1. Four experiments with 108 rats to compare the nutritive value of sow's milk and cow's milk are described. In Exps. 1–3 the milks were fed on a comparable basis of caloric value.

2. In the first experiment, in which the milk intake was equalized, rats receiving diluted sow's milk grew at a significantly faster rate and utilized their calorie intake more efficiently than rats receiving cow's milk.

3. In the second experiment, again with equalized milk intake, rats receiving sow's milk utilized their calorie intake significantly more efficiently than rats receiving diluted evaporated cow's milk.

4. In the third experiment in which the milks were given without stint, rats receiving diluted sow's milk either with or without the addition of a synthetic vitamin supplement, grew at a faster rate, and utilized their calorie intake significantly more efficiently than rats receiving cow's milk either with or without the same vitamin supplement. The vitamin supplement did not improve the nutritive value of either milk.

5. In the fourth experiment the biological value of the proteins in freeze-dried sow's milk (85·1) proved significantly lower than in freeze-dried cow's milk (90·1).

A preliminary investigation was carried out on the effects of two ranges of temperature (room and refrigerator) on the creaming properties of cows' and buffaloes' milk. The results reported show that:

(1) While refrigerator temperature favoured the creaming of cows' milk, it greatly retarded the creaming of buffaloes' milk. This retarding effect was associated with a smaller cream-layer volume and a greater percentage of fat in the skim milk.

(2) At room temperature, the creaming of buffaloes' milk proceeded much more rapidly, suggesting that fat clumping was probably being induced.

(3) For both kinds of milk, when creamed at room temperature, the maximum values of the cream-layer volume and the specific cream-volume were found to be less than when creaming occurred in the refrigerator: reverse temperature relationships were observed in connexion with the maximum fat content of the skim milks.

In conclusion, it may be added that the observed variations in the cream-layer volume, and the fat content of the skim milks resulting from creaming at the two different temperature levels and for the varying lengths of time, would clearly result in some variability in any cheese made from such milk. This would particularly affect the yield, quality, composition and nutritive value of the cheese.

1. The reworking of stored butter stimulates dormant bacteria into renewed growth and, since these are frequently taint-producing organisms, may hasten the deterioration of retail butter.

2. Blends of sweet cream and ripened cream (acid) butters may contain a greater variety of organisms than reworked samples of either type, and conditions may be created which are even more favourable for bacterial activity.

The changes in the volatile acidity and other factors during the ripening process of Stilton cheese have been studied. The growth of the mould was characterized by an increase in the fat-soluble fatty acids derived from the cheese fat.

Pricking the cheese ensured a more uniform blueing and hastened the ripening. There was no evidence that judicious pricking at 2 months after manufacture seriously affected the course of the ripening. Excessive pricking, however, produced abnormal cheese of poor keeping quality.

The loss of calcium and phosphorus during the manufacture of hard pressed (Cheddar) and impressed (Stilton) cheese made from the same bulk of milk has been studied. It is found that there is little loss of mineral salts from the hard pressed variety either after cutting the curd during making, or while the cheese is ripening. In the case of the unpressed variety there is constantly increasing percentage loss of minerals, correlated with an increase of titratable acidity in the whey, until the last stages of manufacture when the cheese are removed from the hoops for scraping.

The figures confirm those previously found (i) that in the cheese examined 57–58% of the calcium and 50–51% of the phosphorus present in the milk originally used, remains in the hard pressed ripe cheese, but that only 6–8 % of the calcium and 27 % of the phosphorus are left in the unpressed variety when ripe.