近交对内蒙古白绒山羊体重和产绒量的影响

内蒙古白绒山羊主要是通过本品种选育进行繁育。随着BLUP方法在内蒙古白绒山羊选育上的应用,很大程度上造成了近交的上升。通过对内蒙古白绒山羊近交程度随世代的变化情况、以及近交对生长性状和产绒性状的影响的详细分析,发现随着近交系数的增加,出生重、断奶重、周岁重及产绒量都趋近于正态分布。当近交系数在0.015625～0.03125区间内,各体重值及产绒量均达到最高值。     

深县猪选育系的近交效应分析

深县猪选育系的近交效应分析王秀利，师守堃（中国农业大学动物科技学院北京１０００９４）黄殿仲（河北省石家庄地区畜牧局）前言在猪的选育提高过程中，目前常常采用部分开放式的系统选育，即优秀祖先或世代猪的基因随时补充进世代群，然后根据需要，再进行闭锁选育。无...     

山西瘦肉型猪新品系(SD-Ⅰ系)6月龄体重遗传趋势分析

用混合模型ＢＬＵＰ法对山西瘦肉型猪新品系（ＳＤ Ⅰ系）选育过程中０～４世代４０头公猪的４４７头后裔６月龄体重进行了遗传趋势评估。结果表明：群体平均育种值随世代的增加而增加，说明ＳＤ Ⅰ系猪选育过程中所采取的育种措施是有效的。各世代间环境条件基本一致，且除０世代外，对表型值都有正的效应。继续进行选育，６月龄体重尚有提高的可能。     

山西肉型猪新品系（SD—Ⅰ系）6月龄体重遗传趋势分析

用混合模型ＢＬＵＰ法对山西瘦肉型猪新品系（ＳＤ－Ⅰ系）选育过程中０－４世代４０头公猪的４４７头后裔６月龄体重进行了遗传趋势评估。结果表明，群体平均育种值随世代的增加而增加，说明ＳＤ－Ⅰ系猪选育过程中所采取的育种措施是有效的。各世代间基本一致，且除０世代外，对表型值都有正的效应。继续进行选育，６月体重有提高的可能。     

日粮能量、蛋白质和微量元素添加剂水平对生长肥育猪综合生产性能的影响

采用Ｌ９（３４）正文试验设计方法，分析日粮能量、蛋＊白质和微量元素添加剂水平对生长肥育猪日增重、饲＊料报酬、胴体品质、肉品品质和经济效益２５项指标的＊影响，发现能量是影响综合生产性能的主要因素，蛋白＊质为次要因素，微量元素添加剂的作用居三。２０－＊３５ｋｇ，３５－６０ｋｇ，６０－９０ｋｇ阶段消化能、蛋白质和微量＊元素添加剂的需要量及其最优组合分别为１３．８１兆＊焦耳／千克、１６％、０．５％；１３．８１兆焦耳／千克、１４％、＊０．５％和１３．８１兆焦耳／千克、１２．２７％、０．４％。此组合＊与饲养标准相比提高经济效益２５．３０％。日粮能量水＊平对胴体脂肪含量、膘厚和肌肉大理石纹有显著影＊响，均随能量水平提高而增加。     

简州大耳羊体重体尺世代选育进展及生长发育规律研究

为探索简州大耳羊的生长发育规律,对简州大耳羊核心群世代选育体重、体尺数据资料进行了分析。结果表明:通过世代选育,简州大耳羊各世代核心群均有所提高,但各世代间增量不同。选育进入第三世代后,体重、体尺指标趋于稳定。同时,抽样测定了简州大耳羊品种群2745只羊的生长性能。结果表明:简州大耳羊个体大、生长发育快,在舍饲条件下,公羊2月龄(断奶)平均体重14.25 kg,母羊12.43 kg;公羊6月龄平均体重29.37 kg,母羊23.14 kg;公羊周岁平均体重47.19 kg,母羊34.67kg;公羊成年平均体重69.68kg,母羊47.26kg。简州大耳羊初生到周岁公、母羊平均日增重分别为120.91 g和86.96 g。简州大耳羊生长发育曲线表明,从断奶至8月龄的体重呈直线上升趋势,从8月龄开始生长发育速度减缓,说明简州大耳羊具有早期生长发育快的基本特征。     

