bluuebunny/crossref_metadata_2025 huggingface dataset:
615. Colour changes in heated and unheated milk V. The effects of temperature of measurement, pH, and the addition of certain ions on the reflectance of separated milk
Authors: Burton H.
Published: June 2009

Variation in the temperature of measurement, pH, and concentration of calcium, citrate and phosphate ions have been consistently found to affect the reflectance of separated milk in such a way that the entire curve of reflectance versus wave-length in the visible spectrum is raised or lowered. At temperatures between 10 and 50°C. the reflectance rises reversibly with temperature. The change is not instantaneous, and if the temperature is changed abruptly the reflectance change to the new value is exponential, with a time constant of about 40 min.

Reflectance is independent of pH in the range 5·8–6·6, but for greater values it drops sharply.

Added calcium ions increase the reflectance of separated milk, and added citrate and phosphate ions decrease it, independently of the simultaneous changes in pH.

It is suggested that the reflectance changes which have been found to occur are all caused by changes in the sizes of the casein particles in milk which are brought about by the factors considered. The results given by other authors on viscosity and bound water content, and on direct electron-micrographic observation of casein, are cited to support this contention.

It is further suggested that the change in casein particle size with temperature may be due to a change in the calcium-ion distribution between solid and liquid phases.

The viscosity and reflectance results for separated milk heated to 70°C. and above are apparently anomalous, but they can be explained on the hypothesis that denatured soluble proteins aggregate into particles having a high ration of length to breadth.
620. Host-phage relationship of cheese starter organisms: III. Significance in selection and maintenance of starter cultures in commercial use
Authors: Czulak J. , Naylor Jill
Published: June 2009

The problem of bacteriophage in cheesemaking has been reviewed recently by Whitehead(1) and Mattick(2). Results since reported by other workers and ourselves call for some modification of and addition to the existing concepts of the problem.
629. Antibiotic treatment of mastitis and its effect on the cell content of the milk
Authors: Blackburn P. S.
Published: June 2009

Antibiotic treatment eliminated organisms from 61% of staphylococcal and from 80% of streptococcal udder infections. In 84% of quarters from which organisms were eliminated the cell counts of the milk were reduced, about half of them to a normal and about one-third to a late-lactation type of cell count in which the majority of the cells are epithelial cells. The remainder became reinfected before there was time for the cell counts to return to normal. It was found that it may take as long as 5 weeks for the cell counts to return to normal after elimination of mastitis organisms, but in quarters in which the cell count eventually fell there was a decrease in the percentage of polymorphs in the milk to less than 30% one week after treatment.
633. The effect of commercial sterilization on the nutritive value of milk as determined in experiments with rats and baby pigs
Authors: de Groot A. P. , Engel C.
Published: June 2009

1. The nutritive value of milk sterilized according to the Stork procedure has been studied in laboratory experiments by the method of Mitchell, the rat-repletion method and growth trials with rats and baby pigs.

2. Determinations of biological value of the milk proteins with three groups of six rats by the Mitchell method yielded mean values of 87·0, 88·0 and 85·1 for raw, pasteurized and sterilized milk respectively. The corresponding digestibilities amounted to 96·8, 96·3 and 94·4. The differences were not statistically significant.

3. The relative nutritive value of the three types of milk for the repletion of protein-depleted rats was studied with three groups of eight rats. The average weight gain on feeding daily 40 ml. of either raw, pasteurized or sterilized milk during 5 days was 27·7, 26·3 and 22·9 g. respectively. Again these differences were not statistically significant.

4. No differences in growth rate were obtained if three groups of twelve male and twelve female young rats were fed on raw, pasteurized or sterilized milk supplemented with trace minerals for a period of 6 weeks. The growth rate of rats on exclusive milk diets was, however, far below normal.

5. In growth experiments with baby pigs, fed equal amounts of pasteurized or sterilized milk supplemented with trace minerals, small but statistically non-significant differences in weight gain were found, in favour of the pasteurized milk. The average weight gain on sterilized milk in four separate growth trials amounts to 97, 95, 98 and 98% of that on pasteurized milk. The average 3% less gain on sterilized milk was ascribed partly to more difficult adaptation and less intake of milk solids.

6. These experiments failed to demonstrate a significant decrease in nutritive value of milk sterilized according to the Stork procedure.
645. Lactobacilli isolated from the surface of normal and slipcoat Stilton cheese
Authors: Sharpe M. Elisabeth , Brindley Marjorie
Published: June 2009

During an investigation of the surface microflora of Stilton cheese during ripening, Brindley(1) isolated lactobacilli from the surface scrapings of normal and slipcoat cheese. Some of these isolates were sent to the National Institute for Research in Dairying to form part of a collection of lactobacilli which was being built up for classification purposes. During the work on classifying lactobacilli these organisms from Stilton cheese were examined and all but one were serologically grouped and identified by physiological tests. They were also tested against a number of type sera which were available, and it was found that, although isolated fromcheese of different origins, most of the strains belonged to the same serological type.
660. Properties and composition of colostrum from Egyptian buffaloes and cows
Authors: El Negoumy A. M.
Published: June 2009

The properties and composition of buffaloes' colostrum have been compared with those of cows' colostrum. The most significant differences found between the two may be summarized as follows:

(1) Buffaloes' colostrum was richer in total solids, lactose, total N, globulin N and proteose-peptone N than cows' colostrum.

