The necessity for a rapid and easy micro-method for the determination of lactose in dairy products arose during our work. The procedure for glucose determination in blood was adopted and modified for dairy products. Quantities of 1–10 mg. lactose can be estimated rapidly. Comparison with the macro-method of Lehman gave satisfactory results.

Individual-quarter machine milking is an important technique in the study of mastitis, dairy-cow management and milking-machine design. In the course of such work equipment for this purpose was found necessary and suitable designs had to be produced.

The milk from twelve individual cows in a mixed herd in Shropshire was sampled twice weekly over a period of 12 weeks, which covered the transition from winter to summer conditions of feeding. Detailed analytical results are tabulated, and certain figures presented in graphical form. In addition, bulk samples of both morning's and evening's milk were obtained and tested for fat and solids-not-fat.

On the whole the results show great individual consistency of composition, but an appreciable rise in the crude protein content of the milk from all cows took place in late April and in May, this effect being attributed to the change-over in feeding to an all-grass diet. From a consideration of the figures obtained, it is deduced that:

(1) The average composition of mid-lactation milk may differ markedly from cow to cow, but appears to be unchanged by minor alterations in the winter rations, provided these are reasonably satisfactory to begin with. There is, however, a marked increase in total protein resulting from the introduction of spring-grass feeding.

(2) The results show that a herd, although well-fed and efficiently managed, may produce milk in the late winter months, and even in the early spring, which is below the legal standard of 8·50% in s.n.f.

1. The results discussed in this part of the report were obtained by examination of milk samples taken at approximately fortnightly intervals throughout a period of one year from 298 farms in eight widely separated areas of England and Wales. The samples were examined by the routine resazurin test, the methylene-blue (4½/5½ hr.) test, the methylene-blue (½ hr.) test and the temperature-compensated keeping quality test using clot-on-boiling (c.o.b.) to determine the end-point. For the first three tests, the treatment of the samples and the standards applied conformed to those prescribed officially for these tests in England and Wales. Details are given of the treatment of samples and testing procedure for the temperature-compensated c.o.b. test. With this test two standards, equivalent to a residual keeping quality at 22° C. of 21 and 24 hr. from 9 a.m. on the day of collection of the milk from the farms, for both evening and morning milk were used.

2. The results are analysed on the basis of the proportion of farms and of samples passing or failing the different tests, the effect of shade atmospheric temperature on the incidence of failures and the relationship between the standards imposed by the c.o.b. tests and the official methylene-blue (4½/5½ hr.) test.

The proportion of farms and of samples passing each test was much higher in winter than in summer and was directly related to the prevailing shade atmospheric temperature. However, a proportion of farms was consistently able to comply with the standards. No more than 5% of the total failures by any test could be ascribed to the 60 (20%) best farms, whereas the 60 (20%) worst farms were responsible for as many as 37–60% of the total failures from the 298 farms.

From raw and pasteurized milk and cheese, human, bovine and pig faeces, human nose and throat swabs, 553 pure cultures were isolated and tested by a cross-streak technique on agar. From the same sources, but without isolation and purification of the cultures, 510 samples were also tested by spotting individual colonies with a test-organism culture of Streptococcus agalactiae. A further 8016 samples were tested after enrichment by a quick assay using Str. cremoris as the test organism. The samples examined failed to reveal antibiotic producing streptococci with the exception of some strains of Str. lactis which produced nisin.

Twenty-three strains of lactic acid streptococci were shown to be types of Streptococcus cremoris or Str. lactis by cultural, biochemical and serological means. The antibiotics produced by the cremoris strains could be differentiated readily from the lactis antibiotics, of which at least five different varieties are described. A cross-test and a resistant-strain test were used to differentiate the antibiotics.

Cheese of the Swiss (Emmenthaler, Gruyère, Danish-Swiss) type is popular on the continent of Europe and in America, but severe losses in ripening are caused by contamination with anaerobic sporeformers. Active gas production by the clostridia during ripening causes distension and spoiling of the cheese which becomes unmarketable.