The records of calf sales to the Ministry of Food have been examined for the years 1943–7 and maps made to show variations in (a) the percentage disposal of the annual calf crop, and (b) the percentage autumn calf sales, in different parts of Great Britain. These have enabled the intensive dairying areas and the extensive rearing areas to be denned.

It is postulated that the variations in the seasonality of calf sales in different areas may be influenced by factors other than husbandry, and that climate may have both direct and indirect effects upon the development of winter oestrus in cattle.

It is suggested that the seasonal distribution of the sale of surplus calves through the collecting centres of the Ministry of Food in west Wales during the years 1943–6 is a reasonably accurate reflexion of the rate of calving in the areas associated with these centres. It is shown that between the centres there is a considerable difference in the seasonal distribution of calf sales, and that the percentage numbers of autumn calf sales (September to December) show a gradual decline from the westerly coastal centres to the easterly inland ones. It is also found that the figures for the milk production and particularly the milk deliveries into the factories during the period September to December support the above suggestion.

There appears to be a west to east cline in the four north Wales counties in: (i) the proportion of calves sold during the autumn months September to December; (ii) the proportion of December milk sales in relation to the September sales; (iii) the proportion of the dairy and breeding herd in milk during the winter; (iv) the quarterly rates of conception in heifers during the period 4 December to 4 March. There does not appear to be any relation between percentage winter milk production and percentage tillage area in this region. It is postulated that the west to east cline is dependent mainly upon factors other than husbandry and that climatic conditions, particularly the hours of bright sunshine during the winter months, have a marked influence upon the breeding performance of cows and heifers during the period December to March.

This investigation has formed part of the survey of animal health and production in Wales, and thanks are due to the scientific branch of Messrs Cooper, McDougall and Robertson, Berkhamsted, for financial support. Grateful acknowledgement is made to the Ministry of Food, Colwyn Bay, for readiness in providing data and helpful advice; to Messrs Pritchard, Auctioneers, Bangor, and Messrs Beardmore, Auctioneers, Abergele, for permission to examine their records; to the Milk Marketing Board for providing the data on milk sales; to Profs. A. N. Worden and E. G. Bowen for the interest they have taken in the work.

Regular testing at 3-monthly intervals for periods extending to 7 years of some 650 to 850 cows in fourteen herds indicated that the majority of the new infections caused by Sir. agalactiae were recorded in the autumn months, August, September and October.

When infections were considered in relation to the stage of lactation, although higher new infection values were recorded at the first test after calving than at later stages, the differences were not statistically significant.

We are indebted to Dr D. N. Lawley for advice on the statistical interpretation of the results of this investigation.

Acknowledgement is also made to the Agricultural Research Council for grants in aid of the investigation.

1. Cows accustomed to preparation for milking 1 min. before putting on the teat cups were on single mornings (a) milked without preparation, (b) milked 3 min. after preparation, (c) milked 6 min. after preparation.

On treatment (a) ‘let-down’ was delayed but thereafter milking rate was not abnormal. Treatment (b) had no pronounced effect on milking efficiency, but treatment (c) resulted in a slightly slower rate of milking and a reduced yield of milk and butterfat.

2. In a second experiment a comparison was made between two established routines, in one of which udder washing, fore-milking and concentrate feeding was done less than 1 min. before milking and in the other more than 20 min. before milking. The data suggest that milking immediately after preparation was the more efficient routine, although the differences were not very great.

1. An experiment is reported in which the influence of washing the udder with hot and cold water and of reducing the milking time to 60% of the normal flow period (interval between putting on teat cups till main flow ceased) was studied over a period of 9 weeks in twenty cows.

2. The temperature of the udder washing water had no measurable effect on output of milk or speed of milking. The reduction in milking time failed to increase rate of milk flow and resulted in a fall in milk yield.

3. An experiment with ten cows is reported in which the teat cups were, for periods of 6 weeks, left on at each milking twice as long as was necessary to carry out a normal milking.

Neither the yield and quality of milk nor the rate of milking were affected.

