母体遗传效应对青海细毛羊生产性能遗传参数估计的影响

为了研究母体遗传效应对青海细毛羊生长性状、产毛性状的影响, 文章采用平均信息最大约束似然法应用不同混合动物模型估计青海细毛羊生产性状的遗传参数, 并采用似然比检验对不同模型进行比较分析。各模型中均包括固定效应、个体直接加性遗传效应、残差效应; 随机效应为：个体永久环境效应、母体遗传效应、母体永久环境效应。不同模型对随机效应作了不同考虑：模型1不考虑个体永久环境效应、母体遗传效应、母体永久环境效应; 模型2考虑母体永久环境效应; 模型3考虑母体遗传效应; 模型4考虑母体遗传效应和母体永久环境效应; 模型5考虑个体永久环境效应和母体遗传效应; 模型6考虑个体永久环境效应、母体遗传效应、母体永久环境效应。各模型估计的初生重遗传力为：0.1896~0.3781; 断奶重遗传力为：0.2537~0.2890; 周岁重遗传力范围：0.2244~0.3225; 成年羊体重遗传力范围：0.2205~0.3983; 产毛量遗传力为：0.1218~0.1490; 羊毛细度遗传力为：0.0983~0.4802; 羊毛长度遗传力为：0.1170~0.1311。与模型1相比, 模型3对于初生重、断奶重差异显著(P<0.01), 对于周岁重、成年羊体重各模型与模型1的似然比检验差异不显著(P>0.05); 与模型6相比, 模型4、5对于羊毛细度差异显著(P<0.01), 模型4对羊毛长度差异显著(P<0.05), 对于产毛量各模型与模型6似然比检验差异不显著(P>0.05)。生长性状中初生重、断奶重受母体遗传效应影响显著, 周岁重、成年羊体重受母体遗传效应影响不显著; 产毛性状中羊毛细度、长度受母体遗传效应影响显著, 产毛量受母体遗传效应影响较弱。     

用不同模型估计绒山羊早期生长性状遗传参数的比较

利用内蒙古伊盟阿尔巴斯白绒山羊种羊场从1993年至2000年间白绒山羊的早期生长性状(包括出生重、断乳重、日增重和周岁重)的场内测定数据,对4种不同动物模型估计遗传参数的差异进行了比较分析。不同模型中对母体遗传效应和母体环境效应作了不同的考虑：模型I,不考虑母体遗传效应和母体环境效应;模型Ⅱ,仅考虑母体遗传效应;模型Ⅲ,仅考虑母体环境效应;模型Ⅳ,同时考虑母体遗传效应和母体环境效应。利用MTD-FREML程序采用非求导约束最大似然法(DFREML)估计各模型中的方差组分,用似然比检验对不同模型的差异进行检验。结果表明：对于出生重,母体遗传效应和母体环境效应都有极显著的影响,应采用模型Ⅳ进行分析;对于断乳重和日增重,母体遗传效应的影响不显著,而母体环境效应的影响极显著,应采用模型Ⅲ进行分析;对于周岁重,母体环境效应的影响不显著,而母体遗传效应的影响显著,应采用模型Ⅱ进行分析。     

母体遗传效应对绒山羊生产性状遗传参数估计的影响

利用非求导约束最大似然法(DF-REML), 比较了内蒙古白绒山羊在两种不同动物模型下估计遗传参数的差异, 两种模型的区别在于是否考虑母体遗传效应。对两种模型的差异用似然比进行检验。结果表明, 母体遗传效应对于体重和绒厚影响极显著(P<0.01), 对于抓绒量、毛长、绒长度以及绒细度影响不显著(P>0.05)。     

影响山西肉用绵羊母本品系生长性状的非遗传因素分析

为研究非遗传因素对山西肉用绵羊母本品系的初生重、断奶重(100日龄)、6月龄重和周岁重的影响,收集了山西肉用绵羊母本品系育种记录.利用SPSS 19.0的GLM过程分析性别、出生年份、出生月份、母亲年龄、出生类型对山西肉用绵羊母本品系生长性状的的影响.结果表明:性别仅对6月龄重有极显著影响(P＜0.01),对初生重、断奶重、周岁重影响显著(P＜0.05);出生年份对初生重和断奶重有极显著影响(P＜0.01),对6月龄重和周岁重影响显著(P＜0.05);出生月份对6月龄重有极显著影响(P＜0.01),对初生重、断奶重和周岁重无影响(P＞0.05);母亲年龄对初生重影响显著(P＜0.05),对6月龄重影响极显著(P＜0.01),而对断奶重和周岁重无影响(P＞0.05);出生类型对6月龄重有显著影响(P＜0.05),对初生重和断奶重有极显著影响(P＜0.01).本分析结果对山西肉用绵羊母本品系的进一步选育和生产具有重要参考价值.     

