广义回归神经网络在凉山半细毛羊成年性状早期预测中的应用研究

通过凉山半细毛羊初生到断奶的5个生产性状:羔羊初生重、羔羊断奶重、初生至断奶日增重、断奶毛长度、断奶毛细度,预测成年(2.5年)的2个生产性状:成年体重、成年剪毛量。用Matlab7.1软件建立广义回归神经网络,并通过预测结果和实测结果的统计分析验证了所构建的广义回归神经网络的有效性。结果显示,该预测模型具有较高的准确性,可以快速高效地预测羔羊成年后的体重和剪毛量,为羔羊的选育和养殖场经济的预算提供依据。     

基于改进BP神经网络的凉山半细毛羊生产性状预测

为了对凉山半细毛羊生产性状进行预测,试验以遗传算法优化的BP神经网络建立预测模型,通过观测凉山半细毛羊从初生到断奶的5个早期性状(羔羊初生重、羔羊断奶重、初生～断奶日增重、断奶毛长度、断奶毛细度)对其2个成年生产性状(成年体重、成年剪毛量)进行预测。预测值与实测值的相关系数分别为0.878和0.889,说明该预测模型具有较高的准确性,且网络训练时间为39.53 s。与传统的BP神经网络相比,预测精度和训练时间都得到较大提高。     

基于广义回归神经网络的羊毛性状预测

凉山半细毛羊初生到断奶的5个生产性状（羔羊初生重、羔羊断奶重、初生-断奶日增重、断奶毛长度、断奶毛细度）预测成年羊毛（2．5年）的3个生产性状（成年剪毛量、成年毛长度、成年毛细度）,用Matlab6．5软件构建广义回归神经网络预测模型,并通过预测结果和实测结果的统计分析验证本研究所构建的广义回归神经网络预测模型的有效性。预测结果和实测结果的统计分析结果显示该预测模型具有较高的准确性,基于广义回归神经网络构建的预测模型在凉山半细毛羊成年羊毛3个性状上的预测被证明是有效的。     

季节差异对云上黑山羊羔羊生长发育及断奶成活率的影响分析

通过收集云南省种羊繁育推广中心相同饲养管理条件下2016—2018年饲养的云上黑山羊所产羔羊的数据,统计分析了春夏秋冬四个季节所产羔羊的初生重、断奶重、日增重和断奶成活率的差异.结果:①夏季产羔羊的初生重、断奶重、日增重均极显著高于秋季产羔羊的对应指标(P<0.01);冬季和春季所产羔羊的初生重、断奶重和日增重差异均不...     

影响云南黑山羊羔羊成活率的因素研究

为研究云南黑山羊羔羊成活率的影响因素,笔者对7121个有效羔羊数据进行了初生重、断奶重、成活率的统计分析。结果表明,随胎产羔数的增多羔羊初生重极显著减小(P0.01);随初生重的增大,羔羊成活率极显著提高(P0.01);随着胎产羔数的增加,羔羊成活率显著降低(P0.05)。云南黑山羊胎产羔羊数和羔羊初生重对羔羊成活率有显著影响且作用相反,实际生产中需注重产羔率和初生重的平衡。     

考力代单双羔母羊主要经济性状的差异性及相关性分析

本文根据大柳种羊场1988年126头母羊的周岁鉴定资料,分析了单双羔羊之间的差异性。结果表明,二者在初生重(x_1)、断奶重(x_3)、周岁体重(y_1)、周岁毛长(y_2)和周岁剪毛量(y_3)5个性状之间存在着显著差异;而断奶日龄的差异不显著。进而分析了上述性状之间的相关性,结果显示断奶重与周岁体重以及周岁剪毛量之间有显著相关,为生产实践中以断奶重作为早期选择的主要指标提供了理论基础。     

