bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capture immunoassay for the diagnosis of bovine mastitis using a monoclonal antibody to polymorphonuclear granulocytes
Authors: O'Sullivan Catherine A. , Joyce Patrick J. , Sloan Teresa , Shattock Alan G. 
Published: June 2009

SummaryA direct capture enzyme-linked immunosorbent assay (ELISA) was developed to measure elevated polymorphonuclear granulocyte (PMN) antigens using horseradish peroxidase (EC 1.11.1.7) conjugated rabbit polyclonal anti-PMN antisera and a monoclonal antibody specific for PMN cells. Optical densities obtained in the ELISA were used to predict the cell counts of milk samples. Predicted counts were not significantly different from actual somatic cell counts (SCC). In a total of 156 bovine milk samples the correlation coefficient between somatic cell counting, taking > 500000 cells/ml as being indicative of mastitis, and the assay was 0·94, yielding an assay sensitivity of 95·2% and a specificity of 97·3%. In further trials the ELISA could detect elevated PMN antigens in milk with SCC as low as 100000 cells/ml. The results indicate that the monoclonal antibody based direct ELISA has excellent potential in the detection and determination of bovine mastitis.
B-mode ultrasonography of mammary glands of cows, goats and sheep during α- and β-adrenergic agonist and oxytocin administration
Authors: Bruckmaier Rupert M. , Blum Jürg W. 
Published: June 2009

SummaryTeat and gland cistern of the mammary glands of five dairy cows, five goats and five sheep were scanned in a water bath during α- andβ-adrenergic agonist and oxytocin administration. A 5 MHz linear array scanner was used to create vertical cut pictures with the scan plane longitudinally through the teat channel. The i.v. injection of the α-adrenergic agonist phenylephrine (30 μg/kg) induced diminution of the section area through teat and gland cistern by 38±17% on average within 1 min in all three species. In contrast, the i.v. injection of theβ-adrenergic agonist isoproterenol (1 μg/kg) did not change the cisternal areas. The i.v. injection of oxytocin (2·0 × 10−3i.u./kg) elicited an enlargement of teat and gland cistern area by 48±12% on average. Ultrasonography proved to be a valuable system for visualizing changes of the cisternal volume. Smooth muscle contractions in response to phenylephrine administration are thought to cause area reduction, whereas an expected smooth muscle relaxation after injection of isoproterenol could not be observed by ultrasonography. Milk ejection as induced by oxytocin administration caused dramatic enlargement of the cistern area in all three species.
Milking of cows in late pregnancy: milk production during this period and during the succeeding lactation
Authors: Rémond Bernard , Ollier Alain , Miranda Guy 
Published: June 2009

SummaryFifteen lactating cows were milked throughout pregnancy, and the effects on milk performance were studied during this period and during the succeeding lactation, relative to 11 conventionally managed cows (2 months dry before calving) as controls. During the last 2 months of pregnancy, only nine cows did not dry off spontaneously. Protein and fat concentrations in milk increased rapidly, but the concentration of lactose, corrected for milk yield, did not change. The ratios of individual caseins to total protein decreased with the quantity of milk produced, but only for yields below ˜ 6 kg/d. The relative proportion of κ-casein tended to decrease in the last milkings. During the succeeding lactation (first 15 weeks after calving and first 6 weeks of grazing) continuously milked cows yielded 4 kg milk/d less than the cows of the other group. The protein content of their milk was higher (2–3 g/kg depending on the period) than that of the control group, and the lactose content tended (p < 0·10) to be lower. Changes in the relative proportions of nitrogenous fractions with time were not different in the two groups. Differences between the two groups in the concentration of protein in milk, and in the concentration of glucose and non-esterified fatty acids in the plasma, suggest a better energy balance for the continuously milked cows during the succeeding lactation.
Factors in ruminant colostrum that influence cell growth and murine IgE antibody responses
Authors: Watson Dennis L. , Francis Geoffrey L. , Ballard F. John 
Published: June 2009

SummaryBovine colostrum was investigated as a source of biologically active molecules capable of stimulating the growth of mammalian cells in culture and modifying the immune response in a murine model. An extract prepared from bovine colostral whey by cation exchange and re versed-phase chromatography stimulated the growth of L6 rat myoblasts, Balb/c-3T3 mouse fibroblasts and BHK-21 baby hamster kidney cells with equal or greater potency than fetal bovine serum. Fractionation of the bovine colostral extract by gel-permeation chromatography in M-acetic acid identified a number of cell-growth factors for each cell type. Bovine colostral extract was compared with an ovine colostral whey preparation for its ability to modulate IgE antibody responses in mice. Doses of 8 and 4 mg/d of ovine colostral whey or bovine colostral extract specifically suppressed IgE antibody responses, whereas at lower doses suppression did not occur. We conclude that bovine colostrum contains cell-growth factors as well as immunomodulatory factors that are able to regulate the IgE response in a heterologous species.
Continuously elevated concentrations of oxytocin during milking are necessary for complete milk removal in dairy cows
Authors: Bruckmaier Rupert M. , Schams Dieter , Blum Jürg W. 
Published: June 2009

