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利用RAD-seq简化基因组测序鉴定狼山鸡保种群个体基因组SNP标记,计算个体(间)分子近交系数和分子亲缘系数,结合系谱信息组建高、低近交两个试验组。分析后代繁殖性状近交衰退系数,评价近交对繁殖性状的影响。结果显示:利用FROH、FGRM、FHOM和FUNI四种分子近交系数结合亲缘系数kin估算的后代分子近交系数较为一致。低近交组后代的平均分子近交系数小于0.04,高近交组(6个家系)后代的平均分子近交系数介于0.14~0.25。近交对各繁殖性状的效应表现并不一致。高近交组后代母鸡开产日龄、300日龄产蛋数发生显著衰退(P<0.05,P<0.01),且与分子近交系数呈显著相关(P<0.05,P<0.01);开产体重和开产蛋重未发生显著性衰退(P>0.05)。研究结果为进一步探讨狼山鸡繁殖性状近交衰退分子机制提供了基础。 相似文献
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不同来源大白猪总产仔数近交衰退评估 总被引：2，自引：2，他引：0
旨在评估两个不同来源大白猪群体经过近8个世代的选育后总产仔数（total number of piglets born，TNB）近交衰退的程度。本研究对1 937头大白猪使用GeneSeek GGP Porcine HD芯片进行分型，其中1 039头来自加系大白猪和898头来自法系大白猪，且两品系均有表型记录和系谱记录，系谱共由3 086头大白猪组成。分别使用系谱、SNP和ROH进行个体近交系数估计，并将近交系数作为协变量利用动物模型对总产仔数进行近交衰退评估。为了精准定位导致总产仔数衰退的基因组片段，又进一步对每条染色体以及显著染色体分段计算近交系数并估计其效应，检测是否能引起总产仔数发生近交衰退现象。对于加系群体，FROH、FGRM和FPED估计的近交系数均值分别为0.124、0.042和0.013，其中FROH和FPED相关最高，相关系数为0.358；对于法系群体，FROH、FGRM和FPED均值分别为0.123、0.052和0.007，其中FROH和FGRM相关最高，相关系数为0.371。利用3种不同计算方法所得近交系数用于估计近交衰退时，加系群体的总产仔数均检测到显著的近交衰退，而且当FROH、FGRM和FPED每增加10%时，总产仔数分别减少0.571、0.341和0.823头；但法系群体仅有FROH估计的总产仔数检测到显著近交衰退，FROH每增加10%时，总产仔数减少0.690头。为了锁定相关的染色体和基因组区段，首先利用ROH估计每条染色体近交系数并进行近交衰退分析发现，加系群体中检测到第6、7、8和13号染色体产生了显著近的总产仔数交衰退，而法系群体未检测到与近交衰退相关的染色体。然后，又将与加系总产仔数近交衰退显著相关的4条染色体平均分为2、4、6、8个片段进行近交衰退检测，其中平均分成8段后的染色片段的长度范围为15.1~25.8 Mb。在第6、7和8号染色体分别检测到1、2和3个与总产仔数相关的近交衰退染色体片段。这些区域注释到了CUL7、MAPK14和PPARD基因与胎盘发育相关，AREG和EREG基因与卵母细胞成熟有关。本研究利用3种近交系数计算方法对两个不同来源的大白猪总产仔数进行近交衰退评估，在加系大白猪中3种估计方法都能检测到近交衰退的现象，而法系群体中只有FROH才能检测到。而且通过ROH方法进一步确定了能引起加系大白猪总产仔数衰退的4条染色体和6个特定的染色体区段，还注释到了与繁殖相关的候选基因。这为揭示近交衰退的遗传机制提供了新的研究手段，也为基因组选种选配提供了参考依据。 相似文献
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品系与高度亲缘是分不开的,同时,高度近交也是品系衰亡的主要因素。因此,在不失品系特性的基础上,有效控制近交系数是品系维持的根本内容。本文就这个问题从理论上做一初步论述。首先是控制种公畜数量问题。在一个闭锁的随机交配群体中,每代的近交率即近交系数增量(△F)的估计公式如下: 相似文献
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小梅山猪最佳近交区域的研究 总被引：2，自引：0，他引：2
将江苏农林职业技术学院小梅山猪育种中心839窝纯种小梅山猪按其近交系数的大小(F=0～39.9%),分成9组,运用数量遗传原理,探讨小梅山猪以产活仔数为主目标性状的繁殖性能近交效应,发现小梅山猪最佳近交区域为近交系数0.1%～14.9%,较佳近交区域近交系数为15%～19.9%;衰退区域近交系数为20%～39.9%。结果表明:小梅山猪具有安全近交区域广、耐近交能力强等优良特性。 相似文献
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本试验旨在分析钙调素(Calmodulin,CAM)基因启动子区域碱基多态性与京海黄鸡产蛋性状和鸡蛋蛋壳质量性状间的关系。采用PCR-SSCP法检测京海黄鸡CAM基因启动子区域碱基多态性。结果表明:京海黄鸡CAM基因启动子区域有3个SNPs(G326A、A327G、C366T),PCR扩增产物SSCP出现6种基因型:AA、AB、AC、BB、BC和CC。AA基因型个体的300日龄产蛋数和66周龄产蛋数显著高于BB型个体(P<0.05)。AA型个体的蛋壳强度和蛋壳重显著小于AB、BB、AC和BC型个体(P<0.05)。CAM基因座对京海黄鸡300日龄蛋重、蛋型指数、蛋壳强度和壳重百分率的主效应指数(MEI)均大于3%。初步推断CAM基因座可能是影响京海黄鸡产蛋数和蛋壳质量性状重要候选基因。 相似文献