Commercial sodium hypochlorites, whether containing KMnO4 or not, are shown to be corrosive at 150 p.p.m. available chlorine and 40° C. to metals such as aluminium, tinned copper, nickel silver and cast stainless steel (18 Cr, 8 Cu, 3 Mo) which are used in dairy equipment. Hypochlorites containing KMnO4 when aged are potentially dangerous to wrought 18/8 stainless steel. The attack is by pitting and therefore especially dangerous to all the metals investigated, and, in general, increases with increase of time of exposure and temperature.

Decay of sodium hypochlorite solutions results in conversion of NaOCl to NaCl and NaC103, which reaction is shown to follow a simple equation fairly closely in various storage conditions.

Attack on metals by sodium hypochlorite can be efficiently inhibited by addition of sodium silicate, which has a specific action in addition to the effect exerted by increase of alkalinity. NaOH and Na2CO3 additions to the same pH are not so effective and increase attack on aluminium.

Increase of pH from 9 to 10·5 by addition of Na2CO3 or sodium silicate reduces bactericidal efficiency of hypochlorites to the same extent.

Penicillin in milk inhibits the growth of some contaminant organisms and thus may have a variable effect in the reductase test for milk quality.

Milks from representative producers have been used to study the influence of storage time and temperature on methylene-blue reduction times. The trends of reduction times are very well expressed as a regression function of both storage factors simultaneously, which therefore appears to describe a fundamental property of raw market milk. It thus becomes possible to compare standards in different countries and producing regions and, by the application of a rational temperature-compensation scale, to maintain reasonably constant production standards throughout the year.

Ten strains of ‘starter’ streptococci were found to be susceptible to penicillin. Streptococcus cremoris strains were markedly inhibited under the conditions employed by doses of 0·10 unit/ml. Str. lactis strains were not inhibited to the same degree unless 0·25–0·30 unit/ml. was present in the milk. These results would indicate that if penicillin is used extensively by farmers and the milk from treated quarters is included in the factory supply, difficulties may arise in cheese manufacture, especially when the more sensitive Str. cremoris strains are used as starter.

Survivor curves show that, under conditions likely to be found in practice, hypochlorite solutions of low alkalinity disinfect milk films on surfaces more rapidly than those of greater alkalinity.

Dehydration of the milk film results in slower disinfection rates by both neutral and alkaline solutions.

Increasing the milk content in the film reduces the rate of disinfection and reduces the effect of the neutral solution to a greater extent than the alkaline.

A variety of lactic streptococcus which is unusual in its growth requirements is described. The culture grows on an agar medium (based on B.D.H. peptone) only under conditions of semi-anaerobiosis. It will grow on the surface, however, if the medium is altered in certain respects, for example: (a) if the B.D.H. peptone is replaced by tryptone, the only peptone which appears to stimulate rapid aerobic growth of the organism; or (b) the lactose in the medium is replaced by glucose; or (c) the pH of the medium is reduced.

Different metabolic mechanisms appear to be involved according to the composition of the medium.

The culture is more sensitive to changes in milk composition than are other strains of lactic streptococci.

1. The fatty acids have been isolated from six samples of butter made rancid with pure cultures of bacteria and moulds, and from six samples of naturally rancid butter.

2. The fatty acids have been fractionated into volatile, solid and liquid groups.

3. The mould samples produced in every case a greater total of fatty acids than bacteria under identical conditions.

4. Bacteria produced relatively less volatile acids than moulds but slightly more solid acids.

5. Of the volatile acids produced it appears that bacteria produce a greater proportion of butyric and caproic acids than moulds.

6. The liquid acids make up by far the greatest proportion of the fatty acids recovered, being in each case between 77 and 85% of the total. Of these, oleic and linoleic probably comprise the majority.

1. Streptococcus lactis cultures were found to vary considerably in their morphological characters when grown in raw and heated milk.

2. This variation in morphology was found to be the main cause for the difference in colony counts between inoculated raw milk and milk heated to 70° C. for 1 hr. over a 6 hr. incubation period at 37° C.

3. Similar T.M.C.'S on inoculated raw and heated milk during incubation at 37° C. explained why the methylene-blue reduction times were the same.

4. It is thought that denaturation of protein may be responsible for the production of short chains in heated milk.

5. The by-products of growth of Str. lactis are responsible for the production of short chains in raw milk after a long incubation time at 37° C.

