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本文应用系统分析原理和方法,在系统分析家庭库伦产业结构要素的基础上,以实现系统生态,经济效益最佳为指导思想,采用多目标规划法建立数学模拟模型,定量化分析了鄂托克前旗不同类型及不同规模的家庭草库伦产业结构,并进行了效益评价。该模拟模型的实质是实现家庭草库伦中“水利-草业-牲畜-牧民”系统平衡和取得最佳生态经济效益的优良化设计模型,是水利和草业有机结合的应用理论研究。 相似文献
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季凤霞 《青海畜牧兽医杂志》1995,(6)
根据环湖地区气候条件对畜群的综合影响,确定春季牲畜转场时的灾害天气指标,对共和、天峻、刚察、海晏、茶卡等地1961~1990年的气象资料进行分析,统计出牲畜转场范围内逐旬、逐候的灾害天气日数,提出了各地的最佳和次佳转场期。 相似文献
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李凤霞 《青海畜牧兽医杂志》1995,25(6):21-22
根据环湖地区气候条件对畜群的综合景,确定春生牲畜转场时的灾害天气指标,对共和、天峻、刚察、海晏、茶卡等地1961-1990年的气象资料进行分析,统计出牲畜转场范围内逐旬、逐修的灾害天气日数,提出了各地的最佳和次佳转场期。 相似文献
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为了分析亚高山草甸季节草场的合理利用,以牧草产量为基础,用线性规划模型计算结果划分了季节草场合理占比面积;并用天然草地合理载畜量的计算标准和线性规划模型分别计算了全年、春季、暖季、冷季放牧草地合理承载量。结果表明,线性规划在季节草场的合理利用上更加有优势;线性规划模型主要应用在定点放牧上,对中等数量牲畜和中等面积以下的放牧方式进行规划;定点放牧方式牲畜不需要长途远徙消耗大量体能,饲料不足可人工补充饲草料。线性规划模型为放牧草地面积的季节性分配和合理利用以及为以草定畜的放牧试验设计和放牧方案的制定提供了科学依据。 相似文献
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饲养牲畜是草地放牧的目标,放牧饲养牲畜是草地饲草资源利用的最有效途径。放牧饲养要素包括草地生产率、适宜载畜率、饲草质量、牲畜生长需要和采食量及放牧方式。本文对这些要素进行了归纳分析,目的在于推进发展草地放牧饲养理论并推导草地生产和保护性利用的关键技术。本文介绍了草地生产率研究方法、适宜载畜率确定标准、划区轮牧区块数计算方法及间歇休牧期和放牧期确定方法。草地放牧饲养理论:基于土壤和气候,改善草地生产和饲草质量,制定适宜载畜率,确定合理放牧方式,满足放牧牲畜最佳生长需要,并维持草地健康,实现“双赢”或“三赢”。草地保护性利用关键技术:放牧场或割草场施肥,调整适宜的载畜率,延迟放牧及间歇休牧,确切的划区轮牧体系,放牧场和割草场等量配置,二时段饲养模式。 相似文献
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Vazquez AI Perez-Cabal MA Heringstad B Rodrigues-Motta M Rosa GJ Gianola D Weigel KA 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2012,129(2):120-128
Mastitis in cows can be defined as a binary trait, reflecting presence or absence of clinical mastitis (CM), or as a count variable, number of mastitis cases (NCM), within a defined time interval. Many different models have been proposed for genetic analyses of mastitis, and the objective of this study was to evaluate the predictive ability and sire predictions of a set of models for genetic evaluation of CM or NCM. Linear- and threshold liability models for CM, and linear, censored ordinal threshold, and zero-inflated Poisson (ZIP) models for NCM were compared in a cross-validation study. To assess the ability of these models to predict future data, records from 620492 first-lactation Norwegian Red cows, which were daughters of 3064 sires, were evaluated in a fourfold cross-validation scheme. The mean squared error of prediction was used for model comparison. All models but ordinal threshold model equally performed when comparing the overall predictive ability. This result was on average, across sick and healthy cows; however, the models behaved differently for each category of animals. For example, healthy cows were predicted better by the threshold and linear models for binary data and ZIP model, whereas for mastitic cows, the ordinal threshold model was by far the best model. Predicted sire effects and rankings of sires were highly correlated across all models. For practical purposes, the linear models are very competitive with the nonlinear models. 相似文献
