bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface oxidation in cold-stored butter: the effects of desiccation and moisture absorption
Authors: Pont E. G. , Rogers W. P.
Published: June 2009

Unwrapped samples of salted sweet-cream butter were stored in darkness at 1°C for 6–8 weeks over silica gel, water, isotonic salt solutions, and in free air. Moisture and fat peroxide gradients from the surfaces to the interior of the stored samples were measured in thin sections obtained by a simple macrotome technique. The surface oxidized at the same rate as the rest of the butter and its rate of oxidation was not affected by moderate drying or moisture uptake. With severe surface drying, especially when induced by silica gel, fat oxidation was inhibited, while moisture uptake by the more heavily salted butters promoted surface oxidation.
The use of quarter samples in the assessment of the effects of feeding treatments on milk composition
Authors: Waite R. , Abbot J. , Blackburn P. S.
Published: June 2009

To investigate whether milk of abnormal quality from some quarters of twelve cows on a Latin square type feeding trial would bias the results for chemical composition, the compositions of milk from normal and affected quarters were compared with each other and with that of the milk obtained from the whole udder by normal milking.

The average number of quarters producing abnormal milk in each of the four periods was eighteen, with only small variation between periods. Cell counts ranged from 50000 to 25 × 106/ml with 31% of them below 500000/ml; as cell count increased, lactose percentage and casein number fell. Pathogenic bacteria were detected in only 70% of the abnormal milks. The solids-not-fat (S.N.F.) percentage of milk from affected quarters was lower on average than that from healthy quarters by 0·43, the decrease resulting entirely from a lowered lactose percentage. The total nitrogen content was the same in both types of milk, but there was 4·5% less casein in milks from affected quarters.

Because in this particular experiment the distribution of the abnormal milks was almost uniform over the four feeding treatments, the results obtained for treatment effect on milk composition by the normal milking method were not biased by the occurrence of disease, but the general level of composition was depressed by 0·2% fat and 0·2% S.N.F. In other experiments the incidence of disease might happen by chance to differ between treatments, with the result that the findings about milk composition could be erroneous.
Determination of leucocyte concentrations in cow's milk with a Coulter counter
Authors: Phipps L. W. , Newbould F. H. S.
Published: June 2009

A technique for determining the concentration of leucocytes in cow's milk is described which is more rapid and accurate as well as much less tedious than conventional microscope methods. The leucocytes are isolated from the fat globules of comparable size by a novel centrifuging procedure. Sizing of the leucocytes with a Coulter electronic counter shows that their volumes range from about 45 to 1770 µm3but a partially overlapping distribution of other particulate matter prevents the accurate determination of the total number of cells present. The numbers counted in truncated leucocyte distributions, however, correlate linearly with total cell counts determined with an improved microscope method up to 6 × 106cells/ml of milk.
Mechanics of machine milking: II. The flow-rate pattern within single pulsation cycles
Authors: Thiel C. C. , Clough P. A. , Westgarth D. R. , Akam D. N.
Published: June 2009

The milk flowing during a single pulsation cycle was collected in a circle of contiguous cups which rotated in a chamber at 1 rev/pulsation cycle just below the end of the teatcup liner. The mean flow rate during the time taken for each collecting cup to pass under the milk stream was calculated and the flow-rate curve for the milkflow period of the pulsation cycle plotted. Flow rates were measured at 130, 97, 65, 32 and 16 c/min, and also after the pulsator had been stopped with the liner open for 0·5 min (0 pulsation).

It was concluded from the series of flow-rate curves at the different pulsation rates that flow rate from the teat increased in about 0·05 sec to a steady value which continued for 0·5 sec or so, and then declined over a period of about 1·5 sec to a new constant value approximately equal to that shown after milk had flowed continuously from the teat for 0·5 min.

These results suggest that once the pressure difference across the streak canal during milking forces the teat sphincter open a considerable time elapses before the muscle control system responds, and that a further much longer period elapses before the full closing force of the sphincter is exerted. Thus, it would appear that at pulsation rates of about 50 c/min and above, the streak canal is closed by pressure exerted on the teat by the closing liner, the sphincter muscle playing no active part because its response rate is slow compared with the pulsation rate. At lower pulsation rates the flow rate declines during each cycle because the sphincter muscle has time to exert a closing force to a greater or lesser extent depending on the duration of the milkflow period.
The variation in the cell count of cow's milk throughout lactation and from one lactation to the next
Authors: Blackburn P. S.
Published: June 2009

Total and differential cell counts were obtained for approximately 38000 fore-milk samples taken from cows of the Institute herd during a period of 12 years.

For most of the period of the experiment the incidence of subclinical mastitis associated with coagulase-positive staphylococci was about 5% of all the quarters in milk, but for a period of about 12 months in the 7th and 8th year of the experiment the herd was free from infection with coagulase-positive staphylococci.

The average cell count for cows in each lactation up to the 7th was calculated, and in addition each lactation was divided into 4 equal periods, and the average cell count for each period determined.

It was found that the average total cell count increased from one lactation to the next, and that this rise was due mainly to an increase in the number of polymorphs in the samples, the counts of cells other than polymorphs remaining relatively constant.

It was also found that the average total cell count rose during the course of any one lactation; but this was due to an increase in both the number of polymorphs and the number of cells other than polymorphs.