晋汾白猪生长发育性状的选育研究

晋汾白猪是以马身猪、太湖猪、长白猪和大白猪为育种素材,通过复杂杂交育种和标记辅助选择而育成的一个瘦肉型猪新品种。试验对6个世代后备猪生长发育性状的选育结果进行分析,结果发现,后备公猪6世代与0世代相比,初生重提高了0.13 kg,断奶重提高了0.56 kg,70日龄体重提高了1.69 kg,180日龄体重提高了12.46 kg,70~180日龄平均日增重提高了107.00 g,差异均显著(P<0.05);后备母猪180日龄体重6世代比0世代显著提高了10.84 kg(P<0.05)。后备公猪和母猪4、5世代的初生重、断奶重、180日龄体重和70~180日龄日增重均显著高于0世代(P<0.05)。选育结果表明,晋汾白猪的生长发育性状取得了较大的遗传进展。     

羊近交衰退的研究进展

近交衰退是动物育种中必须考虑的因素之一。文章介绍了近交衰退产生的机制,以及近交对羊繁殖性状、生长性状和绒毛性状影响的研究进展。分析发现,除了绒毛品质(长度和细度)外,近交对所有分析性状均产生不利影响。近交显著降低母羊繁殖力和羔羊存活率,同时随着近交的增加,母羊产羔性能也略有下降,羔羊初生重、断奶重、2月龄体重、3月龄体重、6月龄体重、9月龄体重及周岁重均表现出不同程度的衰退。近交增加到一定程度后,对产绒量有不利效应,但对绒毛长度和细度无显著影响。     

不同抗应激措施对断奶仔猪的影响

本试验研究了不同抗应激措施对刚断奶仔猪的影响。结果表明，效果较好的措施有：１．在全漏缝地板仔＊猪高床上安置部分木质铺板；２．采用潮拌料过渡饲喂；＊３．开始１星期内添加氯丙嗪或Ｓｅ－Ｖ合剂；４．在断奶后培育阶段添加电解质溶液。这些措施加能使断奶仔猪得到较好的过渡，减少应激反应，提高生产效益。     

长白猪和民猪生长发育的试验研究

为弄清舍饲状态下长白猪和民猪体重和组织器官等生长发育情况，进行了屠宰测定试验。测定结果表明，在8月龄前体重与月龄呈明显的线性相关，生长曲线符合生物生长规律，绝对生长曲线呈钟状对称正态分布，相对生长曲线随月龄下降。对各阶段内脏器官的测定结果表明，胃和大肠的生长强度始终大于体重的生长，肝、肺、肾和小肠的生长强度小于体重的生长。对2种猪生长发育的测定表明，在2．4-4．0月龄阶段，是体重和各组织器官生长发育较强烈的时期。     

新太湖猪选育过程中近交技术的应用及效应分析

利用新太湖猪选育过程中（１９８６～１９９４）６个世代母猪的分娩产仔记录,后备猪生长发育测定资料,分析了近交对繁殖性能和生长发育性状的影响。相关分析表明,近交与产仔数、产活仔数的相关系数分别为－０．１６２５、－０．１５４６。与１８０日龄活重、体高、胸围、及８０ｋｇ时背膘厚度的相关系数分别为－０．１３５,－０．２１１,－０．２１８,－０．２０４。回归分析表明,近交系数每上升１０％,产仔数下降０．３９头,１８０日龄活重下降１．５ｋｇ,背膘厚下降０．０７４８ｃｍ。产仔记录分析表明,母猪近交系数在２０％以下时,产仔数比非近交组下降０．２７头,差异不显著（Ｐ＞０．０５）;近交系数在２０％以上时,下降１．３５头,差异不显著（Ｐ＞０．０５）。生长发育性状表明,近交系数在３０％以上时,１２０日龄活重、１８０日龄活重等性状都显著下降。８０ｋｇ活体背膘厚当个体近交系数上升到２０％以上时,与非近交组相比下降０．１６ｃｍ,差异显著（Ｐ＜０．０５）。     

Inbreeding components of body weight and growth rate in Japanese Quail.

1. The parental inbreeding component of body weight and daily gain was partitioned into paternal and maternal inbreeding components and the latter were found to be the mor important. 2. The contribution of the maternal inbreeding to the depression of characters was more pronounced on 1-d-old chicks, but declined as the chicks grew. 3. The body weight taken near sexual maturity showed a low and non-significant decline. 4. In spite of differences in the body weight of the two populations of Japanese quail the inbreeding components were similar.     

Effects of different rates of inbreeding on the body weight and rate of gain of Japanese quail.

1. The effect of regular full-sib and double first cousin mating on body weight and rate of gain over six generations of Japanese quail was determined. 2. The depression of characters was more pronounced in the full-sib than in the double first cousin mating system, the relative depression due to parental inbreeding and offspring inbreeding depending on the magnitude of parental effect and individual's own genotypic effect on the character. 3. The body weight and rate of gain taken at an early age showed greater depression due to parental inbreeding whereas that taken near sexual maturity was depressed mainly due to individual's own inbreeding.     