SummaryThe importance of elevated concentrations of oxytocin (OT) during the entire milking period was investigated in seven primiparous dairy cows with inherent disturbed milk ejection and in sixteen healthy cows with disturbed milk ejection induced by placing them in an operating theatre. Disturbance of milk removal in both groups has previously been demonstrated to be exclusively due to central blockage of the expected OT release in response to teat stimulation and milking. However, milk ejection can be induced by exogenous OT. OT (0·2 i.u.) was injected i.v. before milking and 49 ± 6% of the total milk was removed. When plasma OT decreased, milk flow stopped. In response to a second and third injection of 0·2 i.u. OT, 30 ± 4 and 7 ± 2% of the milk were removed respectively. The remaining milk was removed with 10 i.u. OT. The lag time from injection of OT to the start of milk flow was inversely correlated with the amount of milk actually removed in response to the OT injection. If 0·2 i.u. OT was injected during intramammary pressure (IMP) recording, IMP immediately increased to its maximum value. After 2·5 ± 0·3 min, IMP decreased to an intermediate IMP (between preinjection and maximum IMP). After two additional injections of 0·2 i.u. OT and after injection of 0·5 i.u. OT, IMP increased to a similar maximum. However, after injection of 0·5 i.u. OT, maximum IMP lasted longer (2·9 ± 0·3 min; P < 0·05) than after injections of 0·2 i.u. If OT was continuously infused (0·15 i.u./min) during milking, milk flow lasted until the udder was completely emptied. IMP increased during OT infusion to a maximum which remained stable until infusion was stopped after 10 min. The same IMP maximum was reached after the first individual OT injection (0·2 i.u.), but when plasma OT decreased towards basal concentrations, milk flow ceased and IMP decreased to an intermediate level. Thus continuously elevated OT concentrations such as those during infusion or during normal milking are necessary for complete milk removal.
Effect of suckling during early lactation and changeover to machine milking on plasma oxytocin and cortisol levels and milking characteristics in Holstein cows
Authors: Tančin Vladimír , Harcek L'Ubomír , Brouček Ján , Uhrinčať Michal , Mihina Štefan 
Published: June 2009

SUMMARYPlasma concentrations of oxytocin and cortisol, and milk yield and flow rates, were compared in three primiparous cows and two cows in their second lactation during suckling and subsequent machine milking. After calving, cows suckled their calves for 3–4 weeks and then the experiment was carried out over 4 d. Blood samples were taken prior to, during and after suckling or evening machine milking (EMM) on day 1 of the experiment (the last day of suckling), day 2 (first EMM) and day 4 (third EMM). After weaning and rehousing, cows were machine milked twice daily. During the first EMM, average milk yield and flow rate in the second minute of milking were significantly lower (P < 0·05) than corresponding values for the other 2 d. Plasma oxytocin concentrations were lower during the first than during the third EMM (P < 0·001) and suckling (P < 0·001), and more oxytocin was released during the third EMM than during suckling (P < 0·01). Cortisol concentrations were higher during and after the first EMM than during the third EMM. Thus in cows sucked for several weeks after calving and then separated from their calves and rehoused we found a transient decrease in oxytocin release, milk yield and flow rates during the first machine milking.
Primary structure of ovine αsl-caseins: localization of phosphorylation sites and characterization of genetic variants A, C and D
Authors: Ferranti Pasquale , Malorni Antonio , Nitti Gianpaolo , Laezza Pasquale , Pizzano Rosa , Chianese Lina , Addeo Francesco 
Published: June 2009

SUMMARYThe primary structures of ovine α>s1-casein variants A, C and D (formerly called Welsh variant) were determined. Separation of variants from whole casein was achieved using a fast and reliable reversed-phase HPLC method. Extended structural characterization of the purified proteins using electrospray mass spectrometry, automated Edman degradation and peptide mapping by means of HPLC-fast atom bombardment-mass spectrometry demonstrated that the mature protein was a mixture of two molecular species that differed in the deletion of residues 141–148 and were therefore 199 and 191 residues long respectively. The 199 residue peptide chain, which accounted for ∼ 80% of the entire translated αsl-casein, was as long as its caprine and bovine counterparts, and had a 98 and 89 % degree of identity with those two proteins respectively. Nine serine residues (positions 12, 44, 46, 64 to 68 and 75) were fully phosphorylated in αsl-casein A, whereas Ser115and Ser41were phosphorylated by ∼ 50 and ∼ 20% respectively. The differences between the three genetic variants A, C and D were simple silent substitutions, which however involved the degree to which the protein was phosphorylated. Variant C differed from variant A in the substitution Ser13→> Pro13which determined the loss of the phosphate group on site 12 of the protein chain, SerP12→>Ser12. A further substitution, SerP68→> Asn68caused the disappearance of both phosphate groups in the phosphorylated residues Ser64and Ser66in variant D; in this last casein variant there was no evidence of phosphorylation at Ser41.
Two dimensional electrophoresis and immunoblotting for the study of ovine whey protein polymorphism
Authors: López-Gálvez Gloria , Juárez Manuela , Ramos Mercedes 
Published: June 2009

