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

INBREEDING EFFECTS ON FEED EFFICIENCY AND REPRODUCTIVE TRAITS IN BROWN EGG LAYERS UNDER RECIPROCAL RECURRENT SELECTION

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。

Cumulative in inbreeding and inbreeding effects on feed efficiency and reproductive traits estimated in two brown egg layer lines Rhode Island Red (AA) and Light Sussex (BB) selected with reciprocal recurrent selection (RRS) for feed efficiency. In one generation, two purelines, their reciprocal crosses and corresponding controls were produced. The increase in average inbreeding over 7 generations for selected lines AA and BB (in parentheses control lines 1AA and 1BB) was 2.58% and 3.23% (9.33% and 8.17%) or 0.43% (1.35%) per generation, based on pedigree data, while that estimated from family structure was 2.91% and 2.83% (5.84% and 5.92%) or 0.42% (0.86%) per generation. The inbreeding depression per 1% inbreeding was highest for hatchabilty (0.5%) and food conversion rate (0.4%), intermediate for egg production (0.3%), and about 0.1% for body weight and egg weight. In our study, because the inbreeding was successfully controled under 3% by 7 generations RRS and suitable percentages of retained breeding animals, the undesirable inbreeding effects were eliminated in the population.