NJS系小鼠的选育研究Ⅱ、近交过程中血清胆固醇含量的定向选择效应

在连续全同胞近交过程中，以７０日龄血清胆固醇含量选育指标，通过后裔鉴定和定向选择，逐代提高血清胆固醇水平。结果表明：随近交世代增加，血清胆固醇水平呈上升趋势。第１５世代前上升快，选择效果明显。１５世代后，逐渐进入选择极限。第１５代可能为选择顶点。７～１５代时，近交世代（ｘ）与血清胆固醇含量（ｙ）呈显著的直线回归关系（Ｐ＜０．０１），回归公式为：ｙ＝１．１３７３＋０．３２４７ｘ，而１５～２０代时二者间的直线回归关系不显著（Ｐ＜０．０５）。６～１１代、１１～１５代、１５～２０代父子间血清胆固醇含量的回归系数分别为：０．２９３４、０．３６８３、０．４２９６（Ｐ＜０．０５）。第２０世代时，雄、雌小鼠血清胆固醇水平分别为６．３７±０．４０ｍｍｏｌ·Ｌ－１、５．０５±０．５４ｍｍｏｌ·Ｌ－１，是选择前的２．２５、２．００倍。这些值已超过小鼠的正常值范围，表明该品系小鼠已呈高胆固醇血症状态

STUDY ON BREEDING FOR NJS MOUSE STRAIN Ⅱ、DIRECTIVE SELECTION RESPONSE OF SERUM CHOLESTEROL IN THE COURSE OF INBREEDING

In order to improve serum cholesterol of NJS mouse strain with generation,offspring test and directive selection were used in the course of continuous brother sister mating.Serum cholesterol at 70 days was regarded as selective index.The results showed serum cholesterol of the strain tended to increase with generation.Before 15th generation,it increased fast and selective response was obvious.After 15th generation,selection tended to limit. 15th generation maybe was selective plateau.It was regression significanely(P<0.01) between generation (x) and serum cholesterol (y) during 7th～15th generations,and the regression equation was Y=1.1373+0.3247x,but it wasn′t (P>0.05) during 15th～20th generations.During 6th～11th、11th～15th、15th～20th generations,the father son regression coefficient in serum cholesterol was 0.2934、0.3683、0.4296(P<0.05),respectively.At 20th generation,serum cholesterol content at 70 day was 6.37±0.40mmol·L -1 、♀5.05±0.54mmol·L -1 .The value was 2.25、2.00 times as much as one of original stock,respectively.It went beyond the bounds of normal value in mice,and it was in a situation of hypercholesterolemia.