The effect of inbreeding on the manifestations of some physiological traits in the Kladrub Black Horse strain

Inbreeding was used in the regeneration process in the breeding of the Kladrub Black Horse. Inbreeding rate is realized in practice, as related to the manifestation of the selected characteristics of this unique horse population. The evaluation of the effect of inbreeding on conception rate and fertility did not demonstrate any differences between the group of inbred mares and non-inbred mares. The study was conducted in mares used for breeding for 10 years. The results provide evidence that inbreeding causes no depression in this characteristics in the Kladrub Black Horse which would otherwise be the first physiological function in the reproduction process to be altered as a result of inbreeding. The evaluation of the effect of inbreeding on growth rate by comparing it with the standard growth curves which were characterized by the exponential function y = A (1 -- e-k(t-to)) did not indicate any statistically significant differences in growth dynamics between foals with a zero Fx value and inbred foals. This study was based on the evaluation of growth rate in the basic body traits and weight. It is inferred that inbreeding does not reduce growth dynamics of different body measurements and weight. Similarly, the evaluation of the body dimensions and weight of inbred and non-inbred adults showed no significant differences. Similar results were obtained from the evaluation of the relation between inbreeding and body constitution, character, and temperament. All the correlation coefficients are very low, almost equal to zero.     

Assessment of inbreeding depression for body measurements in Spanish Purebred (Andalusian) horses

Our aim was to ascertain inbreeding depression in the Spanish Purebred horses for eight body measurements. A total of 16,472 individuals were measured for height at withers, height at chest, leg length, body length, width of chest, heart girth circumference, knee perimeter and cannon bone circumference. Three different multivariate animal models including, respectively, no measure of inbreeding, individual inbreeding coefficients (F_i) or individual increase in inbreeding coefficients (ΔF_i) as linear covariates were used. Significant inbreeding depression was assessed. Even though the models including measures of inbreeding fitted better with data, no effect on estimates of genetic parameters was assessed. However, the inclusion of inbreeding measures affected the ranking order according to the Expected Breeding Values (EBV). Due to the better fit with data and nice properties (the adjustment of individual inbreeding coefficients with the pedigree depth and linear behaviour) the use of ΔF_i in the evaluation models can be recommended for morphological traits in horses.     

近交对狼山鸡繁殖性状影响的研究

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。     

正反反复选择下近交对褐壳蛋鸡饲料利用率和繁殖性状的影响

本文估计了褐壳蛋鸡洛岛红(AA)和浅花苏赛克斯(BB)在正反反复选择(RRS)下的近交系数,分析了近交对选择标准饲料利用率及其相关性状和繁殖性状的影响。试验群体由两纯种及其正反交组合和相应的对照组组成。经过7个世代的RRS和近交试验,试验组AA和BB(括弧里为对照组1AA和1BB)用系谱材料计算出的平均累积近交系数分别为2.58％和3.23％(9.33和8.17%)或每代为0.43%(1.35%),用有效群体含量估计出的AA与BB的相应数值为2.91％与2.83％(5.84%与5.92％)或每代为0.42％(0.86％)。1％近交系数导致的孵化率和饲料利用率的近交衰退较严重(0.5％和0.4％),其次是产蛋性状(约0.3％),而体重和蛋重只有0.1％左右。在本研究中,通过连续7代的RRS与合适的留种率等措施,成功地将闭锁群体的近交系数控制在3%以下的低水平,消除或减轻了近交对饲料利用率等重要经济性状的不利影响。     

Inbreeding depression for economically important traits of Mazandaran native fowls

1. The objective was to investigate inbreeding depression for some economic traits of Mazandaran native fowls using data collected from 1992 to 2012 (21 generations) using a REML animal model of significant fixed and random effects with inbreeding of birds and dams as covariates.

2. The mean inbreeding coefficient (F) for the whole population and dams was 4.67% and 4.12%, respectively, and most of the inbred birds (75.79%) and inbred dams (72.58%) had F < 12.5%.

3. Individual and dam inbreeding trends were 0.55% and 0.53% per year.

4. Inbreeding depression for body weight at hatch, at 8 weeks and 12 weeks of age, age at sexual maturity, weight at sexual maturity, egg weight at 1st d of laying and average egg weight at 28, 30 and 32 weeks of laying due to a 1% increase in individual inbreeding were ?0.11 g, ?3.1 g, ?1.3 g, 0.15 d, 0.59 g, ?0.05 g and ?0.03 g, respectively.

5. A 1% increase in maternal inbreeding resulted in a reduction of 0.06, 0.6 and 3.6 g in body weight at hatch, 8 weeks and 12 weeks of age.

     

Inbreeding and heterosis effects on quantitative traits in a White Leghorn population under long-term reciprocal recurrent selection

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.