Genetic markers for the production of US country hams

The objective of this study was to determine the effect of candidate genes on processing quality traits of US country hams. A total of 321 fresh hams of unknown breed and sex were examined and data on quality and physical traits were collected. The hams were then processed following typical US commercial dry-curing procedures for ham and data on additional traits were collected from the cured hams. Several genes involved in biological processes affecting dry-cured ham production were selected. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) tests were designed for each of the genes where polymorphisms were discovered and association analyses between each marker and the traits collected were performed. Results showed that two genetic markers were significantly associated with cured weight and yield: (i) a gene from the cathepsin family (cathepsin F) and (ii) the stearoyl-CoA desaturase (delta-9-desaturase) gene, involved in lipid metabolism. Moreover, markers that significantly affected colour traits and those having a significant impact on pH and lipid percentage were also identified. These markers could be used for screening and sorting of carcasses prior to ham processing and, eventually in pig improvement programmes designed to select animals possessing genotypes more suitable for the production of dry-cured hams.     

郏县红牛TAFA1基因多态性及其与生长性状的关联分析

本研究旨在探讨TAFA趋化素样家族成员1（TAFA1）基因多态性与郏县红牛生长的关联性。试验共采集了79头郏县红牛成年母牛的血样并提取基因组DNA,利用直接测序法对TAFA1基因上的错义突变SNP rs137516577进行基因型分型,并与郏县红牛体高、体长、胸围、腰角宽、坐骨端宽、尻长、十字部高、荐高、胸深、胸宽、体重等11个生长和体尺性状进行关联分析。同时根据“Animal Omics Datebase”数据库对TAFA1基因的组织表达情况进行分析。结果发现该SNP与体长、腰角宽、坐骨端宽、尻长和体重等性状显著相关（P<0.05）,且GC型个体体长、腰角宽、坐骨端宽、尻长和体重均显著高于GG型（P<0.05）。TAFA1基因在牛大脑组织中表达量最高。结果表明,TAFA1基因上错义突变SNP rs137516577与郏县红牛生长性状相关,可作为郏县红牛生长性状的分子标记。     

Genetic parameters and single versus multi-trait evaluation of udder health traits

Abstract

Genetic parameters were estimated for lactation average somatic cell score (SCS) and clinical mastitis (CM) for the first three lactations of multiparous Finnish Ayrshire cows. A multi-trait linear sire model was used for estimation of covariance components, and the efficiencies of single- versus multi-trait multi-lactation (MT) sire evaluations were compared. Heritability of SCS and CM in the first three lactations ranged from 0.11 to 0.13 and 0.02 to 0.03, respectively. Within lactation, genetic correlations between SCS and CM ranged from 0.68 to 0.72. Within both traits, across-lactation genetic correlations were lowest between 1 and 3, and highest between 2 and 3, with estimates ranging from 0.75 to 0.86 and from 0.81 to 0.98 for CM and SCS, respectively. Residual and phenotypic correlations were low and ranged from 0.09 to 0.13 and from 0.10 to 0.13, respectively. The absolute difference between genetic and residual correlations was from 0.5 to 0.6. Within-lactation genetic correlations between traits that are much less than unity suggest a multi-trait model for genetic evaluation of mastitis resistance. Comparison of model prediction performance between single-trait (ST) and MT models using a data splitting method showed that the MT model was more stable in predicting breeding values in future records of animals. Especially, for young sires and CM, the SD of EBVs from the MT model was 14 to 23% higher than the ST model, indicating more effective use of information in terms of revealing more genetic variation.     

基于全基因组SNP分析8个地方鸡品种的遗传多样性

为揭示江西及周边地区地方鸡的遗传多样性信息,本研究采集了江西省5个地方鸡品种,广东省、浙江省以及江苏省各1个地方鸡品种共125个血样,利用全基因组SNP芯片分析地方鸡品种的群体结构、网络关系及系统进化情况.结果 表明,8个地方鸡品种45647个位点的多态信息含量大多为0.25＜PIC＜0.5,属于中度多态,表明这8个地...     