(2) Buffaloes' colostrum had a much wider range of fat content than cows' colostrum. A distinct difference between the two colostrums lay in the fact that while buffaloes' colostrum was definitely poorer in fat content than normal buffaloes' milk, cows' colostrum was richer in fat content than is normal cows' milk.

Changes in buffaloes' mammary secretion during the transition period from colostrum to milk.

The following is a summary of the most significant trends in the properties and composition of buffaloes' mammary secretion during the transition period:

(1) The specific gravity, acidity and chlorine decreased until they reached a normal value at the fifth milking. This compares well with the trends reported in the literature for cows' mammary secretion during the transition period.

(2) The pH increased gradually until it reached its normal level before the fifth milking.

(3) The highest level of total solids occurred at the first and second milking, and dropped sharply at the third milking to the level normally found in buffaloes' milk.

(4) Changes in the lactose content from the second milking onwards were very slight. This contrasts with the known trend during the transition period in cows, when a gradual increase from a low level at the first milking to higher levels at the following milkings is noticeable.

(5) The total N, globulin N, albumin N and proteose-peptone N decreased from relatively high levels at the first and second milkings to lower levels at later milkings, and thus closely followed the trend shown by the total solids.

Buffaloes' mammary secretion may be considered comparable in its composition to normal buffaloes' milk and suitable for human consumption from 5 to 7 days after parturition.
665. Mammary gland development in the calf as a possible predictor of subsequent milk production
Authors: Elliott Gillian M.
Published: June 2009

A report from the United States Department of Agriculture in 1947(1) claimed that a measurement of the mammary gland development of the calf could give some indication of the animal's future milk production. Although the first report did not contain full experimental results, the few figures that were published, and the very strong recommendation from the authors that the relationship should be tested further, encouraged the launchin g of a field trial at Reading University in 1950.
669. Steam distillation of taints from cream: III. Factors affecting rate of removal of the reference substances, diacetyl and acetoin
Authors: McDowall F. H.
Published: June 2009

1. The vapour/liquid equilibrium coefficient for diacetyl in 35–40% cream has been found to be of the order of 26–28, compared with 39·3 for water. In a 5% aqueous solution of lactose, equivalent to that present in milk and in cream serum, the coefficient was 30. The depression of the equilibrium coefficient by lactose in solution was shown to be independent of the concentration of diacetyl present in the liquid at time of partition, over the range 1–65 p.p.m.

2. The slower rate of removal of diacetyl from cream, per unit weight of steam condensed as compared with its removal from water, was observed to be due mainly to this depressing effect of lactose on the equilibrium coefficient; but there was some evidence that delay in re-establishment of the solubility partition equilibrium as between butterfat and cream serum also contributed to the lowering of the equilibrium coefficient for diacetyl in cream as measured in the laboratory continuous vaporization equilibrium still.

3. Sodium chloride in the solution caused a rise in the equilibrium coefficient for diacetyl from the value of 39·3 for water to about 69 for a 10% salt solution and 82 for a 20% salt solution.

4. Lactose had no effect on the equilibrium coefficient for acetoin, but salt caused a rise from 1·29 for water to approximately 1·75 for a 10% salt solution.

5. The possible effect of lactose on the effectiveness of steam in cream deodorization equipment is referred to.
683. Factors influencing the vitamin content of milk fat: VI. The effect of reduced carotene intake
Authors: McGillivray W. A. , Worker N. A.
Published: June 2009

1. The results of an investigation into the efficiency of utilization by dairy cows of carotene from New Zealand summer pasture and from arachis oil are reported.

2. A 50-fold decrease in the intake of carotene from pasture over a short period was shown to have only a small effect on the vitamin A potency of milk fat, carotene content being reduced by approximately 2μg./g. fat and vitamin A ester by approximately 1·5μg./g. fat. No change was observed in vitamin A alcohol content.

3. Sample-to-sample variations in both the control and treated animals were observed in many cases to exceed the differences due to treatment except during the period of extreme carotene deprivation. Sample-to-sample variations of control and treated animals were also observed to be highly correlated, and it is suggested that variations in the external environment of the animal may have a marked effect on carotene utilization.

4. Carotene in arachis oil was shown to be relatively more effective in maintaining the vitamin A potency of milk fat than summer pasture.

The results of this investigation form a section of a thesis submitted by one of us (N.A.W.) in partial fulfilment of the requirements for the degree of Ph.D. of the University of New Zealand. The authors are indebted to the Department of Scientific and Industrial Research for a grant towards the investigation, and to Mr D. J. Dobson and the farm staff of The Dairy Research Institute (N.Z.) for assistance with the feeding and dosing of the animals and the collection of milk samples. The technical assistance of Miss Fay Frecklington is also thankfully acknowledged.
687. Changes in size of fat globules in cream during Vacreator treatment
Authors: Dolby R. M.
Published: June 2009

The size distribution of fat globules was determined microscopically in cream samples taken from different parts of the Vacreator during treatment of cream.