湖羊初生重性状影响因素分析及遗传力估计

【目的】研究旨在分析场、出生季节、出生月份、出生类型和性别对湖羊初生重性状的影响,并估计该性状的遗传力。【方法】运用SAS 9.2软件对2021年新疆地区3个规模化湖羊养殖企业共计4 570只母羊所产的8 352只羔羊初生重作非遗传因素分析,使用DMU软件对湖羊初生重性状进行方差组分估计,并使用两种单性状动物模型估计该性状的遗传力,根据赤池信息准则(Akaike’s information criterion, AIC)确定最佳固定效应组合和动物模型。【结果】场、出生季节、出生月份、出生类型和性别对湖羊的初生重均有极显著影响(P<0.01)。场1和场2羔羊初生重无显著差异(P>0.05),且均极显著大于场3羔羊的初生重(P<0.01);冬季出生的羔羊的初生重整体较大,其中以1月出生的羔羊初生重最大;出生类型越丰富,其羔羊初生重越小,各出生类型间羔羊初生重均呈现出极显著差异(P<0.01);根据单性状动物模型(考虑母体效应)的计算得出,湖羊初生重性状的直接、母体、总体遗传力分别为0.251、0.668、0.211,属于中等遗传力。【结论】在对羊场首年的生产数据分析...     

兴羔肉羊生长发育规律及遗传评估研究

[目的]探究兴羔肉羊的生长发育特征及遗传特性。[方法]对2018—2019年出生的1 054只兴羔肉羊羔羊的初生重、断奶重、6月龄体重、12月龄体重数据进行统计分析,并采集部分羊只6月龄、12月龄、24月龄的体高、体长及胸围数据。详细记录每只羔羊的出生类型及系谱档案,利用WOMBAT软件对其初生重、断奶重进行遗传评估。[结果]兴羔肉羊羔羊初生重和断奶重的遗传力分别为0.980和0.885,表型相关为0.321,遗传相关为0.396;6月龄时,公羊体重占成年体重的44.21%、母羊体重占成年体重的60.33%,公羊和母羊的体尺数据都达到成年体尺数据的80%以上。[结论]兴羔肉羊的初生重和断奶重具有高遗传力,且符合肉用品种羊早期生长发育快的遗传特性。     

中国美利奴羊（新疆型）繁殖性状的遗传参数估计

本研究旨在估计中国美利奴羊(新疆型)繁殖性状的遗传参数,为优化中国美利奴羊(新疆型)选育方案提供理论支撑。本研究收集了新疆巩乃斯种羊场2003—2017年的中国美利奴羊(新疆型)系谱信息及配种产羔记录8 033条。利用SAS 9.2的GLM过程分析群别、出生年份对4个繁殖性状(头胎妊娠天数、平均妊娠天数、头胎羔羊平均初生重、羔羊平均初生重)的影响,结果表明群别和出生年份对4个繁殖性状均有极显著影响;通过DMU软件对4个繁殖性状进行遗传参数估计,结果表明本研究中头胎妊娠天数(0.05±0.05)与平均妊娠天数(0.04±0.02)均属于低遗传力,羔羊平均初生重(0.11±0.02)属于中等遗传力,头胎羔羊平均初生重(0.38±0.05)属于高遗传力;平均妊娠天数和头胎妊娠天数之间的遗传相关为0.89,羔羊平均初生重与头胎羔羊平均初生重之间的遗传相关为0.53。研究结果发现,在中国美利奴羊(新疆型)育种、选育过程中不应忽视出生年份和群别的影响,在培育繁殖性能优良的细毛羊过程中应提高牧场管理水平及牧工操作技术。     