During the period when the herd was free from infection with coagulase-positive staphylococci the average lactation age of the cows was 4·3 lactations, and the average total cell count was 0·30 million cells/ml, a figure which was the same as that obtained throughout the experiment for animals in their 1st lactation.

Possible relationships between the rise in cell counts and the pathology of mastitis are discussed.
The effect of concentrating milk on the fat retention property of the cheese curd
Authors: Mabbitt L. A. , Cheeseman G. C.
Published: June 2009

Concentration of milk results in a considerable increase in retention of fat by the rennet curd formed under conditions of disturbance. The fat retention property is not conferred by concentration per se but by some effect, probably involving surface phenomena, associated with the process.

Changes in composition of the fat globule membrane due to incorporation of milk protein accompany the improvement in fat retention. It is suggested that casein bound firmly to the globule during the concentration process, forms strong links with the coagulated micelles of the curd.
The effect of equal and unequal intervals in twice-daily milking on the milk yield of ewes
Authors: Morag M. , Fox S.
Published: June 2009

The effect of equal and unequal milking intervals (12 + 12, 10 + 14 and 8 + 16h) was investigated in milch ewes. The treatments were applied to 9 ewes using a double 3 × 3 Latin square. The daily production of milk and fat was unaffected by the changes in milking interval.
A suggested correction to the British Standards hydrometric method for the estimation of total solids in milk
Authors: O'Keeffe M. G.
Published: June 2009

1082 drip samples of fresh milk were taken at a creamery over a period of 3 years and tested for total solids by the current gravimetric method (British Standards Institution, 1963) and the hydrometric method with the fat in the liquid state (British Standards Institution, 1959). On average, the hydrometric method overestimated the total solids by 0·096. It is suggested that the formula which applied before 1 October 1957 is correct and should replace the present formula.
A milking parlour for experimental work with lactating ewes
Authors: Morag M. , Gibb J. A. C. , Fox S.
Published: June 2009

A milking parlour and milking equipment are described which have been found suitable for experimental work on the nutrition and the physiology of lactating ewes.
The effect of oxidation on the iodine values of phospholid in milk, butter and washed-cream serum
Authors: Pont E. G. , Holloway Gwenda L.
Published: June 2009

Phospholipid was isolated from milk, butter, and washed-cream serum by solvent extraction followed by simple counter-current distribution and thin-layer chromatography. Iodine values from fresh samples, determined by a micro-Wijs technique, ranged, for the cephalin fraction, from 70 to 86, for the lecithin fraction from 44 to 55, and for the sphingomyelin fraction from 36 to 44. In washed-cream serum, oxidation with copper and ascorbic acid led to reduction in extractable phosphorus, decreased chromatographic mobility of phospholipid and significant falls in the iodine values of the 3 phospholipid fractions. In milk, slight reductions in phospholipid iodine values were observed following copper-catalysed oxidation but they were not consistently significant. Iodine values of butter phospholipids remained unchanged even after gross oxidative quality deterioration.
A technique for studying the build-up and prevention of milk film on hard surfaces
Authors: Clegg L. F. L. , Cousins Christina M.
Published: June 2009

A laboratory technique using glass and stainless steel slides has been developed to study the build-up of milk film on hard surfaces and its removal with detergent-disinfectant mixtures. Soiling and cleansing treatments were of similar duration to those used in practice but were repeated 6 or 7 times a day for 4 days to simulate 12 or 14 days' milking and washing procedures in the farm dairy; no mechanical assistance was used with the cleaning solutions. Soiling was followed immediately by a pre-rinse, wash and final rinse, allowing a short period for drying before further re-soiling. The technique eventually developed involved treatments repeated 18 times, using solutions at 15·5 °C. The weight of milk film and its content of fat, mineral and ‘protein’ were determined.

Under the conditions of the experiments the following were observed.

(1) The deposit left by all treatments consisted mainly of fat with a smaller proportion of protein and still less of mineral matter.

(2) Glass accumulated slightly less deposit than did stainless steel with an aquablast finish.

(3) Removal of milk film was more complete when sodium hypochlorite was added to certain detergent solutions than when the materials were used separately.

(4) With the treatments studied, the use of the detergent solution from a previous treatment as a pre-rinse did not result in a reduction in the residual film.

(5) A final rinse with 0·1% phosphoric acid virtually eliminated the mineral matter from the residual film.

(6) The substitution of a warm (46°C) for a cold (15·5°C) pre-rinse resulted in a reduction of 40% in residual film and the further use of a warm final rinse effected a reduction of 64%.

(7) The addition of 0·05% wetting agent (Lissapol NDB, I.C.I. Ltd.) to the prerinse effected only marginal improvement in the treatments studied.