母猪繁殖力性状影响因素分析及遗传参数估计

母猪繁殖力是影响种猪场经济效益的重要因素。文章对纯种大白猪、长白猪、杜洛克猪的8491窝产仔记录进行统计分析,建立固定效应模型对总产仔数、健仔数、初生窝重、弱仔数、死胎数、木乃伊胎数和畸形胎数共7个繁殖性状进行最小二乘分析,分析胎次、配种季节、品种对母猪繁殖性能的影响,同时比较了纯繁和杂交的效果。利用动物模型REML(约束最大似然)方法估计繁殖性状的遗传力和遗传相关。结果表明,胎次、配种季节和品种对总产仔数、健仔数、初生窝重影响极显著(P<0.001),胎次和品种对弱仔数影响极显著(P<0.001),但配种季节对弱仔数影响不显著。胎次对死胎数影响显著(P<0.05),而配种季节和品种对死胎数影响不显著,胎次、配种季节和品种对木乃伊胎、畸形胎数影响不显著。长白♂×大白♀交配组合具有最高的总产仔数、健仔数和初生窝重。繁殖性状遗传力估计结果显示,长白猪初生窝重的遗传力最高,为0.227。其余性状遗传力均在0.2以下,为低遗传力性状。3个品种母猪的健仔数与初生窝重、总产仔数与健仔数之间的遗传相关达0.96以上。研究结果为降低非传染性因素造成的种母猪产仔数低的问题以及种猪场对母猪繁殖力的选育提高提供了参考数据和理论依据。     

母猪繁殖力性状影响因素分析及遗传参数估计

母猪繁殖力是影响种猪场经济效益的重要因素。文章对纯种大白猪、长白猪、杜洛克猪的8491窝产仔记录进行统计分析, 建立固定效应模型对总产仔数、健仔数、初生窝重、弱仔数、死胎数、木乃伊胎数和畸形胎数共7个繁殖性状进行最小二乘分析, 分析胎次、配种季节、品种对母猪繁殖性能的影响, 同时比较了纯繁和杂交的效果。利用动物模型REML(约束最大似然)方法估计繁殖性状的遗传力和遗传相关。结果表明, 胎次、配种季节和品种对总产仔数、健仔数、初生窝重影响极显著(P<0.001), 胎次和品种对弱仔数影响极显著(P<0.001), 但配种季节对弱仔数影响不显著。胎次对死胎数影响显著(P<0.05), 而配种季节和品种对死胎数影响不显著, 胎次、配种季节和品种对木乃伊胎、畸形胎数影响不显著。长白♂×大白♀交配组合具有最高的总产仔数、健仔数和初生窝重。繁殖性状遗传力估计结果显示, 长白猪初生窝重的遗传力最高, 为0.227。其余性状遗传力均在0.2以下, 为低遗传力性状。3个品种母猪的健仔数与初生窝重、总产仔数与健仔数之间的遗传相关达0.96以上。研究结果为降低非传染性因素造成的种母猪产仔数低的问题以及种猪场对母猪繁殖力的选育提高提供了参考数据和理论依据。     

基于多性状模型内蒙古绒山羊早期生长性状基因组预测准确性研究

内蒙古绒山羊是经过长期自然选择和人工选育后形成的优良家畜品种,是目前世界一流的绒肉兼用山羊。多性状动物模型被认为可以显著提高畜禽遗传评估的准确性,实现性状间的间接选择。本文基于内蒙古绒山羊个体的系谱、基因型、环境以及早期生长性状的表型记录,建立多性状动物模型,利用ABLUP、GBLUP、ssGBLUP三种方法进行早期生长性状(初生重、断乳重、断乳前平均日增重、周岁重)遗传参数及基因组育种值的估计,进一步利用五倍交叉验证方法评价基因组育种值估计准确性和可靠性。结果显示,3种方法估计的初生重遗传力为0.13～0.15,断乳重遗传力为0.13～0.20,日增重遗传力为0.11～0.14,周岁重遗传力为0.09～0.14,均属于中等偏低遗传力;断乳重和日增重、日增重和周岁重之间存在强的正遗传相关,相关系数分别为0.77～0.79和0.56～0.67,表型相关发现同样的规律;ABLUP、GBLUP和ssGBLUP法估计的初生重育种值准确性分别为0.5047、0.6694、0.7156,断乳重分别为0.6207、0.6456、0.7254;日增重分别为0.6110、0.6855、0.7357,周岁...     