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猪MyoG基因的多态性及其对岔路黑猪胴体和肉质的影响研究 总被引：1，自引：0，他引：1
应用PCR--RFLP技术分析了岔路黑猪(56头)、嘉兴黑猪(50头)和I系金华猪(109头)群体中MyoG基因的基因频率和基因型频率分布,测定了21头纯种岔路黑猪的胴体和肉质性状,并采用一般线性模型分析了MyoG基因型与以上性状的相关性.结果表明:岔路猪群体中AA型纯合子占绝大多数(84%),BB型纯合子最少(4%),A基因频率占90%,嘉兴黑猪群体中只有一种基因型(AA);而金华猪(I系)群体中BB与AB基因型频率相当(分别为45%、46%),B基因频率大约为A基因频率的2倍.MyoG基因对岔路猪胴体重、后腿重、胴体长等胴体性状有显著影响,但对岔路猪肉质性状无显著影响. 相似文献
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胜利白猪近交程度的分析及对主选性状的影响 总被引：1，自引：0，他引：1
胜利白猪Ⅰ、Ⅱ系经过7、8个世代的继代选育,群体平均近交系数分别达到8.36%和8.57%,随着群体纯合度的提升对主选性状有不同程度的影响。对于遗传力(h2)低的性状,如产仔数、产活仔数的影响不大,大体保持在1世代的性能水平。对于遗传力(h2)中、高的性状,如后备猪的生长速度和同胞育肥性能等性状,则随世代选育均有明显的改进,改进幅度在10%以上,显示适度近交没有影响世代选育的效果。杂交试验证明,杂交优势也未因群体近交系数的增大受到影响。 相似文献
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《中国家禽》2017,(3)
研究旨在探讨IGF-1、OVR作为玫瑰冠鸡产蛋性能和蛋品质性状候选基因的可能性,寻找与产蛋性能和蛋品质相关的分子标记。采用PCR-SSCP技术对IGF-1、OVR进行SNPs检测。结果表明:IGF-1外显子3(A-38965G),OVR外显子3(G-5448A)、6(G-8284A)和8(A-9030T)存在突变位点;χ2检验显示:玫瑰冠鸡群体在A-38965G和A-9030T位点处于Har-dy-Weinberg平衡状态;关联分析表明:G-8284A位点BB型鸡的初生重、开产日龄、300日龄平均蛋重均显著高于AA型(P0.05);A-38965G位点AB型蛋重、哈夫单位、蛋白重均显著高于BB型(P0.05);OVR多态位点构建的单倍型中,GAT的蛋壳强度、蛋重均显著高于GAA(P0.05),开产日龄、300日龄总产蛋数均显著高于GGT(P0.05)。这说明IGF-I、OVR与产蛋性能及蛋品质性状间有一定的相关性,因此BB、AB型及单倍型GAT有望作为与玫瑰冠鸡产蛋性能和蛋品质性状相关联的分子标记。 相似文献
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1. Inbreeding and heterosis effects for quantitative traits were estimated in two White Leghorn lines selected with reciprocal recurrent selection (RRS) since 1950. 2. Pedigreed progeny were produced from full-sib, half-sib and unrelated pure line as well as reciprocal cross line matings to estimate inbreeding and heterosis effects "within sires". 3. Inbreeding effects estimated as linear regressions agreed well with estimates considering inbreeding as fixed effect. The inbreeding depression per 10% inbreeding was highest for hatchability (6-7%), intermediate for production-related traits (3%), and about 1% for shell quality, body weight and egg weight. 4. Heterosis effects were estimated by comparing pure line and cross line progeny of the same sires. 5. Results indicate considerably less heterosis for egg production than found earlier, which is interpreted as a consequence of pure line selection. 相似文献
