Estimation of additive and non-additive genetic parameters for reproduction, growth and survival traits in crosses between the Moroccan D'man and Timahdite sheep breeds

Genetic breed differences, heterosis, recombination loss, and heritability for reproduction traits, lamb survival and growth traits to 90 days of age were estimated from crossing D'man and Timahdite Moroccan breeds. The crossbreeding parameters were fitted as covariates in the model of analysis. The REML method was used to estimate (co)variance components using an animal model. The first estimation of crossbreeding effects for Timahdite and D'man breeds shows that breed differences in litter traits are mainly of maternal genetic origin: +1.04 lambs, +1.88 kg, +0.60 lambs, and +2.23 kg in favour of D'man breed for litter size at lambing, litter weight at lambing, litter size at weaning, and litter weight at 90 days, respectively. The breed differences in lamb growth and survival are also of maternal genetic origin for the majority of traits studied, but in favour of the Timahdite breed: +3.48 kg, +45 g day⁻¹ and +0.19 lambs for weight at 90 days, for average daily gain between 30 and 90 days of age, and for lamb survival to 90 days, respectively. The D'man direct genetic effect was low and negative for survival and birth weight of lambs during the first month of life. All traits studied showed positive heterosis effects. Recombination loss effects were not significant. Therefore, crossbreeding of Timahdite with D'man breeds of sheep can result in an improved efficiency of production of saleable lambs. Heritability estimates were medium for litter size but low for the other reproduction traits. Direct heritabilities were low for body weights and lamb survival at 90 days and the corresponding maternal heritabilities showed, however, low to moderate estimates. For litter traits, the estimates of genetic and phenotypic correlations were positive and particularly high for genetic correlations.     

朝鲜鹌鹑遗传多样性微卫星标记分析

选用鹌鹑上的12个微卫星位点,对随机选取朝鲜鹌鹑的40个个体进行多态性检测,共检测到55个等位基因,每个座位平均等位基因数为4.583个。该群体平均多态信息含量和平均杂合度分别为0.6945和0.7111,表明朝鲜鹌鹑属多态性较丰富的群体。     

Genetic parameters of growth and in vivo computerized tomography based carcass traits in Pannon White rabbits

Genetic parameters for average daily gain between the age of 5 and 10 weeks (ADG), the average cross-sectional area of the m. Longissimus dorsi (L) (between the 2nd–3rd and 4th–5th lumbar vertebrae-based on in vivo computerized tomography (CT)) and dressing out percentage (DoP) were estimated in a group of 28,686 Pannon White rabbits reared in 5044 litters and born between 2000 and 2003. Using multivariate animal models with Bayesian procedures, estimated heritabilities were moderate and moderately high for ADG, L and DoP (0.21 to 0.29, 0.25 to 0.42 and 0.19 to 0.71, respectively). Litter effects were moderate for ADG, L and DoP estimates (0.20 to 0.22, 0.10 to 0.18 and 0.09 to 0.30, respectively). Genetic correlation coefficient estimates between ADG and L and ADG and DoP were moderate and negative (− 0.41 to − 0.01, − 0.70 to + 0.10). A moderately high positive genetic correlation was found between L and DoP (0.13 to 0.83).     

基于SSR标记的木豆种质资源遗传多样性与群体结构分析

种质资源遗传多样性和群体结构分析是作物种质资源保护和作物遗传育种的前提条件.本研究从96对简单序列重复(Simple sequence repeat,SSR)标记中筛选出42对多态性标记,对不同地理来源的72份木豆(Caj anus caj an)种质资源遗传多样性和群体结构进行了分析.结果表明:42对SSR标记在72...     