1. Hypochlorite was allowed to react with glycine and with skim milk in various proportions, and the germicidal power of the resultant mixtures was determined.

2. The results indicated that chloramino compounds formed by interaction of hypochlorite and protein or amino-acid have a definite but slow disinfecting action against Str. cremoris.

3. The chloramino compounds did not appear to be more strongly germicidal at pH 9·5 than at pH 7·0 under the conditions of the experiments.

1. The present position in the problem of ‘slow’ starter due to phage lysis has been reviewed.

2. The sources of some 450 strains of lactic streptococci, collected from a wide field, are given. The methods used in their selection for use as starter together with storage conditions, suitable to maintain their activity, have been discussed.

3. The sources from which phages for the lactic streptococci have been obtained and the methods of ‘building up’ a phage of high titre from dairy products, have been discussed. Attempts have been made to isolate phages from pig-faeces, after feeding starter strains to pigs, to adapt phages to strains previously unattacked and to establish interrelationship of the phages and strains of lactic streptococci with phages and strains of enterococci.

4. The strains of lactic streptococci have been classified in eleven phage types by modifying a method described for the phage typing of staphylococci. Identification of a type has been based on the reactions of a ‘phage pattern’ and not on the reaction of a single phage. It has not been possible to adapt one phage to lyse all the strains of one type and to replace the several phages on which type identification originally depended but, adapted phages have indicated the subdivision of some types.

5. The application of the ‘phage-resistant carrier’ strain phenomenon to phage typing has been investigated. The results have helped in the typing of some strains.

6. Phages used in typing the strains have been classified by means of antiphage sera, prepared from a selection of the test phages. On the data presented the majority of the phages were divided into three groups and the results have been discussed with reference to the phage types suggested.

7. The significance of phage typing, adaptation of phage and phage carrying in the selection of starter strains has been considered and the best method of applying this information to the control of ‘slowness’ in cheese factories has been discussed.

1. Breads were made from flour of 85% extraction alone or supplemented with either 6% dry skim milk or 5·56% full-fat soya flour or 3% milk and 2·78% soya flour.

2. The biological values of the proteins of the breads, determined on rats by the balancesheet method, at an 8% level of protein intake, were respectively 56·7, 59·3, 62·6 and 61·9, and the true digestibilities 91·9, 90·6, 90·9 and 90·8.

3. The soya-flour protein exerted a supplementary effect on the proteins of the plain and of the milk bread. The possible reasons for this supplementary relationship are discussed.

4. Milk proteins had no such supplementary effect on the bread proteins.

Our thanks are due to Dr P. Halton of the Cereals Research Station for the preparation of the breads and to Mr G. Cooper for help with the nitrogen analysis.

The burette is provided with a long capillary jet which can pass down the graduated tube of the butyrometer into the bulb. Splashing of mercury and inclusion of air bubbles are thus avoided. To reduce the overall height, the jet is connected to the burette by an S-shaped tube. The butyrometer is carried on a support which can slide vertically.

A method is described for the colorimetric determination of lactic acid in milk and unsweetened milk products. The protein and lactose is removed after precipitation with copper sulphate and calcium hydroxide at 45° C, the lactic acid in an aliquot of the filtrate is oxidized to acetaldehyde in sulphuric acid in the presence of copper sulphate, a purple colour is developed with p–hydroxydiphenyl, and the colour intensity is measured in a photoelectric absorptiometer or other suitable instrument.

Recoveries of from 96 to 103%, averaging 100%, were obtained when 20–400 mg. lactic acid/100 ml. were added to fresh milk.

The proposed method has an advantage over existing methods in the ease and speed with which large numbers of determinations can be carried out simultaneously whilst retaining the essential accuracy.

A simple and rapid phosphatase test is described which is based on the use of p–nitrophenylphosphate as the substrate. Execution of the test requires few and easy operations: incubation of the milk at 37° C. with a buffered solution of the substrate, followed directly by a visual comparison of the intensity of yellow colour of liberated p–nitrophenol with that of boiled-milk standards containing known amounts of p–nitrophenol. The test permits the detection of minor processing faults with an incubation time of only 30 min. In this form it should prove of value in creamery control. A more searching, but equally simple test is obtained by increasing the period of incubation to 2 hr.