粳稻品质性状间及其与植株性状和产量性状间的遗传相关

利用朱军等提出的种子性状遗传模型,采用 3×3 NCⅡ正反交设计的亲本和部分组合F2代种子,分析了品质性状糙米率、垩白粒率、垩白面积和AC间及上述品质性状与株高、穗部性状等的遗传相关,以期为粳稻育种后代选择提供指导。结果表明,精米重与糙米率存在极显著的母体加性相关;虽然控制品质性状的主要遗传效应分量与植株性状相应遗传效应分量遗传协方差不显著,但在其他相应遗传效应分量方面存在着复杂的关系。     

云南香型软米水稻资源农艺性状遗传效应研究

选取5份云南地方香型软米水稻种质资源和6份自育香型软米保持系按5×6不完全双列杂交设计(NCⅡ)配制成30个组合,采用加性-显性-上位性遗传模型,分析云南香型软米11个农艺性状的遗传效应。结果表明,云南香型软米多数农艺性状的遗传主要受加×加上位性效应、加性×环境效应、显性×环境效应的影响,还存在不同程度的加性效应和显性效应,单株产量受基因加性效应、显性效应、加×加上位性效应、加性×环境效应、显性×环境效应的影响;株高、有效穗的遗传率以普通狭义遗传率为主,其他性状的普通狭义遗传率和互作狭义遗传率均达极显著水平;产量构成性状之间存在不同类型和不同程度的遗传相关,多数性状之间以加×加上位性、加性×环境和显性×环境互作效应显著。     

猪IGF2基因外显子4b的遗传多态性及其遗传效应

采用PCR-SSCP方法检测猪胰岛素样生长因子2(insulin-like growth factor 2,IGF2)基因外显子4b的多态性,并分析其对初生重、断奶重、6月龄重和背膘厚的遗传效应。根据猪IGF2基因的DNA序列(AY044828)设计引物,在exon4b上发现了一个多态性位点,并对纯合子进行测序,发现13位C→A转换,且存在3种基因型(AA、AB、BB)。统计结果表明,3种基因型在各品种中的分布不一致,长白猪与大白猪比较,莱芜猪与大薄莲猪比较,沂蒙黑猪和里岔黑猪比较差异不显著(P>0.05);其他猪种间基因型分布的差异均显著(P<0.05)。固定效应模型分析结果表明,初生重,断奶重和背膘厚基因型间差异显著(P<0.05),而6月龄重基因型间差异不显著(P>0.05)。最小二乘分析结果表明,BB基因型个体同AA和AB、基因型个体比较初生重和断奶重的差异显著(P<0.05),3种基因型在初生重和断奶重的大小排列顺序为AA>AB>BB;AA基因型个体同AB和BB基因型个体比较背膘厚的差异显著(P<0.05),3种基因型在背膘厚的大小排列顺序为BB>AB>AA。因此,推测IGF2基因对个体的生长速度和胴体瘦肉率存在一定的影响,将IGF2基因应用于猪育种过程中的标记辅助选择可以加快猪的育种进程。     

