bluuebunny/crossref_metadata_2025_split huggingface dataset:
The onset of mammary secretion of medium-chain-length triglyceride fatty acids in the cow milked pre-partum
Authors: Thompson Gordon , Faulkner Anne 
Published: June 2009

SummarySix Friesian cows were milked daily, and arterial and mammary venous blood samples were taken between day 266 of gestation and day 6 after parturition. Samples of blood plasma were analysed for their content of acetate and progesterone, and mammary secretion for potassium, isocitrate, 2-oxoglutarate and triglyceride fatty acids.The onset of secretion of medium-chain triglyceride fatty acids was preceded by, or coincided with, increases of potassium and isocitrate concentration in the secretion. The onset of fatty acid secretion was not accompanied by any change in the gland's extraction of acetate from the circulation, and did not occur at a consistent time relative to parturition or changes in plasma progesterone concentration.
Ability of bovine mammary macrophages to enhance proliferation of autologous blood and mammary secretion lymphocytes
Authors: Concha Carlos , Holmbebg Olof 
Published: June 2009

SummaryCells were obtained by centrifuging the mammary secretion of healthy udders of 19 cows during the dry-period and during mid-lactation. The suspended cells were incubated in plastic wells. Those adhered cells classified as mammary macrophages were incubated with pokeweed mitogen (PWM). Autologous peripheral blood lymphocytes were added to wells containing untreated macrophage cultures or cultures pretreated with PWM. In seven cows autologous dry-period mammary lymphocytes were added instead of blood lymphocytes. The macrophages + lymphocyte cultures were subjected to the lymphocyte stimulation test (LST). For comparison, peripheral blood lymphocytes and dry-period secretion lymphocytes were also subjected to the LST in the presence of PWM. In all cases, mitogenic responses were higher in pretreated macrophage cultures than in background control cultures.The stimulation indices (SI) showed that PWM-pretreated dry-period mammary macrophages enhanced the proliferation of autologous peripheral blood lymphocytes to a greater extent than did blood lymphoeytes plus PWM (49±10v. 30 ± 6;P≤ 0·05). Mammary macrophages taken from the same cows but during midlactation also clearly induced proliferation of autologous peripheral blood lymphocytes but to a lesser extent than dry-period macrophages (16 ± 2v. 49±10; 16±2v. 30±6;P≤ 0·01 andP≤ 0·05).The PWM pretreatment of mammary macrophages increascd the proliferation of autologous dry-period mammary lymphocytes by at least a factor of three (28±8v. 8±2P≤ O·05).The present results indicate that bovine mammary macrophages pretreated with PWM enhance proliferation as well as modulation of mammary and peripheral blood lymphocytes. The modulation of lymphocyte stimulation as demonstrated herein vitro, has great significance regarding aspects of local immunostimulation related to modern treatment of mastitis.
The composition of Alpine goats' milk during lactation in Greece
Authors: Voutsinas Leandros , Pappas Christophoros , Katsiari Maria 
Published: June 2009

SummaryVariations in chemical composition and in some physico-chemical properties of milk from a herd of lactating Alpine goats imported into Greece were determined from week 8 after parturition until the end of lactation (35 weeks, 35 samples). The average composition (g/100 g) of the milk was: fat 3·44, protein 3·35, casein 2·46, lactose 4·30, ash 0·79, total solids 11·76 and solids-not-fat 8·32. The average pH was 6·57 and titratable acidity was 16·76 (°D). The averaged density was 1·030. The mean mineral contents (mg/100 g) of the milk were: Na 53·12, K 157·67, Ca 140·06, P 110·00, Mg 13·59, citrate 106·97. All constituents studied as well as pH and density were significantly (P < 0·05) dependent on the stage of lactation. Titratable acidity was not significantly affected by stages of lactation. There were significant (P < 0·001) differences in Na/K and Ca/P ratios in the milk between lactation stages. Trends with lactation for each of the components and physico-chemical properties determined are reported and correlations between constituents in the milk are given.
Measurement of proteolysis in milk and cheese using trinitrobenzene sulphonic acid and a new dissolving reagent
Authors: Humbert Gérard , Guingamp Marie-France , Kouomegne Rosalie , Linden Guy 
Published: June 2009