Gender differences for growth in North American Atlantic salmon

An assumption in aquaculture of Atlantic salmon is that male and female growth within families is perfectly genetically correlated. That is, families would rank identically if based on male growth only or female growth only. Also, growth in freshwater and sea water is assumed to be highly correlated between males and females within families. However, structural analysis of the DNA of Atlantic salmon has found that the linkage maps of females differ significantly from that of males. Genetic variability for any trait measured on females could be greater or lesser than on males. Thus, male and female growth might be considered as separate traits giving rise to families ranking differently depending on gender. A multiple trait family model for weight and length at 3 years of age in Atlantic salmon according to gender was applied to data on North American Atlantic salmon obtained from the Oak Bay Hatchery in New Brunswick, Canada. Genetic correlations between male and female growth in both freshwater and sea water were estimated by Bayesian methods. The estimates support the possible existence of gender dimorphism in North American Atlantic salmon for growth traits.     

Genetic correlations between male reproductive traits and growth traits in growth performance tested Duroc,Landrace and Yorkshire breed boars

Male‐related traits at 180–225 days of age for 6464 grow‐finish performance tested boars were measured from 2000 to 2016. Heritability estimates and genetic correlations among average daily gain, feed efficiency, back fat thickness, teat counts, mounting libido, leg locomotion, penile length, sperm motility, sperm concentration and total sperm counts were estimated by VCE software using a multiple traits animal model in each breed. Growth‐tested boars had heritability estimates of male reproductive traits in 0.34–0.56 of teat counts, 0.12–0.20 of libido, 0.08–0.12 of locomotion, 0.17–0.58 of penile length, 0.04–0.21 of sperm motility and concentration, 0.17–0.30 of total sperm counts. Total sperm counts were genetically positively correlated with penile length in all breeds. Boars with higher total sperm counts had genetically better libido and locomotion. Genetic correlation between feed efficiency and sperm motility and feed efficiency and sperm concentration were positive in Duroc and negative in Landrace and Yorkshire. Sperm motility and concentration were genetically negatively correlated with average daily gain in Yorkshire. Male reproductive traits of imported breeds could be improved with care in the change of growth traits, especially in Yorkshire.     

基于SNP芯片分析青峪猪保种群体的遗传结构

为了更好地了解青峪猪在世代更替过程中遗传结构的变化,更好的保护和利用青峪猪遗传资源,本研究利用50K SNP芯片,对青峪猪保种群内141头（26头公猪,115头母猪）健康成年个体进行SNP测定,通过多种分析软件对青峪猪保种群体和各个世代进行系谱校正,进而实施群体遗传多样性、遗传距离以及遗传结构变化等分析。结果显示,该封闭保种群由3个重叠世代构成,群体有效含量为12头,且整个群体可以分为6个含有公猪的家系和1个不含公猪的家系。其中,第3世代的有效群体含量最少,仅为3头,多态性标记比例随着世代的增加不断下降;141头青峪猪的平均遗传距离为（0.260 4±0.025 2）,26头种公猪的遗传距离为（0.263 3±0.023 7）。随着繁殖世代的增加,各世代群体的遗传距离有轻微的上升趋势,部分种猪之间的亲缘关系和遗传距离较近;在141头青峪猪群体中共检测到1 481个基因组上长纯合片段（runs of hemozygosity,ROH）,78.01%的长度在200 Mb以内,基于ROH值计算的近交系数表明整个群体的平均近交系数为0.055,且各世代的近交系数在不断上升,到第3世代时已经达到了0.075。综上所述,通过对青峪猪分子水平的群体遗传结构研究表明,该保种群体在闭锁的继代繁育过程中存在群体遗传多样性损失,需要加强选配或导入外血以确保青峪猪遗传资源的长期保存。     