(8) Omission of the pre-rinse and corresponding lengthening of the detergent treatment had no consistent effect.
Comparison of milks processed by the direct and indirect methods of ultra-high-temperature sterilization. I. An experimental ultra-high-temperature sterilizer and its characteristics
Authors: Burton H. , Perkin A. G.
Published: June 2009

An experimental ultra-high-temperature milk sterilizer, of 1140 1/h capacity and capable of operation as a plate-type indirect heating plant or as a steaminto-milk direct heating plant, has been installed for comparisons of the milk produced by the direct and indirect processes. The sterilizer and its ancillary equipment are described, together with methods of plant sterilization and milk processing. Time-temperature profiles of the plant are given for both modes of operation.
Nature of ceramide in bovine milk
Authors: Fujino Y. , Fujishima T.
Published: June 2009

Ceramide, an N-acyl derivative of sphingosine bases, has been isolated for the first time from bovine milk in the free form and its constitution studied. Sixteen component fatty acids were found, among which C23:0 (38·1%), C24:0 (29·5%), C22:0 (17·9%) and C16:0 (7·2%) were predominant. Seven component long-chain bases were detected. The principal bases were C18-sphingosine (35·0%) and C16-sphingosine (31·6%).
The role of the primary phase of rennin action in the coagulation of cow's milk
Authors: Wheelock J. V. , Penney J. P.
Published: June 2009

The rennin coagulation time of cow's milk was inversely proportional to the amount of glycopeptides released by rennin action on the milk and to the initial velocity of the release of the glycopeptides. It was shown that the rennin coagulation of milk is largely determined by the primary phase of rennin action and, therefore, by the amount of κ-casein that is susceptible to attack by rennin.
Effect of 75% replacement of dietary N by urea and ammonium sulphate on the composition and properties of sheep's milk
Authors: Tanev G.
Published: June 2009

A 23-week trial was conducted using 4 groups each of 6 ewes to study the effects on milk yield and composition of substituting non-protein nitrogen (NPN) for 75 % of the dietary nitrogen. The control group received a winter ration which included silage followed by a summer ration containing lucerne. The test groups received substitutes of urea, ammonium sulphate, or urea+(NH4)2SO4. The milk yield of the test groups was lower (P< 0·01) than that of the control group. Depression of the fat content of the milk reached statistical significance (P< 0·01) in the groups receiving (NH4)2SO4and urea+(NH4)2SO4. In comparison with the control group, the protein content of the milk was greater in the group receiving urea and smaller in the other 2 test groups. The milks of the test groups had lower amounts of essential amino acids in the free state and higher amounts of non-essential amino acids than did the control milk. Milk-clotting time was increased in the test groups; the increase was greatest (P< 0·01) for the group receiving (NH4)2SO4and least (P< 0·05) for that receiving urea.
The N-acetyl neuraminic-acid content of the milk of various species
Authors: Morrissey P. A.
Published: June 2009

Average N-acetyl neuraminic-acid (NANA) content of milk from cow, sheep, goat, mare, donkey and sow (about 10 samples from each species) was 17·7, 10·1, 6·4, 6·1, 12·0 and 64·0mg/100 ml, of which 14·2, 8·4, 3·2, 3·1, 5·0 and 53·7mg/100 ml respectively was in the casein fraction. The NANA content of casein showed marked species variation ranging from an average of 2·18 % for the sow to 0·09 % for the goat.

About 28 % of the casein NANA of mare's milk was liberated in the fraction soluble in 12 % TCA by the action of rennin at pH 6·6 compared with 75 and around 100 % for donkey's and sow's milk respectively; about half the total NANA in the casein of cow's, sheep's and goat's milk was released under the same conditions.
The effect of reduction and alkylation on the primary phase of rennin action on unheated and heated milk
Authors: Wilson G. A. , Wheelock J. V. , Kirk A.
Published: June 2009

The effects of cystine-reducing and sulphydryl-alkylating agents on the extent of the primary phase of rennin action on unheated and heated milk samples were studied. Alkylating agents alone had a negligible effect, but heated samples, reduced with tri-n-butyl phosphine prior to alkylation with a mono-functional agent (sodium iodoacetate) did not show the usual inhibition of the primary phase. Heated samples, reduced and alkylated with a bi-functional agent (ethylene dibromide) which can re-cross-link the broken disulphide bonds, however, did give the normal inhibition. These results suggest that effects on the primary phase due to heat treatment of milk are determined to a large extent by rearrangement of the disulphide cross-links, and if these are permanently broken, heat appears to have little effect.

The results differ in some important respects from those obtained on the complex formed between isolated β-lactoglobulin and isolated κ-casein, and therefore throw doubt on the generally held view that there is a similar type of interaction in whole milk.
Sulphur compounds in relation to Cheddar cheese flavour
Authors: Manning D. J.
Published: June 2009

Comparisons are made between the sulphur-containing volatiles of 4 Cheddar cheeses, using a gas chromatograph equipped with a flame photometric detector.

Two of the cheeses were made aseptically from whole milk, with and without starter, the third was made from whole milk with starter in an open vat, and the fourth was made from skim-milk also in an open vat. Only the cheeses made from whole milk with a starter culture developed normal Cheddar flavour; the cheese made without starter and the skim-milk cheese had little or no flavour.

Considerable differences were found in the chromatograms of the 4 distillates and in particular methanethiol was found only in the distillates from the cheeses having Cheddar flavour.
Fluoro-opto-electronic cell-counting on milk
Authors: Madsen P. Schmidt
Published: June 2009

The equipment tested (Fossomatic) is a fully automatic electronic instrument for counting the somatic cells in milk samples. The results are printed on a paper strip and displayed on a digital counter. The capacity is 180 samples/h.

Counting results obtained with the instrument have been compared with direct microscopic cell counts and particle counts by Coulter counter. The correlation coefficient with microscopic cell counts was 0·922–0·988, and with counts by the Coulter counter it was 0·916–0·992.

