Bandy T R, Eisen E J
J Anim Sci. 1984 Sep;59(3):630-42. doi: 10.2527/jas1984.593630x.
Genetic differences in performance of dams were estimated by linear contrasts using means of two selected lines of mice and reciprocal F1's, F2's and backcrosses. The lines were selected for increased 6-wk body weight (W) or increased litter size (L). Genetic differences estimated were direct average (gD), direct heterosis (hD), maternal average (gM), progeny average (gP), and progeny heterosis (hP). For dam weight and feed consumption from 12 to 21 d postpartum (pp), gD was the largest genetic difference and favored line W. For litter size, litter weight at birth, litter efficiency (litter weight gain/dam feed consumption) from birth to 12 d pp and within litter mortality from 1 to 21 d pp, gD favored L and, except for hD in litter efficiency, was the most important genetic difference for these traits. Direct heterosis was the only significant difference for litter weight at 21 d pp, litter efficiency from 12 to 21 d pp and within litter mortality at parturition. The gM were larger in W than in L for dam weight and feed consumption, and for litter size and weight at birth, but they were usually of smaller magnitude than gD. The gP were significant only in litter traits measured before 12 d pp and favored W. For no trait measured was hP of consequence. Line differences in dam and litter weight accounted for genetic differences in dam feed consumption. Genetic differences in litter size at birth were not due to line differences in dam weight. The lower mortality within litters nursed by crossbred dams was responsible for hD on litter weight and litter efficiency. Within but not among lines, higher mortality rates were associated with larger litters.
通过线性对比，利用两个选定品系的小鼠以及正反交F1、F2和回交后代的均值，估计母鼠性能的遗传差异。这两个品系分别是6周龄体重增加（W）品系和窝仔数增加（L）品系。估计的遗传差异包括直接平均效应（gD）、直接杂种优势（hD）、母体平均效应（gM）、后代平均效应（gP）和后代杂种优势（hP）。对于产后12至21天（pp）的母鼠体重和采食量，gD是最大的遗传差异，且有利于W品系。对于窝仔数、出生时窝仔体重、出生至产后12天的窝仔效率（窝仔体重增加/母鼠采食量）以及产后1至21天的窝内死亡率，gD有利于L品系，并且除了窝仔效率的hD外，是这些性状最重要的遗传差异。直接杂种优势是产后21天窝仔体重、产后12至21天窝仔效率和分娩时窝内死亡率的唯一显著差异。对于母鼠体重和采食量，以及窝仔数和出生时窝仔体重，W品系的gM大于L品系，但通常其幅度小于gD。gP仅在产后12天之前测量的窝仔性状中显著，且有利于W品系。对于所测量的任何性状，hP都无显著影响。母鼠和窝仔体重的品系差异解释了母鼠采食量的遗传差异。出生时窝仔数的遗传差异并非由于母鼠体重的品系差异。杂种母鼠哺育的窝内较低死亡率导致了窝仔体重和窝仔效率的hD。在品系内部而非品系之间，较高的死亡率与较大的窝仔数相关。
