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分娩後における牛の初乳および常乳中のα-ラクトアルブミン(α-LA),β-ラクトグロブリン(β-LG),免疫グロブリンG(IgG)および血清アルブミン(BSA)含量をSingle radial immunodiffusion法を用いて免疫化学的に定量した.供試材料は,健康な経産ホルスタイン種乳牛から分娩後2週間,経時的に採取した.分娩直後の初乳中のα-LA含量の平均値は173.5mg/dlであったが,分娩後6日には136.1mg/dlに減少した.β-LG含量は,分娩直後の1,137.9mg/dlから急激に減少して分娩後6日には332.3mg/dlになった.分娩直後の初乳中のIgG含量は,8,085.3mg/dlで初乳総蛋白質量の64.5%を占めた.IgG含量は,分娩後搾乳の4回目までほぼ50%ずつ減少して6日後には188.5mg/dlになった.BSA含量は,分娩直後の181.3mg/dlから6日後には13.9mg/dlに減少した.α-LA含量は分娩の翌日に最高値を示したが,その他の乳清蛋白質含量の最高値は分娩直後の初乳でみられた.分娩後2週間を通して,総蛋白質量に対するα-LAの相対比率と乳糖含量との間には,正の高い相関関係が認められた.

Summary 1.Slow freezing of milk or cream caused a gradual precipitation of the caseinate system and an immediate destruction of the fat emulsion. 2.Freezing did not alter the heat stability of skim milk until the product had been held frozen for several months at –18° C. (0.4° F.) or below. Freezing caused an immediate increase in the amount of casein which could be centrifuged from milks heated before freezing. Freezing, therefore, caused a slow and gradual increase in the size of the casein aggregates but the change was not noticeable until the freezing period was well advanced. 3.The destruction of the fat emulsion in cream during slow freezing was lessened by adding cane sugar or increasing the solids-not-fat content of the cream before freezing. Homogenization slightly retarded fat separation when low fat creams were frozen. Freezing destroyed the fat clumps formed in cream by homogenization and restored to the cream the heat stability which it possessed before processing. 4.Fresh whole milk was pasteurized, condensed to ⅓ its weight, canned and frozen without any detrimental effects to the body or flavor of the product. This milk when held frozen at a low temperature and reconstituted at any time within a four-week period by the addition of cold water, yielded a product which often could not be distinguished from fresh market milk. Its use where fresh market milk is expensive or not available was suggested. 5.A process for the preparation of large quantities of normal undenatured casein and of milk serum was developed. Frozen homogenized cream was thawed at a temperature below the melting point of the fat; clear milk serum was collected from the melting mass and the residual mixture of fat and casein was utilized in the preparation of normal casein or to raise the protein solids of ice cream mix.

The biuret reaction was applied to a quantitative colorimetric test for milk serum protein solutions. The method is simple and rapid, the solutions are free of turbidity and the response is nearly linear. Full development of the Cu-protein color requires about 30min., after which the color is stable at least 24 hr. Lactose and calcium phosphate were found to interfere in direct application of the test to whey. Dialysis of the whey was necessary to obtain normal values. Concentrations of NaCl, Na 2 S0 4 or ethanol as used in protein fractionation interfered with the test. Standard curves were prepared for protein solutions containing known concentrations of these reagents. The color response of casein is different than that for milk serum protein; therefore, mixtures of these proteins cannot be analyzed by the biuret test.

The ascorbic acid content of evaporated milk has been investigated by Meulemans and de Haas (9), who concluded that the canned product contains as much vitamin C as does " p r e p a r e d " fresh milk. These workers apparently used a direct titration procedure with 2,6-dichlorobenzenoneindophenol and obtained data ranging from 20 to 30 rag. per liter of ascorbic acid in evaporated milk reconstituted to a fluid basis. Henry, Houston, Kon and Osborne (3), using the precipitation technique of Kon and Watson (8), titrated milk serum with the indophenol dye and found losses of about 30 per cent in the total ascorbic acid content of evaporated milk due to manufacture, with a subsequent gradual loss in storage. Appreciable quantities of dehydroascorbic acid were noted upon reduction of the milk serum with hydrogen sulfide, scrubbing with nitrogen and subsequent titration. Woessner, Elvehjem and Schuette (13) found only insignificant amounts of dehydroascorbic acid in evaporated milk using a photoelectric method and extrapolating galvanometer readings to zero time, which procedure they found corrected errors due to spurious reducing substances resulting from the effect of hydrogen sulfide on milk ingredients other than dehydroascorbic acid. These workers state that the metallic nature of the manufacturing equipment is not related to the ascorbic acid content of evaporate(~ milk nor are the use of stabilizing salts, the degree of preheating or geographical considerations. Kon and Henry (7) noted a loss of 43 per cent in the ascorbic acid content of fresh fluid milk as a result of sterilizing at a temperature of 230 ° F., whereas Josephson and Doan (5) showed that moderately high temperatures (170 ° F. to boiling) cause a stabilization of the ascorbic acid of milk as a result of heat produced, sulfhydryl, reducing substances derived from certain milk proteins.