Present status of the conservation of livestock genetic resources in Brazil

Brazil has various species of domestic animals, which developed from breeds brought by the Portuguese settlers soon after the discovery of the country. After being submitted to a long process of natural selection, these breeds present characteristics adapted to specific Brazilian environmental conditions, and are known as “criollo”, “local” or naturalized breeds. From the beginning of the 20th century, some exotic breeds, selected in temperate regions, have begun to be imported, and, although more productive, they do not have adaptive traits, such as resistance to disease and parasites found in the naturalized breeds. Even so, they gradually replaced the native breeds, to such an extent that the latter are in danger of extinction. To avoid further loss of this important genetic material, in 1983 the National Research Center for Genetic Resources and Biotechnology (Cenargen) of the Brazilian Agricultural Research Corporation (Embrapa) decided to include conservation of animal genetic resources among its priorities. The conservation activities have been conducted under the Brazilian Genetic Resources Network — Renargen, and is carried out by various research centres of Embrapa, universities and State research institutions, as well as by private farmers, with a single coordinator at national level, Cenargen. The in situ conservation of cattle, horses, buffaloes, donkeys, goats, sheep and pigs is being carried out by Conservation Nuclei, located in the animal's original habitat. Ex situ conservation is centred at the Brazilian Animal Germplasm Bank (AGB), kept at Cenargen. This is responsible for the storage of semen and embryos of various breeds of domestic animals threatened with extinction. Presently the AGB has almost 60,000 doses of semen and more than 250 embryos, as well as over 7000 DNA samples. An important challenge for this program is to increase awareness within the different segments of society in terms of the importance of the conservation of animal genetic resources. The development and evolution of Renargen and its efforts to facilitate the conservation of genetic resources of livestock in Brazil are described in this paper.     

辽宁绒山羊杂交改良子午岭黑山羊的效果及遗传分析

本文对用辽宁绒山羊杂交改良子午岭山羊的生长发育、生产性能、绒纤维品质及遗传规律进行了分析,结果表明各代杂种羊的各个指标均较子午岭山羊有提高。杂种羊体重比子午岭山羊体重提高10％以上,子午岭成年母羊产绒量为115克,杂种一、二、三代分别为282、330、355克,产绒量显著提高(P<0.01),接近当地辽宁绒山羊(370克)。本文估测了高代杂种F_3主要经济性状的遗传参数,结果表明,体重、产绒量、绒纤维细度的遗传力分别为0.562、0.138、0.455。产绒量与体重、绒纤维的长度的遗传相关分别为0.674、0.882。绒纤维细度与体重的遗传相关为-0.086。根据估测的遗传参数,结合生产实际,提出选择指数I_8=-0.00425x_1+0.1898x_2+0.8785x_3,其中x_1=产绒量(克);x_2=体重(千克);x_3=细度(微米),可在生产中试用。     

中国畜禽遗传资源的研究进展

作为生物多样性重要组成部分的家畜遗传资源库对当今和将来人类的食品和农业生产具有主要的经济、科学及文化价值.本文论述了动物遗传资源的现状、系统分类、评价方法,动物遗传资源的保存和利用研究进展.     

The role of reproductive technologies in breeding schemes for livestock populations in developing countries

The world is faced with the challenge to meet the increasing demand for livestock products while conserving animal genetic resource diversity and maintaining environmental integrity. Genetic improvement of local breeds can help to improve the livelihood of the livestock keepers, to increase the production of animal products and to conserve genetic diversity. Implementing breeding schemes in developing countries has proven to be very difficult. The objective of this paper is to discuss the role of reproductive technologies for the creation and dissemination of genetic improvement in livestock populations in developing countries. In the paper opportunities are discussed for implementing breeding schemes which minimize the need for extensive pedigree and performance recording. It is shown that genetic progress can be generated in a small population. Community-based breeding schemes offer a good starting point for involving farmers in improving local breeds. Artificial insemination to exchange genetic material between communities offers an opportunity to increase the rate of genetic improvement while restricting the rate of inbreeding. Furthermore, artificial insemination is a promising technique for dissemination of genetic gain to producers at a relatively low cost. Opportunities to use semen sexing in a crossbreeding scheme are presented. It is concluded that tailor-made solutions and long-term commitment are needed in order to meet the needs of farmers to increase their livelihoods and to meet the needs of the growing population of consumers.     

