Characteristics of female C57BL/6J mice used in this study
| . | Birth success . | N . | Mean ± s.e.m. . | Range . |
|---|---|---|---|---|
| Age at parturition (days) | 265 | 72±0.2 | 68-85 | |
| Body mass at parturition (g) | 265 | 24.1±0.10 | 19.8-30 | |
| Number of pups born | 265 | 6.4±0.10 | 2-10 | |
| Birth litter mass (g) | 265 | 12.4±0.14 | 4.4-18.2 | |
| Birth pup mass (g) | 265 | 2.0±0.03 | 1.3-4.6 | |
| Number of pups weaned | 256 | 6.1±0.12 | 1-10 | |
| Weaned litter mass (g) | 256 | 54.0±0.76 | 4.9-83.9 | |
| Weaned pup mass | 256 | 8.7±0.06 | 4.9-12.5 | |
| Age at BMR measurement (days) | 304 | 115±0.5 | 100-135 | |
| Body mass at BMR measurement (g) | No | 39 | 22.2±0.25 | 19.6-28.0 |
| Yes | 265 | 24.2±0.08* | 17.7-26.0 | |
| Total | 304 | 24.0±0.09 | 17.7-28.0 | |
| BMR (W) | No | 39 | 0.185±0.0070 | 0.083-0.303 |
| Yes | 265 | 0.194±0.0020NS | 0.102-0.299 | |
| Total | 304 | 0.193±0.0019 | 0.083-0.303 |
| . | Birth success . | N . | Mean ± s.e.m. . | Range . |
|---|---|---|---|---|
| Age at parturition (days) | 265 | 72±0.2 | 68-85 | |
| Body mass at parturition (g) | 265 | 24.1±0.10 | 19.8-30 | |
| Number of pups born | 265 | 6.4±0.10 | 2-10 | |
| Birth litter mass (g) | 265 | 12.4±0.14 | 4.4-18.2 | |
| Birth pup mass (g) | 265 | 2.0±0.03 | 1.3-4.6 | |
| Number of pups weaned | 256 | 6.1±0.12 | 1-10 | |
| Weaned litter mass (g) | 256 | 54.0±0.76 | 4.9-83.9 | |
| Weaned pup mass | 256 | 8.7±0.06 | 4.9-12.5 | |
| Age at BMR measurement (days) | 304 | 115±0.5 | 100-135 | |
| Body mass at BMR measurement (g) | No | 39 | 22.2±0.25 | 19.6-28.0 |
| Yes | 265 | 24.2±0.08* | 17.7-26.0 | |
| Total | 304 | 24.0±0.09 | 17.7-28.0 | |
| BMR (W) | No | 39 | 0.185±0.0070 | 0.083-0.303 |
| Yes | 265 | 0.194±0.0020NS | 0.102-0.299 | |
| Total | 304 | 0.193±0.0019 | 0.083-0.303 |
Pups were weighed individually at weaning, but at birth the pup mass was calculated from birth litter mass and the number of pups in each litter. Animals were considered successful at birth if they gave birth to live pups. Successful and unsuccessful animals were compared by unpaired t-test. *P<0.001, t=−7.37; NSP=0.237, t=−1.2. BMR=basal metabolic rate.