Goat milk was obtained from the right lactiferous sinus following instillation of PR8 influenza type A virus. The proteins precipitated from goat milk serum by (NH4)2SO4 were found to contain antibody activity and further purification was undertaken. In the development of the method the protein solutions were subjected to paper chromatography and paper and polyacetate high voltage electrophoresis, both before and after a number of isolation and purification steps. In addition, preparations from each step were run on the Technicon amino acid analyzer for the presence of amino acids and (or) peptides.As a working procedure, a preparation obtained after cold acetone precipitation was subjected to rivanol treatment, and after electrophoresis a single protein band containing the antibody was obtained. This material was further purified by gel filtration using a Bio-Rad P150 column. The antibody containing protein was finally isolated in the eluate by a fraction collector using phosphate buffer as the eluting fluid. There was excellent recovery of the antibody activity in each preparation.

Summary A method of rendering the brown pigment of evaporated milk soluble in milk serum by tryptic digestion of the proteins proved a satisfactory preliminary step to photoelectric measurement of color. Using this principle, the optical densities of 11 commercially produced evaporated milks were evaluated when fresh and at monthly intervals during storage for 1 yr. at room temperature. Discoloration was evident in all fresh samples. Color increased rather rapidly during the first 3 mo. of storage, after which time further color development was quite gradual. More color develops in samples held at higher storage temperature and storage at 4° C. will substantially inhibit color development. One vacuum-packed sample discolored more readily at all storage temperatures than did an air-packed sample of corresponding initial color. The investigation has demonstrated that "browning" is still a significant problem in the evaporated milk industry. A number of factors involved in the heat-induced browning of skimmilk also were studied. These included time and temperature of heating, preheating, pH, the roles of certain milk components, particularly casein and the significance of certain compounds of importance in other browning systems. Casein and lactose were observed to be the principal reactants in production of the color. The temperature range 100 to 120° C. appeared critical in the browning of skimmilk. Heating for a period of 1 hr. at 100° C. produced no appreciable discoloration, whereas browning was readily evident in samples heated for 7.5min. at 120° C. The tendency to discolor as a result of autoclaving was observed in decreasing order in skimmilk, rennet whey and "protein-free" rennet whey. The comparative resistance of the latter material to browning suggests that inorganic phosphates are not of direct importance in the heat-induced browning of milk. The region of pH 6.0 to 7.6 was found to be of critical importance in the browning of milk. A change of as little as 0.1 of a pH unit in this range produced a noticeable difference in color. Studies of the effect of preheating skimmilk on its tendency to brown on reheating suggests that browning in the case of milk is stepwise, at least in part. Although preheated skimmilks showed no difference in color, small differences proportional to the extent of preheating were observed following a second heat treatment. The additions of hydroxymethylfurfural, methyl glyoxal or acetaldehyde in quantities up to 0.5g. per liter and glycine up to 1g. per liter had no significant effect on heat-induced browning of skimmilk. Further study of the contribution of amino acids to browning in milk systems, established that milk subjected to tryptic digestion browns less readily than undigested milk and that either enzymatically or acid-digested casein browns less readily in the presence of lactose than does intact casein. In discussion of the phenomenon, it is suggested that intact casein may act in the manner of a stronger base than casein hydrolysates. Supporting evidence for this hypothesis is drawn from earlier work in which compounds isolated from heated milk to date also have been reported as products of the alkaline degradation of sugars.

Summary 1.The serum of winter produced milk showed physical characteristics at variance with that of summer produced milk. It was clarified with greater difficulty. An adjustment of the salt balance and pH improved somewhat the technique used for the preparation of the serum from winter milk. The time at which these changes occur varies from year to year. 2.The serum of winter produced milk showed lower nutritive value than that of summer produced milk as measured by its use in supplementing a highly purified diet as a source of the vitamin B complex. 3.The significance of these studies lies in the relation of fresh plant tissue as contrasted with field dried material to subtle changes in the milk secreted.

Thirty-six Holstein cows were fed the following rations in two trials which lasted 50 days each: A) forage ad libitum plus 1kg concentrate per 3kg milk; B) concentrate ad libitum plus 2.7 to 3.2kg air-dry forage; C) B plus 7% partially delactosed whey, 1.25% NaHC0 3 , and 0.5% MgO in the concentrate. Milk yields tended to be lower for B than A and C in Trial 1, though differences were not significant. Cows were earlier in lactation in Trial 2 than 1, and milk production did not differ between treatments. Protein concentrations in milk were higher for high-grain groups in both trials. Greater yields of milk protein (P α -Casein and β -lactoglobulin accounted for the increase in milk protein, whereas milk serum albumins and "other nitrogens" decreased. Concentration of α -lactalbumin was correlated 0.88 with milk production.

Acetic, propionic, and butyric acids in milk and ripened cheeses were separated quantitatively by a gas-chromatographic technique, using uncoated porous polyaromatic polymer beads as the column packing. Milk sera and aqueous extracts of ripened cheeses were injected directly on to the column and the eluted fatty acids estimated by a hydrogen flame detector. Quantitative recoveries of acetic, propionic, and butyric acids added to milk were obtained. The sensitivity of the method is sufficient for cheese-ripening studies.