A considerable increase in numbers of small globules (splitting) was found in samples which had passed the equilibrium valve. Smaller increases took place in the pasteurizing chamber and in the extractor pump. Increase in numbers of large globules (clumping) occurred in the cooler section.

Splitting of globules could be reduced: in the pasteurizer by reducing velocity of incoming steam; at the equilibrium valve by reducing the vacuum drop across the valve or by introducing part of the steam at the infuser instead of into the pasteurizer.

It is concluded that splitting of globules in the Vacreator is due to a homogenizing effect where steam and cream travel at a high velocity. Flash-boiling causes clumping but not splitting of globules. These conclusions should apply to any equipment for pasteurization or deodorization of cream with direct steam.

The thanks of the author are due to Mr J. Singleton (Superintendent) and Mr B. Le Heron (Buttermaker) of the Institute factory for arranging and carrying out Vacreator treatments of cream, to Dr F. H. McDowall for helpful advice and criticism and to Mrs R. P. Haverkamp for assistance in measuring fat globules.
691. Oxygen consumption and lactose synthesis rates of mammary gland slices from lactating guinea-pigs
Authors: Naito M.
Published: June 2009

The shape of the lactation curve in guinea-pigs has been studied. The peak was found to occur between days 2 and 3.

The oxygen consumption and lactose synthesis rates were investigated in mammary gland slices and results expressed on both DNA and DW bases.

Oxygen consumption rates on a DNA basis tended to be low at the onset of lactation and high at the peak. Lactose synthesis on a DW basis tended to decline linearly from the onset of lactation, but on a DNA basis showed a peak coinciding with that of the lactation curve.

The significance of these findings has been discussed.
708. Phospholipids in New Zealand dairy products: II. Seasonal variations in the phospholipid content of butter and of milk and cream
Authors: McDowell A. K. R.
Published: June 2009

Samples of milk, skim-milk and raw cream from one factory and of pasteurized cream, buttermilk and butter from two factories were taken twice monthly for varying periods for estimation of total phospholipids and (in butter only) of lecithin, cephalin and sphingomyelin.

Seasonal variations in the phospholipid contents of milk, skim-milk and raw cream over 13 months probably were due to the greater proportion of small fat globules in autumn (late lactation) milk compared with spring (early lactation) milk.

There were regularly recurring seasonal variations in total phospholipid content of the butters over 3 years. Maximum results were found during autumn and minimum results in winter. Lecithin, cephalin and sphingomyelin contents followed the same trends as the total phospholipid contents.

Seasonal variations in phospholipid contents of buttermilks and butters were due mainly to variations in the amount of phospholipid per unit of fat in the cream. Differences in butter-making technique had little effect on the proportion of phospholipids from the cream retained in the butter.

Average results for total phospholipid content of the products examined were: milk, 0·038% (0·031–0·050%); skim-milk, 0·018% (0·014–0·023%); buttermilk, 0·156% (0·103–0·191%); butter, 0·133% (0·099–0·181%). The average result for percentage of total phospholipid in the fat of the raw creams examined was 0·44% (0·38–0·51%); and in the fat of the pasteurized creams 0·41% (0·35–0·49%). Average weighted results for total phospholipid and for lecithin, cephalin and sphingomyelin contents of butter were 0·139, 0·041, 0·051 and 0·047% respectively.
713. The relation between the chemical composition of milk and the stability of the caseinate complex: II. Coagulation by ethanol
Authors: Davies D. T. , White J. C. D.
Published: June 2009

1. The variation in the stability of milk protein to ethanol and the relationship between milk composition and ethanol stability were examined.

2. Samples of herd bulk milk were very similar in stability to ethanol; the range of aqueous ethanol solutions required to coagulate the caseinate complex in an equal volume of milk was only 80–84% (v/v) ethanol. Samples from individual cows showed a wide variation in stability; coagulation was caused by ethanol solutions ranging in strength from 66 to 90% (v/v) ethanol.

3. Colostrum was very unstable to ethanol but stability rapidly increased during the post-colostrum period to higher levels in mid-lactation. Late lactation and subclinical mastitis milk showed no definite bias towards stability or instability.

4. The strength of ethanol required to coagulate the caseinate complex in an equal volume of milk was inversely related to the concentration of ionized calcium in the milk. The correlation coefficient was –0·76 (significant at 0·001 level) indicating that approximately 60% of the variation in stability was accounted for by the variation in the concentration of ionized calcium.

5. The relationships between the concentrations of other milk constituents and stability to ethanol could be attributed to the interrelations of the concentrations of these constituents and the concentration of ionized calcium.
724. Levels of feeding of concentrates for dairy heifers before and after calving
Authors: Broster W. H. , Ridler B. , Foot A. S.
Published: June 2009

1. Two levels of steaming-up and two levels of concentrates feeding during the first 84 days of lactation have been compared in a 2 x 2 factorial experiment over three winter seasons, using fifty-two Shorthorn and thirty-six Friesian heifers. The levels of steaming up were 2 cwt. and ½ cwt. of concentrates fed over the last 21 and 14 days of pregnancy, respectively. The levels of concentrates during lactation were 5 and 3 lb. per 10 lb. milk per day. Roughages were fed for maintenance. After the 84th day of lactation all animals were given the same treatment for the remainder of the lactation. Milk yield, milk composition and live weight were measured throughout the lactation.