基于SNP芯片的云上黑山羊遗传结构分析

为从分子水平对云上黑山羊遗传结构做出评价,本研究以云上黑山羊核心群母羊108只(来自7个育种核心场、10个群体)、育种素材云岭黑山羊和努比山羊各11和14只、对照组波尔山羊10只为试验动物,用Illumina公司Iselect Goat60k芯片技术在全基因组范围内进行单核苷酸多态性(SNP)分析,并运用GenAlEx 6.5、Cervus 3.0、SNPRelate、Plink 1.07、Mega 4.0进行遗传多样性参数统计计算、主成分分析和系统进化树构建。试验获得143个样本在48 116个SNPs位点上的分型结果,其中波尔山羊10个样本单独聚集,与云上黑山羊、努比山羊、云岭黑山羊存在较大的遗传距离,较小的遗传一致度和较小的基因流,在聚类进化树中显示为一个独立分支,这些结果与波尔山羊实际遗传背景完全一致,显示出它在本研究中的对照组作用,同时证明本研究方法可行、结果可靠;云上黑山羊108个样本具有高度一致性,在聚类系统树中这些样本聚为一个大簇,而努比山羊(14个)和云岭黑山羊(11个)的样本各自聚为一簇;UPGMA进化树显示,云上黑山羊与努比山羊关系较近,与云岭黑山羊关系稍远,这与云上黑山羊育种导血方案结果相一致。云上黑山羊新品种在基因组水平上可与其育种素材明显区分,在基因组层面已具备独立品种特点。     

Genetic evaluation strategies for multiple traits and countries

Genetic evaluation strategies were studied using simulated data for three lactation traits in each of two importing and two exporting countries, each running a typical progeny test program. Conversion (CNV), multiple-trait across-country evaluation (MACE) and global animal model (GAM) strategies were considered. Base populations were either unselected, or all males were above average, and exporting countries had higher genetic means than importing countries. With unselected base populations, errors of prediction (ERP) for top (highest predicted merit) bulls were equivalent (P>0.10) for MACE and GAM strategies and higher for CNV (P<0.01), while GAM had lower ERP (P<0.01) for all bulls. With selected base populations, MACE strategies had lower ERP than GAM for top bulls (P<0.01) and lower but similar ERP (P>0.05) for all bulls. Strategies to evaluate multiple traits per country consistently had lower ERP than strategies evaluating one trait per country. Evaluations were biased, favouring bulls from importing countries on foreign scales of evaluation, for all strategies and with either selected or unselected base populations. True merits of top bulls selected with MACE or GAM were similar (P>0.05) and greater than CNV (P<0.01), and 90-95% of the top 1% selected bulls were the same for multiple-trait MACE and GAM strategies.     

Relationship between perilipin genes polymorphisms and growth,carcass and meat quality traits in pigs

The perilipins (PLIN) belong to a family of structural proteins that play a role regulating intracellular lipid storage and mobilization. Here, PLIN1 and PLIN2 have been evaluated as candidate genes for growth, carcass and meat quality traits in pigs. A sample of 607 Duroc pigs were genotyped for two single‐nucleotide polymorphisms, one in intron 2 of the PLIN1 gene (JN860199:g.173G>A) and the other at the 3′ untranslated region of the PLIN2 gene (GU461317:g.98G>A). Using a Bayesian approach, we have been able to find evidence of additive, dominant and epistatic associations of the PLIN1 and PLIN2 polymorphisms with early growth rate and carcass length. However, the major effects were produced by the dominant A allele at the PLIN2 polymorphism, which also affected the carcass lean weight. Thus, pigs carrying an additional copy of the A allele at the g.98G>A PLIN2 polymorphism had a probability of at least 98% of producing carcasses with heavier lean weight (+0.41 kg) and ham weight (+0.10 kg). The results obtained indicate that the PLIN2 polymorphism could be a useful marker for lean growth. In particular, it may help to reduce the undesired negative correlated response in lean weight to selection for increased intramuscular fat content, a common scenario in some Duroc lines involved in the production of high quality pork products.     