Summary Skimmilks were progressively depleted of casein colloids by centrifuging, supernatant liquids and deposited colloids being thus obtained. The deposits were washed by redispersing in distilled water and recentrifuging. Densities were determined on the supernatant liquids and on water suspensions of the washed colloids. The analysis of the data on supernatant liquids is novel, in that the apparent specific volume is first calculated for the casein complex hydrate and the specific volume of the unhydrated complex derived from this, a procedure required because the solvent is not water but milk serum. Within close limits, the values obtained are the same as those calculated directly from the densities of suspensions of washed deposits, and also agree with values calculated from the separate specific volumes of the components of the complex. The apparent specific volumes found vary slightly with composition, and are to a first approximation linearly related to the calcium content of the complex. For a colloid fraction of milk of average calcium content the apparent specific volume found is 0.697, and the extremes are 0.694 and 0.700, all with probable errors of about 0.4%. Use of these values in calculating the densities of the hydrated and solvated casein colloid particles as they exist in milk is discussed. The data are for Jersey and Holstein milks.

Summary Milk was heat-treated at eight temperatures between 56° and 96° C. for 30 minutes, and the proteins in the serum obtained after removal of the denatured serum proteins with the casein at pH 4.6 were examined by a quantitative electrophoretic procedure. The denaturation curves obtained for each of the milk serum proteins indicated that the immune globulins are the least, and α-lactalbumin the most, heat resistant, with β -lactoglobulin and serum albumin showing an intermediate sensitivity. With the identification of three components in the electrophoretic patterns of the "proteose-peptone" fraction which were apparently present in the unheated milk, more of the electrophoretic entities of the milk serum proteins have now been elucidated.

Summary Use of an argentometric-amperometric titration procedure has revealed that the only source of -SH groups in skimmilk is the serum proteins. Casein and protein-free milk serum were found devoid of such groups. Praetionation of the serum protein material into a number of components by (NH 4 ) 2 SO 4 additions and pH adjustments revealed that β -lactoglobulin can account for practically all the -SH groups present. Study of the contributions of various major serum protein fractions to heat-induced cooked flavor in skimmilk demonstrated βlacto-globulin to be responsible for the flavor. Conversion of -SH groups to H 2 S as a result of heat treatment may explain, in a general way, the mechanism whereby β -lactoglobulin gives rise to cooked flavor. The AgNO 3 titration, when conducted in aqueous medium, appears to measure the same quantity of -SH groups in heated milk as nitroprusside and thiamin disulfide. When conducted in alcoholic medium the total number of -SH groups capable of activation by heat treatment presumably can be determined in unheated skimmilk. The argentometric-amperometric method gives values for -SH content of slightly less than half of those obtained with o -iodosobenzoate for both skimmilk and β -lactoglobulin.

SummaryTwo possible hypotheses for the mechanism of milk clotting were tested. The results obtained constituted strong evidence against one and suggested that the second is improbable. Milk was separated into a 5-fold-concentrated casein micelle suspension and milk serum. Pre-renneting of the serum did not reduce the rate of clotting on subsequent addition to the micelle suspension whether or not the conditions were such that the para-κ-casein became extensively aggregated. Washing of casein micelles up to 3 times with milk dialysate at 23°C extracted very little casein from the micelles and did not increase the clotting time of micelles resuspended to about the same concentration as in milk. The results appear to constitute decisive evidence against the hypothesis of milk clotting proposed by Parry & Carroll (1969). S-carboxymethyl-κ-casein, S-carboxymethyl-κ-casein containing 2·5 dimethylaminonaphthalene sulphonyl residues per mole, and rennin-treated dimethylaminonaphthalene sulphonated-S-carboxymethyl-κ-casein all bound Ca to the same extent at 30°C and pH 6·5, over the range 0·5–15·3 mM-CaCl2. This adds support to existing evidence that milk clotting does not involve formation of Ca bridges between casein micelles.

The structures of the triglycerides containing short chain fatty acids of bovine milk serum were determined by a combination of argentation-thin-layer and liquid-liquid partition chromatography. Some 168 different molecular species of triglycerides containing short chain acids were detected on the basis of a difference in degree of unsaturation or carbon number exclusive of positional isomers. All species present in amounts greater than the order of 0.01% were determined. The short chain fatty acids were widely distributed among the triglycerides, but significant amounts of triglycerides containing more than one short chain acid were detected. Although previous evidences for an interrelationship in the biosynthesis of triglycerides and lecithin were observed, comparison of the fatty acid and molecular species composition of the classes in milk serum in the present study did not reveal a direct relationship between the synthesis of these compounds.

β -Lactoglobulin can be easily separated from milk because it is the whey protein most resistant to precipitation by trichloroacetic acid. After removing casein from milk by acid precipitation, the residual whey is made up to contain 3% trichloroacetic acid. All proteins other than β -lactoglobulin precipitate and can be filtered. The nitrate is concentrated by negative pressure dialysis, dialyzed free of low molecular weight materials, and lyophilized. The recovered β -lactoglobulin had a specific rotation of −27.8 at 575 m μ , pH 4.75, an intrinsic viscosity of 4.1, and an electrophoretic mobility of −5.65×10 −5 cm 2 /v/sec in veronal buffer pH 8.6, 0.1 ionic strength. It is monophoretic in this buffer. These values agree closely with those obtained in similar analyses of a commercially available sample of 3 × crystallized β -lactoglobulin prepared by salt fractionation.