Milk contains indigenous plasmin-like and thrombin-like proteinases and also exogenous proteinases, mainly extracellular enzymes of psychrotrophic bacteria. Their activities lead to protein hydrolysis which may have important effects on milk quality and cheese yield. It is also useful to estimate proteolysis and its development during cheese ripening.Milk opacity or turbidity due to calcium phosphocaseinate micelles and fat globules necessitates preliminary sample treatment, i.e. precipitation and filtration before spectrophotometric measurement. It is possible to eliminate these firs steps of sample treatment by dispersing the colloidal constituents. Some authors have already used different dissolving mixtures for sample analysis. Nakai & Anh Chi Le (1970) were the first to determine protein contents of milk and dairy products by absorbance measurement at 280 nm after clarification. Bosset & Blanc (1977) used the Biuret method. Owen & Andrews (1984) measured free amino groups with 2,4,6-trinitrobenzene sulphonic acid (TNBS). Humbert et al. (1982) and Stead (1987) used synthetic or specific substrates for proteinase determination.In this work, we report the application of a new dissolving reagent to measure free amino groups in milk and cheese.
The diagnosis of subclinical mastitis by redefinition of the interquarter ratio and definition of the interquarter variation using analysis of variance methods
Authors: Knudsen Kim , Jensen Niels Einar 
Published: June 2009

SummaryA definition is proposed for the interquarter ratio of markers of inflammation in the bovine mammary gland which in contrast to present measurement procedures has well-defined distributional properties and thus facilitates statistical analysis. Our proposal of an interquarter ratio is equally applicable to evaluation of both single and multi-sample experiments. Finally, we define a new index for diagnosis of subclinical mastitis at the cow level, the interquarter variation, which assesses the degree of dispersion of the four quarter levels for values of any continuous inflammatory marker.
Cleavage of the linkage between colloidal calcium phosphate and casein on heating milk at high temperature
Authors: Aoki Takayoshi , Umeda Taketoshi , Kako Yoshitaka 
Published: June 2009

SummaryIn order to examine the effect of heating on the changes in the linkage between colloidal Ca phosphate (CCP) and casein, high-performance gel chromatography of casein micelles disaggregated by 6 M-urea was carried out using 6 M-urea simulated milk ultrafiltrate as the effluent. Although the CCP content increased when whey protein-free (WPF) milk was heated at 60–90 °C for 10 min, almost no changes in the content of casein aggregates cross-linked by CCP were observed. The content of casein aggregates cross-linked by CCP decreased from 51·9 to 46·1% in WPF milk and from 52·3 to 43·6% in concentrated WPF milk on heating at 135–140 °C for 75 s, indicating the cleavage of the linkage between CCP and casein. The cleavage of the linkage between CCP and casein on heating was considered to occur without liberation of ester phosphate groups. It was suggested that the transformation of CCP to another form was responsible for the cleavage between CCP and casein on heating milk at high temperature
Comparative emulsifying properties of sodium caseinate and whey protein isolate in 18% oil in aqueous systems
Authors: Foley John , O'Connell Catherine 
Published: June 2009

SummaryBoth whey protein isolate (WPI) and Na caseinate gave similar emulsion capacity-concentration profiles at pH 7. The emulsion capacity of aqueous solutions of WPI was relatively independent of pH while the values for caseinate fell in the isoelectric region. Saline (7·59 g/1) compared with aqueous solutions improved emulsion capacity, particularly above pH 7. At low concentration, WPI had greater emulsifying capacity and gave finer globule dispersion than sodium caseinate. Increase in emulsifier concentration, within a certain range, increased stability, improved dispersion and reduced capacity. Ethanol up to about 20% w/w improved the emulsion capacity of both proteins while at 50% the phases separated. Heat treatment (> 65 °C) of WPI solution before emulsion formation impaired capacity and stability. Heat treatment of preformed WPI emulsions did not have the same effect. Na caseinate and WPI each formed a thin continuous layer of relatively uniform thickness over the oil globule surfaces while denatured WPI appeared aggregated and relatively unevenly distributed at the oil-aqueous interface.
Heat-related changes to the hydrophobicity of cheese whey correlate with levels of native β-lactoglobulin and α-lactalbumin
Authors: Regester Geoffrey O. , Pearce R. John , Lee Victor W. K. , Mangino Michael E. 
Published: June 2009

