In order to compare the old and the modified methods of the methyleneblue reduction test, 185 samples of raw milk were examined. We followed Wilson's method absolutely, but included two tubes in each test, one of which was inverted and the other not.

The results obtained and their interpretation agreed with the theoretical expectations given in our previous paper, and briefly outlined at the beginning of the present paper.

It is found that the deviations in the reduction time, corresponding to a given initial number of cells, are smaller by the modified than by the old method, and that the average time of reduction is shorter.

The smaller variation in the reduction time corresponding to a given number of cells at the beginning of the test is due probably to a more uniform distribution of the bacteria in the milk following the inversion of the tube. Wilson's suggestion that the shortening of the reduction time in the modified method is due to the stimulation of bacterial growth proves to be entirely correct. We obtained the average coefficients of multiplication in the old method of 0·660, and in the modified of 0·885.

Our results confirm on the whole the positive value of the modification of the methylene-blue reduction test as suggested and worked out by Wilson.

A study was made of the changes in the iodine value of milk fat from cows following the feeding of linseed oil (450g) at intervals of 6 days. Three cows in midlactation and of differing age and breed were used. The experiment consisted of a series of 3 collection periods, each of 6 days' duration, with 12 days between periods. Three doses of oil were given (6 days apart) between periods 1 and 2, the last dose of oil being given immediately before the start of period 2. The mean iodine values for the 3 periods were 35·5, 40·5 and 34·7 respectively. There was a distinct pattern of change in iodine value with time after feeding the oil, a maximum of 45·5 being attained on the second day with a subsequent decline to 38·5 on the sixth day. Analysis of variance showed that these effects were significant and due to oil-feeding, whereas changes in yield and content of fat and production of milk could be accounted for by normal decline in lactation. It was concluded that the periodic feeding of a large dose of linseed oil produces a significant increase in the iodine value of milk fat and avoids the possible disadvantages of continuous fat supplementation.

The technique of paper chromatography of bacterial extracts has been successfully applied to the routine examination of lactobacilli from cheese. One hundred and nine strains isolated on selective media have been grouped by their chromatogram patterns, and selected strains from these groups have been shown to have biochemical characteristics giving relationships which are in agreement with the chromatogram groupings. The results indicate that the technique can be used routinely for the rapid identification of strains of lactobacilli.

It was previously found that low concentrations of oleic acid in the growth medium inhibited the growth of Streptococcus cremoris strain C 13. However, a variant of this strain has now been isolated which is capable of growth in relatively high concentrations of oleic acid. This was achieved by the extended incubation of inocula of strain C 13 in milk containing various concentrations of oleic acid.

Milk quotas, based on an average fat content, severely limit milk production on UK farms. Predictions of the time-course of lactation are incorporated into most computerized herd management programs but these models take no account of food inputs, body weight change or milk composition. Dynamic models are generally used to simulate metabolic pathways and, as such, have little direct relevance to commercial milk production. Dynamic models can be converted to an adaptive-predictive model that partitions food energy into milk and non-milk constituents. This paper reports the development of an adaptive-predictive model to partition food into milk and non-milk components. Additional functions further partition milk energy into the principal constituents, fat, protein and lactose.

A series of experiments is described, outlining a study of 5 factors likely to influence the efficiency and reproducibility of a standardized method used for the electronic counting of somatic cells in milk. Samples containing cells covering 5 ranges from 250000 cells/ml to 1500000 cells/ml were used and the results analysed statistically.

The residual error was given special consideration, and was found not to contribute to any significant degree to the accuracy of the method. Sample volumes of 0·5 ml and 0·1 ml used for counting were compared, and there was a decrease in accuracy using the smaller volume. The influence of individual technician skill was studied with 4 workers having differing degrees of experience, and no significant addition to the overall error was observed. The effect of agitating bulk tank milk for between 0 and 2 min before sampling was examined. Variations were considerable for agitation times of less than 1 min, but the recommended mixing time of 2 min was found to be adequate with milk quantities between 450 l and 2250 l (100 and 500 gal), and at the 5 cell-count levels chosen.

The distributions of the cell counts at the 5 levels were found to be normal with the marginal exception of samples tested at 250000 cells/ml.

All aspects of the technique, sample preparation, use and calibration of the Coulter Counter, etc, should be closely followed to ensure that no inaccuracies will result from inadequate maintenance of the machine or other equipment employed in the test.

The C.O.B. test has been carried out at 15 min. intervals on raw milk samples stored at 20°C. to examine worker and replicate variability. Within experimental limitations, the differences between workers were not significant (P>0·05) and, in general, good agreement was found between the five replicates examined for each milk sample, coefficients of variation less than 4·0%. The change from absence to presence of a precipitate generally occurred with successive tests, but there were indications that the times to increased intensity of clotting differed with samples.

Captain H. Barkworth was responsible for the plan and design of these experiments which were carried out by members of his staff at Shardlow.

The vapour/liquid equilibrium coefficients for the steam distillation of indole and skatole from water solution over the range of concentrations 0·1 to 20–30 ppm. were found to be 2·4 and 4·7, respectively. The coefficient for indole in a cream containing 30% fat was found to be 0·31, and for skatole, in a cream containing 40% fat, 0·14. It is concluded that complete removal of indole and skatole contaminations from cream by use of steam distillation equipment is not commercially practicable.