2. The treatments were annotated as HH, HL, LH and LL, the first letter indicating level of steaming-up and the second the level of concentrates feeding in the first 12 weeks of lactation.

3. Mean milk yields were as follows:

4. The LH treatment reqiuird 3 cwt. more concentrates than HL to produce the same amount of milk.

5. The response to additioal concentrates on the LH treatment after calving was l lb. additional milk per l lb. additional starch equivalent.

6. Butterfat percentages were higher (3·69%) in both groups on low-lactation feeding than in the two groups on high-lactation feeding (3·43%). The HL group (i.e. the group that received high steaming-up and low-lactation feeding) combined high milk yield with a higher butterfat percentage, and at current milk and feedingstuff prices and under the conditions of the trials, this group showed a greater cash return than the groups on the other three treatments.
726. Histological changes in the mammary gland of guinea-pigs during lactation
Authors: Naito M.
Published: June 2009

Certain histological factors of the mammary gland and the DNA content unit per dry weight were studied at four stages of lactation in guinea-pigs.

The porosity index, the number of alveoli per field, the number of cells per field and the DNA content, showed maximal values at parturition and minimal values at the peak of lactation, whereas the opposite trend was shown by the value for modal alveolar diameter and the number of cells per modal alveolus.

The relationships between these results are discussed.
738. Phospholipids in New Zealand dairy products: III. Effect of storage on the phospholipids and on the partition of phosphorus in butter
Authors: McDowell A. K. R.
Published: June 2009

Average values for the total phosphorus content of sera from unsalted butter samples and for the phosphorus contents of the various fractions of the sera after partition with trichloroacetic acid were: total P, 83·6 mg./100g.; acid-soluble P, 32·4 mg./100 g.; inorganic P, 28·8 mg/100 g.; acid-insoluble P, 51·2 mg./100 g.; and phospholipid p, 33·6 mg./100 g.

There was no evidence that decomposition of the phospholipids or other organic phosphorus compounds occurred in salted or unsalted sweet-cream butters during storage at –10° C. for 8 months.
The effect of concentrates of high or low starch equivalent, both fed at two levels, on the milk production of dairy cows
Authors: Castle M. E. , Maclusky D. S. , Morrison J. , Watson J. N.
Published: June 2009

1. In a winter feeding trial, using eight Ayrshire cows, two concentrates with digestible crude protein contents of 15% and starch equivalents of 63 and 79 were each fed at 2·6 and 4·6 lb./gal. of milk.

2. The basal ration was hay, silage, dried grass and fodder-beet.

3. Milk yield was significantly increased from 30·9 to 34·7 lb./day when the amount of concentrate fed increased from 2·6 to 4·6 lb./gal., but the average milk yields when the concentrates low in starch equivalent were fed did not differ significantly from those obtained when the concentrates high in starch equivalent were fed at the same levels.

4. The fat content of the milk was similar on all four rations with an average value of 3·84%, whereas the solids-not-fat varied from 8·53% on the low starch concentrate fed at the lower rate to 8·77% on the high starch concentrate fed at the higher rate.

5. The cows which were fed at the rate of 4·6 lb./gal. were significantly heavier by an average of 33 lb./cow than the ones fed at the rate of 2·6 lb./gal. The two different qualities of concentrate did not cause differences in live weight.

6. The weight of dry matter in the basal ration consumed per day was similar on all four treatments.

7. A comparison of feeding costs and the value of the milk showed that the largest margin was obtained with the low starch equivalent concentrate fed at the rate of 2·6 lb./gal.

8. It was concluded that because of the loss in live weight on the lowest level of feeding, and because the quality of the concentrate gave no improvement in milk yield or liveweight and little improvement in milk composition, the optimal level of feeding in this experiment was 4·6 lb./gal. of the low starch equivalent concentrate.
Parition of riboflavin in cow's milk
Authors: Modi V. V. , Owen E. C. , Darroch R. A.
Published: June 2009

1. The partition of riboflavin between the free and the protein-bound forms was measured in the milk of six Ayrshire cows, three of which were treated with l-thyroxine.

2. As lactation progressed there was a slow decline in the total riboflavin content of the milk for which the initial values were 0·86 to 1·09 µg./ml. milk. The rate of decline ranged from 0·01 to 0·003 µg./ml. milk per day.

3. Thyroxine had its expected effects in stimulating milk yield and heart rate, and in preventing the rise of phosphatase in the milk as lactation progressed, but it did not affect either the concentration or the partition of riboflavin.

4. Reasons are advanced for the marked contrast between the effect of thyroxine in increasing the phosphorylation of thiamine and the absence of any such effect on riboflavin.

We thank Miss S. McLauchlan and Miss M. Lightbody for technical assistance, and Glaxo Laboratories Ltd., Greenford, Middlesex, for a gift of L-thyroxine.
The growth of aerobic spore-forming bacilli in sterilized milk
Authors: Higginbottom Constance , Taylor Margaret M.
Published: June 2009

The sterilization of homogenized milk at 115·5°C for 15 min in bottles having a partial vacuum in the headspace produced conditions inhibitory to the growth from very small numbers of spores ofBacillus subtilis, B. licheniformis, B. cereusandB. breviswhen compared with growth in the same milk sterilized in open bottles.B. circulansdiffered from the other strains tested in showing greater inhibition in milk sterilized in open bottles than in milk sterilized under partial vacuum.