SummaryCorrelations were identified between levels of the native whey proteins, β-lactoglobulin and α-lactalbumin and the surface and total hydrophobicities of cheese whey in response to different heat treatments. Heat-induced changes in the native βlactoglobulin content and surface hydrophobicity of whey exhibited the most significant linear relationship while correlations between total hydrophobicity and the native proteins were less significant because of an atypical rise in the n−heptane-binding capacity of whey after high-temperature treatment. The content of native β-lactoglobulin in whey was more sensitive to heating than the content of native α-lactalbumin, while heat-related changes in the total hydrophobicity of whey were generally greater than similar changes in surface hydrophobicity.
Effects of oxytocin, machine stripping and milking rate on production loss of cows milked once a day
Authors: Carruthers Vicki R. , Davis Stephen R. , Copeman Peter J. A. 
Published: June 2009

SummaryThe effect of treatments designed to improve the efficiency of milk removal and minimize loss of production in cows milked once a day (OAD) was assessed in short-term trials involving Friesian and Jersey cows. Trial 1 involved 80 cows and compared twice a day (TAD) milking with OAD milking with the administration of 20 i.u. of oxytocin (OX), OAD milking with udder massage before and during milking (OS) and no treatment during OAD milking (OC). The OX and OS groups had increased yields of milk and milk solids when treatments were applied, though yields were not restored to previous TAD levels. The percentage increase shown by OX cows was greater than that of OS cows for fat yield. The level of residual milk in the udder after milking was lower for the OX group than for the OAD and TAD controls. In Trial 2, 12 cows were subjected to fast or slow rates of milking OAD in each of two periods. Losses in milk, fat and protein yields averaged 9·1, 9·9 and 1·0% respectively. Increased rate of milking reduced milking time and time to let-down but did not affect response to OAD milking. The results showed that treatments that increased the evacuation of the udder during milking and decreased the level of residual milk reduced losses in production that occur on OAD milking. Increasing the rate of milking was ineffective in reducing losses on OAD milking.
Classification of newly calved cows into moderate and severe responders to experimentally inducedEscherichia colimastitis
Authors: Messom Georgette Vandeputte-Van , Burvenich Christian , Roets Eddy , Massart-Leën Anne-Marie , Heyneman Roger , Kremer Wim D. J. , Brand Arie 
Published: June 2009

SummaryIn the present study newly calved cows were tentatively classified as moderate and severe responders to experimentally inducedEscherichia colimastitis based upon the reactive oxygen species (ROS)-generating capacity of their blood neutrophils before infection. The groups differed in blood and milk composition prior to infection. This initial classification was supported by the corresponding variation in clinical symptoms and in the changes in milk production and composition measured during mastitis. Responses of newly calved cows toEsch. colichallenge varied from mild to severe symptoms of inflammation in infected glands and differed in the intensity of systemic disturbances and general illness. Losses in milk yield and compositional changes were most pronounced in inflamed glands and in severe responders. In inflamed glands milk yield and composition did not return to preinfection level in either moderate or severe responders. The yields of lactose, α-lactalbumin, casein and fat followed the same pattern as milk yield. It is concluded that the severe and long lasting systemic disturbances observed in severe responders can be ascribed to absorption of endotoxin from infected glands into circulation, indicating the important role of endotoxin in the pathology of coliform mastitis in periparturient cows. Evaluation of the ROS-generating capacity of blood neutrophils and blood and milk composition before infection might help to predict the cow's sensitivity toEsch. colimastitis.
Binding of Mg2+ and Ca2+ to β-casein A1: a multi-nuclear magnetic resonance study
Authors: Wahlgren N. Magnus , Dejmek Petr , Drakenberg Torbjörn 
Published: June 2009

