percentage of birds in each flock with: moderate or severe foot lesions was 11.1% (range 0-71.5%); moderate or severe hock burn was 1.3% (range 0-33.3%); and, breast burn was 0.02%. 4. A general linear model was developed to examine factors associated with mean flock FPDS. Assuming a linear relationship, within the range of data collected and with all other factors remaining the same, every 1% increase in the proportion of Genotype A birds in the flock was associated with an increase in mean FPDS of 0.003, every one-point increase in litter score was associated with a 0.326 increase in mean FPDS and every one-point increase in flock mean HBS was associated with a 0.411 increase in mean FPDS. Flock mean FPDS was associated with feed supplier and was higher in winter. 5. The general linear model developed for flock mean HBS, found that every one-point increase in mean FPDS increased mean HBS by 0.090, every one-point increase in litter score increased HBS by 0.119 and, every 1% increase in small/emaciated birds decreased mean HBS by 0.333. Reduced HBS was also associated with increased final litter depth, younger slaughter age and an increased percentage of dietary wheat. For every 1% increase in Genotype A birds, a decrease in flock mean HBS of 0.003 would be expected. 6. An effect of hatchery was also identified. 相似文献
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Lewis TW Ilska JJ Blott SC Woolliams JA 《Veterinary journal (London, England : 1997)》2011,189(2):227-233
A linear mixed model analysis of elbow and hip score data from UK Labrador retrievers was used to estimate the heritability of elbow score (0.16-0.19) and to determine a moderate and beneficial genetic correlation with hip score (0.40). A small improvement in the genetic trend of elbow score was observed during the years 2000-2008, equivalent to avoiding only the worst 3-4% of scored dogs for breeding, but close to what may have been anticipated if the current British Veterinary Association-approved guidelines were followed. Calculations suggested that a correlated response to indirect selection on hip score may elicit a greater response than direct selection on elbow score and that the genetic trend in elbow score may be explained as a consequence of the stronger selection pressure that has been placed on hip score. Increases in the accuracy of estimated breeding values for elbow score of 4-7% for dogs with elbow data only and 7-11% for dogs with both hip and elbow score were observed from bivariate analysis of elbow and hip data. A selection index confirmed the benefits of bivariate analysis of elbow and hip score data by identifying increases in accuracy (directly related to the response to selection) of 14% from the use of optimum coefficients compared to use of hip data only. The quantified genetic correlation means that hip score effectively acts as a 'secondary indicator' of elbow score in this breed and the preponderance of hip data means that it acts as a major source of information that may be used to improve the accuracy of estimates of genetic risk for elbow dysplasia. 相似文献
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R P Cowart R J Lipsey H B Hedrick 《Journal of the American Veterinary Medical Association》1990,196(8):1262-1264
A group of 85 commingled feeder pigs was fed on a totally confined feeding floor until slaughter. Mean daily weight gain was calculated for each pig. At slaughter, the nose of each pig was cross-sectioned and scored for conchal atrophy by use of 2 methods. One method ascribed a score based on a linear measurement of the distance between the ventral scroll of the ventral conchae and the ventral floor of the nasal cavity. The other method ascribed a score based on a subjective evaluation of the degree of conchal degeneration according to previously published guidelines. The amount of pulmonary consolidation attributable to pneumonia was also estimated for each pig. Association was not found between growth rate and conchal atrophy, as determined by linear measurement scores. A negative correlation existed between growth rate and conchal atrophy, as determined by subjective evaluation scores. Pigs with extensive pneumonic lesions (consolidation of 20 to 30% of total lung volume) grew slower than pigs with milder pneumonic lesions. Results of this study indicate that subjective evaluation scores of conchal atrophy may be more useful in predicting growth rate than are linear measurement scores. 相似文献
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An experiment was conducted to compare three weaning ages on cow-calf performance and steer carcass traits. Crossbred steers (n = 168; 1/2 Simmental x 1/4 Angus x 1/4 Hereford) were randomly assigned to three treatments with eight pens per treatment: groups were 1) weaned at an average of 90 d of age (90 +/- 13 d) and placed in the feedlot, 2) weaned at an average of 152 d of age (152 +/- 13 d) and placed in the feedlot, and 3) weaned at an average of 215 d of age (215 +/- 13 d) and placed in the feedlot. The number of days steers were finished decreased by 55 and 38 d (linear, P = .0001) as weaning age increased when slaughtered at a constant fat end point (.81 cm). Weaning at an average of 90 and 152 d of age improved overall ADG by .15 and .07 kg/d, respectively, over weaning at an average of 215 d of age (linear, P = .005). Over the entire finishing period, intake increased (linear, P = .0006) and efficiency was poorer (linear, P = .004) as weaning age increased. Owing to differences in finishing days and intake, total concentrate consumed increased (linear, P = .03) as weaning age decreased. No differences (P > .21) were observed for carcass weight, longissimus muscle area, or yield grade. No differences (P > .19) were observed in marbling score or percentage of steers grading greater than or equal to Choice or Average Choice. Cow body condition score improved (linear, P = .0001) as weaning age decreased. Pregnancy rate improved 12 percentage units (linear, P = .15) for cows on the 90-d weaning treatment. In this study, early weaning improved gain and feed efficiency, but it increased total concentrate consumed. 相似文献