The extent of the inhibition became less as the size of the inoculum was increased. It became less also as the temperature of incubation approached the optimum growth temperature of the bacillus, and was influenced by the strain of the bacillus and the source of the milk but not by the degree of heat treatment within the range 107–117·5°C for 15 min. Inhibition was manifested by a prolongation of the lag phase, and in addition with some strains inhibition of spore germination could be demonstrated.

Spore formation following vegetative growth occurred more readily in milk sterilized in open than in evacuated bottles.

Milks sterilized under partial vacuum frequently failed to show any growth from small inocula in 30 days at 22°C although growth occurred readily in milk sterilized in open bottles.
Certain non-biological properties of sterilized milk in relation to the treatment of the milk and the temperature of heating
Authors: Higginbottom Constance , Taylor Margaret M.
Published: June 2009

The effect of the temperature of laboratory sterilization of homogenized milk on the titratable acidity, the colour of the milk, the yellowing of the filtrate from the Aschaffenburg turbidity test, the acid-ferricyanide-reducing substances and on pH has been determined. The greater changes in these properties in milk sterilized under reduced oxygen tension compared with milk sterilized in open bottles was shown to be due, in part at least, to the slower rate of cooling in the evacuated bottles. Samples of commercial sterilized milk have also been examined and their properties have been compared with those of the sterilized milk produced in the laboratory.
The distribution of bacteria in New Zealand Cheddar cheese
Authors: Rammell C. G.
Published: June 2009

The distribution and development of bacteria during the maturing of New Zealand Cheddar cheese have been studied using stained sections of cheese. The starter streptococci usually occur singly and in small groups throughout the mass of the cheese, their distribution on a microscopic scale being very irregular. In contrast, the bacteria developing later form discrete microcolonies, most of which are associated with the curd junctions. Instead of adding lactobacilli to milk, smaller numbers may be added to the dry curd before cheddaring or after milling. Some observations on the physical structure of cheese are made.
The short-term effects of the level of concentrates given to Ayrshire cows and of adding 0·75 1b sodium acetate to the daily diet
Authors: Balch C. C. , Taylor J. , Thomson I.
Published: June 2009

1. In an experiment with twenty-four Ayrshire cows, four treatments were compared in a change-over experiment in which each cow completed four periods each of 4 weeks. In all the treatments the cows received daily 4 lb of concentrates and roughage according to their initial live weight. For milk yields above 10 lb the cows received 4 lb of a concentrate mixture per 10 lb of additional milk produced in the previous week in one treatment, and 3 lb in the other three treatments. Two of the treatments with the lower rate of feeding were supplemented with 0·75 lb of sodium acetate daily, given in either one or three doses.

2. Digestion trials were made with the hay and concentrates to aid in the estimation of their starch equivalents. The allowance made for the maintenance requirements of the cows appears to have been close to that recommended by Woodman (1957).

3. On one treatment the cows in fact received 4·29 lb of concentrates/10 lb of milk produced, and gave on average 36·6 lb of milk (35·2 lb of 4% fat-corrected milk) in the last 2 weeks of the experimental period with a daily decline in milk yield of 0·14 lb/day. On the other treatments the cows in fact received 3·48 lb of concentrates/10 lb of milk produced, and averaged 34·4 lb of milk daily with an average daily decline of 0·21 lb/day; this differed significantly from the rate of decline observed with the higher rate of feeding.

4. The addition of 0·75 lb of sodium acetate to the daily diet, in one or three doses, exerted no detectable effect on milk yield or composition, apart from a small effect on the solids-not-fat (S.N.F.) percentage which was of doubtful meaning.

5. At the higher rate of concentrate feeding the S.N.F. content was 0·10% higher than at the lower rate of feeding. This difference and the resulting difference in the yield of S.N.F. (0·21 lb daily) were significant.
Hesion and consistency of butter
Authors: Jansen K.
Published: June 2009

An apparatus, which has certain advantages over that designed by Claassens, is described for measuring the combined forces of cohesion and adhesion (‘hesion’). The effects of varying the loading rate are discussed. Heidebroek & Pietsch's theory, which is applicable to adhesion between lubricated metal surfaces, is shown not to hold for butter.

Hesions measured with the new apparatus are compared with the frictional and consistency parameters of Prentice's butter extruder and also with the liquid-fat index. The relationships depended largely on temperature. The majority were significant (P < 0·01). A linear relation was found between Prentice's two parameters, leading to a high correlation coefficient (0·88).

Preliminary experiments are described on the effects of prolonged working and also on the relationship between hesion and weight variations during the printing of butter.
The composition of Iraqi sheep's milk
Authors: Nejim H. T.
Published: June 2009

The bulked milk from a flock of Awassi sheep was analysed in two successive seasons. In the second season a wider range of analyses of samples taken from the time the first few ewes came into milk until almost the end of the production season (minimum and maximum numbers in milk 8 and 199) gave the following average values: specific gravity, 1·0366; titratable acidity, 0·217%; pH, 6·65; fat, 6·88%; protein, 6·18%; lactose, 5·75%; solids-not-fat, 12·99%; ash, 0·928%; CaO, 0·29%; p2O5, 0·32%; CaO in ash, 31·5%; P2O5 in ash, 34·3%.