Reproducibility showed a coefficient of variation of 2–5 %. The carry-over between the samples was 2·0 %. Preserving milk samples with 0·05 % potassium dichromate did not influence cell counts, whereas freezing the samples reduced the counts 30 %.
Carnitine secretion into milk of ruminants
Authors: Snoswell A. M. , Linzell J. L.
Published: June 2009

Total acid-soluble carnitine concentration in cow's, goat's and ewe's milk was 117, 101 and 872 nmol/ml respectively, of which acetylcarnitine made up 30% in goats, 10% in cows and 11% in ewes. The concentration of carnitine in the arterial blood of goats decreased significantly (P< 0·01) with the onset of lactation from 18·1 to 8·4nmol/ml and during lactation in goats and cows there was a significant arterio-venous difference of carnitine across the udder, with mean extractions of 14 and 5% respectively. Calculation of the udder uptake of carnitine, from these figures and from udder blood-flows, showed that in goats the amount lost in the milk was much less than that taken from the blood, but in cows about the same. Two groups of lactating ewes on low and high nutritional planes were sampled at 2-weekly intervals from 2 to 8 weeks of lactation. The concentrations of total acid-soluble carnitine and acetylcarnitine in the milk were similar in the 2 groups and remained relatively constant over this period, but the total acid-soluble carnitine concentration in jugular blood from the ewes on the low nutritional plane was significantly (P< 0·01) higher than from the ewes on the higher nutritional plane from the fourth week of lactation. The total acid-soluble carnitine concentration in liver of goats was 290 nmol/g wet wt; mammary gland, 324; kidney-cortex, 692; heart, 2030 and skeletal muscle, 14300. Carnitine acetyltransferase (E.C. 2.3.1.7) activity of mammary tissue from lactating ewes was 0·6 μmol per min per g wet wt of which approximately half appeared to be ‘latent’ or membrane bound. Acetate thiokinase (E.C. 6.2.1.1) activity in this tissue was found to be 1·5 μmol per min per g wet wt and was predominantly localized in the cytoplasm. Carnitine palmitoyltransferase (E.C. 2.3.1.21) activity in the same tissue was 0·8 μmol per min per g wet wt while no acetylcarnitine hydrolase activity could be detected. The results suggest that carnitine in mammary tissue is extracted from the blood for the oxidation of both acetate and long-chain fatty acids and that some is lost in the milk.
High-melting-point triglycerides and the milk-fat globule membrane
Authors: Wooding F. B. P. , Kemp P.
Published: June 2009

The initial milk-fat globule membrane (MFGM) consists of a unit membrane with a layer of dense material 10–20 nm thick on one side. Extraction of isolated initial MFGM preparations 3 times with chloroform: methanol removes 90% of the triglycerides and most of the phospholipids. This extraction has no significant effect on the width or morphology of the dense material examined subsequently in the electron microscope, although all trace of the unit membrane disappears. This indicates that the dense material is more likely to be derived from protein from the secretory cell cytoplasm than from high-melting-point triglycerides from the milk-fat globule as has previously been asserted.
Effect of feeding fat to dairy cows receiving a fat-deficient basal diet: II. Fatty acid composition of the milk fat
Authors: Banks W. , Clapperton J. L. , Ferrie Morag E.
Published: June 2009

The effects on the fatty acid composition of milk fat of feeding various oil-enriched diets (soya oil, red palm oil/palmitic acid and tallow) to dairy cows receiving a fat-deficient basal diet are reported. It was found that a linear relation was obtained between the dietary intake of C18fatty acids and their output in milk fat. A similar relation, applicable only to the oil-rich diets, was found for the C16acids. The significance of these relations is discussed. Fatty acid compositions and yields are discussed and compared with literature examples in which similar oil-rich diets were fed, but in which the low amount of fat in the basal diet did not markedly depress milk yield. The proportion oftrans-isomer in the octadecenoic acid was found to increase appreciably on feeding soya oil, and to a lesser extent with dietary tallow. A linear relation between the 18:0 and 18:1 contents of milk fat was found, and its significance is discussed.
Lactostrepcins - acid bacteriocins produced by lactic streptococci
Authors: Kozak Witold , Bardowski Jacek , Dobrzański Władysław T.
Published: June 2009

All 47 non-nisin producing strains ofStreptococcus lactisand 12/13 strains ofStr. lactissubsp.diacetylactisexamined produced bacteriocins, for which the term lactostrepcins is suggested. Seven strains ofStr. cremorisexamined produced no bacteriocins active against 3 lactic streptococci strains used as indicators. The strains examined were divided into 3 groups: I, those producing lactostrepcins active against only one streptomycin resistant mutant ofStr. lactis60 indicator strain; II, those producing lactostrepcins active against all 3 indicator strains; III, those not producing lactostrepcins active against the indicator strains employed. The lactostrepcins were sensitive to various proteolytic enzymes and to phospholipase D, but retained full or partial activity after dialysis. Most of the bacteriocins studied were fully active only within the pH range 4·2–5·0 and were reversibly inactivated at pH 7·0 or 8·0. Results suggested occurrence of 4 different lactostrepcins. The lactostrepcins produced by all group I strains were the same, but there were differences among the lactostrepcins produced by group II strains. Lactostrepcins killed some β-haemolytic streptococci and some strains ofLactobacillus helveticus. One of the lactostrepcins was also active against certainLeuconostocstrains, but not against otherLeuconostocstrains, nor againstL. helveticusor other Gram-positive bacteria.
Effect of lipases on the ripening of Egyptian Ras cheese
Authors: El-Salam Mohamed H. Abd , El-Shibiny Safinaz , El-Bagoury Ekram , Ayad Elyen , Fahmy Nadia
Published: June 2009