Summary25Mg, 43Ca and 31P NMR have been used to study the binding of Mg2+ and Ca2+ ions to β-casein A1. The concentration dependence of the line width of the 25Mg NMR signal shows that β-casein contains at least two different types of binding sites for Mg2+ ions, one with strongly bound, slowly exchanging ions and one with more weakly bound ions which undergo fast exchange. The strong Mg2+ binding site has an unexpectedly high binding constant, Kbstrong 104 M–1, which has not been reported earlier. Mg2+ and Ca2+ compete for the Ca2+ binding sites of β-casein, while Na+ does not compete for these binding sites under physiological conditions. The dependence of the 43Ca NMR chemical shifts on total concentration of Mg2+ and Ca2+, in the presence of β-casein, could be equally well fitted with a model assuming up to five identical and independent sites as with a model assuming five or more sites with negative cooperativity. The proton dissociation constant, pka, for the strongest Ca2+ binding site was found to be 7·1.
Growth ofListeria monocytogenesin Camembert and other soft cheeses at refrigeration temperatures
Authors: Back Jonathan P. , Langford Sarah A. , Kroll Rohan G. 
Published: June 2009

SummaryListeria monocytogenessurvived and, under most conditions, multiplied when inoculated directly into the cheese milk of laboratory made Camembert cheeses. The rate and extent of growth was reduced at lower storage temperatures. Significantly higher rates of growth occurred at the surface compared with the centre of the cheeses, and these were probably associated with increased pH and proteolysis at the cheese surface due to the mould ripening process. Similar results were obtained with Camembert cheeses surface inoculated after manufacture. There was also temperature-dependent growth of List, monocytogenes on a range of inoculated commercially manufactured soft cheeses. Significant growth occurred in Cambazola, French and English Brie, blue and white Lymeswold, French Camembert and Brie with garlic. Little if any growth occurred in blue and white Stilton, Mycella, Chaume and full fat soft cheese with garlic and herbs at the temperatures examined.
Enzyme-induced coagulation of casein micelles: a number of different kinetic models
Authors: Hyslop Douglas B. 
Published: June 2009

SummarySeveral mathematical models are presented in an attempt to describe the kinetics of the enzyme-induced coagulation of casein micelles. In each model the primary phase of the clotting reaction is assumed to follow first order kinetics. The only differences amongst the various models centre on the definition of the flocculation rate constant, which is defined in seven different ways. The rate constants are defined and discussed in terms of activation energy and functionality theory. The first model is such that the number of functional sites is two. The second is such that the number is much larger. The third and fourth are such that there is an exponential energy barrier, one which has a magnitude proportional to the extent of proteolysis caused by the clotting enzyme. These two definitions differ only in the pre-exponent. In one case the pre-exponent is a constant, whereas in the other it is dependent on the size of clotting particles. The fifth and sixth definitions are also energy barrier rate constants, but the energy barrier changes in an arbitrary fashion with respect to time during proteolysis. The seventh definition assumes a large number of functional sites, but such that the number increases with extent of proteolysis. In the Payens nomenclature (Payens, 1989), all models could be considered to be ‘source’ models, and all are derived using the Drake moment equation (Drake, 1972). Only the first model has a truly constant flocculation rate parameter, and only this model has a relatively simple analytical solution. All other models yield analytical solutions only by way of infinite series expansions. Thus, all models are presented in terms of power series expansions, and only through the first five time-dependent coefficients. This confines all models to the early stages of coagulation. In all cases the first three coefficients are virtually the same. The first two coefficients involve only proteolysis, and the third includes initial flocculation information. Time-dependent changes in the flocculation rate constant begin to take effect in the fourth coefficient. When the fourth coefficients of the third and seventh models are compared, a simple relationship is suggested between free energy barrier removal and functional site generation, but only assuming that the number of functionalities is large.
Phagocytic activity of bovine polymorphonuclear neutrophil leucocytes
Authors: Zecconi Alfonso , Bronzo Valerio , Piccinini Renata , Spreafico Giovanna , Ruffo Gianfranco 
Published: June 2009