The results are compared with the published compositional figures for sheep's and cow's milks.
Some aspects of machine milking rate
Authors: Wilson G. F.
Published: June 2009

A study was made of the machine milking rates of a sample of Jersey cows comprising daughter-dam pair groups, obtained from thirteen New Zealand herds during mid-lactation.

Twenty-one per cent of the variation in maximum rate of flow occurred within herds and the remainder between herds. Differences in the type of preparation of cows for milking did not have a significant effect on the average milking rates for herds. The variance in milking time between cows within poorly prepared herds was greater, however, than that in the better prepared herds.

Heritability estimates for maximum rate of flow, derived from the regression of daughters' records on dams' records, were found to be of the order of 80%.
A note on the effect of heat on the colour of goat's milk
Authors: Burton H.
Published: June 2009

Goat's milk heated at temperatures in the range 94—120 °C underwent the same colour changes as previously found for cow's milk, i.e. whitening followed by browning. The rate of browning varied with temperature according to Arrhenius's Law, and had a Q10 between 95 and 120 °C of 2·6—2·7. This is slightly lower than the value found for cow's milk. It was difficult to produce whitening curves for milk heated at 75—100 °C because of unexplained reflectance variations. It appeared that the amount of whitening which could be produced became less as the interval after milking increased.
Fatty acid composition of sow's colostrum, milk and body fat as determined by gas-liquid chromatography
Authors: deMan J. M. , Bowland J. P.
Published: June 2009

As determined by gas-liquid chromatography, the mean fatty acid composition (weight percentages of total fatty acids) of milk fat from sows fed a diet to meet U.S. N.R.C. nutrient requirements was: oleic, 35·3; palmitic, 30·3; linoleic, 13·0; palmitoleic, 9·9; stearic, 4·0; myristic, 3·3; linolenic, 2·5; unidentified 0·7 and 0·5, presumably n-odd chain and branched fatty acids; lauric, 0·3; and capric, 0·2. The corresponding fatty acid composition of colostrum fat was: oleic, 41·7; palmitic, 22·5; linoleic, 20·9; palmitoleic, 5·0; stearic, 5·7; myristic, 1·4; linolenic, 2·4; and unidentified acids, 0·3 and 0·1. Dietary fat increased fat levels in the milk and influenced fatty acid composition of the milk fat. Backfat resembled colostrum fat more than milk fat.
Examination of an antibiotic produced by coagulase-negative staphylococci isolated from the bovine udder
Authors: Jones G. W. , Edwards S. J.
Published: June 2009

An antibiotic produced by coagulase-negative staphylococci isolated from the bovine udder was examined by deferred antagonism tests and its inhibitory properties compared with those of other staphylococci. While inhibiting the growth of representative phage types of bovine pathogenic staphylococci, its activity against corynebacteria was more restricted than that of Staphylococcus aureus NCTC 6507 and 8004. Only minimal amounts of inhibitory substance were produced in liquid media, larger amounts were produced on solid media and the incorporation of a blood plasma factor further increased production. The inhibitory substance resisted treatment with pepsin and trypsin and withstood boiling for 30 min. Its characters in relation to inhibitory substances produced by other staphylococci are discussed.
Changes in the quantity and composition of mammary gland secretion in the dry period between lactations. II. The complete dry period
Authors: Smith A. , Wheelock J. V. , Dodd F. H.
Published: June 2009

The changes in yield and composition of mammary gland secretion throughout the whole of the dry period have been investigated in 6 cows. The yields of lactose, potassium, fat and casein decreased to very low values for the greater part of the dry period but then increased slightly just before parturition. Similar trends were observed for sodium and chloride but they were much less marked. During the middle of the dry period the concentrations of sodium, potassium and chloride tended towards those of blood serum while the concentrations of fat and lactose decreased to < 1%.
The C-terminal sequence of amino acid residues of κ-casein isolated from buffalo's milk
Authors: El-Salam M. H. Abd , Manson W.
Published: June 2009

When κ-casein from buffalo's milk was treated with carboxypeptidase A (EC 3. 4. 2. 1),4 amino acids, valine, threonine, serine and alanine were released from the protein in a manner consistent with the view that they originate in the C-terminal sequence of a single peptide chain. The amounts produced suggest a minimum molecular weight for buffalo κ-casein of approximately 17000, in agreement with the value calculated from the phosphorous content on the basis of the presence of 2 phosphorus atoms/molecule. A comparison is made with the C-terminal sequence reported for bovine κ-casein.
Identification of fatty acids from butterfat using a combined gas chromatograph-mass spectrometer
Authors: Ryhage Ragnar
Published: June 2009

The identification and approximate quantitative determination of methyl esters of fatty acids from commercial butterfat was obtained with a combined gaschromatograph-mass spectrometer instrument. Fifty-two components, straight chain saturated and unsaturated, as well as branched chain compounds, were identified. Seven monomethyl saturated fatty acid methyl ester isomers were identified for both C15and C17, i.e. with chain lengths of 14 and 16 carbon atoms, respectively. Multibranched fatty acids with molecular weights of 326 and 368 were found. The results were obtained in one day.
The major fatty acids in whole milk fat and in a fraction obtained by crystallization from acetone
Authors: Mattsson Sonja , Swartling P. , Nilsson R.
Published: June 2009

Summer and winter milk-fat samples from 14 dairies in Sweden were fractionated by crystallization from acetone solution (1:8) at 15 °C. The composition of the major fatty acids of the parent milk fat and of the acetone insoluble fraction were examined by GLC, and the gross triglyceride pattern by TLC on plates of silicic acid treated with silver nitrate.

