Relationship between pup growth, mother weight, food or water intake in four strains of mice.

The partial correlation coefficients were computed between pup growth rate on day 12 of lactation and mother weight on day 11 or daily food or water intake by mother between days 4 and 11 in the 1st to 3rd lactations of four strains of mice, SHN, SLN, C3H/He and GR/A, in order to estimate the influence of food and/or water intake on lactational performance (pup growth) and mother weight. In SHN mice, pup growth rate had negative and positive correlations with food intake and mother weight, respectively, in the 1st lactation. This indicates that food ingested is used for mother weight increase rather than for lactation. On the contrary, there was a positive correlation between pup growth rate and food intake in the 3rd lactation of SHN mice and in the 2nd lactation of GR/A mice, suggesting the preferential contribution of food to lactation. In neither SLN nor C3H/He mice apparent relations between variables were seen. These results suggest the careful choice of mouse strains for studies on nutrition and lactation.