Models of infantile undernutrition in rats: effects on milk.

Although there are at least six commonly used methods for producing malnutrition in suckling rat pups, no attempt has been made to determine the quality of the nutrients available to the pups in each of these methods. In the present study, milk composition was determined for each of these methods and related to maternal nutritional status. These methods were: 1) large litters were fostered on the dams; 2) the dams were fed low protein diets; 3) the dams were fed a reduced amount of good quality diet; 4) and 5) the pups were removed from the dams and kept 4) with a non-lactating female or 5) in an incubator for half of the day; and 6) some of each dams' teats were destroyed. Maternal nutritional status was affected only in the cases where the dams' diet was deficient (methods 2 and 3), producing weight loss and lowered hematocrits in both cases and lowered serum protein when the low protein diet was fed. The low protein diet condition resulted in a lower nitrogen content and an elevated total fat content of the mild. It was concluded that previous consideration of all of the above methods as equivalent in terms of the quality of the milk produced is not justified.