Estimation of genetic parameters for post-weaning traits of Kermani sheep

The objective of the present study was to estimate genetic parameters for post-weaning traits in Kermani sheep. Traits were included 6-month weight (6MW), 9-month weight (9MW), yearling weight (YW), greasy fleece weight at first shearing (GFW) and greasy fleece weights at various shearings (RFW). Data and pedigree information used in this research were collected at Breeding Station of Kermani sheep during 1993–2004. Genetic parameters were estimated with single- and multi-traits analysis using restricted maximum likelihood (REML) procedures, under animal models. Log likelihood ratio test indicated the most appropriate model for 6MW and 9MW should included direct additive genetic effects as well as maternal permanent environmental effects. However the most appropriate model for YW and GFW had only the direct additive genetic effects. The effects of sex, age of dam and year of birth were significant on body weight traits (P < 0.01). GFW was influenced significantly by sex and year of birth (P < 0.01) but was not affected by age of dam (P > 0.05). Type of birth was no significant effect on studied traits (P > 0.05). Also, the age of lamb at weighing time was a significant influence on 6MW, 9MW and YW. Direct heritability estimates for 6MW, 9MW, YW and GFW were 0.32, 0.03, 0.15 and 0.15, respectively. Maternal permanent environmental estimates of 0.09 were obtained for 6MW and 9MW. Genetic correlation estimates between mentioned traits ranged from 0.51 to 0.99. Phenotypic correlations were generally lower than those of genetic correlation and varied from 0.05 to 0.79 for various traits. The environmental correlations estimates between GFW with growth traits were low, but between other traits were positive and high, ranged from 0.54 to 0.72. The value of repeatability estimated for greasy fleece weight was 0.22.     

Estimation of genetic parameters for post-weaning traits of Kermani sheep

The objective of the present study was to estimate genetic parameters for post-weaning traits in Kermani sheep. Traits were included 6-month weight (6MW), 9-month weight (9MW), yearling weight (YW), greasy fleece weight at first shearing (GFW) and greasy fleece weights at various shearings (RFW). Data and pedigree information used in this research were collected at Breeding Station of Kermani sheep during 1993–2004. Genetic parameters were estimated with single- and multi-traits analysis using restricted maximum likelihood (REML) procedures, under animal models. Log likelihood ratio test indicated the most appropriate model for 6MW and 9MW should included direct additive genetic effects as well as maternal permanent environmental effects. However the most appropriate model for YW and GFW had only the direct additive genetic effects. The effects of sex, age of dam and year of birth were significant on body weight traits (P < 0.01). GFW was influenced significantly by sex and year of birth (P < 0.01) but was not affected by age of dam (P > 0.05). Type of birth was no significant effect on studied traits (P > 0.05). Also, the age of lamb at weighing time was a significant influence on 6MW, 9MW and YW. Direct heritability estimates for 6MW, 9MW, YW and GFW were 0.32, 0.03, 0.15 and 0.15, respectively. Maternal permanent environmental estimates of 0.09 were obtained for 6MW and 9MW. Genetic correlation estimates between mentioned traits ranged from 0.51 to 0.99. Phenotypic correlations were generally lower than those of genetic correlation and varied from 0.05 to 0.79 for various traits. The environmental correlations estimates between GFW with growth traits were low, but between other traits were positive and high, ranged from 0.54 to 0.72. The value of repeatability estimated for greasy fleece weight was 0.22.     

(Co)Variance components and genetic parameter estimates for growth traits in Moghani sheep

Genetic parameters were estimated for birth weight (BW), weaning weight (WW), yearling weight (YW), average daily gain from birth to weaning (ADG1) and average daily gain from weaning to yearling (ADG2) in Moghani sheep. Maximum number of data was 4237 at birth, but only 1389 records at yearling were investigated. The data was collected from 1995 to 2007 at the Breeding Station of Moghani sheep in Jafarabad, Moghan, Iran. (Co)Variance components and genetic parameters were estimated with different models which including direct effects, with and without maternal additive genetic effects as well as maternal permanent environmental effects using restricted maximum likelihood (REML) method. The most appropriate model for each trait was determined based on likelihood ratio tests and Akaike's Information Criterion (AIC). Maternal effects were important only for pre-weaning traits. Direct heritability estimates for BW, ADG1, WW, ADG2 and YW were 0.07, 0.08, 0.09, 0.09 and 0.17, respectively. Fractions of variance due to maternal permanent environmental effects on phenotypic variance were 0.08 for ADG1. Maternal heritability estimates for BW and WW were 0.18 and 0.06, respectively. Multivariate analysis was performed using the most appropriate models obtained in univariate analysis. Direct genetic correlations among studied traits were positive and ranged from 0.37 for BW–ADG2 to 0.85 for ADG1–YW. Maternal genetic correlation estimate between BW and WW was 0.33. Phenotypic and environmental correlation estimates were generally lower than those of genetic correlation. Low direct heritability estimates imply that mass selection for these traits results in slow genetic gain.     

