绵羊FSTL3基因g.40674542C>T位点多态性与产羔数的关联分析

文章旨在探究绵羊FSTL3基因g.40674542C>T位点多态性与绵羊产羔数之间的关系,以期为绵羊高繁殖力分子育种提供新的遗传标记。利用全基因组重测序结合Sequenom MassARRAY~SNP技术对常年发情绵羊品种(小尾寒羊、策勒黑羊和湖羊)和季节性发情绵羊品种(滩羊、苏尼特羊和草原型藏羊)FSTL3基因g.40674542C>T位点多态性进行了检测,并与小尾寒羊产羔数进行了关联分析。结果表明:FSTL3基因g.40674542C>T位点存在CC、TC和TT三种基因型,基因型频率和等位基因频率在两种发情模式绵羊品种间差异均不显著(P>0.05);g.40674542C>T位点在6个绵羊品种中均表现为低度多态(PIC<0.25),经卡方适合性检验,该位点在小尾寒羊、湖羊和草原型藏羊中处于哈代温伯格平衡状态(P>0.05),在其余3个绵羊品种中处于哈代温伯格不平衡状态;g.40674542C>T位点不同基因型与小尾寒羊第一、第二以及第三胎产羔数均无显著关联(P>0.05)。说明FSTL3基因g.40674542C>T位点不适合用于小尾寒羊产羔数选育。     

淮阴苜蓿SSR指纹图谱的构建

采用不同的取样策略,利用SSR分子标记研究淮阴苜蓿（Medicago sativa Huaiyin）遗传多样性,确定最佳取样数,在此基础上利用筛选的SSR引物构建淮阴苜蓿的指纹图谱,并对淮阴苜蓿进行品种鉴定。本研究对320株淮阴苜蓿的单株基因组DNA设置6个处理（10、20、30、40、50、60单株DNA随机等量混合）,每处理8个重复,利用筛选的4对SSR引物进行遗传多样性分析。结果表明,40株单株随机DNA的混合样品的遗传多样性指数开始趋于稳定,由此取40株即可代表淮阴苜蓿群体。采用取样数为40株单株DNA混合样,利用筛选的3对SSR引物构建淮阴苜蓿指纹图谱,并对15份供试苜蓿材料进行检测,结果表明,该方法所构建淮阴苜蓿SSR指纹图谱可以用于对淮阴苜蓿品种的鉴定。     

Comparison of genetic improvement for litter size at birth by direct and indirect selection in swine herd

Responses to selection for number of piglets born alive (NBA) by the total number of piglets born (TNB), the NBA, and the NBA plus number of piglets born dead (NBD) were compared using the accuracy of selection and expected genetic gain calculated from the selection index with family information and the real response to selection, using data generated by Monte Carlo computer simulation. The accuracy of selection for NBA selected by TNB was higher than that by NBA only if the genetic correlation between TNB and NBA was close to 1.0, or the value of heritability for the TNB was much larger than that for the NBA. The accuracy of selection for the NBA selected by the combination of the TNB and the NBA was generally highest in the three selection methods in each family structure. Selection by the TNB resulted in the greatest expected genetic gain for the TNB among the selection methods. In the best linear unbiased prediction (BLUP) selection, the genetic gain for the NBA accumulated by the NBA tended to be similar to that accumulated by the combination of the NBA and the NBD, and both genetic gains at generation 10 were significantly larger than that by the TNB (P < 0.001). The accumulated responses selected by the two‐trait animal model BLUP estimated from genetic parameters with errors were similar to those estimated from the true parameters, and there was no significant difference between them. These results indicate that selection by the NBA or by the NBA and the NBD gives more genetic improvement in the NBA than that by the TNB.     

Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Geographic variation in life‐history traits among populations of wide‐ranging species is influenced by both spatial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concurrently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine amongpopulation differences in strategies of reproductive energy allocation. Adult females from the southern population were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated population differences in overall reproductive output after accounting for body size. The trend for greater reproductive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corroborated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub‐tropical southern environments. In contrast, allocating greater resources to early reproduction may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.     

蛋重和蛋形指数对黑凤鸡种蛋孵化率的影响

测量了黑凤鸡种蛋的蛋重和蛋形指数，研究蛋重和蛋形指数对黑凤鸡种蛋孵化率的影响。结果表明：黑凤鸡种蛋蛋重在36．8。46．9g，蛋形指数在0．675--0．789孵化率较高。     

散养模式下白羽肉鸭屠宰性能与体尺指标相关性研究

本研究对30只94日龄中畜小型白羽肉鸭(CMD)在大群地面散养方式下的屠宰性能和体尺指标进行了测定,并对测定结果进行了相关分析,结果发现活重与体斜长、龙骨长、胸宽、胫围、半潜水长等体尺指标的相关系数分别达到0.588、0.660、0.618、0.654、0.582,均达到极显著水平(P<0.01);全净膛重与体斜长、龙骨长、胫围、半潜水长等体尺指标的相关系数分别达到0.476、0.566、0.552、0.455,均达到显著(P<0.05)或极显著水平(P<0.01)。此外,研究分别建立了活重与体斜长、龙骨长、胸宽、胫围、半潜水长以及全净膛重与体斜长、龙骨长、胫围、半潜水长的回归模型,两个回归模型经F检验均达到显著水平(P<0.05)。     

Patient and tumour factors influencing canine mast cell tumour histological grade and mitotic index

The aim of this study was to identify patient and tumour factors most frequently associated with high histological grades of canine mast cell tumours (MCTs). Search criteria in a shared database of multiple Animal Referral Hospital locations within Australia generated 400 canine MCTs in 286 patients. Patient and tumour data were extrapolated and the association between a tumour being histologically high grade and patient and tumour factors, including: patient breed, patient gender and neuter status, patient age at MCT excision, tumour location and tumour size was assessed using univariate analysis. The study consisted of 90 (21.9%) tumours meeting histological high‐grade criteria. Shar peis were the most likely breed to have high grade MCTs, whereas the Pug and the Golden Retriever were the least likely breeds to develop high‐grade MCTs. No significant difference in risks could be established between the age at which the tumour was excised, or the gender and neuter status of patients. MCTs of the inguinal region were the most likely single location to be high grade. Tumour size did not influence the likelihood of a tumour being high grade or low grade. The results of this study suggest that patient and tumour factors may play a role in the histological grades of canine MCTs.     