Genetic correlations between osseous fragments in fetlock and hock joints, deforming arthropathy in hock joints and pathologic changes in the navicular bones of Warmblood riding horses

The results of a standardized radiological examination of 5231 Hanoverian Warmblood horses were used to investigate heritability of and genetic correlations between prevalent radiographic findings in the equine limbs. Radiographic findings were categorized by joint location and type of visible alterations and analyzed as all-or-none traits. Heritabilities and correlations were estimated multivariately for most prevalent radiographic findings in equine limbs using Residual Maximum Likelihood (REML) and Gibbs Sampling (GS). Linear animal models and linear sire models were used for REML; sire threshold models were used for GS analyses. Heritabilities and residual correlations from linear model analyses were transformed from observed scale to underlying liability scale. Osseous fragments were seen in fetlock joints (OFF) of 23.5% and in hock joints (OFH) of 9.2% of investigated horses. Deforming arthropathy in hock joints (DAH) was diagnosed in 12.0% and pathologic changes in navicular bones (PCN) in 25.8% of investigated horses. Heritabilities differed little between analyses with animal and sire models and with REML and GS. Ranges of heritability estimates were h² = 0.16–0.44 with REML and h² = 0.07–0.43 with GS. Genetic correlation estimates were larger in GS than in REML analyses. Additive genetic correlation between OFF and DAH was positive (r_g = 0.25 to 0.77). Negative additive genetic correlations were determined between OFF and OFH (r_g = − 0.17 to − 0.82), between OFH and DAH (r_g = − 0.14 to − 0.81), and between OFH and PCN (r_g = − 0.19 to − 0.26). No relevant additive genetic correlations were estimated between PCN and OFF, and between PCN and DAH. The results of the present study indicate that the prevalences of common radiographic findings in the limbs of young riding horses are relevantly influenced by genetics and probably caused by different genes. Genetic correlations between radiological health traits therefore deserve closer attention in horse breeding. The quantitatively most important radiographic findings should be concurrently considered as individual traits in order to provide for general improvement of radiological health of the limbs of young Warmblood riding horses.     

22份虉草种质资源遗传多样性的ISSR分析

采用ISSR(inter-simple sequence repeat)分子标记法对来自不同地域的22份虉草(Phalaris arundinacea L.)种质材料进行遗传多样性和亲缘关系分析,为虉草种质资源有效利用提供理论依据。用10条扩增清晰、多态性较好的引物,共扩增出160个位点,其中多态性位点145个,多态性位点百分率(PPB)为90.62%,平均有效等位基因数(Ne)为1.5263±0.0874,平均Nei’s基因多样性(H)为0.3063±0.0436,平均Shannon多样性信息指数(I)为0.4601±0.0646,种质间遗传相似系数(Gs)为0.4938~0.8250。通过UPGMA(unweighted pair-group method with arithmetic means)聚类方法对22份虉草材料进行聚类分析。结果表明,在Gs为0.58时可将22份虉草材料分为两大类群,第Ⅰ类群包含A-1和A-2共2份材料,其余材料均归为第Ⅱ类群;在Gs为0.71时可将第Ⅱ类群的20份材料细分为4个亚类群,第Ⅰ亚类群包含9份材料,主要来自俄罗斯西北部和中国中西部地区;第Ⅱ亚类群包含6份材料,多数来自俄罗斯中东部和中国镇江地区;第Ⅲ亚类群包含3份材料,来自中国和美国;第Ⅳ亚类群包含2份材料,来自中国通辽地区。用ISSR标记技术可有效揭示虉草种质资源的遗传多样性,试验中来自不同地域的22份虉草种质材料遗传多样性较为丰富。试验结果表明虉草种质资源遗传分化与地理来源有一定的相关性,但遗传聚类与地理来源不完全一致。     