12.
本文报道了蛋鸡饲料利用率及其相关性状和孵化率的杂种优势。材料来源于一个正反反复选择饲料利用率的试验,8个世代共有蛋鸡13408只。试验组(括弧里为对照组)各性状的平均杂种优势分别为:饲料利用率-2.0％ (-0.8％)、饲料消耗量2.9％(3.0％)、产蛋量4.5％(3.6％)、产蛋率2.9％(3.1)、蛋重1.9％(0.8％)、试验期初体重3.7％ (4.5％)、试验期末体重4.3％(5.0％)、受精率2.1％(-0.2％)、受精蛋孵化率15.0％ (4.5％)和入孵蛋孵化率10.2％(7.6％)。正反交组合的杂种优势不同,这可能是由性连锁导致的。 相似文献
13.
1. The rate of inbreeding and its effect on reproduction and egg production traits were studied in White Leghorn lines selected for egg production traits. The experiment was carried out for 10 generations in a control line (C) and in lines selected for increased egg number (EN), egg weight (EW) and egg mass (EM). 2. Data were available on reproduction traits, such as percent fertile eggs (PF), percent hatched of fertile eggs (PHF) and percent hatched of total eggs set (PHT), and on egg production traits such as age at 1st egg (AFE), egg number and egg weight. 3. The rate of increase in average inbreeding per generation was 1.50, 1.24, 1.14 and 0.18% for the line EN, EW, EM and C, respectively. The effect of inbreeding on reproduction and production traits was estimated by including the inbreeding coefficient of the hen (Fh), embryo (Fe) and mate (Fs) as a partial linear regression in the model. 4. There was a significant effect of inbreeding on reproduction traits in line EW attributable to the inbreeding of the hen, embryo and mate. No such effect was observed in the other lines. 5. In all lines inbreeding tended to reduce egg number and delay sexual maturity. In general, all lines reacted differently to inbreeding. 相似文献
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1. Cumulative inbreeding attributable to selection in a finite population after long‐term reciprocal recurrent selection (RRS) and modified RRS (MRRS) was studied in two White Leghorn lines.
2. Pedigree information was analysed for a period of 24 generations. In one generation, progeny of full‐sib, half‐sib and unrelated pure‐line as well as reciprocal cross‐line matings were produced.
3. The structure of the two pure lines, which have been consistently used as part of the commercial cross, was documented in terms of numbers of sires and dams mated to produce sons and daughters, and variance of family size. On average, 87 sires and 870 dams per generation were mated to produce offspring.