The sedimentation analysis was based on the opacity transfer velocity of micelle under ultracentrifugal field and photograms were taken with a schlieren optical system on the plate. The sedimentation coefficients determined at 30°C in milk serum were 440 S at pH 6.8 and 570 S at pH 5-8, respectively, at the maxima of the concentration gradient curves. The distribution of sedimentation coefficient at pH 6.8 ranged from 250 to 1500 S. The distribution of micelle size calculated from these results ranged from 850 to 2100 A in diameter with a most probable value of 1200 A. The size distribution was calculated also at pH 5.8. The micelle size at pH 5.8 was smaller in diameter by about 10% than at pH 6.8, indicating the shrinkage of micelles with decreasing pH.

An equilibrium-diffusion process was developed which utilizes Sephadex G-25 for removing low molecular weight solute materials from whey and skimmilk systems. Two successive treatments by the process removed a total of about 67% of the minerals and about 51% of the lactose from acid whey and about 36% of the minerals and about 72% of the lactose from concentrated skimmilk. Equilibration of the low molecular weight constituents between the milk serum phase and the interior of the Sephadex beads was complete within 1 min or less. The extent of fractionation achieved is primarily a function of the mixing ratio of product and Sephadex and the number of successive contact treatments used. The equilibrium-diffusion technique may be useful for developing large-scale, continuous processes for fractionating whey and skimmilk systems into low molecular weight and colloidal constituents.

Summary Milk serum proteins were electrophoreticalfy fractionated, using cellulose acetate membrane as a stabilizing medium in a veronal buffer (pH 8.6, ionic strength 0.05), at 200 v for 2 hr at 25 C. The strips were stained with Ponceau S dye and analyzed in a Spinco Analytrol or eluted and read in a Coleman Jr. Spectrophotometer. Choice of buffer, effect of ionic strength and pH of buffer, position of serum application, effect of voltage, effect of temperature, and concentration of serum solution were studied for optimum resolution of the serum proteins. Five distinct fractions were identified as blood serum albumin, beta-lactoglobulin, alpha-lactalbumin, pseudo-, and euglobulin in their decreasing rates of migration. Standard deviations and coefficients of variation for these five fractions indicated that the procedure was reliable. The dye-binding capacities of the five proteins were approximately the same and a linear relationship was established between dye uptake and protein concentration. Use of the method seems to offer significant advantages for investigating milk serum proteins.

Summary Eighty-one samples of fresh bulked milk, collected in ten regions of the United States in winter, spring, and fall seasons, were analyzed for nitrogen distribution, sulfhydryl content, and susceptibility of the serum proteins to heat denaturation. The variability in content of serum proteins and in their heat denaturability imposes serious limitations on the use of serum protein analyses for assessing dry milks of unknown history for specific uses. The sulfhydryl content not only exhibits a natural variability but is further affected by aging of the milk and contamination with copper.

N a previous study of the certified milk sold in the city of Detroit it was found possible to detect, by plating methods, Br. abortus in the milk from 3 of 5 herds studied.' Two hundred and thirty samples of certified milk were collected and plated from December, 1928, to September, 1929, in an attempt to isolate members of the Brucella group. These samples were taken from bottles ready for delivery and were plated when at about the same age as milk reaching the consumerfrom 30 to 48 hours old. Br. abortus was isolated from 10 of the 230 samples, the positive samples being obtained from but 3 of the 5 herds studied. Of the positive samples, an average of 2 organisms per c.c. was found, the highest count.being 8. Since September, 1929, steps have been taken by the Medical Milk Commission and public health authorities of Detroit to eliminate from these herds all animals which, on the basis of serological tests, were considered to be infected with Br. abortus. This study was undertaken to answer the question: " Do animals which give negative serological tests excrete Br. abortus in their milk?" The work consisted of an examination of the milk from each quarter of the udders of all animals composing the 5 certified herds producing milk for the city of Detroit. This included a bacteriological study by plating methods to isolate organisms of the Brucella group, and a serological study of Br. abortus agglutinins present in the milk serum. Records of blood serum agglutination on these animals were available through the courtesy of the Board of Health and owners of the herds, from which all data on blood serology were taken. The specimens were taken from April, 1930, to August, 1930. Samples from each quarter, in separate sterile tubes, were immediately taken to the laboratory and examined. One-half c.c. of milk from each was placed in 0.1 c.c. portions on poured liver agar plates, making a total of 20 plates for each animal. These were placed in tall

Summary A pure salt solution was prepared to simulate the composition of salts in milk serum, in order to study the mineral balance in milk. The salts were distributed into soluble and colloidal phases and a sediment was separated from the solution by centrifugation. Storage resulted in formations that resembled “lime grains.” Analysis showed that 35.9, 72.9, 51.8, and 80.9% of Ca, Mg, P, and citric acid, respectively, were soluble. The Ca :P ratio in the sediment was 1.46, indicating predominance of tricalcium phosphate. Heating decreased soluble Ca and pH, whereas cool-aging had the reverse effect. Variations in soluble Mg and citric acid were insignificant, but soluble P decreased on heating and on cool-aging in the pasteurized lot. The Ca :P ratio in the sediment from the untreated aliquot decreased to 1.26 on cool-aging, but pasteurization increased it to 1.63, which decreased again to 1.08 on cool-aging. Adding Ca increased Ca :P ratio, whereas adding P decreased it. The pH decreased with added Ca and increased with added P. Undissolved Ca, Mg, and citric acid in the sediment, when accounted for as tribasic salts, left 0.5 mg. of P and 0.4 mg. of Mg unaccounted for per 100 ml. of solution.