Genetic evaluation of Ethiopian Boran cattle and their crosses with Holstein Friesian for growth performance in central Ethiopia

Breed additive and non-additive effects, and heritabilities of birth weight (BWT), weaning weight (WWT), 6 months weight (SMWT), yearling weight (YWT), eighteen months weight (EWT), 2 years weight (TWT) and average daily weight gain from birth to 6 months (ADG1) and from 6 months to 2 years (ADG2) were estimated in Ethiopian Boran (B) cattle and their crosses with Holstein Friesian (F) in central Ethiopia. The data analysed were spread over 15 years. Ethiopian Boran were consistently lighter (p < 0.01) than the B-F crosses at all ages. Ethiopian Boran also gained lower weight than all the crosses. At birth, 50% F crosses were significantly (p < 0.01) lighter than all the other crosses. However, the differences in SMWT, YWT, EWT, TWT, ADG1 and ADG2 were all non-significant among the crosses. The individual additive breed differences between B and F breeds were positive and significant (p < 0.01) for all traits. The individual heterosis effects were significant (p < 0.05) for all traits except WWT for which the effect was non-significant. The maternal heterosis effects were significant (p < 0.01) for BWT (2.5 kg) and WWT (-3.0 kg). The heritability estimates for all traits in B and crosses were generally moderate to high indicating that there is scope for genetic improvement through selection. Selection within B and crossbreeding should be the strategy to enhance the growth performance under such production systems.     

利用高密度SNP芯片分析杭猪的群体遗传结构

旨在更好地了解杭猪保种群体的遗传多样性、亲缘关系和家系结构,有效保护和利用杭猪遗传资源。本研究使用50K SNP芯片对30头杭猪（4头公猪,26头母猪）保种个体进行了单核苷酸多态性（single nucleotide polymorphism,SNP）测定,通过Plink软件对获得的基因型数据进行质控,用于最小等位基因频率、观察杂合度、期望杂合度和多态信息含量的计算,分析杭猪保种群的遗传多样性;使用Plink计算连续性纯合片段（runs of homozygosity,ROH）、构建状态同源（identity by state,IBS）距离矩阵,并计算得到基于连续性纯合片段的近交系数;采用Gmatrix软件构建G矩阵,分析杭猪保种群的亲缘关系;使用Mega X软件构建公猪进化树,分析保种群体的家系结构。结果表明,30头杭猪共得到57 466个SNPs标记,平均检出率为0.988 3±0.000 4,通过质检SNPs数为34 156;平均最小等位基因频率为0.228±0.137,平均多态信息含量为0.255±0.098;平均观察杂合度为0.359±0.181,平均期望杂合度为0.314±0.140。杭猪保种群体平均IBS遗传距离为0.241 7±0.033 6,公猪平均IBS遗传距离为0.178 3±0.025 5;G矩阵分析结果与IBS距离矩阵一致,两个结果均表明杭猪保种群部分个体之间亲缘关系较近。30头杭猪个体共检测到828个ROHs,83.33%的ROH长度在10 Mb以内,平均长度为（6.96±9.62） Mb,个体ROH平均总长度为（191.95±201.56） Mb。基于ROH的平均近交系数为0.078±0.082,其中公猪平均近交系数为0.219±0.082,说明杭猪保种群整体的近交程度不严重,但公猪存在近交。进化树结果表明,杭猪保种群体目前只有2个家系,其中1个家系包含4头公猪,另一个家系不含公猪。综上所述,杭猪保种场的保种群公猪的血缘数量少,母猪近交程度低,公猪存在近交,需要引入新血统或创建新血统来维持家系结构的平衡以利于杭猪遗传资源的长期保存,防止杭猪遗传多样性的丢失。     