4. Cumulative inbreeding values determined from pedigree data were compared with estimates from effective population size and variation of family size.
5. The increase in average inbreeding over 23 generations was 11.9% for line A and 10.8% for line B or 0.49% per generation, based on pedigree data.
6. Estimates from family structure were slightly higher: 12.6% for line A and 12.0% for line B or 0.54% per generation.
7. The increase in inbreeding appeared to be linear and independent of the selection method (MRRS compared to RRS). 相似文献
15.
1. Four Japanese quail lines were developed using 13 generations of reciprocal recurrent (lines AA and BB) or within-line selection (lines DD and EE) for high egg number until 98 d of age. In these lines and their reciprocal crosses, egg production, egg weight and mortality were monitored for up to 21 months to evaluate the impact of selection method and line origin on long-term production and heterosis. 2. Both hen-housed total egg number (EN) and hen-day egg laying rate (ELR) were consistently lower in recurrent lines than in lines under within-line selection: after 13 months of test, the difference was -47.1 eggs for EN and -20% for ELR%, whereas mortality was similar at around 20%. 3. Line EE was the best pure line for early egg production (55.2 eggs at 98 d of age) and also gave eggs which were consistently about 2 g larger than those from line DD but it had the highest overall mortality (78.5%) of all lines. On average, line DD laid 399 eggs (EN) over the whole experiment, 84 more than Line EE. 4. Crossbreds from the 2 types of pure lines and line DD had similar patterns and rates of egg production during the whole experiment, as indicated by the similarity of the curves adjusted for those lines by using the monomolecular model for EN and the modified compartmental model for ELR. 5. However, heterosis was higher from recurrent selection lines and it increased more with time than did heterosis from within-line selection lines. 相似文献
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C Hagger 《Journal of animal science》1992,70(7):2045-2052
Two generations of selection on restricted BLUP breeding values were applied in an experiment with laying hens. Selection had been on phenotype of income minus feed cost (IFC) between 21 and 40 wk of age in the previous five generations. The restriction of no genetic change in egg weight was included in the EBV for power-transformed IFC (i.e., IFCt, with t-values of 3.7 and 3.6 in the two generations, respectively). The experiment consisted of two selection lines plus a randomly bred control of 20 male and 80 female breeders each. Observations on 8,844 survivors to 40 wk were available. Relative to the base population average, the restriction reduced genetic gain in IFC from 4.1 and 3.9% to 2.0 and 2.2% per generation in the two selection lines, respectively. Average EBV for egg weight remained nearly constant after a strong increase in the previous five generations. Rates of genetic gain for egg number, body weight, and feed conversion (feed/egg mass) were not affected significantly. In the seventh generation, a genetic gain in feed conversion of 10.3% relative to the phenotypic mean of the base population was obtained. 相似文献
17.
The present study compares embryonic mortality between lines selected for different production traits, assesses the effects of inbreeding of the hen and embryo on embryonic mortality, and estimates genetic parameters of embryonic mortality. The experiment covered 10 generations of selection for increased egg number (EN), egg weight (EW), egg mass (EM) and a control line (C). The data included age at 1st egg, egg number and egg weight. Percent fertile eggs (PF), percent hatched of fertile eggs (PHF) and percent dead chick at hatch (PDH) were also recorded for the selected parents. PDH was higher in the selected lines than in the control line. Among the selected lines, the EW line had the highest embryonic mortality. Inbreeding of the hen and embryo had no significant effect on PDH in any of the lines. Estimates of heritability for PDH were 0.10+/-0.05, 0.02+/-0.02, 0.03+/-0.02 and 0.02+/-0.02 for lines EN, EW, EM and C, respectively. There was a positive genetic correlation between egg weight and PDH in line EW indicating that selection for increased egg weight was associated with high embryonic mortality. A negative genetic correlation between PDH and reproductive traits in line EN was observed, which is favourable. 相似文献
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S.A. Rafat D. Allain & H. de Rochambeau 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2009,126(3):189-197