The effect of added gastric lipases on the ripening and flavour development in Ras cheese was studied. Ras cheese was made from pasteurized milk with the addition of Italase, Capalase K or Capalase KL at the rate of 12 g/100 kg milk before renneting and analysed at different intervals for fat, moisture, salt, pH, soluble tyrosine and tryptophan and Shilovich ripening index. The organoleptic properties of the cheeses were also assessed. The addition of lipases was found to accelerate the development of flavour, particularly when Capalase K was used. These lipases had no effect on the gross composition of cheese during ripening.
Developments in column chromatography for the separation and characterization of casein micelles
Authors: McGann Thomas C. A. , Kearney Robert D. , Donnelly William J.
Published: June 2009

Skim-milk was fractionated by permeation chromatography on CPG-10 (300 nm) at 20 °C with synthetic milk serum. The elution profile, which was highly reproducible, showed 3 partly resolved peaks. On treatment with 0.1% glutaralde-hyde before chromatography, a similar profile was obtained indicating no appreciable micellar dissociation during chromatography of the milk. The casein composition of the eluent fractions, determined by quantitative chromatography on hydroxyapatite, showed that 12.1% of total casein was associated with the low molecular weight peak. The micelle content of ²- and κ-casein increased with increasing elution volume, and the ±s/κ ratio showed a progressive diminution from 4·3 to 2·3. Large differences were found in the colloidal phosphate contents and the weight average diameters of the micelle fractions which clearly show that CPG-10 fractionates on the basis of molecular size.
Factors affecting the concerntration of vitamins in milk: II. Effect of breed, season and geographical location on riboflavin
Authors: Thompson S. Y. , Kon S. K.
Published: June 2009

In a survey done in 1943–44 there was no seasonal difference in the riboflavin content of milk from 10 different areas in England and Wales that could have been associated with the change from stall to pasture feeding, and mean values were about 160 μg/100 ml for both the periods November-April and May-October. However, values for the 6 months August-January were higher (about 175 μg) than for the 6 months February-July (about 150 μg). Over a 12 months' period the mean riboflavin contents of Shorthorn and Guernsey milk from the Institute's farm were 142 and 191 μg/100 ml, respectively.
Steam distillation of taints from cream: IX. Vapour/liquid equilibrium relationships for indole and skatole in water and cream
Authors: McDowall F. H.
Published: June 2009

The vapour/liquid equilibrium coefficients for the steam distillation of indole and skatole from water solution over the range of concentrations 0·1 to 20–30 ppm. were found to be 2·4 and 4·7, respectively. The coefficient for indole in a cream containing 30% fat was found to be 0·31, and for skatole, in a cream containing 40% fat, 0·14. It is concluded that complete removal of indole and skatole contaminations from cream by use of steam distillation equipment is not commercially practicable.
Factors affecting the fat globule sizes during the homogenization of milk and cream
Authors: Goulden J. D. S. , Phipps L. W.
Published: June 2009

The homogenization of milk and cream with a piston-type homogenizer has been studied. An examination has been made of the influences upon the mean fat globule diameters of changes in milk fat content, flow rate and homogenization temperature. The results are discussed in terms of the variations in the parameters q and P0 of the empirical equation d = (P0/P)q relating the globule diameter d to applied pressure P.
Attempts to relate the selenium content of heat-treated milks with their nutritive properties
Authors: Henry Kathleen M.
Published: June 2009

Fink (1954) and Fink & Schlie (1955a) fed rats on a diet intentionally marginal in vitamin E and the sulphur-amino acids, in which dried milk supplied the protein (10%). They were able to relate the development of fatal liver necrosis in rats to heat damage of dried milks. Using their method, no liver necrosis developed in our rats with 2 spray-dried skim-milks, evaporated milk and milk subjected to ultrahigh temperature treatment, with or without subsequent in-bottle sterilization. With a roller-dried skim-milk sent to us from Germany by Fink and found by him to be of ‘middle degree necrogenity’, no liver necrosis occurred in hooded or albino rats bred in our laboratory, but the lesion developed in albino rats from an outside source. It was found that this milk had a lower selenium content than 2 British spray-dried milks. With rats given a necrogenic diet, differences were observed between and within strains in their susceptibility to liver necrosis and in their ability to utilize dietary selenium.
The effect on growth rate and on milk yield and composition of finely grinding the hay and cooking (flaking) the maize in mixed diets for growing and for milking heifers
Authors: Balch C. C. , Broster W. H. , Rook J. A. F. , Tuck Valerie J.
Published: June 2009

