1. The nutritive value of milk sterilized according to the Stork procedure has been studied in laboratory experiments by the method of Mitchell, the rat-repletion method and growth trials with rats and baby pigs.
2. Determinations of biological value of the milk proteins with three groups of six rats by the Mitchell method yielded mean values of 87·0, 88·0 and 85·1 for raw, pasteurized and sterilized milk respectively. The corresponding digestibilities amounted to 96·8, 96·3 and 94·4. The differences were not statistically significant.
3. The relative nutritive value of the three types of milk for the repletion of protein-depleted rats was studied with three groups of eight rats. The average weight gain on feeding daily 40 ml. of either raw, pasteurized or sterilized milk during 5 days was 27·7, 26·3 and 22·9 g. respectively. Again these differences were not statistically significant.
4. No differences in growth rate were obtained if three groups of twelve male and twelve female young rats were fed on raw, pasteurized or sterilized milk supplemented with trace minerals for a period of 6 weeks. The growth rate of rats on exclusive milk diets was, however, far below normal.
5. In growth experiments with baby pigs, fed equal amounts of pasteurized or sterilized milk supplemented with trace minerals, small but statistically non-significant differences in weight gain were found, in favour of the pasteurized milk. The average weight gain on sterilized milk in four separate growth trials amounts to 97, 95, 98 and 98% of that on pasteurized milk. The average 3% less gain on sterilized milk was ascribed partly to more difficult adaptation and less intake of milk solids.
6. These experiments failed to demonstrate a significant decrease in nutritive value of milk sterilized according to the Stork procedure.