Responses in carcass lean pH at 24 hours post-mortem in lines of Large White pigs selected for growth rate on a fixed ration over a set time

A restricted maximum likelihood analysis applied to an animal model showed no significant differences (P > 0.05) in pH value of the longissimus dorsi measured at 24 h post-mortem (pH24) between high and low lines of Large White pigs selected over 4 years for post-weaning growth rate on restricted feeding. Genetic and phenotypic correlations between pH24 and production and carcass traits were estimated using all performance testing records combined with the pH24 measurements (5.05–7.02) on slaughtered animals. The estimate of heritability for pH24 was moderate (0.29 ± 0.18). Genetic correlations between pH24 and production or carcass composition traits, except for ultrasonic backfat (UBF), were not significantly different from zero. UBF had a moderate, positive genetic correlation with pH24 (0.24 ± 0.33). These estimates of genetic correlations affirmed that selection for increased growth rate on restricted feeding is likely to result in limited changes in pH24 and pork quality since the selection does not put a high emphasis on reduced fatness.     

动物遗传标记的研究进展及应用

遗传标记已经从形态标记发展到分子遗传标记。中间经历了细胞标记和生化标记。本文阐述了各个阶段遗传标记的特点、原理、及其应用;总结了各种标记方法的优缺点,阐述了分子遗传标记。由于各种遗传标记的不同优势,在实际应用中应该相互结合相互补充,从各个角度揭示生物的遗传本质,以便更好地培育优良品种,保护生物多样性,保存人类赖以生存的生物源和生态环境。     

Direct genetic, maternal and litter effects on behaviour in German shepherd dogs in Sweden

The aim of this study was to study genetic (co)variation of broader behavioural traits in German shepherd dogs and to test whether there is maternal and litter influence on these traits. Data were extracted from the Swedish Dog Mentality Assessment (DMA) from 1989 to 2001 on 5959 German shepherd dogs. Based on previous results, personality traits were created from the 15 behavioural variables extracted from the test. These personality traits were (1) Playfulness, (2) Chase-proneness, (3) Curiosity/Fearlessness, and (4) Aggressiveness. A trait Boldness was constructed from all behaviour variables except those included in Aggressiveness. Mixed linear models with fixed effects of sex, test type, test year, test month, age, and judge were used. Models with all combinations of random effects of animal (direct genetic), genetic and non-genetic maternal, and litter were tested. The best model included effects of animal and litter. Direct heritability estimates were between 0.09 and 0.23, highest for Playfulness and Curiosity/Fearlessness. Maternal heritabilities were all low (0.01-0.08), lowest and not significant if litter or non-genetic maternal effects were included in the model. Additive genetic correlations among Playfulness, Chase-proneness, and Curiosity/Fearlessness were higher (0.54-0.74) than genetic correlations with Aggressiveness (0.29-0.40). Litter variance ratios (c²) were larger than the maternal heritabilities (0.03-0.10). Boldness had a direct heritability estimate of 0.27 and a direct genetic correlation with Aggressiveness of 0.37. We conclude that there is substantial additive genetic variation, that the mother has rather little influence (both genetically and environmentally) and that the litter seems to have a larger influence than the mother for these personality traits. Genetic improvement in these behaviour traits is thus possible.     

Genetic evaluation of Atlantic salmon for growth traits incorporating SNP markers

Genetic evaluations of individual fish were calculated for growth traits in North American Atlantic salmon with and without inclusion of genetic markers. The number of SNP markers was reduced to 6,000 and further to 270 in order to reduce the problem of overparameterization. SNP genotypes were predicted for all ungenotyped animals in the pedigree. Analysis of traits used a model with polygenic effects and SNP markers together. Polygenic effects refer to the additive genetic effects that remain after accounting for SNP genotypes. SNP marker genotypes were included as covariates to evaluate fish for growth traits (weight and length) in different environments (freshwater and seawater) with genders separated. Including regressions on SNP marker genotypes reduced the sum of squares of residuals by 2.7%–12.5% and increased the variability of Mendelian sampling effects (i.e., within‐family variation) compared to traditional animal model evaluations. Genetic evaluations may be carried out with a few hundred markers which may be more affordable for genotyping large numbers of fish.     