Genetic characterization of Barbari goats using microsatellite markers

Genetic variation in Barbari goats, a highly prolific breed distributed widely in the northern part of India, known for better milk and meat quality, was studied as a part of genetic characterization and conservation. The genomic DNA from 50 unrelated Barbari goats were amplified via PCR with a panel of 21 microsatellite markers, and resolved through 6 per cent denaturing polyacrylamide gel electrophoresis followed by silver staining. The number of alleles ranged from 4 to 11, with allele sizes ranging from 88 to 220 bp. The distribution of allele frequencies was between 0.0104 and 0.5208. Polymorphism information content varied from 0.5563 to 0.8348. The population was not in Hardy-Weinberg equilibrium for all except two microsatellite loci (ILSTS044 and ILSTS060). The observed heterozygosity ranged from 0.8478 to 1.0000 while the expected heterozygosity ranged from 0.6208 to 0.8509. Based on the results of the present study, there is a good scope for exploiting the genetic variability in the Barbari goats for further improvement of performance.     

Genetic closeness of Zanskari and Spiti ponies of India inferred through microsatellite markers

The Zanskari and Spiti ponies were characterized for genetic variation using a set of 25 equine microsatellite markers. The DNA was isolated from the 42 blood samples of Zanskari and 32 blood samples of Spiti ponies collected from their respective breeding tracts. The DNA was amplified by polymerase chain reaction at the studied microsatellite loci and amplified product was resolved for alleles by denaturing urea-polyacrylamide gel electrophoresis. The allelic frequency data so obtained was statistically analyzed using POPGENE computer program. The PCR product size-range varied from 84 to 102 at locus HTG6 to 238 to 244 at locus UCDEQ425. The observed number of alleles ranged from four to nine with a mean (± standard deviation) of 5.80 ± 1.32 alleles per locus in Zanskari and 5.40 ± 1.04 alleles per locus in Spiti ponies. The mean observed heterozygosity was found to be 0.61 ± 0.06 and 0.56 ± 0.09 for Zanskari and Spiti ponies, respectively. The Nei's standard and unbiased genetic distance were found to be 0.11 and 0.09, respectively, indicating close genetic relatedness of Zanskari and Spiti ponies.     

运用SNP芯片评估马身猪保种群体的遗传结构

旨在研究马身猪保种群体的遗传多样性、亲缘关系和家系结构.本研究利用Illumina CAUPorince 50K SNP芯片检测39头保种马身猪的单核苷酸多态性(single nucleotide polymorphism,SNP);采用Plink软件计算最小等位基因频率、多态信息含量、观察杂合度和期望杂合度,分析保种...     

Genetic Characteristics of Frizzled and Incomplete Frizzled Feather and SNP Detection of KRT75 Gene