杜泊羊与湖羊杂交羔羊生长发育规律研究

为探究纯种羔羊与杂种羔羊生长发育规律,试验选择体质状况良好、发育正常的初生纯种杜泊羊羔羊、纯种湖羊羔羊和杜湖杂交羊羔羊各100只,对其体重和体尺性状进行测定,分析其生长发育特点。结果表明:杜泊羊羔羊体高的变异系数最大,湖羊和杜湖杂交羊羔羊体重的变异系数最大;除杜泊羊羔羊断奶重与体高呈负相关外,3个羔羊群羊只断奶重与体尺指标均呈正相关;不同品种羔羊初生重差异显著或极显著(P0. 05或P0. 01),随着羔羊的生长发育差距不断缩小,但杜泊羊与杜湖杂交羊之间均差异显著(P0. 05);不同品种羔羊体尺指标在各周龄的变化具有明显的差异,3个羔羊群羊只初生重与产羔数均呈负相关,且湖羊羔羊呈显著负相关(P0. 05)。说明3个羔羊群羊只有各自的生长发育规律且品种间存在差异,可以利用其生长发育规律和差异进行杂交改良。     

青海高原毛肉兼用半细毛羊经济性状遗传力估测

对青海省柴达木地区青海高原毛肉兼用半细毛羊9个主要经济性状进行了遗传力估测。结果表明,初生重、断奶重、周岁剪毛量、羊毛细度、毛长、剪毛前体重、剪毛量都是高遗传力性状,也是青海高原毛肉兼用半细毛羊育种过程中的主要选择依据;断奶重、周岁剪毛量、剪毛前体重与剪毛量之间呈强正遗传相关,断奶重可作为对剪毛量进行早期选择的参数;断奶重与羊毛细度之间呈负遗传相关。     

Estimates of genetic parameters and genetic change for reproduction,weight, and wool characteristics of Columbia sheep

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight and wool traits were estimated using REML with animal models for Columbia sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station (USSES), Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated using the parameters estimated from the single-trait and bivariate analyses were compared with respect to genetic trends. Number of observations were 31,401 for litter size at birth and litter size at weaning, 24,741 for birth weight, 23,903 for weaning weight, 29,572 for fleece weight and fleece grade, and 2,449 for staple length. Direct heritability estimates from single-trait analyses were 0.09 for litter size at birth, 0.06 for litter size at weaning, 0.27 for birth weight, 0.16 for weaning weight, 0.53 for fleece weight, 0.41 for fleece grade, and 0.55 for staple length. Estimate of direct genetic correlation between littersize at birth and weaning was 0.84 and between birth and weaning weights was 0.56. Estimate of genetic correlation between fleece weight and staple length was positive (0.55) but negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.70). Estimates of genetic correlations were positive but small between birth weight and litter size traits and moderate and positive between weaning weight and litter size traits. Fleece weight was lowly and negatively correlated with both litter size traits. Fleece grade was lowly and positively correlated with both litter size traits, while staple length was lowly and negatively correlated with the litter size traits. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small. Estimates of correlations between staple length and birth weight (0.05) and weaning weight were small (-0.04). Estimated breeding values averaged by year of birth from both the single-trait and multiple-trait analyses for the prolificacy and weight traits increased over time, but were unchanged for the wool traits. Estimated changes in breeding values over time did not differ substantially for single-trait and multiple-trait analyses, except for traits highly correlated with another trait that was responding to selection.     

Estimates of genetic parameters and genetic change for reproduction,weight, and wool characteristics of Targhee sheep

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight, and wool traits were estimated using REML with animal models for Targhee sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station, Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated with the parameters estimated from the single-trait and bivariate analyses were compared across years of birth with respect to genetic trends. The numbers of observations were 38,625 for litter size at birth and litter size at weaning, 33,994 for birth weight, 32,715 for weaning weight, 36,807 for fleece weight and fleece grade, and 3,341 for staple length. Direct heritability estimates from single-trait analyses were 0.10 for litter size at birth, 0.07 for litter size at weaning, 0.25 for birth weight, 0.22 for weaning weight, 0.54 for fleece weight, 0.41 for fleece grade, and 0.65 for staple length. Estimate of direct genetic correlation between litter size at birth and weaning was 0.77 and between birth and weaning weights was 0.52. The estimate of genetic correlation between fleece weight and staple length was positive (0.54), but was negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.69). Estimates of genetic correlations were near zero between birth weight and litter size traits and small and positive between weaning weight and litter size traits. Fleece weight was slightly and negatively correlated with both litter size traits. Fleece grade was slightly and positively correlated with both litter size traits. Estimates of correlations between staple length and litter size at birth (-0.14) and litter size at weaning (0.05) were small. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small, whereas estimates between weight traits and staple length were positive and small. Estimated breeding values averaged by year of birth from both the single- and seven-trait analyses for the prolificacy and weight traits increased over time, whereas those for fleece weight decreased slightly and those for the other wool traits were unchanged. Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection.     