This Research Paper addresses the hypothesis that using teatcups with automatic valves, without cutting off the vacuum prior to cluster removal, could increases the risk of mastitis and affect other milking variables on goats. A first trial used 46 intramammary infection (IMI)-free goats that had been milked with normal teatcups (without automatic valves) during a pre-experimental period of 8 ± 2 d postpartum. These animals were divided into two groups (n = 23), randomly assigning each group to teatcups with automatic valves (teatcups A) or without automatic valves (teatcups B) for a 20-week experimental period. During this period, several strategies were applied to increase teat exposure to pathogens in both experimental groups. In the first eight weeks of the experimental period, the new IMI rate per gland was significantly higher (P < 0·05) in the group of animals milked with teatcups A (6 of 46; 13%) than in the group milked with teatcups B (1 of 46; 2%). However, throughout the rest of the experimental period the same number of glands appeared with new IMI (n = 7) in both animal groups. SCC was higher in goats milked with teatcups A, but no significant differences were found in the remaining variables (milk production and composition, frequency of liner slips + teatcup fall-off). In a second experiment, in a crossover design (54 goats in fourth month of lactation, 2 treatments – teatcups A and B – in 2 experimental periods each lasting 1 week), no differences were observed in total milk, average milk flow, total milking time or teat thickness changes after milking between both teatcups. However, teatcups A worsened slightly the maximum milk flow. We concluded that the use of teatcups with automatic valves, without cutting off the vacuum prior to cluster removal, increases the risk of mastitis on goat livestock farms.

The collection of samples of milk from individual quarters has usually been done either by hand milking or by sampling by hand at the commencement of milking, before the application of the teat-cups for milking by machine. The former method is laborious, and may not be entirely accurate, as it depends a great deal on constant care throughout the milking to ensure that each quarter is milked into the correct container. If the quarters are milked separately by hand, the yield of milk from the individual quarters may be affected, and if the cow is not accustomed to being milked by hand, hand milking for quarter sampling may disturb her, and affect the yield, and so the composition of the milk. Quarter sampling by hand before the commencement of machine milking does not provide a representative sample of the yield of milk from the quarter, and it does not permit a measurement of quantity of milk produced by each quarter. In connexion with some work on the composition of milk from quarters showing a positive brom-thymol blue test (Hume(i), McDowall(2, 3)) and on the influence of such milk on the quality of cheese and butter made from it (McDowall(4)); the collection of full quarter samples of milk on a considerable scale was required. For this purpose a special milking-machine claw, a milking-machine bucket, and a strip bucket were constructed. These are illustrated in Fig. 1, I–IV.

Levels of Cu and Fe in fresh milk and in bulk pasteurized milk were measured. The endogenous levels varied during the lactation period. The level of Cu in bulk pasteurized milk was greater than the endogenous level, suggesting some contamination. This apparent Cu contamination was greater in winter than in summer. No similar contamination was observed with Fe. The levels of Cu and Fe in butter manufactured each month and in retail butter were measured. Higher levels of Cu were detected in ripened cream butter produced in winter compared to that produced in summer. No similar trend was evident for Fe in ripened cream butter. Very low levels of Cu, Fe and lipid oxidation were detected in Irish sweet cream butter and consequently Cu and Fe contamination and resultant oxidation are not a problem in this product.

Lyphan paper M 25 can be used for pH measurements in milk and whey in the pK range 5·4—6·6. As a rule the error does not exceed 0·1 pH.

In very acid milk and whey (pH < 5·4) lyphan paper of the L series may be used. Generally the deviation does not exceed -0·2 pH. In alkaline milk and whey lyphan paper cannot be used.

In milk and whey from cows infected with mastitis M 25 may be used unless the pH exceeds 7.

The results reported suggest that it is possible to follow the ripening of Parmesan cheese by means of histochemical reactions for proteins, glycoproteins, acid mucopolysaccharides and lipids containing choline.

The blue colour, formed when the proteins of the curd were stained with Bonhag's reagent, slowly turned to violet and then to red as ripening progressed.

Glycoproteins and acid mucopolysaccharides, although present in very small amounts, appeared to be a constant characteristic of the cheese.

Lipids containing choline, which were absent from the curd, were clearly visible in 3 to 7-month-old cheese. They then decreased and were absent in the ripened cheese.

This study aimed to estimate live body weight from body measurements for Holstein × Zebu dairy cows (n = 156) reared under conditions of humid tropics in Mexico using multivariate adaptive regression splines algorithm (MARS) with several train-test proportions. The body measurements included withers height, rump height, hip width, heart girth, body length and diagonal body length. The data were divided into 65:35, 70:30 and 80:20 split data for training and testing sets, respectively. The MARS algorithm was used to construct a prediction model, which predicted the body weight from the body measurements of the test dataset. The results emphasized that the MARS algorithm had an explanation rate for 80:20 train and test set of 0.836 and 0.711, respectively, with minimum Akaike information criterion values. This indicates that it is a reliable way of predicting body weight from body measurements. The results suggest that body weight prediction can be performed with the MARS algorithm in a reliable way, therefore, this algorithm may be a useful tool for animal breeders and researchers in the development of feeding and selection-aimed approaches.