The study was mainly focused on the genetic characteristics of frizzled feather trait,the phenotype difference between frizzled feather（FF）and incomplete frizzled feather（IFF),and SNP analysis of the candidate gene KRT75 in the frizzle and incomplete frizzle chickens of different feather colors,which could provide scientific gist for the frizzle gene mapping,development and utilization of the two kinds of chicken.The resource population（homozygous Yellow feather Kirin chicken×Huaixiang chicken）of hybrid F2 was established.The back,neck,wing primary and wing-bow feather were observed and the scatter diagram of rachis bending degree was drawn.The blood of 10 white frizzle feather Kirin（WFF）chicken,10 Yellow frizzle feather Kirin（YFF）chicken,10 Royal,25 Yellow feather incomplete frizzle（YFIF）chicken and 15 Black feather incomplete frizzle（BFIF）chicken from homozygous WFF chicken×Royal chicken of hybrid F1 were extracted,then the DNA of those samples were extracted.The primer of KRT75 was designed,the PCR products were also sequenced after purification,Chromas 2.22 and DNAMAN software were used to analysis of sequence peaks photos and sequence alignment,respectively.The amount of orthogonal and reciprocals cross in hybrid F1 was 127 and 139, respectively, which all were the slight（incomplete）frizzled feather phenotype,with no different penetrance.The resource population of hybrid F2 were consisted of 55 frizzle chicks including some hens and cocks,106 incomplete frizzled and 68 contour feather chicken,the proportion of which was coincided with Mendelian segregation ratio of 1:2:1 by χ²-test（P>0.05),therefore it preliminary verified that the frizzle gene F was autosomal incomplete dominant inheritance.FF and IFF curved upward deviating from the skin,and the line slope of trend line of FF was 3.5 times than that of IFF.It found that there was no 69 bp deletion mutation in exon 5 region of KRT75 gene in WFF and YFF chicken,but 3 SNPs（T71C,T83C,C95T）were deleted in the 69 bp,which were homologous CC in WFF and YFF chicken,of two were heterozygous in YFIF chicken,while all were heterozygous in BFIF chicken.2 SNPs（T662C and T770C）were also deleted in exon 6,heterozygous of which were only deleted in BFIF chicken.The haplotype analysis indicated that 9 haplotypes were detected in 60 individuals,hap1/hap1 was specific genotype of WFF and YFF chicken.The haplotypes of two incomplete frizzle feather chicken were apparently different,hap4 was specific haplotype of YFIF chicken,while hap6,hap7,hap8 and hap9 were specific haplotypes of BFIF chicken.The frizzle gene F was autosomal incomplete dominant inheritance,there were obvious differences between FF and IFF traits,5 SNPs in exon 5 and 6 of KRT75 gene probably were the reference of molecular markers as distinguishing between frizzle and incomplete frizzle chicken.     

卷羽与半卷羽遗传特性分析及KRT75基因SNP位点检测

本试验通过对卷羽性状遗传特性和卷羽、半卷羽差异及对不同羽色卷羽、半卷羽鸡的候选基因KRT75序列SNP分析,为进一步对卷羽性状基因的定位和卷羽、半卷羽鸡的开发利用提供科学依据。以纯系黄色卷羽麒麟鸡和片羽怀乡鸡为素材,正反交构建F2代资源群体,对24周龄卷羽、半卷羽和片羽鸡背羽、颈羽、翅膀主翼羽和翼肩羽观察并绘制背羽羽轴弯曲程度散点图。随机抽取25周龄黄羽、白羽麒麟鸡和贵妃鸡各10只,F1代黄羽半卷羽鸡25只,以及白羽麒麟鸡×贵妃鸡杂交F1代黑羽半卷羽鸡15只的血样提取DNA,设计引物,PCR扩增纯化后测序,Chromas 2.22和DNAMAN软件用于分析测序峰形图和序列比对。结果显示,杂交F1代正交组127只,反交139只,不论公、母表型较一致,无外显率不同,均呈现轻度卷羽（半卷羽）,F1代间交配产生的F2代资源群体：卷羽鸡55只,半卷羽鸡106只,片羽鸡68只,公、母鸡均有卷羽,经过卡方适合性检验符合孟德尔遗传分离比1∶2∶1（P>0.05）,因此初步验证了控制卷羽基因F呈常染色体不完全显性遗传;卷羽、半卷羽鸡羽毛均背离皮肤向上弯曲,卷羽趋势线直线斜率是半卷羽的3.5倍;白羽和黄羽麒麟鸡外显子5处均不存在69 bp缺失,此69 bp发现3个SNPs：T71C、T83C、C95T,其中片羽鸡无突变,黄羽和白羽麒麟鸡均为纯合子,黄羽半卷羽鸡2个位点为杂合子,黑羽半卷羽鸡3个位点均为杂合子;外显子6处检测到了2个SNPs分别为T662C和T770C,仅在黑羽半卷羽鸡中为杂合子,其他均为纯合子,单倍型分析从60个个体中检测到了9种单倍型,hap1/hap1纯合型是黄羽和白羽麒麟鸡特异性的基因型,黄羽和黑羽半卷羽鸡的单倍型存在明显差异,hap4单倍型是黄羽半卷羽鸡特有的单倍型,hap6、hap7、hap8、hap9为黑羽半卷羽鸡特有的单倍型。卷羽性状基因F为常染色体不完全显性遗传,卷羽和半卷羽存在明显差异,KRT75基因序列外显子5和6处的5个SNPs可能作为区别卷羽和半卷羽鸡的分子标记参考。     