Skim milk and Ca-caseinate solution were homogenized at various conditions by a Gaulintype homogenizer and the changes in nitrogen distribution were studied; from the results of which it was confirmed that a decrease in casein nitrogen and an increase in non-casein nitrogen occurred through homogenization, and that among the ingredients of non-casein nitrogen the increase of proteose-peptone nitrogen was comparatively large.Casein particles are considered to include proteose-peptone as their components. When homogenized, a considerable amount of this proteose-peptone is set free through mechanical impact. This proteose-peptone is electrophoretically different from the proteose-peptone which originally exists in milk serum.

Summary A rapid determination of milk cations is presented. A trained technician can make four to six complete analyses a day for sodium, potassium, calcium, and magnesium. The cation exchange resin Dowex 50 is used to eliminate, quantitatively, the total amount of cations from a milk serum prepared according to the procedure of Jenness (2) and Murthy and Whitney (4) . Then, the cations are quantitatively eluted with 3.5 N HCl and analyzed by flame spectrophotometry. The accuracy of the method is due to the fact that the analyzed solution does not contain other substances than the cations to be analyzed—hydrochloric acid and ammonia. The interference of phosphoric acid, especially, and of organic materials, is avoided.

Summary When phosphorus isotope P 32 was given orally to a cow in mid-lactation, the blood showed a marked activity after 59min., mainly due to the activity of blood plasma acid-soluble phosphorus fraction. Later, two activity maximums were noted in both whole blood and blood plasma; the first appeared about 5 to 6 hr. after the beginning of the test and the second one about 30 hr. later. During the first of these periods, only the acid-soluble phosphorus fraction in plasma was labeled. The blood plasma phospholipid phosphorus fraction did not show any activity until several hours later. The increase in the specific activity of phospholipid phosphorus fraction also was much slower than in the plasma acid-soluble phosphorus fraction. The comparison of the specific activity of phosphorus in different blood and milk fractions at different periods following administration of P 32 shows clearly that both the acid-soluble phosphorus in the milk serum and the casein phosphorus originate from the blood plasma acid-soluble phosphorus fraction and not from the phospholipid phosphorus fraction. On the basis of the proportionally high activity of both the casein phosphorus and the acid-soluble phosphorus in milk serum, it is considered that possibly only one fraction of the phosphates usually determined as blood plasma inorganic phosphates serves as the main precursor of the phosphorus in milk. There was some evidence to indicate that blood plasma phospholipids also may be removed from the blood by the mammary gland.

A study was made of the effects of heat at 85 or 90°C. for 30min. on the rennet coagulability of skimmilk and of artificial systems composed of caseinate centrifuged from skimmilk and dispersed in milk dialysate with and without added milk serum proteins. Such heat treatments of skimmilk cause an immediate prolongation of the rennet clotting time at 35°C. and a further prolongation (hysteresis) when the heated sample is held following heating. These effects occurred with the artificial systems only if they contained β -lactoglobulin. Furthermore, 0.2% β -lactoglobulin added to skimmilk enhanced the magnitude of both the immediate prolongation and the hysteresis. Thus, heat treatment appears to alter β -lactoglobulin or to cause it to complex with casein in such a way that it inhibits rennet clotting. The rate of action of rennet at 16°C. is slower on heated than on raw milk, hence the heat-induced reactions involving β -lactoglobulin appear to interfere with the primary (enzymatic) action of rennet. Heat treatment of eight samples of skimmilk at 85°C. for 30min. caused an average transfer of 6mg. of calcium and 4mg. of phosphorus per 100ml. from the dissolved to the colloidal state. The dissolved calcium and phosphate tended to return to their original concentrations when heated milk was held cold. Dialysis of heated milk against a large volume of raw milk increased the colloidal phosphate and partially restored the rennet coagulability. These changes in state of calcium and phosphate occurred in the absence of β -lactoglobulin and were not enhanced in magnitude by added (0.2%) β -lactoglobulin. Thus, they seem to be independent of that protein. The hysteresis phenomenon may result from loss of colloidal calcium phosphate from the caseinate particles on holding after heating.

A method has been studied to investigate the purine and pyrimidine derivatives of milk from cows on normal feed and protein-free feed, by deproteinization with TCA1, extraction of ether-soluble material, treatment with active charcoal for purification, fractionation of the eluate by the method of Le Page, finally identification by the ion-exchange thin-layer chromatography. The composition of the purine and pyrimidine derivatives of milk produced by protein-free cows and by normally fed cows was about the same: predominantly orotic acid and several minor components, mainly CMP, UMP, traces of adenosine derivatives, and other not definitely identified compounds. Uric acid could not be estimated due to its low solubility and complete retention on the charcoal. Total UV-absorption at 280 nm for normal feed milk serum was between 4200–4700 O.D.U./l while protein-free milk serum gave different values between 3600–6900 O.D.U./l.