Genetic parameters for litter size,piglet growth and sow's early growth and body composition in the Chinese–European line Tai Zumu

Genetics of piglet growth in association with sow's early growth and body composition were estimated in the Tai Zumu line. Piglet and sow's litter growth traits were calculated from individual weights collected at birth and at 3 weeks of age. Sow's litter traits included the number of piglets born alive (NBA), the mean piglet weight (MW) and the standard deviation of weights within the litter (SDW). Sow's early growth was measured by the age at 100 kg (A₁₀₀), and body composition included backfat thickness (BF₁₀₀). A main objective of this study was to estimate separately the direct genetic effect (d) and the maternal genetic effect (m) on piglet weight and daily weight gain during lactation. Variance components were estimated using the restricted maximum likelihood methodology based on animal models. The heritability estimates were 0.19 for NBA, 0.15 and 0.26 for SDW and MW at 3 weeks and 0.42 and 0.70 for A₁₀₀ and BF₁₀₀. The NBA was almost independent from SDW. Conversely, the A₁₀₀ and BF₁₀₀ were correlated unfavourably with SDW (r_g<−0.24, SE<0.12). A stronger selection for litter size should have little effect on litter homogeneity in weights. Selection for lean growth rate tends to favour heterogeneity in weights. The direct effect on piglet weight at birth and daily weight gain accounted for 12% (h² (d) = 0.02) and 50% (h² (d) = 0.11) of the genetic variance, respectively. The association between d and m for piglet weight was not different from zero at birth (r_g = 0.19, SE = 0.27), but a strong antagonism between d and m for daily weight gain from birth to 3 weeks was found (r_g = −0.41, SE = 0.17). Substantial direct and maternal genetic effects influenced piglet growth until weaning in opposite way.     

Evaluation of genetic trends and determination of the optimal number of cumulative records of parity required in reproductive traits in a Large White pig population

Genetic improvement of the reproductive performance of pigs is important for pig breeding despite their low heritabilities. The objectives of this study were to investigate the effectiveness of selection concerning reproductive traits and to determine the optimal number of parity records required for accurate estimation of breeding values (BVs) in the open population of a commercial pig breeding company. The study used records of 2220 purebred Large White pigs (9845 litters) farrowed between 1998 and 2009 in the two herds of the Pacific Ocean Breeding Co. Ltd. The traits studied included farrowing interval (FI), total number of piglets at birth (TNB), average weaning weight per litter (AWW), and raising rate (RR). A statistical model was applied to the 4‐trait repeatability animal model. The heritabilities of FI, TNB, AWW and RR were low. The genetic trends in TNB (h² = 0.09) showed approximately 1.0 increase in 6 years from 2003 to 2008. The predicted error variances indicated that up to fourth parity records are necessary for accurate genetic evaluation. The present study results indicated that even reproductive traits with low heritability can be improved.     

绵羊DUSP6基因多态性及其与产羔数关联分析

文章旨在探究绵羊DUSP6基因g.125589716G>A、g.125587728C>T、g.125589714C>T、g.125589006G>A四个位点多态性及其与产羔数之间的关系,以期找到与绵羊高繁殖力相关的分子标记。利用全基因组重测序结合Sequenom MassARRAY誖SNP技术对多羔绵羊品种(小尾寒羊、湖羊、策勒黑羊)和单羔绵羊品种(滩羊、苏尼特羊、萨福克羊、草原型藏羊)DUSP6基因上述4个多态位点进行检测,并与小尾寒羊产羔数进行关联分析。结果表明:绵羊g.125589716G>A位点在多羔绵羊品种中存在AA、GA、GG三种基因型,在单羔绵羊品种中存在GA、GG两种基因型;g.125587728C>T、g.125589714C>T位点在单、多羔绵羊品种中均存在CC、CT、TT三种基因型;g.125589006G>A位点在单、多羔绵羊群体中均只存在GA、GG两种基因型。绵羊DUSP6基因g.125589716G>A位点基因型频率在单、多羔绵羊品种之间差异显著(P<0.05),等位基因频率在单、多羔绵羊品种间差异极显著(P<0.01);g.125587728C>T、g.125589714C>T位点基因型频率和等位基因频率在单、多羔绵羊品种间差异均达极显著水平(P<0.01);g.125589006G>A位点基因型频率和等位基因频率在单、多羔绵羊品种间差异不显著(P>0.05)。关联分析表明,DUSP6基因各SNPs多态性与小尾寒羊不同胎次产羔数之间无显著关联(P>0.05)。综上说明,绵羊DUSP6基因g.125589716G>A、g.125587728C>T、g.125589714C>T以及g.125589006G>A等4个位点的多态性与小尾寒羊各胎次产羔数之间均无显著关联(P>0.05),不适用于小尾寒羊多羔性状选育。