The fatty acid composition of the milk fat was similar to that of milk fat from other countries and varied according to season and also, to a smaller extent, from region to region. Four fractions, representing 33–45, 41–34, 18–14 and 7–6 % of the fat and which contained progressively smaller proportions of saturated acids, were obtained by TLC.

The acetone insoluble glyceride (AIG) fraction was characterized by a smaller content of short-chain fatty acids and unsaturated fatty acids, and a larger content of saturated long-chain fatty acids, than the parent milk fat. AIGs from summer milk fat contained a larger proportion of C18acids and a smaller proportion of C6–C16acids than AIGs from winter milk fat.

Four fractions representing 62–70, 15–8, 16–15 and 7 % of the AIG fraction were obtained by TLC. The distribution of the triglycerides in the AIG fraction differed from that in the parent milk fat, mostly in the relative amounts of glycerides in the 2 most saturated TLC fractions. The seasonal variation was largely confined to these 2 fractions.
Storage of chilled cream in relation to butter quality
Authors: McDowell A. K. R.
Published: June 2009

The quality of fresh and stored butter made from chilled cream collected over 3 days and stored either by accumulation in a vat or by separate storage of each batch was compared with that of butter made from unchilled cream collected over one day.

Provided each batch of cream after separation at 85 °F was cooled to 55 °F before addition to the vat, accumulation of cream at either 40 or 48 °F gave butter similar in quality to the control butter. Butter from cream cooled to 55 °F and held at this temperature, however, was slightly inferior in quality. The addition of the cream to the vat with no cooling, or cooling only to 70 °F, after separation gave butter of inferior quality due to rancid or stale flavours.

Butter from cream cooled either to 70 or 50 °F before storage of each batch in separate containers at either 40 or 50 °F was only slightly inferior in quality and in keeping quality to the control butter.

Defects in the chilled cream butters appeared to be due to lipolysis caused either by activation of the natural lipase of the cream or by lipolytic bacteria or both.
The relationships between dietary fatty acids, plasma lipid composition and milk fat secretion in the cow
Authors: Moore J. H. , Steele W. , Noble R. C.
Published: June 2009

The effects of the isocaloric replacement of starch in a low-fat concentrate mixture by either 5 or 10% ‘stearic acid’ (85% pure) or by 10% ‘palmitic acid’ (85% pure) on the composition of the plasma lipids were investigated in a feeding experiment with 12 cows in mid-lactation. The concentrate mixtures were given with a high roughage diet that supplied daily 4·4 kg of hay and 2·7 kg of sugar-beet pulp. A study was made of the relationships between the compositions of the plasma and milk lipids.

The inclusion of 10% ‘stearic acid’ or 10% ‘palmitic acid’ in the concentrate mixture increased the concentration of total plasma fatty acids. Irrespective of dietary treatment, about 40% of the total plasma fatty acids occurred in the cholesteryl ester fraction, 54% in the phospholipid fraction, 3% in the triglyceride fraction and 3% in the unesterified fatty acid fraction. There was a positive curvilinear relationship between the concentration of unesterified fatty acids in the plasma and the yield of total milk fatty acids.

In the plasma triglycerides, the concentrations of 16:0 and 16:1 were decreased and the concentration of 18:0 was increased when the concentrate mixture contained ‘stearic acid’; the concentration of 16:0 was increased and the concentrations of 18:0, 18:1 and 18:2 were decreased when the concentrate mixture contained ‘palmitic acid’. Similar changes were observed in the compositions of the plasma unesterified fatty acids when the cows were given the different diets.

In the plasma cholesteryl esters, the concentration of 16:0 was decreased and the concentrations of 18:3 and 20:4 were increased when the concentrate mixture contained stearic acid; the concentrations of 16:1, 18:3 and 20:4 were increased and the concentration of 18:2 was decreased when the diet was supplemented with palmitic acid. The addition of stearic acid to the diet increased the concentration of 18:0, 18:1 and 18:3 in the plasma phospholipids but decreased the concentrations of 16:0, 18:2, 20:3 and 20:4. When the diet contained palmitic acid the concentrations of 16:0, 16:1, 18:1 and 18:3 in the plasma phospholipids were increased but the concentrations of 18:0, 18:2 and 20:3 were decreased.

The major fatty acid circulating in the plasma of the cows was 18:2, which accounted for about 45% of the total plasma fatty acids. Only about 0·7% of the total plasma 18:2 occurred in the plasma triglycerides.

