1. An investigation was carried out, using objectively measurable stimuli, to examine the method of assessing the size of the mammary glands of calves by palpation. The method was that described by Swett.

2. The results indicate that the estimated sizes may be very different from the true sizes, although the two are generally highly correlated. In most cases the estimated sizes are significantly smaller than the true sizes.

3. Different judges give very different estimated sizes for the same true sizes, thus it is not justifiable to compare directly glands which have been stated to be of the same size by different judges.

An analysis has been carried out on the milk yield, milk composition and milking-rate records collected in one herd of dairy cows.

It has been shown from the results of eighty-six heifers that for each pound per minute increase in inherent milking rate (i.e. peak flow) the standard lactation yield increases by 419 lb., the maximum daily yield by 0·9 lb., the lactation length by 8 days and the persistency index by 10 days, whilst the lactation solids-not-fat percentage decreases by 0·03 and the fat percentage by 0·04. All except the last coefficient were significant, although it was also shown that the relationship with solids-not-fat percentage was due to an interaction. Similarly, by the calculation of partial regression coefficients it was demonstrated that the relationship between milking rate and standard lactation yield was due to the effect of milking rate on maximum daily yield, lactation length and persistency.

The various theories commonly used to explain the increasing fat content of cow's milk with stage of milking are examined and found inadequate. It is suggested that the trends in fat content as a cow is being milked may be explained by the clustering of the fat globules and the consequent partial filtering out of the clusters as the milk flows from the gland. Evidence for clustering of fat in cow's milk at body temperature is presented and the application of the theory to the sow discussed.

Some few months ago the National Agricultural Advisory Service, South West Sub-Centre, encountered several farms in their area where failure to reach the required standard for designated milk appeared to be connected in some way with pronounced pitting corrosion of aluminium alloy milking buckets, and, on the suggestion of Dr A. R. T. Mattick of the National Institute for Research in Dairying, Reading, the authors of this note were given the opportunity of examining a corroded pail and of tracing the source of the corrosion, if possible.

1. The numbers and species of micro-organisms surviving in commercial high-temperature short-time pasteurized milks sampled direct from the cooling section of the pasteurizer have been determined and compared with those in the corresponding raw milk and in the raw milk after low-temperature pasteurization in the laboratory.

2. The geometric mean counts at 37° C. for twenty-five samples of raw, L.T. and H.T.S.T. pasteurized milks were 74,130, 1,740 and 3,200 per ml. respectively. The corresponding figures at 30° C. were 123,030, 7,080 and 8,510 per ml.

3. The percentage destruction of the bacteria was slightly smaller at all four plants for the H.T.S.T. pasteurized milks than for the corresponding L.T. pasteurized milks. The mean percentage destruction for the L.T. pasteurized milks was 97·7% for bacteria growing at 37° C. and 94·3% for bacteria growing at 30° C. The corresponding figures for the H.T.S.T. pasteurized milks were 95·9 and 93·1%.

1. Commercial samples of milk of Swiss origin, sterilized by rapid heating to high temperatures, developed a positive phosphatase reaction on storage.

2. The optimum temperatures of storage for the development of this positive phosphatase reaction was 30° C.

3. These commercial samples were sterile when received and remained sterile during storage.

4. The developed phosphatase is apparently identical with the normal alkaline phosphatase of raw milk as judged by (a) heat stability, (b) pH optimum and rate of hydrolysis at different pHs, (c) comparison of results by Kay-Graham and Aschaffenburg & Mullen tests.

1. Agglutinating type sera were prepared in rabbits for fourteen representative strains in a collection of sixty-eight group N (‘lactic’) streptococci.

2. Common type antigens, distinct for each named species, were found in strains of Str. lactis (inhibitory varieties), Str. diacetilactis and Str. cremoris.

3. Certain individuals in each of the named ‘groups’ contained additional heterologous antigens, some of which were identical to heterologous (but not the common) antigens in strains of other groups.

4. Quantitative differences in the representation of common antigens were also found.

5. Str. lactis OJ and Str. cremoris HP were shown to be mirror images of each other so far as their type antigens are concerned, containing two common type antigens in inverse proportions of 4:1 respectively. Str. lactis OJ possesses the ‘cremoris group’ type antigen, and the implications of this observation are discussed.

In the determination of aldehyde values of slightly oxidized butterfat samples by Schibsted's method, the colour of the butterfat prevents accurate matching with the colour standard. Interference by butterfat colour is eliminated, and more accurate results are obtained if the colour is measured in a photoelectric colorimeter at a wavelength of 510 mµ. A small constant correction for the absorption by butterfat at this wave-length may be made.

A method for determining the size distribution of fat globules in cream has been described. A thin film (20 μ) of the diluted cream on a microscope slide is preferred to a deeper preparation (0·1 mm.) in a counting chamber in which rise of fat globules to the upper surface is necessary for easy observation. The latter method is less convenient and can give too low an estimate of the proportion of the smallest globules (1 μ and under).

Cream should be diluted 1 in 50 and the concentration of gelatin in the dilution should be sufficient (4–6%) to give a rapid gel formation. The mixture should be cooled till the gelatin thickens before being transferred to the slide if it is to give the most uniform distribution of globules.

It is shown that Vacreator-treatment of cream causes a considerable increase in the proportion of fat present as globules less than 2 μ and a small increase in the proportion present as globules over 10 μ in diameter. Flash-pasteurization, on the other hand, causes a slight decrease in the proportion of fat present as small globules and a considerable increase in that present as large globules.

Butter from flash-pasteurized cream contains numerous large fat globules and fat aggregates, while butter from Vacreator-treated cream contains few large globules. It is suggested that the more uniform subdivision of fat in butter from Vacreator-treated cream explains why butter from Vacreator-treated cream is superior in texture to butter from flash-pasteurized cream.

1. Eighty-three experimental washed curd cheese were made to investigate the effects of variations in the washing and scalding processes upon the qualities of texture and eyehole formation.

2. Texture was influenced markedly by the amount of washing received by the curd, and a ‘half-wash’ procedure which gave the most satisfactory results is described. Good texture was also favoured by low scalding temperatures (98–107° F.) and short scalding times (8–20 min.).

3. Eyehole formation was affected by scalding time (particularly exceeding 30 min.) rather than temperature.

4. The best combination of conditions appeared to be a ‘half wash’ with scalding at 103° F. for a period not exceeding 25 min.

5. Large cheese moulds (30 lb.) failed to yield a satisfactory product and their use is not recommended.

1. Cultures of Str. faecalis, L. plantarum and a strain of Leuconostoc, when added to cheese milk, all brought about an increase in Cheddar flavour intensity in the resultant cheese.

2. Examination of the cheeses for tyramine content showed that the formation of the amine bore no relationship to the increases in flavour intensity. The production of tyramine appeared to be merely incidental in the cheese-ripening process.

3. A survey among the lactic acid bacteria disclosed only one species containing a significant amount of the L( – )-tyrosine decarboxylase enzyme—L. brevis. This species added to cheese milk causes an objectionable ‘yeasty’ flavour in the final cheese.