The chief aims of this paper were the following: (i) to describe the demography and genetic structure in two divergent selected lines for total fleece weight (TFW) of French Angora rabbits with overlapping generations; (ii) to describe the effects of inbreeding during an experiment of divergent selection. A study of longevity with the survival kit showed that there was no significant difference in the risk of death or culling between the low line (LL) and high line (HL). A significant effect of inbreeding (p < 0.05) was observed with a 30% higher risk factor in the highest class of inbreeding coefficient compared with the other classes. The means of generation interval were 562 and 601 days in LL and HL, respectively. The numbers of generations for LL and HL were 3.90 and 3.64, respectively. Generation intervals decreased significantly from 1995 to 2000 (p < 0.05). The number of daughters in HL was very variable. The number of animals per generation was higher in HL than in LL. Each buck left nearly three daughters to the next generation (2.52 in LL, 3.24 in HL). In both lines, the effective number of ancestor genomes still present in the genetic pool of the generation was around eight from the reference population of 1995 to that of 2001. Inbreeding in HL was always higher than in LL. The effect of inbreeding was also significant (p < 0.05) on TFW and live weight. The animals with the lowest inbreeding category produced a higher TFW (p < 0.05) than the others. The observed selection differentials were lower than that expected owing to the breeding animal management rules in order to control inbreeding increase. 相似文献
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D. SHARMA D.C. JOHARI M.C. KATARIA R.C. HAZARY D. CHOUDHARI S.C. MOHAPATRA 《British poultry science》1998,39(1):31-38
1. Data on 13,773 pullets, the progeny of 30 to 50 sires and about 135 to 220 dams per generation of a strain of White Leghorn under long term selection for part period egg production over 16 generations, were examined. 2. Realised genetic gain per generation was highly significant for egg production (2.55 eggs), egg weight (- 0.51 g), age at sexual maturity (- 2.30 d) and 40 week body weight (- 11.73 g). 3. The significant genetic response of 4.46 to 4.72 eggs per generation was realised in the first 8 generations only, which was accompanied by a marked decline in egg weight (- 1.67 and- 0.79 g per generation) and in age at sexual maturity (- 4.63 and- 6.39 d per generation). The 20 and 40 week body weights showed significant improvement in the last 4 generations. 4. Realised heritabilities were much lower in the last 8 than in the first 8 generation. 5. The additive genetic variance for most traits, except 20 week body weight and genetic covariances of egg production with egg weight and age at sexual maturity, declined significantly. 6. Natural selection did not seem to play any major role. No appreciable change in fitness traits was observed in the selected line. 7. The time trends were non-significant for all the traits in the control line, indicating its stability over generations. 相似文献
20.
V.H. Nielsen & I.R. Korsgaard 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2006,123(6):362-368
Mice selected for weight gain from 3 to 9 weeks of age on a normal (N) protein diet containing 19.3% protein and a reduced (R) protein diet with 5.1% protein were reared on both diets in generations 7 and 9. The lines NH, NC, NL, RH, RC and RL (H, high; C, control; L, low) were tested for weight gain on diet N and R and for feed intake and feed efficiency on diet N in generation 7. In generation 9, the lines were tested for body composition traits (fat, protein and water percentage) at 3, 6, 9 and 12 weeks of age on both diets. A significant (p < 0.0001) genotype × environment interaction for growth rate was observed in generation 7. Weight gain at both the protein levels was best improved by selection at the protein level itself. Furthermore, the ranking of the lines on diet N was similar for weight gain, feed intake and feed efficiency. In generation 9 at 9 weeks of age, the ranking of the lines for fat percentage was equal to the ranking for weight gain in generation 7 on both test‐diets. The association between weight gain and protein or water percentage was less pronounced, particularly on diet R. These results suggest that the largest genetic improvement in growth rate is obtained when the protein content of the feed is the same in selection and production. However, when selection is carried out in one environment while the animals have to perform under conditions with varying nutrient protein contents, selection in an inferior environment may be advantageous. 相似文献