【作者】 杨朝武；

【导师】 蒋小松； 朱庆；

【作者基本信息】 四川农业大学 ， 动物遗传资源保护学， 2009， 博士

【摘要】 针对优质肉鸡育种和开发中肉质评定、育种目标、育种方法以及选择方案等环节存在的不足,本研究主要做了四个方面的工作:肉质评价和肉质指数的制定;优质肉鸡育种目标的研究;配套系杂交繁育体系的构建和优化;配套系选择方案的研究,旨在从经济学和育种学相结合探讨适合于优质肉鸡育种的最优策略,力求为生产实践中优质肉鸡选育提供理论基础和技术支持。本研究主要得到如下结论:（1）以四川省畜牧科学研究院与四川省大恒家禽育种公司培养的5个纯系为研究材料,首先对影响肉质的8个指标进行了聚类分析,筛选出4个典型性状,分别是粗脂肪含量（CP）、pH、肌纤维密度（MFN）及滴水损失率（DLR）,然后采用这4个性状借助改进的主成分分析（IPCE）对10个系别的优质鸡肉质进行了综合评价,总体上S01系肉质最好,S03系次之,而D99系肉质最差,由于性别因素对肉质的影响,各系内母鸡肉质均高于公鸡,根据肉质的优劣顺序对集,利用多维偏好线性规划（LINMAP）推导出4个典型性状的权重,进而制定了优质鸡的肉质指数MQI:MQI₁=0.5400CP+0.3953pH+0.6110MFN-0.5463DLR;MQI₂=0.2581CP+0.1888pH+0.2920MFN+0.2611DLR,并分析确定了MQI的取值范围。通过肉质指数可以方便地对优质鸡肉质进行评价,同时在制订综合育种指数或者育种目标评估时,可将肉质指数作为一个独立的性状值与其它性状同步纳入。（2）重点从优质肉鸡生产中扩繁群、孵化阶段、商品代及加工处理几个阶段着手,结合育种实际确定了优质肉鸡育种的肉质、繁殖、生产三类7个目标性状:肉质性状、年产蛋量、受精率、孵化率、出栏体重、饲料转化率和产肉性能,利用边际利润法推导了生产和繁殖类性状的边际效益,而肉质性状的边际效益则是假设肉质指数服从正态分布,优质肉鸡的肉质指数存在一个“最适”分布范围,“最适”范围内、外的肉质存在市场价格差的思路得出;敏感性分析表明生产性能改变对性状边际效益有一定的影响,各类性状的边际效益随着该类性状生产性能的改变而逆向变化,如,产蛋量降低10%导致其自身边际效益提高37.9%,受精率及孵化率的边际效益提高18.8%,但某一类性状生产性能的改变不影响其它类性状的边际效益,另外产品不同价格水平下性状的边际效益会发生改变,其中出栏体重及肉质指数受市场价格因素的影响强于其它性状。（3）对A、B、C、D四个纯系模拟三元杂交和双杂交繁育模式,共两大类48个繁育系统。育种效益评估表明三元杂交系统中C×（A×B）♀配套组合的育种效率为最高,双杂交系统中（C×D）×（A×B）♀最优,三元杂交和双杂交两种繁育体系相比较,三元杂交的成本利润比及育种群与商品代的规模比是双杂交配套的1.03倍和5.99倍,而双杂交配套系统的贴现总利润、每只商品鸡的利润均为三元杂交的1.05倍。结合边际利润法和系统分析原理对48个配套模式中效率最高的（C×D）×（A×B）♀组合内各目标性状的育种重要性进行了评估:单独从各纯系内来看,C系中育种重要性较大的性状依次是13周龄体重（35.95%）、料肉比（25.09%）、屠宰率（14.37%）和肉质指数（10.36%）,D系中育种重要性较大的性状依次为屠宰率（38.17%）、料肉比（19.51%）、年产蛋量（15.84%）及13周龄体重（12.59%）,A系中育种重要性居前三位的是肉质指数（32.05%）、年产蛋量（24.91%）、料肉比（15.71%）,B系中育种重要性较大的两个性状分别是年产蛋量（55.95%）和屠宰率（11.32%）;从整个繁育系统来看,B系年产蛋量是最重要的生产性状,其育种重要性高达18.06%,育种重要性居于第二位的是C系的13周龄体重,为10.55%,其次为A系的肉质指数及D系的屠宰率,育种重要性分别为7.1340%,7.1318%。结合各性状的育种重要性,通过育种目标简化确定了各系的目标性状,C系为出栏体重,D系为产肉性能和出栏体重,A系为肉质指数和年产蛋量,B系为年产蛋量。（4）模拟PLS、CCPS选择方法在（C×D）×（A×B）♀配套组合中对各专门化品系目标性状的选育,研究表明纯种与杂种性能的遗传相关(r_pc)、选择方法、杂种性能的遗传力及育种群规模均为影响选择效率的重要因素,结果显示CCPS的效率普遍高于PLS,但当r_pc值较大时采用CCPS较采用PLS的相对效率明显小于当r_pc值较小时的情况,如在基础群规模ns=60时选育A系肉质,当r_pc=0.2时,采用CCPS法在第10世代的累积遗传进展是采用PLS法的20.01倍,r_pc=0.4时为10.52倍,而当r_pc=0.8时仅为4.43倍,这种情况对C系体重、D系产肉性能及B系产蛋性能呈相同的规律,由此可以推导,当纯种和杂种性能的遗传相关较小时,一般采用CCPS代替PLS,但CCPS的缺点是群体平均近交系数上升较快;当A系采用PLS-MAS及CCPS-MAS选育肉质性能时,遗传进展较单纯使用表型信息的PLS和CCPS有明显的提高,同时有效的控制了近交系数的上升,但研究也表明MAS选育对短期选择更有利。总的来看CCPS和MAS的结合确实可以给选育带来额外的进展。更多还原

【Abstract】 In the last three decades,production of quality chickens has increased rapidly in China and great progress has been made in the field of chicken genetics and breeding. However,with the fast development of quality chicken industry,much more requirements are claimed for the innovation of quality chicken breeding techniques.Aiming at optimizing selection schemes for the quality chicken breeding,this dissertation considers four aspects of quality chicken breeding:evaluation of meat quality,construction of meat quality index,definition of breeding goals,and optimization of selection schemes for specialized lines.The performance data of five commercial quality chicken lines were used to testfy the relevant models developed in this study.The main results and conclusions are as follows:（1） Four representative traits were selected by cluster analysis from eight traits related with meat quality,that is,crude fat content,pH,muscle fiber density and drip loss, and then the meat quality was qualified by using the modified principal component analysis in five quality chicken.The results showed that the meat quality of S01 line was the best,S03 the second,and D99 the worst.Moreover it was found that meat quality of female chickens is higher than that of male chickens in all of the five lines.After getting the sequential data set of meat quality,the meat quality（MQI） was constructed by the linear programming techniques for multidimensional analysis of preference.The MQI not only simplify the qualification of meat quality but also can be brought into the breeding objective as an individual trait performance.（2） Seven objective traits:meat quality,annual egg production,fertilization rate, hatchability,finish weight,feed conversion rate and meat productivity were selected based on actual quality chicken production from three classes traits（meat quality,production and reproduction traits）.And then the marginal benefits of production and reproductive traits were deduced by marginal profits principal,but for the meat quality trait,its marginal benefit was calculated based on the hypothesis that MQI obey normal distribution and the MQI of quality distribute within the optimum range,then there is an market price difference between the MQI within the optimum range and the outside.Sensitivity analyses show that changes of trait performance play an important role in the marginal benefit, which decreasing with the performance improvment of traits self-class.The marginal benefit of egg production,fertilization rate（hatchability） increased by 37.9%,18.8% respectively with the egg production decreased by 10%.Some results also show that marginal benefit varied with the different level of market prices.（3） Total 48 crossbreeding systems,including 24 three-way crossbreeding systems and 24 four-way corssbreeding systems were simulated based on four pure lines A,B,C and D. Cost-benefit evaluation analyses show that C×（A×B）♀and（C×D）×（A×B）♀crossbreeding system is the most high in the three-way and four-way corssbreeding systems respectively, and four-way is better than three-way,the cost/profit ratio and the GGP scale/CS scale ratio of three-way is 1.03 and 5.99 times as much as that of four-way,but the average discounted profit and the profit per commercial chicken of four-way is 1.05 times as much as that of three-way.The maginal profits principal combined with systematic analysis was used to evaluate the marginal benefit and breeding importance of objective traits for each line in foue-way crossbreeding system（C×D）×（A×B）♀,the result indicated that the importance of finish weight（35.95%）,feed conversion ratio（25.09%） and meat productivity（14.37%） were the most important traits in line C,meat productivity（38.17%）, feed conversion ratio（19.51%）,egg productivity（15.84%） and finish weight were the most important in line D,MQI（32.05%）,egg productivity（19.51%） and feed conversion ratio （15.71%） were the most important in line A,egg productivity（55.95%） and meat productivity（11.32%） were the most important traits in line B.Judging from the whole crossbreeding system,egg productivity of line B is the most important objective traits, finish weight of line C is the second,MQI of line A,and meat productivity of line D is the third and forth respectively.Based on these,the study determined the representative selection traits by simplification of breeding objective.（4） Pure line selection（PLS） and combined crossbred and purebred selection（CCPS） were used to breed the objective traits of each specialized line in four-way crossbreeding system（C×D）×（A×B）♀,the simulated selection experiments show that the hereditability of crossbred performance and the beginning generation scale play an important role in selection efficiency besides the selection method and correlation coefficients of purebred and crossbred phenotype(r_pc).And the slection efficiency of CCPS is higher than that of PLS in general,especially the lower r_pc,however,the relative efficiency of CCPS to PLS with lower r_pc is higher than that of higher r_pc,for example,efficiency of CCPS is 20.01, 10.52 and 4.43 times as much as that of PLS with beginning generation scale ns= 60 and r_pc is equal to 0.2,0.4 and 0.8 respectively in line A,same regularity existing in line B,C and D.Thus we deduced that CCPS could use instead of PLS with the lower r_pc,but CCPS has the disadbantage that would increase the inbreeding speed. PLS-MAS and CCPS was used to select in line A,the genetic gains improved much more relative to PLS vs.CCPS which use phenotype information only in the breeding schemes, meanwhile,inbreeding speed appears to be in control effectively.Based on this we can conclude that the CCPS and MAS could bring additional genetic gains for breeding schemes.更多还原