The ribonuclease of milk has not been investigated, although there has been in recent years a rapid expansion of our knowledge of ribonuclease in body fluids such as cerebral spinal fluid ( Houck, 1958 ), blood ( Levy and Rottino, 1960 ; Rabinovitch and Dohi, 1957 ; Zittle and Reading, 1945 ), urine ( Levy and Rottino, 1960 ), and the extracellular fluid of skin ( Tabachnick and Freed, 1961 ). Zittle and DellaMonica (1952) noted that certain purified fractions of bovine milk showed phosphodiesterase activity when ribonucleic acid was used as the substrate. Bailie and Morton (1958) showed that the nucleic acid content of mammary gland microsomes diminished when the microsomes were incubated in milk serum for 12 hours, and suggested that the phosphodiesterase of Zittle and DellaMonica (1952) might have caused the decrease in nucleic acid. They suggested that milk microsomes (with a low nucleic acid content) might be derived from mammary gland microsomes, which contained a much higher nucleic acid content. In this report evidence is presented for the presence of relatively high concentrations of ribonuclease in cow's milk. Some properties of this enzyme, as well as its partial purification, are described.

SummaryThe freezing point and pH of milk ultrafiltrate were different from the values obtained for the original milk. It was estimated that from 3·2 to 4·6% of the soluble material in milk was retained by the ultrafiltration membrane. Comparison of the composition of ultrafiltrate and rennet whey showed that the soluble material retained consisted mainly of calcium and citric acid. A similar effect was observed with dialysis, although the quantity of soluble material retained was much less. Rennet whey was considered more representative of milk serum than either ultrafiltrate or diffusate.

Mit Hilfe der Elektrophorese und des Koagulationsbandes nach Weltmann werden die Einflusse von ultravioletten Strahlen auf die Eiweiskorper des mit der Ultrazentrifuge gewonnenen Milchserums untersucht. Dabei zeigen sich unter Versuchsbedingungen, die mit denen der Praxis der Milchbestrahlung vergleichbar sind, Veranderungen an den Proteinen. Diese Veranderungen treten jedoch fruhestens bei Bestrahlungszeiten von 20 sec Dauer auf und nehmen mit langerer Bestrahlungszeit zu. Sie dokumentieren sich elektrophoretisch bei kurzdauernder Bestrahlung in einer Abflachung der — in Analogie zum Blutserum so benannten — α- und β-Globulinfraktion, bei langdauernder Bestrahlung in einem Abflachen und Verbreitern auch der Albuminfraktion. Das γ-Globulin scheint selbst bei 60 min Belichtung unverandert. Mit Hilfe des Koagulationsbandes nach Weltmann wird auserdem eine Beeintrachtigung der Stabilitat der Milchserumproteine nach 40 sec Bestrahlung festgestellt. Die Versuchsbedingungen werden denen der Praxis gegenubergestellt und dabei die Schlusfolgerung gezogen, das die zur Rachitisprophylaxe ubliche Milchbestrahlung von 0,5 sec keinen mesbaren Einflus auf die Milchserumeiweiskorper ausuben durfte.

SummaryA new method for determining the composition of the colloidal phosphate of milk has been developed, based on analysis of milk free from colloidal phosphate. Preparation of this material is described.The results suggest that the so-called colloidal calcium phosphate of milk should be more properly described as a colloidal phosphate—citrate.This colloidal phosphate—citrate shows considerable analytical resemblance to the precipitate formed on neutralizing acidified milk serum. Both can be represented approximately by the empirical formula of a hypothetical citrate apatite.

Summary The addition of 1mg. of cysteine HCl per milliliter of unheated skimmilk resulted in a semen diluent which maintained the livability of bull spermatozoa stored at 4° C. equally as well as did skimmilk heated at 92° C. for 10 minutes. Cysteine HCl levels of 0.5 and 2.0mg. per milliliter were almost as effective in supporting livability as was 1.0mg. per milliliter; 0.25 and 4.0mg. per milliliter were definitely inferior to the optimum level. Gluthathione also was shown to be effective in supporting spermatozoan livability in unheated skimmilk, but methionine was found to be ineffective, indicating that the beneficial effect was due to the sulfhydryl groups. When cysteine HCl was added to protein-free milk serum for use as a diluter, no improvement in spermatozoan livability was obtained, indicating that the sulfhydryl compound exerted its effect by acting on the nondialyzable portion of the unheated skimmilk rather than by acting directly on the spermatozoa.

The spermatozoa of horses are much weaker and have much shorter viability than those of other domestic animals, such as bulls, sheep, etc. At present. a large number of mares are artificially inseminated in Japan. The insemination has been, however, practised generally with fresh semen just after ejaculation, because effective methods of sperm preservation are not yet found. For the wider practical application of the artificial insemination, more suitable methods of preservation must be found. Thus we investigated various dilution media which have been examined hitherto by other authors and then effects of sperm serum on the viability of spermatozoa were also studied.In the experiment sperm was preserved at 4°C. Results obtained here were as follows:1) Viability of spermatozoa was short in ejaculated semen.2) Sperm serum caused remarkable reducation of viability of spermatozoa.3) Physiological salt-, Ringer-, Tyrode-, Lockesolution gave bad effects on spermatoza and blood serum, milk serum, lactose-solution, secreting fluids of female sexual organs (follicle and uterus), etc. did not show favourable results.4) 5.25% glucose-, 10% cane sugar-solution gave comparatively good results and glucose buffer solution, such as phosphate-, citrate- and sulphatebuffer and egg yolk extract did not substantially differ from glucose-solution.