Genetic analyses for linear conformation traits in Pura Raza Español horses

A linear assessment methodology was developed for the conformational data in the Pura Raza Español horse (Andalusian horse). The final design included 31 linear traits (20 primary and 11 secondary). A total of 4158 records from 2512 horses collected during 2008 and 2011 were included in the genetic evaluation. The genetic analyses were executed twice, the first one only with the first conformation assessment record of each animal (dataset 1: 2512 horses and records), and the second one, only for animals with more than one conformation records available (dataset 2: 876 horses and 2522 records). Genetic parameters were estimated using REML methodology (in a linear animal model), and age, sex, geographic region and combination of appraiser×event were included as fixed effects in the model. For the analysis with dataset 2, permanent environment was also included as random effect. The pedigree file traced back the relationships to include a total of 12,385 (dataset 1) and 3025 (dataset 2) horses. After the repeatability and reproducibility of the system were evaluated, according to our results, the appraisers used the whole scale and showed an adequate level of repeatability (≥0.95), and the reproducibility of analyzed traits was over 0.90 for all traits. Despite the fact that the quality of the morphological assessment can be considered adequate, further training is recommendable for appraisers in order to improve uniformity. Heritabilities with dataset 1 were low-moderate, ranging from 0.06±0.026 (angle of shoulder) to 0.35±0.044 (head length) for the primary traits, and from 0.08±0.032 (frontal angle of knee) to 0.23±0.035 (head-neck junction) for the secondary ones. Heritabilities found with dataset 2 were slightly lower than those obtained with dataset 1. Genetic correlations between traits were also obtained, which ranged from 0.92 to 0.00 in both datasets. These results must be taken into account in order to reduce the number of traits routinely collected in this population.     

Estimates of genetic parameters for milkability from automatic milking

Genetic parameters were estimated by restricted maximum likelihood with a multi-trait animal model for three milkability traits with serial data from an automatic milking system from a research farm (401 dairy cows) collected between September 2000 and June 2003 (320834 milkings). Furthermore, daily values for milk yield and milkability were formed from all single milkings resulting in 104 132 records and, subsequently, an estimation of genetic parameters was carried out based on these daily values.The resulting estimated heritability coefficients (based on daily values) are h² = 0.55, h² = 0.55 and h² = 0.39 for average milk flow, maximum milk flow and milking time, respectively. The heritabilities are at a high level and thus breeding for good milkability makes sense. The genetic correlations between the three milkability traits are near unity with r_g = 0.98 between average and maximum milk flow, r_g = − 0.89 between average milk flow and milking time and r_g = − 0.86 between maximum milk flow and milking time. Thus it may be sufficient to record only one of these traits in performance tests. The genetic correlations between milk yield and average milk flow, maximum milk flow and milking time are r_g = 0.51, r_g = 0.44 and r_g = − 0.23, respectively.In future, serial data on milkability, already existing on many farms with automatic milk yield recording, should be used to greater extent for selective breeding with the aim of achieving good milkability.     

基于线粒体DNA Cyt b研究城市化对上海金线侧褶蛙遗传结构的影响

城市化在全球范围内快速扩张,已经成为影响物种进化的重要力量。两栖动物的迁移能力较弱,城市化导致两栖类被完全或部分的隔离,丢失更多的遗传多样性。本研究对上海市的金线侧褶蛙(Pelophylax plancyi)的mtDNA Cyt b部分序列进行分析,共扩增出235条序列,获得61个单倍型。研究表明城市区域遗传多样性较低,上海市的金线侧褶蛙分化程度处于中低的水平(Max F_ST=0.296;Min F_ST=0.004),各种群之间遗传分化有限。黄浦江及其支流可能作为水上扩散通道,有助于基因交流,各城市公园之间的遗传分化差异并不显著;而长江阻碍了种群之间的交流,城市公园和郊区,以及岛屿种群之间的遗传分化显著。此外,单倍型网络和系统发育分析表明,上海的金线侧褶蛙并没有对应城市化程度形成相应的单系。     