The results are discussed in relation to the changes in the composition of the milk fatty acids produced by the cows when they were given the experimental diets.
Observed ratios of 90Sr/Ca and 137Cs/K in the food of nursing mothers and in their milk
Authors: Calapaj G. G. , Ongaro D.
Published: June 2009

The 90Sr/Ca and 137Cs/K ‘observed ratios’ (OR) in the food intake of nursing mothers and in their milk have been determined. Between 4 and 7 days after parturition, groups of mothers were put on a controlled diet for 4 days. Pooled samples of milk were then taken from each group. 90Sr, Ca, 137Cs and K were determined in the pooled samples and in all foods taken during the experimental period. 90Sr/Ca ratios were determined in 4 experiments and 137Cs/K ratios in 3. The OR for the 4th day's intake did not differ significantly from average ratios for the whole 4 days, so that a state of metabolic equilibrium appears to have been reached. The 90Sr/Ca OR was fairly constant and considerably less than unity, but the 137Cs/K OR was greater than unity and varied considerably between experiments.

Since potassium, which is metabolically analogous to caesium, showed a fairly constant ratio between intake and excretion in the milk, the physiological behaviour of 137Cs must be quite different from that of 90Sr. The maternal organism therefore provides the baby with efficient protection against 90Sr but not against 137Cs.
Carbohydrate analysis of the glycopeptides released by the action of rennin on whole milk
Authors: Sinkinson G. , Wheelock J. V.
Published: June 2009

A gas-liquid chromatographic method is described for the simultaneous estimation of the carbohydrates attached to the glycopeptides released by the action of rennin on whole milk. The method can also be used for κ-casein. Certain of the findings may be applicable to other glycoproteins or glycopeptides. In particular: (a) the conditions for methanolysis of the carbohydrates from the glycopeptides must be chosen carefully to avoid decomposition ofN-acetyl neuraminic acid; (b) it is not possible to obtain a satisfactory calibration forN-acetyl neuraminic acid using the free acid as a standard.
The detection of clinical mastitis with in-line filters
Authors: Hoyle J. B. , Dodd F. H.
Published: June 2009

A simple in-line filter is described which can be fitted into the milk tube of a. milking machine in order to detect clinical mastitis. It consists of a stainless steel mesh, on which the clots are retained, and it is fitted obliquely into a short length of clear plastics tube. The filter has been developed as an alternative to the fore-milk cup. Tests made over 9 months in a 60-cow herd show good agreement between the fore-milk cup and the in-line filter recordings. For general service production the filters are made by moulding.
Structure of the casein micelle. The accessibility of the subunits to various reagents
Authors: Dumas B. Ribadeau , Garnier J.
Published: June 2009

Carboxypeptidase A (CPA, mol. wt = 34600) and 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride, mol. wt = 270) were shown to react with the 3 casein subunits, αs1-, β- and κ-caseins, which constitute the micelle. Virtually all of the C-terminal amino acids were released by CPA from these subunits without disrupting the micellar structure.

It was verified that the rate of dissociation of the micelle into low molecular weight complexes is considerably slower than the rates at which these reagents act on micellar components. It is concluded that dansyl chloride, CPA, and probably also rennin, whose molecular weight is similar to that of CPA, are able to penetrate to the interior of the micelles. This was confirmed in a quite independent way with a non-reacting agent, myoglobin (mol. wt = 17000).

It is postulated that the casein micelle has a sponge-like structure in which the 3 different subunits are distributed fairly uniformly.

Micellar fractions obtained by differential centrifugation from skim-milk and colostrum were examined for their content of αs1-, β-, κ- and para-κ-caseins by the use of CPA as described by Ribadeau Dumas (1968). The results confirm that there is a real difference in κ-casein content of the micelles, according to their rate of sedimentation.
The influence of various treatments on the drainage of continuously made curd
Authors: Berridge N. J. , Scurlock P. G.
Published: June 2009

The effect of layer thickness and orientation, and of pressure, temperature, and disturbance on the drainage rates of continuously made curd were determined. The effects of heat treatment of the milk and adjustments of its pH were briefly examined. An increase in temperature of the curd caused the expected increase in drainage rate as did also the application of pressure. Vertical layers of curd drained more quickly than almost horizontal layers, and keeping curd in whey retarded its drainage. The effects of pH change over the narrow range of interest (6·1–6·5) were relatively small. Pasteurization of the milk had no effect. Disturbance of the curd had the most pronounced effect in increasing its rate of drainage.
Local cooling of the mammary gland and milk production in the cow
Authors: Holmes C. W.
Published: June 2009

An experiment has been performed with 2 Jersey cows to determine the effect of a reduction in udder temperature on milk production. One half of the udder was covered while the other half was cooled by an increase in air movement at an air temperature of 6−10°C; for closely clipped udders it was estimated that the cooling conditions might be equivalent to an air temperature of −10°C with low air movement. Yields of milk, fat, protein and lactose were reduced significantly at the morning milking after 22 h cooling; the decreases which occurred at the afternoon milking after 9 h cooling, in all components except fat, were not significant. Wisconsin Mastitis Tests on the milk indicated that changes in udder health did not contribute to these effects.
Purification of rennin
Authors: Castle A. V. , Wheelock J. V.
Published: June 2009

A method based on salt fractionation, iso-electric precipitation and gel filtration chromatography is described for the purification of the enzyme rennin (E.C. 3.4.4.3).