Milk serum and cheese whey sterilized by filtration inhibited 22 of 56 strains of propionibacteria comprising eight species. The darkly pigmented Propionibacterium rubrum and Propionibacterium thoenii strains were unaffected by the whey filtrates. A susceptible Propionibacterium shermanii was selected for further testing. Boiling whey for ten minutes or pasteurizing milk at 82C for 16 seconds eliminated the inhibitory activity. The antibacterial substance(s) appeared to be nondialyzable and labile to treatment with Pronase, a proteolytic enzyme capable of cleaving a wide variety of proteins and peptides. The inhibitory principle(s) also was found in skimmilk obtained either by warm or cold separation. The principle(s) in whey active against propionibacteria appeared to differ from other natural inhibitors reported in milk, primarily in its ability to suppress the growth of catalase-positive organisms, and in its insensitivity to sulfhydryl compounds in the culture medium. Because of the wide ranging inhibitory activity of milk whey against several individual strains and species of propionibacteria, this phenomenon could have a direct bearing on flavor and eye development in Swiss cheese, especially where natural propionibacteria in milk is relied upon to effect these changes in the maturing cheese.

The study reported in this article relates to the instillation of three viruses into the mammary glands of goats. The PR8 strain of influenza A virus (Myxovirus influenzae) and mumps virus (Myxovirus parotidis) replicated in the gland and antibody formation occurred in a few days. Adenovirus 3 failed to replicate but repeated instillations led to antibody synthesis.The antibody of each was concentrated. Influenza PR8 was found to possess two activities, complement fixing which gave reactions with all strains of type A examined, and neutralizing antibody which was specific for the PR8 strain.In the case of adenovirus 3, the milk contained neutralizing antibody only. It was specific for adenovirus 3.Mumps virus replicated in the gland and antibody formation followed. The properties of this antibody have not been studied.

Milk and fractions therefrom were lyophilized and the powder was mixed with silicic acid, acidified, and extracted with ethyl ether in a Soxhlet extractor. The free fatty acids (FFA) extracted in this manner were isolated on an anionic exchange resin, converted to methyl esters, and analyzed by gas-liquid chromatography. The data were quantitated by use of internal standards. Most of the FFA of milk were distributed in the fat and the fat globule membrane fraction. Milk serum free of lipid material contained less than 10% of the FFA. Hence, milks with higher fat content contain more FFA, and milks standardized with skimmilk contain less than the original. Heating of milk had a pronounced effect upon the quantity of FFA; as heat treatments increased, the FFA decreased. Induced lipolysis caused a marked increase in FFA. In general, the FFA composition of milk, regardless of treatment, was comparable to the fatty acid composition of milk glycerides.

Summary The action of the milk fat in milk as a foam depressant has been discussed in connection with the theories which have been proposed to explain the phenomenon. The consequences of these theories have been investigated experimentally. Contrary to some of the ideas expressed adsorption experiments indicate that the action of milk fat is not due to the removal by the fat of the protein adsorbed at the air/milk serum interface; and surface tension, and superficial viscosity measurements indicate that the action is not attended by any significant changes in the dynamic and static surface tension, or in the superficial viscosity of milk serum. The destructive action of milk fat and other lipoids on foam depends in some way upon the ability of these substances to spread on pure water, and consequently the theories relating to the destructive action of fat on foam which do not take into consideration the importance of spreading, are open to criticism. It has been pointed out that the presence in a thin film of a globule of a substance which will spread may be considered tantamount to the existence of a rupture, and the suggestion has been made that the decrease in foaming power occurring when skim milk is added to milk serum is capable of interpretation on the basis of the equivalence noted between the existence of a rupture, and the presence of a spreading substance in a thin film. Procedures have been described for the measurement of dynamic surface tension, and of an index of superficiual viscosity.

Summary While recent findings have emphasized the complexity of milk phospholipids (P-lipids), as revealed by the classes present and their fatty acid compositions, results of this study indicate that these P-lipids occur in units of relatively homogeneous lipid composition. Disposition of the P-lipids was studied using cream separation, churning, and ultra-centrifugation to fractionate the lipids in milk. The classes of P-lipids present in the various milk fractions were revealed by thin-layer chromatography (TLC), and the fatty acid composition of total P-lipids in the fractions was determined by gas chromatography (GC). The results demonstrated the same classes of P-lipids (mainly cephalin, lecithin, and sphingomyelin) in similar proportions with much the same total fatty acid composition in milk, skimmilk, cream, and buttermilk. This unity also was detected in fractions derived by freezing and sawing tubes of milk or buttermilk that had been centrifuged in a manner (25,000× g for 6 hr) to yield differentiation of the P-lipids by sedimentation. In both milk and buttermilk the bulk of the P-lipids tended to deposit with a particle that settled mainly in the upper level of the casein layer. The evidence is consistent with the concept of a membrane of fairly homogeneous lipid composition in milk serum and on the surface of milk fat globules. Current evidence suggests that this membrane is derived at least in part from the cytoplasmic membrane in the apical region of the secreting cell. Some affinity of unsaturated lipids for protein phase was noted and may be relevant to lipid oxidation and enzymatic phenomena.