畜禽遗传资源的地理信息系统

畜禽品种资源信息由于具有明显的分散地域特征,因而宜用地理信息系统对其各种数据进行综合与分析。基于这样的考虑,我们进行了畜禽品种资源信息系统的前期研究,结合信息系统、数据库系统和数量遗传学的理论,开发了该系统的部分软件,主要的研究工作包括：１．图形、图像数据库的建立,录入了部分家畜家禽的图像资料和有关的特性特征的数字和文字资料,建立了全国及分省区的地图库。可以方便地按品种名称和地图两种途径进行检索。２．可视化操作环境的制作。本系统采用了多窗口切换、图形菜单及事件管理等手段,使系统具有良好的人机交互界面,适于具有不同计算机应用水平的人员使用。３．品种资源状态预警系统的前期研究。可根据群体数量对品种资源状态做简单预警。     

苜蓿属种质资源遗传多样性RAPD分析

本文用RAPD标记分析10份苜蓿属(Medicago L.)种质的遗传多样性和亲缘关系,为苜蓿优秀种质资源开发保护和杂交育种提供基础信息。结果表明:33个引物在这10份材料间共扩增出353条带,其中263条带为多态性带,多态位点百分率为74.5%,各引物扩增的条带数为5～17条不等;遗传距离范围为:0.488～0.686,平均值0.592。聚类分析结果表明:10份材料大体划分为3类:草原1号、草原3号、美国苜蓿王和达菲成为第1类;雅酷、呼盟、蒙古和锡盟是第2类;秋柳独自成为1类。     

New genetic parameters to exploit genetic variability in low input production systems

Under low input production systems, low heritabilities for growth traits have been a major limiting factor for recommending selection to improve animal productivity. Heritabilities low values were usually due to a large error variance leading to a dilution of the genetic variability. A total of 11,802 Barbarine lambs, from 606 breeding rams and 2428 breeding ewes, born during the period 1972–2002 and raised in a low production system were used in this study. The objective was to derive new genetic parameters that reflect in a proper way the available genetic variabilities for growth traits even under a low production system. Three classical heritability estimators and two new proposed genetic parameters (ratios) were computed and compared: the additive (h²a), the maternal (h²m), the total (h²t) heritabilities, the additive genetic ratio (a²) and the genetic maternal ratio (m²). Main results of this study showed that the direct animal model has led to higher heritability estimates than the animal maternal model. Estimates were 0.30, 0.30 and 0.31 for weights at 10 days, 30 days and 90 days, respectively. For average daily gains, estimates were 0.22 and 0.26 between 10–30 days and 30–90 days, respectively. Under maternal model, h²a varied from 0.05 to 0.08, h²m varied from 0.08 to 0.12 and h²t varied from 0.11 to 0.17. Maternal heritabilities were higher than additive heritabilities, but both remained relatively small. Values of additive genetic ratios were 0.20, 0.19, 0.20, 0.32 and 0.39 for W10, W30, W90 ADG13 and ADG39, respectively. The maternal genetic ratios were 0.41, 0.45, 0.37, 0.41 and 0.40 for W10, W30, W90, ADG13 and ADG39, respectively. These results showed that a² and m² describe better the contribution of the additive and maternal effects to the available genetic variability compared to classical heritability estimates because they remain unaffected by the residual error variance even under low-input production systems. These new parameters (ratios) represent, consequently, appropriate indicators for the contribution of the additive and maternal genetic effects to the total genetic variability and encourage breeders to find ways to exploit them.