The volatile fatty acids produced during fermentation in the rumen have been shown to vary in their nutritive properties. Armstrong & Blaxter (1957) found that for lipogenesis in the adult sheep the value of the acids increases with increasing chain length. Rook & Balch (1961) showed that the individual acids have characteristically different effects on the synthesis of the various constituents of milk. In consequence the nature of the end products of fermentation must be one factor affecting the utilization of foods for productive purposes.
The action of rennin on casein: the effect of modifying functional groups on the casein
Authors: Hill R. D. , Laing Raione R.
Published: June 2009

k-Casein and whole casein when photo-oxidized in the presence of methylene blue lose the ability to clot when treated with rennin. Two effects are involved—first the photo-oxidation alters the k-casein fraction so that the rennin is unable to split off the glycopeptide fragment, and secondly, in whole casein the photo-oxidation interferes with the aggregation in the presence of Ca++that normally follows rennin action. As a result of amino acid analysis and specific treatments which affect other photo-oxidizable side chains, it is concluded that both of these effects are caused by the alteration of histidines.
A modification of the acid degree value test for lipolytic rancidity in milk
Authors: Hunter A. C. , Wilson Judith M. , Barclay Grace W.
Published: June 2009

While using an acid degree value test during work on lipolysis in milk, difficulty was encountered in extracting the fat from the milk of certain cows, especially milk of high butterfat content and milk from newly calved cows. This difficulty was overcome by increasing the quantity of reagent used. A study was made of the quantities of reagent required for milks of different butterfat content and for colostrum. No effect on the acid degree value occurred as a result of increasing the quantity of reagent. A modification of the test is recommended, using an increased quantity of reagent.
The effects of dietary tallow and cottonseed oil on milk fat secretion in the cow
Authors: Steele W. , Moore J. H.
Published: June 2009

The effects of the isocaloric replacement of part of the dietary concentrate mixture by either tallow or cottonseed oil on the yield and composition of the milk fat was investigated in 2 feeding experiments with a total of 26 cows in midlactation. The concentrates were given with high- or low-roughage diets that supplied either 9·1–9·5 or 1·8–3·2kg hay/day.

In expt 1, the addition of cottonseed oil to the high-roughage diet increased the yield of milk fat during the first 8 days but decreased it during the last 4 days of a 28-day feeding period. In contrast, the inclusion of tallow in the high-roughage diet resulted in an increased yield of milk fat that was sustained throughout the period of 28 days. In expt 2, the intake of dietary fat was less than it was in expt 1 and the inclusion of tallow or cottonseed oil in either the high- or low-roughage diets had little effect on the yield of milk fat.

The inclusion of either fat in the diet increased the yields and percentages of stearic and oleic acids and, in general, decreased the yields and percentages of the medium-chain fatty acids (10:0, 12:0 and 14:0) in the milk fat. The addition of tallow to the diet did not appear to alter the yields of the short-chain fatty acids (C4–C8, 4:0, 6:0 and 8:0) in the milk fat. When the low-roughage diets resulted in a decreased yield of milk fat, the secretion of all the fatty acids in the milk fat was reduced, but the reduction in the secretion of oleic acid was less than the reductions in the secretions of the other constituent fatty acids.
A preliminary study by gel filtration and ultracentrifugation of the interaction of bovine milk caseins with detergents
Authors: Cheeseman G. C.
Published: June 2009

The detergents sodium dodecyl sulphate and octyl phenoxy polyethoxyethanol interact with casein and cause dissociation of the high-molecular-weight casein aggregates. It is presumed that the detergent binds with hydrophobic regions in the casein molecule. The size of the complexes formed between detergents and αs1-casein, β-casein and κ-casein, as estimated by gel filtration and sedimentation velocity experiments, suggests that the caseins were complexed as monomers.

During gel filtration under non-reducing conditions, detergent-κ-casein complexes were separated from other major components because of their conversion through formation of disulphide bonds into high-molecular-weight aggregates. This reaction, which did not occur in sedimentation velocity experiments, was presumably facilitated by the changes in the equilibrium between the individual caseins during gel filtration.

Sedimentation velocity experiments showed that a ratio of about 40 detergent molecules to 1 casein molecule was required to give the smallest casein-detergent complex.
The effect of nitrogen source in the diet on milk production and amino-acid uptake by the udder
Authors: Kellaway R. C. , Ranawana S. S. E. , Buchanan J. H. , Smart L. D.
Published: June 2009

Two experiments were carried out with Friesian cows grazing improved winter pastures. In expt 1, 12 cows were fed 6·6kg/d of a barley-based concentrate containing either no N supplement, or supplements of casein, formaldehydeprotected casein or urea which provided 48 g N/d. In expt 2, 12 cows were fed 2·6kg/d of a barley-based concentrate containing either casein, formaldehyde-protected casein or equal mixtures of both, all of which provided 96g N/d.

In expt 1, although the production of fat-corrected milk was 7·1% higher and that of total solids 6·1% higher on the protected casein than on the casein diet, production of milk and milk constituents on the control and urea diets were similar to values obtained for cows fed protected casein. In expt 2, milk production and composition were unaffected by treatments.

The concentrations of amino acids in jugular plasma and mammary uptake per litre of plasma were not affected by the experimental diets in expt 1, and were unrelated to milk yield in either experiment. In expt 2 the concentrations of glycine, serine and threonine in jugular plasma were significantly higher in the diet in which none of the casein was protected. Mobilization of muscle protein may have been responsible for the elevated levels of glycine in cows fed this diet. Mammary uptakes of essential amino acids in expts 1 and 2 were respectively 47 and 42% of those available, whereas the uptakes of non-essential amino acids were respectively 24 and 17% of those available.