SummaryTwo different investigations were conducted on the chemiluminescent activity of bovine milk polymorphonuclear neutrophil leucocytes (PMN) activated by different stimuli: zymosan, derived from the wall ofSaccharomyces cerevisiae(Experiment A), andStreptococcus uberisandEscherichia coli(Experiment B). In Experiment A, a quarter with a phagocytic activity of PMN < 20 mV/1000 PMN following stimulation with zymosan was found to be 23 times more likely to be a clinical mastitis case than a quarter with phagocytic activity above this threshold value. In Experiment B, calculation of the odds ratio showed similar results following stimulation withStr. uberisorEsch. coli. These results provide evidence that immunocompromisation of mammary gland defences could predispose to clinical mastitis. They also support the need to challenge phagocytic cells with appropriate stimuli, and theEsch. colitest seems to be the most sensitive.
Changes in free fatty acids during the ripening of Idiazabal cheese: influence of brining time and smoking
Authors: Nájera Ana I. , Barron Luis J. R. , Barcina Yolanda 
Published: June 2009

SummaryThe effect of brining time and smoking on the free fatty acid content of Idiazabal cheese during ripening was examined. The main free fatty acids considered underwent at least some increase during the first stage of ripening before day 90 and tended to level off around a constant value towards the end of the ripening period. There were significant differences in free fatty acid levels during ripening among cheeses with different brining times and between smoked and unsmoked cheeses. Brining time and smoking exerted marked effects on lipolytic activity during cheese ripening, depending upon the free fatty acid involved and ripening time. In general, brining and smoking led to increases in free fatty acid levels at the end of the ripening period; the different behaviour of butyric acid may be due to a specific lipolytic activity.
Action of plasmin on bovine β-casein in a membrane reactor
Authors: Visser Servaas , Noorman Henk J. , Slangen Charles J. , Rollema Harry S. 
Published: June 2009

SummaryThe degradation of bovine β-casein by plasmin was used as a model system to investigate the applicability of an enzyme recycle reactor for the continuous production and isolation of peptide fractions. A simple, ultrafiltration-type membrane reactor was used incorporating a commercially available hollow-fiber module normally employed for dialysis purposes (artificial kidney). The results were compared with those obtained in a batch reactor process, using HPLC to monitor the course of proteolysis.Peptide fragments were isolated and were characterized using amino-acid analysis and N-terminal end-group determination. Sixteen peptide fragments were identified, which together accounted for virtually all the potential cleavage sites in β-casein. In the system studied the N-terminal half of β-casein appeared to be more sensitive to plasmic hydrolysis than the rest of the molecule.
Chemical characterization of bioactive peptides from in vivo digests of casein
Authors: Meisel Hans , Frister Herman 
Published: June 2009

SummaryThe in vivo formation of biologically active caseinopeptides was studied. It was proved that bioactive peptides were released in the small intestine of minipigs in the course of luminal digestion of diets containing bovine casein. An opioid peptide and a phosphopeptide were isolated from jejunal chyme and were chemically characterized. The opioid peptide has been identified as a fragment of β-casein (60–70). This peptide, named β-casomorphin-ll, displayed substantial opioid activity in an opiate receptor-binding assay. The caseinophosphopeptide has been shown to be a fragment of αs1-casein (66–74). Casein-derived phosphopeptides exhibit a potent ability to form soluble complexes with Ca and trace elements. Evidence exists that casomorphins and caseinophosphopeptides participate in the regulation of nutrient entry.
Biologically active casein peptides implicated in immunomodulation
Authors: Migliore-Samour D. , Floc'h F. , Jollès P. 
Published: June 2009

SummaryMaternal milk should not only be considered as a nutrient, but also as a protecting agent against aggressions from the neonate's new environment. Breastfeeding facilitates transmission of a passive immunity by multifunctional factors which have a direct effect on the neonate's resistance to bacterial and viral infections. Among these factors are the main milk proteins, the caseins: during enzymic digestion of human and bovine caseins, immunomodulating peptides are released. Corresponding synthetic peptides stimulatedin vitrophagocytic activity of murine and of human macrophages and exertedin vivoa protective effect againstKlebsiella pneumoniaeinfection of mice. These data suggest that casein peptides may exert a stimulating function on the immune system of the newborn.