1. The behaviour of dairy cattle under normal commercial conditions of management was studied in two series of observations:

(a) Four cows were observed continuously for 24 hr. on four occasions at approximately two-weekly intervals.

(b) A herd (average fifty-two cows) was observed continuously for 24 hr. on twelve occasions at approximately monthly intervals.

2. Under our conditions and within our definitions, the cows grazed 6–52 hr., lay down 9–22 hr. and loafed 8–26 hr. on an average during 24 hr.

3. The cows ruminated 5–60 hr. per 24 hr.; 4–52 hr. when lying down and 1–08 hr. when loafing.

4. On average the animals defaecated 1T6 times, urinated 9–8 times, and drank 3–8 times in 24 hr.

5. One animal walked an average distance of 1–74 miles per 24 hr., excluding journeys to the cowshed.

6. No aspect of grazing behaviour was found to be strongly related to either current milk yields or air temperature.

7. When on ‘good’ pasture, as compared to ‘poor’, the animals grazed for a shorter time, walked less, and took fewer drinks.

8. From the results of the herd observations a similar periodicity of behaviour during 24 hr. was observed throughout the year but was more apparent when environmental conditions were similar.

9. When the herd was confined to 5 ft. concrete standings during the winter nights, the animals did not rest as comfortably as when out of doors.

10. Major peaks of grazing or eating were recorded after each milking followed by periods of lying down, especially during the night.

11. Time of sunset has been related to the time when grazing ceased and the herd lay down.

12. In view of the data collected, tentative suggestions for improving grazing management are made.

1. A study has been made of the interrelationships between persistency and maximum yield as components of the lactation curve, and of the importance of environment and heredity in determining the shape of the lactation curve of Ayrshire cows.

2. Persistency was defined as the linear constant of the exponential curve expressed as a percentage, maximum yield as the highest 30-day yield as calculated from the records, and total yield as the yield of milk from 15 days to 8½ months after calving.

3. The study was based on milk records computed by the official method of the Scottish Milk Records Association. The data used in much of the work was obtained from five herds of Ayrshire cows and involved 2392 lactations during the period 1920–39.

4. In an exploratory test involving 100 lactations it was found that the exponential curve fitted ninety-five of the lactation curves and that the fit was improved in forty-eight of these ninety-five curves by using the parabolic exponential curve. Five of the lactations were too erratic to be fitted by any simple mathematical curve.

Since the publication of the original paper (1) on the occurrence of slow-reducing coliform organisms in raw milk, further investigational work has been undertaken. During the course of the work two different types of coliform organisms appeared to be responsible for the slow reduction of methylene blue: (a) those having a long lag phase of growth, and (b) those destroyed by a bactericidal substance present in raw milk.

1. Examinations have been made of milk pasteurized by the L.T. ‘Holder’ and H.T.S.T. processes using the same original bulk raw milk. In the preparation of samples care was taken to eliminate the possibility of post-pasteurization contamination. It was hoped that any differences found would be due solely to the effects of the pasteurizing processes above.

2. Samples were examined by (a) colony counts and coliform tests when fresh and after ageing at 18°C. for 24 and 48 hr., (b) methylene-blue and resazurin reduction tests when fresh and after ageing at 18°C. for 45½hr., (c) keeping quality at 18°C. to end-point of 68% alcohol and clot-on-boiling tests. All bacteriological and dye reduction tests were carried out at incubation temperatures of 37, 30 and 22°C.

3. In seven trials the experiments were repeated after storage of the original raw milk for 24 hr. at 40–50°F. (4·4–10·0°C.).

4. Some detailed examinations were made of the bacterial floras of the raw and corresponding pasteurized milks, both when fresh and after ageing.

1. The acid phosphatase content of milk is reasonably constant from quarter to quarter in normal uninfected cows.

2. The acid phosphatase content of milk from infected quarters is enhanced in comparison with the uninfected quarters. The differences found were from 4·1 to over 50 enzyme units per 100 ml. milk.

3. It has been shown that a Streptococcus agalactiae suspension is capable of hydrolysing phenylphosphate at pH 4–1, and it is suggested that this organism is largely responsible for the enhanced enzyme content of the milk from the infected udder.

1. Mammary tissue of the cow and the rat contains acid phosphatase. The respective pH optima are 5·5–5·8 and 6·0.

2. The enzyme in cow mammary tissue is probably one of type AII in the Folley & Kay (10) classification.

3. The acid phosphatase of cow mammary tissue is inhibited by a factor in raw cows' milk. This factor is destroyed by heat.

4. On the basis of rate of hydrolysis of phenylphosphate at the optimum pH there is about 5 times more alkaline phosphatase in the mammary tissue of the cow than acid phosphatase.

5. The effect of adrenalectomy and replacement therapy through the administration of cortical steroids has no marked effect on the acid phosphatase of rat mammary tissue.

In the first part of this study, brief notes are given on the better known varieties of the soft pickled group of cheese which the authors believe to be best suited to warm climatic conditions.

Domiati cheese, a variety of this group, characterized by the addition of an appreciable amount of salt to the milk prior to rennetting, is described in detail. An outline of the steps of its manufacture, the pickling process, and the effect of the amount of salt added to the milk on the composition of the resulting cheese is given.

In the second part the effects of varying additions of salt to both cows' and buffaloes' milk on rennet coagulation, rate of whey drainage, chemical composition and yield of cheese and whey were investigated.

In grading Cheshire cheese, assessments are made of the ‘body’, ‘texture’, ‘crumbliness’, flavour and overall quality. In commercial grading in this country (England) it is not usual to apply a scoring system to these various characteristics, although, in judging cheese for show purposes, points would be assigned to each item. American practice, at least according to the literature, suggests that score cards are in general use for each particular dairy product, so that the various items may be assessed in quantitative terms. For experimental purposes, where it is required to assess the effect of specific variations in conditions of manufacture or storing of the cheese, or to assess the relation between instrumental tests and the judgements of graders and others, some quantitative form of expression of these judgements is essential. However, it has to be borne in mind that the process of forcing the judgement into an arbitrarily selected numerical scale may lead to a certain amount of distortion and may not be entirely satisfactory. Modifications of procedure desirable in the interests of statistical planning may also be unacceptable, in view of the dislocation they may cause to the ingrained habits of the professional foodgrader.

During the autumn of 1946, samples of two Cheddar cheese, one of Canadian, the other of New Zealand manufacture, which had been held in a frozen state (in cold store) for about 7 years were presented to this Institute.