Summary The time and temperature relationships determining the extent of denaturation of serum proteins of fluid skimmilk have been established for temperatures ranging from 145 to 175° F. There is a ten-fold decrease in the time required for a given percentage denaturation of the serum proteins for each 13.5° F. increase in the temperature. Any application of heat to milk may be detrimental to its utility, and since heat treatments are cumulative, the successful manufacture of a product such as low-heat nonfat dry milk solids depends not only upon adequate control of the time and temperature of pasteurization but also on each of the other manufacturing processes. Such control may be based upon the turbidimetric estimation of the milk serum proteins.

1. 1. Freshly secreted bovine milk serum actively incorporated labelled glycerol into the various glycerolipid classes occurring in milk, particularly triglycerides, phosphatidylcholine, and phosphatidic acid. 2. 2. Addition of long-chain fatty acids and ATP significantly enhanced the amount of glycerol utilized. 3. 3. The evidence suggests that microsomal material containing the enzymes responsible for glycerolipid synthesis is secreted with other milk components.

SUMMARYIt has been shown that there is a time-dependent transfer of β-casein and the milk serine proteinase system from micelles to milk serum with change of temperature from 38 to 4 °C. It has been established that the γ-caseins can be formed by proteolytic degradation of β-casein. By a simple extraction technique, the very hydrophobic γ-casein fraction was separated from stored milks (26 and 4 °C) and estimated quantitatively. The results showed that the proteolytic degradation of β-casein is faster at 4 °C than at room temperature and this can be explained by the immobilization of enzyme and substrate at the micelle surface at higher temperatures (26 °C).The results indicate that irreversible changes during cooling for short periods do not cause problems in milk processing, but the formation of γ-caseins and phosphopeptides may influence the technological properties of raw milk stored for more than 48 h.

Studies on the synthetic mechanism of milk casein in mamma with tracing of Isotope was began with tracing of Ca45 in goat's venous injection.Ca in blood is accumulated remarkably in mammary gland and after 30 minutes Ca removes into milk, but its Ca disappears after 27 hours.In milk Ca combines with casein and lactose, and residue exists in milk serum as soluble matter.

Denaturation of whey proteins by heat was higher in ultracentrifugal milk serum collected at 105,000× g for 30 minutes (no micellar casein) than in skimmilk with whole micellar casein. Denaturation decreased with increased micellar casein in milk serum. Denaturation further decreased when micellar casein was added to skimmilk. Buffalo milk whey proteins were more susceptible to heat denaturation than those of cow milk, with or without micellar casein. Micellar casein in the milk system partially stabilized whey protein against heat denaturation. Cow micellar casein stabilized more than buffalo micellar casein in their respective milks.

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In connection with the routine agglutination test of blood samples from dairy and beef cattle herds for bovine infectious abortion (Brucella infection) an opportunity has been provided on different occasions to note the correlation of specific agglutinins for Brucella species in the blood and milk of cows. Over a period of years the presence of Brucella agglutinins in the blood serum and their absence in the milk serum * of the same animal has been observed. Notwithstanding that these observations have repeatedly shown that agglutinins in the milk are not reliable guides in the diagnosis of Brucella infection in cattle, few comparisons to show the relation of agglutinins in the blood and milk serums of the same animals have been reported. The comparative results of the blood and milk serum agglutination reactions in the same animals included in this report are based upon the standard tube or slow agglutination method, using two dilutions?1: 50 and 1: 200. Complete agglutination in both dilutions or complete agglutination in 1: 200 was regarded as positive. A positive 1: 50 and a negative 1:200 was regarded as doubtful. The blood samples were collected from the jugular vein and the milk samples from the four quarters of the udder. The clear blood serum for the agglutination test was obtained in the usual way by centrifugation, or by allowing the blood samples to stand until the clear serum escaped from the clot. The milk serum, or whey, was obtained by adding one drop of rennin to 4 or 5 cc. of milk and, after incubating for 30 minutes at 37 C, the clot was broken and the clear whey brought to the surface by centrifugation. In our experience the relative proportion of negative milk serum agglutination tests in lactating animals that react positively to the blood test are illustrated in the following results obtained from two groups of dairy cows. In herd 1 of 91 animals, 77, or 84.62^, of the blood and milk samples gave complete agreement in the test for Brucella agglutinins. Fifty-two

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This report describes the development of a method for the production and isolation of neutralizing antibodies against rabies virus (ERA strain) and other agents in the goat mammary gland during active lactation. The rabies virus did not propagate in the gland, but neutralizing antibodies were produced by serial instillations of the antigen. This process was termed 'sham infection.' Antibodies first appeared in the milk about the 20th day and the titer increased until the 28th day. The antibodies were found to be associated with the lactogammaglobulin. The milk globulins were fractionated by gel chromatography and the fraction containing the antibody was isolated. This fraction was further purified and characterized by immunodiffusion, immunoelectrophoresis, and an analytical ultracentrifugation technique. The neutralizing antibody activity after the 29th day was associated with the milk serum IgG fraction. This active fraction was found to have a sedimentation coefficient of 6.8 Svedberg units.