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Bharat Merino sheep

(Co)variance components and genetic parameters of weight at birth (BWT), weaning (3WT), 6, 9 and 12 months of age (6WT, 9WT and 12WT, respectively) and first greasy fleece weight (GFW) of Bharat Merino sheep, maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. Data were collected over a period of 10 years (1998 to 2007). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for BWT, 3WT, 6WT, 9WT and 12WT and first GFW were 0.05 ± 0.03, 0.04 ± 0.02, 0.00, 0.03 ± 0.03, 0.09 ± 0.05 and 0.05 ± 0.03, respectively. There was no evidence for the maternal genetic effect on the traits under study. Maternal permanent environmental effect contributed 19% for BWT and 6% to 11% from 3WT to 9WT and 11% for first GFW. Maternal permanent environmental effect on the post-3WT was a carryover effect of maternal influences during pre-weaning age. A low rate of genetic progress seems possible in the flock through selection. Direct genetic correlations between body weight traits were positive and ranged from 0.36 between BWT and 6WT to 0.94 between 3WT and 6WT and between 6WT and 12WT. Genetic correlations of 3WT with 6WT, 9WT and 12WT were high and positive (0.94, 0.93 and 0.93, respectively), suggesting that genetic gain in post-3WT will be maintained if selection age is reduced to 3 months. The genetic correlations of GFW with live weights were 0.01, 0.16, 0.18, 0.40 and 0.32 for BWT, 3WT, 6WT, 9WT and 12WT, respectively. Correlations of permanent environmental effects of the dam across different traits were high and positive for all the traits (0.45 to 0.98).     

Estimation of genetic parameters and variance components for growth traits in Romosinuano cattle in the Colombian humid tropics

(Co)variance components and genetic parameters were estimated for body weights of a Romosinuano herd located in Sinú Valley, Cordoba, Colombia. Restricted maximum likelihood methods were used with a univariate animal model for birth weight, weaning weight (270 days), 16-month weight (480 days), weaning daily gain, and post-weaning daily gain. Models included random animal direct and maternal genetic effects, maternal permanent environmental effect (c2), and sex-year-month of birth and age of dam, as fixed effects. Estimates of direct effect for birth weight, weaning weight, 480-day weight, weaning daily gain, and post-weaning daily gain were: 0.25 +/- 0.0001, 0.34 +/- 0.063, 0.33 +/- 0.066, 0.32 +/- 0.062, and 0.17 +/- 0.052, respectively. Estimates of direct maternal genetic effects were low and ranged from 0.06 +/- 0.003 for birth weight to 0.20 +/- 0.054 for weaning daily gain. The genetic correlations between direct and maternal genetic effects were negative and low for 480-day weight (-0.05 +/- 0.219) and showed values of -0.37 +/- 0.007, -0.34 +/- 0.133, -0.33 +/- 0.135, and -0.38 +/- 0.232 for birth, weaning weight, weaning, and post-weaning daily gain, respectively. Permanent environmental maternal effects were not significant; the highest values were found for weaning weight, and weaning daily gain (0.086 +/- 0.031 and 0.078 +/- 0.031, respectively). We conclude that direct and maternal effects should be included in a selection program for all of these traits, and also that selection of weaning weights would be the most productive way to improve performance in Romosinuano cattle.     

Estimates of (co)variance components due to direct and maternal effects for body weights in Jamunapari goats

Estimates of (co)variance components were obtained for weights at birth, weaning and at 6, 9 and 12 months of age in Jamunapari goats maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, over a period of 23 years (1982 to 2004). Records of 4301 kids descended from 204 sires and 1233 does were used in the study. Analyses were carried out by restricted maximum likelihood (REML), fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits. The best model was chosen after testing the improvement of the log-likelihood values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Heritability estimates for weights at birth, weaning and at 6, 9 and 12 months of age were 0.12, 0.18, 0.13, 0.17 and 0.21, respectively. Maternal heritability of body weight declined from 0.19 at birth to 0.08 at weaning and was near zero and not significant thereafter. Estimates of the fraction of variance due to maternal permanent environmental effects were 0.09, 0.13 and 0.10 for body weights at weaning, 6 months and 9 months of age, respectively. Results suggest that maternal additive effects were important only in the early stages of growth, whereas a permanent environmental maternal effect existed from weaning to 9 months of age. These results indicate that modest rates of genetic progress appear possible for all weights.     