An attempt was made to determine the amino acids most likely to limit milk production. Milk:uptake concentration ratios were obtained using our values for amino-acid uptakes and values published previously for the concentration of amino acids in milk. The results of these calculations suggest that the amino acids most likely to limit milk production are threonine, phenylalanine and methionine.
The Role of β-lactoglobulin in the primary phase of rennin action on heated casein micelles and heated milk
Authors: Wheelock J. V. , Kirk A.
Published: June 2009

It has been shown that the inhibition caused by heat treatment, of the primary phase of rennin action on casein micelles, is dependent on the presence of β-lactoglobulin. The degree of inhibition increased with increasing amounts of added β-lactoglobulin for both heated casein micelles and heated skim-milk to a constant value. The results are fully consistent with the hypothesis that the inhibition is caused by complex formation between β-lactoglobulin and κ-casein when milk is heated.
Relationships between blood composition and fertility in dairy cows – a field study
Authors: Rowlands G. J. , Little W. , Kitchenham B. A.
Published: June 2009

Three hundred and fifty-one lactating dairy cows, which were between 40 and 100 d post-calving, were selected from cows sampled during metabolic profile testing of 21 herds. Blood samples were analysed for packed cell volume (PCV), blood glucose and haemoglobin, and serum urea-N, albumin, total protein, inorganic phosphate, Ca, Mg, Na, K, Cu and Fe. After adjusting for herd and date of sampling and each cow's age, stage of lactation, milk yield and interval from calving to first service, concentrations of albumin and K (P < 0·01) and PCV (P < 0·05) were inversely related and concentrations of globulin (derived as the difference between total protein and albumin) directly related (P < 0·05) to the number of services required for conception. Conception rates to first service were inversely related to lactation number but not to milk yield on day of sampling.
Influence of age, dietary protein and weaning on calf abomasal enzymic secretion
Authors: Garnot P. , Toullec R. , Thapon J.-L. , Martin P. , Hoang Minh-Thu , Mathieu C.-M. , Dumas B. Ribadeau
Published: June 2009

Using fistulated calves, the influence of the age, type of dietary protein and weaning on the secretion of chymosin and pepsin by the abomasum were studied. The abomasum secreted both chymosin and pepsin when the animals were fed milk. Chymosin secretion appeared to be independent of the age of the animals, whereas a slow increase in pepsin secretion was observed as the calves aged. Several preruminant animals were fed either a skim-milk diet or a milt substitute in which proteins were provided by fish, soya or whey concentrates. Each of these 3 milk substitutes led to a decrease in chymosin secretion without modification of pepsin secretion. Chymosin secretion was partly restored when the calves were again given a skim-milk diet. At weaning, chymosin secretion dropped abruptly, but the pepsin level was not affected. These results indicate that milk (most probably its casein fraction) is responsible for the activation of chymosin secretion.
Fractionation of whole casein on hydroxyapatite. Application to a study of buffalo κ-casein
Authors: Addeo F. , Chobert J.-M. , Ribadeau-Dumas B.
Published: June 2009

When whole caseins from cow and Italian buffalo (Bubalus arnee) were fractionated by chromatography on a column of hydroxyapatite they behaved in a similar manner. κ-Casein was eluted with 5 mM phosphate buffer, pH 6·8, containing 0·2 M-KCI, 4·5 M-urea and 2 mM-2-mercaptoethanol, but β- and αs-caseins were retained and could be eluted successively by a linear gradient from 5 mM to 250 mMphosphate buffer. Buffalo κ-casein preparations, obtained from bulk milk or from milks of individual animals by chromatography on hydroxyapatite, produced identical electrophoretic patterns at pH 8·6. By further fractionation of these κ-caseins on DEAE-cellulose, in each case, at least 7 components were purified; they had different electrophoretic mobilities but were all sensitive towards chymosin. The major fraction migrated like component 1 of bovine κ-casein B.
Autotransplantation of the goat mammary gland
Authors: Peaker Malcolm , Fleet Ivan R.
Published: June 2009

The modified technique for transplanting one mammary gland of a lactating goat to the neck, with the mammary (pudic) artery and vein anastomosed to the carotid artery and jugular vein respectively, is described. This technique was successful in 6 operations and there were no significant differences between the milk yield of the transplanted and control (in situ) glands at any stage after operation. These results are compared with those from an earlier series in which no special provision was made for lymphatic drainage and in which anticoagulant therapy and treatment of the gland prior to attachment were not standardized.
Proteolysis and aggregation of casein micelles treated with immobilized or soluble chymosin
Authors: Dalgleish Douglas G.
Published: June 2009

The relationship between extent of κ-casein proteolysis and aggregatability of milk casein micelles has been studied using chymosin either bound to porous glass supports or free in solution. Both enzyme preparations demonstrated that, overall, 86–90 % of the κ-casein had to be destroyed before any aggregation could occur. Based on these results, a mathematical model of chymosin action on casein is described involving (i) the attack on κ-casein by chymosin, via a Michaelis–Menten mechanism (ii) the probability that sufficient κ-casein on any micelle is destroyed to allow aggregation, and (iii) the aggregation of para-casein micelles by a von Smoluchowski mechanism.
Analysis of somatic cell volume distribution as an aid to the diagnosis of mastitis
Authors: Hoare Roderic J. T. , Sheldrake Richard F. , Nicholls Paul J. , McGregor Gavin D. , Woodhouse Victoria E.
Published: June 2009

