We investigated the relationship between litter size at birth and within‐litter birth weight (BW) characteristics of laboratory mice as a pilot mammal for pig. We obtained records of number born alive (NBA) and total and mean litter BW (LWB, MWB), and maximum and minimum values of within‐litter BW (MaxIWB, MinIWB), range and standard deviation (Range, SDIWB), skewness (Skew), and kurtosis (Kurt) of within‐litter BW for 656 litters at first parity. Pearson's correlations of NBA were highly positive with LWB (0.92), weakly negative with MWB (–0.31), MaxIWB (–0.19), and MinIBW (–0.33), and those of MWB were negligible with Range, SDIWB, Skew, and Kurt (–0.10 to 0.06). Estimated heritabilities, treated as dam traits, were 0.32 for NBA, 0.39 for LWB, 0.24 for MWB, 0.28 for MaxIWB, 0.05 for MinIWB, 0.16 for Range, 0.17 for SDIWB, and 0.00 for Skew and Kurt. Estimated genetic correlation between NBA and LWB was high (0.95). Therefore, LWB could be promising for efficiently improving NBA. The estimated genetic correlation of NBA was negligible with MWB (0.00), positive with MaxIWB (0.10), Range (0.48), and SDIWB (0.36), and negative with MinIWB (–0.36), suggesting that selection for increased NBA brings larger SDIWB and lighter MinIWB.

中文翻译：

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作为猪试验动物的实验室小鼠出生时产仔数与窝内出生体重特征的关系

我们调查了作为猪试验哺乳动物的实验室小鼠出生时的窝产仔数与窝内出生体重 (BW) 特征之间的关系。我们获得了活产数 (NBA) 和总窝体重和平均窝体重 (LWB, MWB) 的记录，以及窝内体重的最大值和最小值 (MaxIWB, MinIWB)、范围和标准差 (Range, SDIWB)、偏度 (偏斜）和峰度 (Kurt) 为 656 窝第一胎次的窝内 BW。Pearson 的 NBA 相关性与 LWB (0.92) 呈高度正相关，与 MWB (–0.31)、MaxIWB (–0.19) 和 MinIBW (–0.33) 呈弱负相关，而 MWB 与 Range、SDIWB、Skew 和 Kurt 的相关性可忽略不计（–0.10 至 0.06）。估计的遗传力，作为大坝性状处理，NBA 为 0.32，LWB 为 0.39，MWB 为 0.24，MaxIWB 为 0.28，MinIWB 为 0.05，Range 为 0.16，SDIWB 为 0.17，和 0。00 代表 Skew 和 Kurt。估计 NBA 和 LWB 之间的遗传相关性很高 (0.95)。因此，LWB 有望有效改善 NBA。估计的 NBA 遗传相关性与 MWB (0.00) 可忽略不计，与 MaxIWB (0.10)、Range (0.48) 和 SDIWB (0.36) 呈正相关，与 MinIWB (–0.36) 呈负相关，这表明选择增加 NBA 会带来更大的 SDIWB和更轻的 MinIWB。