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通过生长曲线非线性拟合模型可以预测家畜的生长发育速率以及生长曲线的变化情况。本研究运用Logistic、Gompertz和Von Bertalanffy模型分析拟合了高原型藏羊的早期生长发育曲线。结果表明:3种模型均能较好地拟合高原型藏羔羊的生长曲线(R2>0.99),其中,以Von Bertalanffy模型拟合效果最佳。在Von Bertalanffy模型中,公羔拐点月龄、拐点体重和最大日增重分别为1.35、12 kg和246.67 g·d?1,母羔拐点月龄、拐点体重和最大日增重分别为1.36、11.96 kg和239.33 g·d?1。根据此模型建立的高原型藏羊早期发育阶段的生长曲线,可为早期选育提供理论依据。 相似文献
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不同能量水平对朗德鹅生长曲线的影响研究 总被引:2,自引:0,他引:2
在不同能量水平下,运用Logistic模型和Gompertz模型对朗德鹅0~10周龄生长曲线进行了分析和非线性曲线拟合研究。结果表明,不同生长阶段,朗德鹅公鹅、母鹅的适宜能量水平不同,Logistic模型和Gompertz模型都能很好地拟合朗德鹅的生长曲线,但Gompertz模型在拟合度和预测体重效果方面相对较好。中等能量水平下,2周龄前公鹅、母鹅的生长曲线基本一致,之后公鹅则明显高于母鹅,且保持较长时间的快速生长状态,公鹅的拐点体重显著高于母鹅,但拐点日龄的出现却晚于母鹅。 相似文献
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运用动物模型BLUP法时敖汉细毛羊的早期性状和产毛性状进行分析得出:模型(1)适合估计周岁重、断乳毛长度和断乳毛细度;模型(4)适合估计初生重和断乳重;模型(5)适合估计产毛量、体重和毛长度;模型(7)适合估计毛细度、毛弯曲分、毛密度分和毛油汗分. 相似文献
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It is costly and time‐consuming to carry out dairy cattle selection on a large experimental scale. For this reason, sire and cow evaluations are almost exclusively based on field data, which are highly affected by a large array of environmental factors. Therefore, it is crucial to adjust for those environmental effects in order to accurately estimate the genetic merits of sires and cows. Index selection is a simple extension of the ordinary least squares under the assumption that the fixed effects are assumed known without error. The mixed‐model equations (MME) of Henderson provide a simpler alternative to the generalized least squares procedure, which is computationally difficult to apply to large data sets. Solution to the MME yields the best linear unbiased estimator of the fixed effects and the best linear unbiased predictor (BLUP) of the random effects. In an animal breeding situation, the random effects such as sire or animal represent the animal's estimated breeding value, which provides a basis for selection decision. The BLUP procedure under sire model assumes random mating between sires and dams. The genetic evaluation procedure has progressed a long way from the dam‐daughter comparison method to animal model, from single trait to multiple trait analysis, and from lactational to test‐day model, to improve accuracy of evaluations. Multiple‐trait evaluation appears desirable because it takes into account the genetic and environmental variance‐covariance of all traits evaluated. For these reasons, multiple‐trait evaluation would reduce bias from selection and achieve a better accuracy of prediction as compared to single‐trait evaluation. The number of traits included in multiple‐trait evaluation should depend upon the breeding goal. Recent advances in molecular and reproductive technologies have created great potential for quantitative geneticists concerning genetic dissection of quantitative traits, and marker‐assisted genetic evaluation and selection. 相似文献