Milk supply in rodents can also be modulated by a number of approaches [48, 50, 51] . Variations in litter size lead to differences in adult body weight, although generally the effects in mice are less drastic (around 10% in adulthood) than those observed in offspring nursed by a-casein deficient dams. Alternatively, milk protein concentration can be manipulated by changing the protein content of diet of the nursing dams [45] . Specific alterations in milk composition have been more difficult to achieve technically and have relied on rearing rodent pups by gastrostomal nutrition away from their mothers [52] . However, this results in a radically different early environment as these pups are not exposed to the normal maternal behaviour [53] . Therefore the effect of specific protein restrictions during lactation has not been addressed in detail.