1. A 142-day feeding experiment with twenty-one dairy heifers aged 7–17 months is described.

2. The addition of 0·127 lb. per animal per day of urea to a diet supplying a limited amount of protein resulted in an extra daily live-weight increase of 0·24 lb. per day. This increase was statistically significant and the animals appear therefore to have utilized the urea nitrogen in their metabolism.

3. Animals receiving the same quantity of additional nitrogen in the form of protein showed slightly better live-weight gains than those receiving the urea; although the difference was not significant it seems probable that the protein was a more efficient nitrogen supplement than urea.

1. An experiment is described in which comparisons were made between the effect of (a) mangels (control feeding), (b) artificially dried grass, (c) sprouted maize, and (d) kale used as dietary supplements on the production and nutritive properties of the milk of dairy cows.

2. No significant differences were found between any of the foods in their effect on yield of milk, or its content of fat or solids-not-fat.

3. The feeding of kale and of artificially dried grass markedly increased the colour and vitamin A content of the milk, but sprouted maize had no more effect in this respect than mangels.

4. As compared with the feeding of mangels, sprouted maize and artificially dried grass had no measurable effect on the vitamin B complex level of the milk.

5. The vitamin B2 (complex) level was more variable and was lowest in the milk from the sprouted maize cows. It is not known, however, whether the difference was due to the feeding or to differences in the cows themselves.

6.The same statement applies to figures for the vitamin C level which was highest in the sprouted maize milk.

7. The growth-promoting properties of the milks produced on mangels, artificially dried grass and sprouted maize were compared. The milks were fed, supplemented either with minerals alone, or with minerals plus sugar as a source of energy. In one series of experiments the milks were given adlibitum, in another the intake was “equalized.” No differences were found and it is concluded that under English conditions, this technique does not disclose the presence in milk of a new essential factor.

1. The yield and composition of the milk secreted during a 12-day fast is recorded. The solids-not-fat, the nitrogen partition, the chloride, lactose, fat and phosphatase contents are discussed.

2. The presence of an unknown substance in the “abnormal” milk obtained from two of the cows is recorded, and it is shown that similar amounts of an unknown constituent must also have existed in the starvation milk analysed in the course of their work by Overman & Wright(i). The nature of this substance has not yet been elucidated.

3. Certain substances in the blood were estimated before, during and after the fast, and the possibility of relating changes in them with corresponding changes in the milk is discussed.

On injecting a neutral solution of pure trimethylamine oxide into two quarters of an udder, the quarters increased in turgidity up to 2·5 hr. and then relaxed. The oxide diffused rapidly out of the quarters during the third and fourth hours after injection and a maximum concentration was shown in the urine at the end of the third hour. In a period of 8·3 hr., 76 % of the oxide available for diffusion was recovered from the urine.

The milk obtained 7 hr. after injection contained 7–8 mg. % of tertiary nitrogen, but the secretion had not in that time regained normal composition owing to the interference with the natural functioning of the quarters.

The frequency distribution of the chloride contents of 7802 samples of milk, grouped into morning and evening samples, monthly samples for three consecutive years from the Institute herd, samples from Shorthorn, Guernsey, Ayrshire and Friesian cows, and other miscellaneous samples, has been determined. The mode for morning milk is 81–90 and for evening milk 71–80 mg. %. The mode for Guernsey and Shorthorn milk is 71–80 and for all (6076) samples, 81–90 mg. %. The mode for milk from herds of Friesians known to give milk of low content of solids-not-fat was 111–120 mg. %, but this must not be taken as the value for this breed generally. The average for Shorthorn milk is 97, Guernsey 93, Institute herd 93, all samples 98, special Friesian herd 128 and bulk Institute milk 85 mg. %.

Factors influencing the chloride content of milk such as breed, age of cow, lactation period, number of lactations, seasonal effects, and udder troubles have been discussed from inspection and by deduction from the series of values obtained.

The electrical conductivity of milk increases with chloride content but there is some deviation from the linear law. The conductivity increases at a greater rate than the chloride content in samples high in chloride, probably owing to the increase in electrolytes other than chloride.

It has been repeatedly pointed out(1, 2, 3) that the properties of cheese during the different stages of its manufacture should be correlated with the hydrogenion concentration rather than with the titratable acidity. Little systematic work has, however, so far been carried out in this direction, except for a study of the relationship between pH and titratable acidity in Cheddar cheese by Brown & Price(4). In planning work on similar lines, it was realized that the potentiometric methods of determining pH require expensive equipment and skilled attention, so that a supplementary colorimetric method, if sufficiently accurate to indicate the major changes in pH, should appeal more strongly to the practical cheesemaker on account of its cheapness and simplicity and the ease with which the outfit can be transported.

Measurements are reported of the solubility, in water and in sodium chloride solution of different concentrations, of the protein of cheese at various times after manufacture. The solubility in 3–10 % sodium chloride solutions reached approximately 100% within 7 days after manufacture of the cheese, both for normal and high rennet cheese, and remained at that value throughout the life of the cheese (8 months). Since the proteins of cheese are thus shown to be equally soluble in sodium chloride solutions corresponding in concentration to those encountered in the whole range of commercial cheese(1), the effect of salt concentration on cheese quality is not to be attributed to a variation in the solubility of the protein in the brine.

Rinds from home-produced and Dominion Cheddar cheese contain from 15 to 20 % of moisture, but those from unripe cheese contain up to 27 %. Salt tends to diffuse into the interior of cheese while the rind is slowly drying, but the rate of diffusion is not quantitatively proportional to the moisture content, although closely approached in cheese requiring a long period of ripening.

There is an appreciable loss of fat from the rind through absorption by the bandage. The fat has a high acid value and carries the characteristic taste of the rind.

Rinds have a higher crude protein content than the interior of cheese; the extent of protein breakdown is less but can be correlated with that in the interior of the cheese.

Rinds contain higher calcium and phosphorus contents in the dry matter and a higher Ca/P ratio than the interior of cheese.

The fibre content of rinds is negligible. The content can be gauged from a visual inspection of a sample for portions of bandage.

An apparatus is described for measuring the elastic and plastic deformations of cheese curd under a compressive load at the time when it is ready for cutting. A figure inversely proportional to shear modulus can be obtained with considerable accuracy, and is believed to serve as the best single criterion of “firmness” in deciding the optimum time to cut the curd.

The keeping quality of milk is a factor which is of considerable importance from the commercial aspect, yet the relationship which exists between the keeping quality and the bacteriological standards as laid down in the Milk Special Designations Order, 1936, has not been fully explored. Wilson compared the keeping quality at 17·5°C. of samples of mixed morning and evening milk with the reduction times at different temperatures and found, in each case, a relatively poor correlation. Since the samples consisted of mixed morning and evening milk it is not possible to state the age of the milk when the tests were commenced. Much of the Tuberculin Tested milk sold in the Provinces is bottled on the farm, and consequently the milk produced in the morning is bottled separately from that produced in the evening.