Electronic somatic cell counts (ESCC) and relative cell volume distributions (RCVD) in milk samples were obtained simultaneously on a Coulter Counter Model TA and their potential assessed, either singly or in combination, for identifying mastitic quarters and cows in 2 herds. Using log (ESCC) alone the probability Pm of misclassifying quarters infected with major pathogens was 6–7 % for herd 1 and 18–1% for herd 2. The inclusion of RCVD variables with log (ESCC) did not substantially improve the chance of detecting quarters infected with major pathogens. However, the RCVD variables did improve the chance of identifying quarters infected by major and minor pathogens compared to the use of log (ESCC) alone, the Pm figures being reduced by about one third.

When testing composite quarter samples, where milk from infected quarters was diluted with that from uninfected quarters, the inclusion of RCVD variables decreased the Pm compared to the use of log (ESCC) alone. In herd 1 the improvement was from 26–1 to 3·0 %, while in herd 2 the effect was less marked, the Pm being reduced from 28–6 to 21–6%. However, as the RCVD assessment is provided simultaneously with ESCC, the additional information is obtained at minimal cost.
Light scattering investigation of the stability of bovine casein micelles to dilution
Authors: Parker Thomas G. , Horne David S.
Published: June 2009

Dialysed whey and dialysed ultracentrifugate from skim-milk were found to be satisfactory dilution media for light scattering studies on bovine casein micelles at 20 °C. Both milk dialysate and milk ultracentrifugate were only useful at fairly low levels of dilution and even then only for short periods of time. Whey, pH-adjusted to that of the original milk, was found to be an unsuitable diluent medium. Most of the instability of casein micelles to dilution could be attributed to some form of Ca phosphate precipitation or Ca phosphate–casein micelle aggregation.
Biological responses of the bovine teat to milking: information from measurements of milk flow-rate within single pulsation cycles
Authors: Williams David M. , Mein Graeme A. , Brown Murray R.
Published: June 2009

The mass flow-rate (FR) of milk from the bovine teat within individual pulsation cycles was measured by continuous computation of the average optical density of the milk–air mixture within a teatcup. Measurements during milking were made on both live and excised teats using a range of teatcup liners, vacuum levels and pulsation characteristics. During a typical pulsation cycle, soon after the start of milking, milk FR from live teats reached a peak within 100 ms of the start of the flow period and fell to about 60% of the maximum value between 0·5 and 1·5 s of flow. If the liner was held open for longer than 1·5 s, the FR typically declined a further 10% over the next 10–15 s. After 10–15 s little or no further change occurred in milk FR at normal milking vacuum levels. Milk flow from excised teats reached a steady value within 100 ms of the start of the flow period and showed no subsequent fall in FR.

Within individual pulsation cycles the changes in FR from live teats are affected by: (i) the degree of compressive load applied by the collapsed liner to the teat in the preceding cycle; and (ii) the duration of application of the compressive load. Increasing the degree of compressive load or the length of time of loading increases the peak milk FR of the next cycle by reducing the degree of congestion in the tissues of the teat surrounding the teat canal. Muscular effects are of secondary importance. The relatively small changes in milk FR associated with muscle contractions of the teat can be seen most clearly at low milking vacuum levels (below about 30 kPa) or with an unsupported teat (e.g. using a very distensible, thin-walled liner).
Calculation by computer of individual concentrations in a simulated milk salt solution: II. An extension to the previous model
Authors: Lyster Richard L. J.
Published: June 2009

The computer program described by Wood, Reid & Elvin (1981) has been extended to include the complexes formed in alkaline solutions of Ca citrate and phosphate. Mg complexes are also included. Supersaturation with respect to various solid phases is tested for and the composition of the aqueous phase adjusted accordingly. Additional tests of the program have confirmed its accuracy and shown how the results depend on the values chosen for the relevant equilibrium constants.
Effects of adding potassium iodate to milk before UHT treatment: I. Reduction in the amount of deposit on the heated surfaces
Authors: Skudder Paul J. , Thomas Elmer L. , Pavey John A. , Perkin Allen G.
Published: June 2009

Additions of potassium iodate to milk at 0·05 and 0·1 mM (10 and 20 ppm) before UHT treatment markedly reduced the rate at which pressure built up during processing. This permitted the use of longer processing times before unacceptable pressures were reached in the heat exchangers. Iodate reduced the amount of protein deposited, particularly in the higher temperature sections of the plant, but had no effect on the deposition of minerals. The more compact nature of the highly mineral deposits offered less resistance to the flow path. Reduction in the amount of protein deposited is likely to be caused by increased denaturation of β-lactoglobulin and oxidation of heat activated sulphydryl groups by the iodate, thus reducing the formation of high molecular weight polymers of sulphur-containing proteins at the heated surfaces. Increasing the level of sulphydryl groups in the milk through the addition of L-cysteine-HCl caused an increase in the amount of deposit formed during UHT treatment. Whilst little detrimental effect on the quality of the milk resulted from additions of iodate at 0·05 mM, milks with 01 mM-iodate became bitter during subsequent aseptic storage. Bitterness was a result of iodate-induced proteolysis of casein.