凉山半细毛羊新品种的选育技术与经验

凉山半细毛羊新品种的育成,是采用表型选择和基因型选择相结合产生的结果。在初生期、断奶期、育成期和成年期采取表型鉴定、逐步选择淘汰的制度。根据羔羊断奶期性状与育成期性状之间的显著相关性对羔羊单性状进行早期选择。应用同期发情与后裔测验相结合的方法,对种公羊基因型值用BLUP法进行选择。同时,加强育种工作的组织领导,组建独具特色的三级繁育体系,改善育种羊群的饲养管理条件,圆满完成了国家下达的半细毛羊新品种选育的任务,填补了国内粗档半细毛羊品种的空白。     

基于概率神经网络的凉山半细毛羊评价研究

根据凉山半细毛羊标准,通过MATLAB随机函数rand内插生成10个包含不同内插值数量的训练数据集,从中选取最优训练数据集用于构建4个概率神经网络。结果表明:网络分级与标准分级的回归分析相关系数(R)分别为0.9995、0.9996、0.9987和0.9960。进一步通过凉山半细毛羊样本数据对网络进行可靠性验证,分级的准确率达100%。说明以最优的训练数据集所构建的凉山半细毛羊概率神经网络评价分级模型准确可行。     

Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheep

Genetic parameters for Columbia, Polypay, Rambouillet, and Targhee sheep were estimated using REML with animal models for prolificacy, weight, and wool traits. All bivariate analyses included a covariance between additive genetic effects for the two traits plus appropriate additional covariances. Number of observations by breed ranged from 5,140 to 7,095 for prolificacy traits, from 7,750 to 9,530 for weight traits, and from 4,603 to 34,746 for wool traits. Heritability estimates ranged from .03 to .11 for prolificacy traits (litter size at birth and litter size at weaning), from .09 to .26 for weight traits (birth weight and average daily gain), and from .25 to .53 for wool traits (fleece weight, fleece grade and staple length). Estimates of direct genetic correlations among prolificacy and among weight traits were positive and ranged from .58 to 1.00 and .18 to 1.00, respectively. Estimates of direct genetic correlation between fleece weight and staple length were positive (.50 to .70) but were negative between fleece weight and fleece grade (-.60 to -.34) and between staple length and fleece grade (-.72 and -.40). Prolificacy and wool traits were essentially uncorrelated. Weight and prolificacy traits were slightly positively correlated. Weight traits had a moderate positive direct genetic correlation with fleece weight and staple length, but were uncorrelated with fleece grade. These estimates of genetic parameters between prolificacy, weight, and wool traits can be used to construct multiple-trait selection indexes for dual-purpose sheep.     

新疆细毛羊与澳州美利奴杂交的杂交优势

利用19只公羊和5群母羊来测定初生、断奶和周岁时的杂交优势水平。公羊的基因型包括:纯种新疆细毛羊(XX)、纯种澳州美利奴(AA)和它们的一代杂种(F_1):母羊的基因型只有两个,即(XX)和(F_1)。试验于1987—1989年在新疆维吾尔自治区南山种羊场进行,试验设计了一个不同基因型之间的随机交配,以便估计性状的遗传参数和杂交优势水平。 用计算机分析了552个后代的记录。初生重、断奶重、周岁体重、断奶毛长、周岁毛长和周岁剪毛量的杂交优势分别是4.0％、2％、11.55％、0.4％、6.05％和3.49％。生长发育性状的杂交优势水平明显地高于羊毛生长性状的杂交优势水平。