Development of genomic predictions for Angus cattle in Brazil incorporating genotypes from related American sires

Genomic prediction has become the new standard for genetic improvement programs, and currently, there is a desire to implement this technology for the evaluation of Angus cattle in Brazil. Thus, the main objective of this study was to assess the feasibility of evaluating young Brazilian Angus (BA) bulls and heifers for 12 routinely recorded traits using single-step genomic BLUP (ssGBLUP) with and without genotypes from American Angus (AA) sires. The second objective was to obtain estimates of effective population size (N_e) and linkage disequilibrium (LD) in the Brazilian Angus population. The dataset contained phenotypic information for up to 277,661 animals belonging to the Promebo breeding program, pedigree for 362,900, of which 1,386 were genotyped for 50k, 77k, and 150k single nucleotide polymorphism (SNP) panels. After imputation and quality control, 61,666 SNPs were available for the analyses. In addition, genotypes from 332 American Angus (AA) sires widely used in Brazil were retrieved from the AA Association database to be used for genomic predictions. Bivariate animal models were used to estimate variance components, traditional EBV, and genomic EBV (GEBV). Validation was carried out with the linear regression method (LR) using young-genotyped animals born between 2013 and 2015 without phenotypes in the reduced dataset and with records in the complete dataset. Validation animals were further split into progeny of BA and AA sires to evaluate if their progenies would benefit by including genotypes from AA sires. The N_e was 254 based on pedigree and 197 based on LD, and the average LD (±SD) and distance between adjacent single nucleotide polymorphisms (SNPs) across all chromosomes were 0.27 (±0.27) and 40743.68 bp, respectively. Prediction accuracies with ssGBLUP outperformed BLUP for all traits, improving accuracies by, on average, 16% for BA young bulls and heifers. The GEBV prediction accuracies ranged from 0.37 (total maternal for weaning weight and tick count) to 0.54 (yearling precocity) across all traits, and dispersion (LR coefficients) fluctuated between 0.92 and 1.06. Inclusion of genotyped sires from the AA improved GEBV accuracies by 2%, on average, compared to using only the BA reference population. Our study indicated that genomic information could help us to improve GEBV accuracies and hence genetic progress in the Brazilian Angus population. The inclusion of genotypes from American Angus sires heavily used in Brazil just marginally increased the GEBV accuracies for selection candidates.     

Estimates of genetic parameters for growth traits in Kermani sheep

Birth weight (BW), weaning weight (WW), 6-month weight (W6), 9-month weight (W9) and yearling weight (YW) of Kermani lambs were used to estimate genetic parameters. The data were collected from Shahrbabak Sheep Breeding Research Station in Iran during the period of 1993-1998. The fixed effects in the model were lambing year, sex, type of birth and age of dam. Number of days between birth date and the date of obtaining measurement of each record was used as a covariate. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two-trait animal models. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, WW, W6, W9 and YW were estimated to be 0.10 +/- 0.06 and 0.27 +/- 0.04, 0.22 +/- 0.09 and 0.19 +/- 0.05, 0.09 +/- 0.06 and 0.25 +/- 0.04, 0.13 +/- 0.08 and 0.18 +/- 0.05, and 0.14 +/- 0.08 and 0.14 +/- 0.06 respectively. Direct and maternal genetic correlations between the lamb weights varied between 0.66 and 0.99, and 0.11 and 0.99. The results showed that the maternal influence on lamb weights decreased with age at measurement. Ignoring maternal effects in the model caused overestimation of direct heritability. Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs.