Instituto de Ciencia y Tecnología Animal, Universitat Politècnica de València, 46071 Valencia, Spain.
J Anim Sci. 2013 Jul;91(7):3113-20. doi: 10.2527/jas.2012-6043. Epub 2013 May 8.
The aim of this work was to estimate direct and correlated responses in survival rates in an experiment of selection for ovulation rate (OR) and litter size (LS) in a line of rabbits (OR_LS). From generation 0 to 6 (first selection period), females were selected only for second gestation OR estimated by laparoscopy. From generation 7 to 13 (second selection period), a 2-stage selection for OR and LS was performed. In stage 1, females having the greatest OR at second gestation were selected. In stage 2, selection was for the greatest average LS of the first 2 parities of the females selected in stage 1. Total selection pressure in females was about 30%. The line had approximately 17 males and 75 females per generation. Traits recorded were OR estimated as the number of corpora lutea in both ovaries, number of implanted embryos (IE) estimated as the number of implantation sites, LS estimated as total number of rabbits born recorded at each parity, embryo survival (ES) estimated as IE/OR, fetal survival (FS) estimated as LS/IE, and prenatal survival (PS) estimated as LS/OR. Data were analyzed using Bayesian methodology. The estimated heritabilities of LS, OR, IE, ES, FS, and PS were 0.07, 0.21, 0.10, 0.07, 0.12, and 0.16, respectively. Direct and correlated responses from this study were estimated in each period of selection as the difference between the average genetic values of last and first generation. In the first selection period, OR increased 1.36 ova, but no correlated response was observed in LS due to a decrease on FS. Correlated responses for IE, ES, FS, and PS in the first selection period were 1.11, 0.00, -0.04, and -0.01, respectively. After 7 generations of 2-stage selection for OR and LS, OR increased 1.0 ova and response in LS was 0.9 kits. Correlated responses for IE, ES, FS, and PS in the second selection period were 1.14, 0.02, 0.02, and 0.07, respectively. Two-stage selection for OR and LS can be a promising procedure to improve LS in rabbits.
本研究旨在估计排卵率（OR）和窝产仔数（LS）选择实验中家兔品系的存活率的直接和相关反应（OR_LS）。从第 0 到 6 代（第一选择期），仅对通过腹腔镜估计的第二次妊娠 OR 进行雌性选择。从第 7 到 13 代（第二选择期），对 OR 和 LS 进行了两阶段选择。在第一阶段，选择具有最大的第二次妊娠 OR 的雌性。在第二阶段，选择的是第一阶段选择的雌性的前两次产仔的最大平均 LS。雌性的总选择压力约为 30%。该品系每代大约有 17 只雄性和 75 只雌性。记录的特征是通过腹腔镜估计的双侧卵巢黄体数（OR）、估计的植入胚胎数（IE）作为植入部位数、通过每次产仔记录的总产仔数（LS）估计的窝产仔数、估计的胚胎存活率（ES）作为 IE/OR、胎儿存活率（FS）作为 LS/IE 和产前存活率（PS）作为 LS/OR。使用贝叶斯方法分析数据。LS、OR、IE、ES、FS 和 PS 的估计遗传力分别为 0.07、0.21、0.10、0.07、0.12 和 0.16。每个选择期的直接和相关反应估计为最后一代和第一代的平均遗传值之间的差异。在第一选择期，OR 增加了 1.36 个卵，但由于 FS 下降，LS 没有观察到相关反应。在第一选择期，IE、ES、FS 和 PS 的相关反应分别为 1.11、0.00、-0.04 和-0.01。经过 7 代 OR 和 LS 的两阶段选择，OR 增加了 1.0 个卵，LS 的反应为 0.9 只仔兔。在第二选择期，IE、ES、FS 和 PS 的相关反应分别为 1.14、0.02、0.02 和 0.07。OR 和 LS 的两阶段选择可以成为提高家兔 LS 的有前途的程序。