The Norwegian sheep breeding scheme: description, genetic and phenotypic change

The developments in Norwegian sheep breeding since the early 1990s are reviewed. For the largest breeding population, the Norwegian White Sheep, results are presented for both genetic and phenotypic changes. Of the nine traits that make up the aggregate genotype, the largest gain per year, in per cent of the corresponding phenotypic average, was found for carcass grade (1.66%) and carcass weight (0.99%), number of lambs born at 1, 2 and 3 years of age (0.32% to 0.60%) and the maternal effect on weaning weight (0.26%). For fat grade, a genetic deterioration was estimated. This may be due to the too small weighting of this trait in the aggregate genotype and the true genetic parameters being somewhat different from the estimates in the prediction of breeding values. For lamb as well as ewe fleece weight, genetic change was close to zero - interpreted as mainly a correlated response to other traits in the aggregate genotype. Data for the two traits of fleece weight were, respectively, selected and few. Thus, phenotypic change was calculated for all traits except for fleece weight, and in addition for number of lambs at weaning, being indirectly selected for through number of lambs born. For all traits, with the exception of fat grade, advantageous phenotypic change was estimated. For weaning and carcass weight, the phenotypic change was less than the genetic change, while the opposite was observed for carcass and fat grade and number of lambs born. The latter traits can be more easily controlled by environmental actions, and the results thus exemplify the interdependency between environmental and genetic change.     

Bayesian inference in genetic parameter estimation of visual scores in Nellore beef-cattle

The aim of this study was to estimate the components of variance and genetic parameters for the visual scores which constitute the Morphological Evaluation System (MES), such as body structure (S), precocity (P) and musculature (M) in Nellore beef-cattle at the weaning and yearling stages, by using threshold Bayesian models. The information used for this was gleaned from visual scores of 5,407 animals evaluated at the weaning and 2,649 at the yearling stages. The genetic parameters for visual score traits were estimated through two-trait analysis, using the threshold animal model, with Bayesian statistics methodology and MTGSAM (Multiple Trait Gibbs Sampler for Animal Models) threshold software. Heritability estimates for S, P and M were 0.68, 0.65 and 0.62 (at weaning) and 0.44, 0.38 and 0.32 (at the yearling stage), respectively. Heritability estimates for S, P and M were found to be high, and so it is expected that these traits should respond favorably to direct selection. The visual scores evaluated at the weaning and yearling stages might be used in the composition of new selection indexes, as they presented sufficient genetic variability to promote genetic progress in such morphological traits.     

Estimates of genetic parameters and genetic trends for live weight and fleece traits in Menz sheep

Menz sheep are indigenous to the highlands of Ethiopia, and highly valued for their meat and wool production. The area is characterized as a low input mixed barley-sheep production system. In 1998, a selection experiment was set up to evaluate the response of Menz sheep to selection for yearling live weight (WT12) and greasy fleece weight (GFW) combined in an economic index. In this paper, we report the results of this breeding program obtained between 1998 and 2003. Average annual genetic selection responses for WT12 and GFW were 1.506 and 0.043 kg in the selected flock and 0.392 and −0.008 kg in the control flock. Annual genetic trends in the selected flock, estimated by regressing BLUP estimated breeding values on year of birth, were 0.495 ± 0.053 kg for WT12, 0.012 ± 0.002 kg for GFW, and Birr 5.53 ± 0.55 for the aggregate breeding value (1 Ethiopian Birr = 0.115 USD). Corresponding values for the control flock were 0.276 ± 0.065 kg, 0.003 ± 0.002 kg and Birr 2.93 ± 0.69. Correlated responses in birth weight (WT0), weaning weight (WT3), 6-month weight (WT6) and staple length (STPL) in the selected flock were 0.038 ± 0.005 kg, 0.271 ± 0.03 kg, 0.388 ± 0.039 kg and 0.011 ± 0.017 cm, respectively. Heritabilities, estimated by fitting a multitrait individual animal model were 0.464 ± 0.014, 0.477 ± 0.016, 0.514 ± 0.017, 0.559 ± 0.019, 0.393 ± 0.016 and 0.339 ± 0.014 for WT0, WT3, WT6, WT12, GFW and staple length (STPL), respectively. Phenotypic and genetic correlations between all traits were positive, except for STPL and WT12. Estimates of genetic parameters and observed genetic trends confirm that selective breeding can lead to significant genetic improvement in Menz sheep.