SUMMARYDifferent electrophoretic techniques have been applied to the study of ovine whey protein polymorphism. Isoelectric focusing (IEF) over the pH gradient 3·5–9·5 was a suitable method for resolving both genetic variants of ovine β-lactoglobulin (β-lg); using this type of IEF, ovine β-lg A seemed to be defined by a major and a minor ‘satellite’ band. Approximate isoelectric point, relative molecular mass, amino acid composition and N-terminal sequence of this minor band were determined. A good separation of ovine β-lg was achieved using ultrathin layer isoelectric focusing (UTLIEF) over the pH gradient 2·5–7·0. However, addition of urea in UTLIEF gels led to some differences in the patterns of the ovine whey proteins when compared with those obtained by IEF on gels not containing urea. Two dimensional electrophoretic techniques provided a considerable separation of ovine whey proteins. Immunoblotting applied to a two dimensional separation permitted the identification of the bands belonging to β-lg and α-lactalbumin fractions.
Mathematical analysis of the relationship between blood flow and uptake of nutrients in the mammary glands of a lactating cow
Authors: Cant John P. , McBride Brian W. 
Published: June 2009

SummaryA dynamic mathematical model of blood flow regulation in the mammary glands of a lactating cow was constructed from a principle of local vasodilator release in response to changes in intracellular adenylate charge. An equation was derived to predict uptake of the milk precursors acetate, glucose, amino acids and fatty acids, as affected by mammary blood flow rate. Metabolism of the precursors to milk components and CO2 was simulated with a set of empirically derived equations. Relative rates of ATP production and utilization regulated both the number of perfused capillaries and the conductance of arteriolar segments in the mammary glands. The model simulated local control phenomena of functional and reactive hyperaemia, and simulation of autoregulation under changing arterial pressure suggested a predominance of precapillary sphincter regulation. It was predicted that an increase in blood flow without the mammary capacity to utilize blood metabolites efficiently would be detrimental to milk synthesis. Conversely, increased blood flow through changes in mammary activity resulted in predictions of higher milk production. It was proposed that the equation for uptake,be used in analysis of mammary arteriovenous differences.
Relationship between numbers of α2- and β2-adrenoceptors on blood cells of bulls and milkability of their daughters
Authors: Roets Eddy , Burvenich Christian , Hamann Jorn 
Published: June 2009

SUMMARYMilk yield and milking time were measured on one occasion for several daughters (n= 6–44) from 16 bulls at morning milkings. Blood from the bulls was collected, and platelets and mononuclear leucocytes were isolated. The α2-adrenoceptors on platelet membranes were identified by binding of [3H]rauwolscine, whereas for the determination of β2-adrenoceptors on intact mononuclear leucocytes, [3H]CGP–12177 was used. It was found that mean milk flow rate was highly correlated (P< 0·001) with the α2-adrenoceptor densities on blood platelets. No correlation was found with the β2-adrenoceptors on mononuclear leucocytes. It is concluded that estimation of the α2-adrenoceptors on blood platelets from bulls could eventually be used to investigate milking characteristics of cows, and might be useful in the future as a marker in genetic studies.
Teat thickness changes may provide biological test for effective pulsation
Authors: Hamann Jörn , Mein Graeme A. 
Published: June 2009

SummaryPulsation rates of 40, 60 and 80 cycles/min were combined with pulsator ratios of 50, 60, 70 or 80% in two experiments with different liners. Machine-induced, short-term changes in teat thickness of 14 cows were compared with milk flow rate characteristics and machine strip yields to evaluate the effectiveness of pulsation in relation to liner type. Post-milking teat thickness increased progressively as the b phase of the pulsation cycle was lengthened, and as the d phase was shortened, at all pulsator rates and with either liner. Teat thickness values increased significantly (P< 0·05) when the d phase was <15%. For ratios of 50 and 60%, teat thickness decreased progressively as pulsation rate was increased. At the higher ratios, thickness values were lowest at 60 cycles/min. Pulsation settings that tended to increase teat thickness values also increased both peak milk flow rates and machine strip yields. The influence of liner type on teat thickness changes appeared to be at least as important as the influence of pulsator ratios and greater than the effect of pulsation rate. If so, then international standards for acceptable pulsation characteristics cannot be defined solely in terms of pulsator settings. A limit of ±5% for machine-induced changes in thickness of the teat apex would be an additional guideline for effectiveness of pulsation in relation to both liner type and vacuum level. This could provide a basis for a dynamic test applied to milking cows under field conditions.
Milk yield, oxytocin and β-endorphin gradually normalize during repeated milking in unfamiliar surroundings
Authors: Bruckmaier Rupert M. , Pfeilsticker Hans-Ulrich , Blum Jürg W. 
Published: June 2009

SummaryFor six successive milkings, six dairy cows were relocated immediately before milking to an unfamiliar operating theatre, a procedure previously shown to inhibit oxytocin release and milk ejection. Two control milkings were performed in familiar surroundings. After milk flow had ceased, two i.v. injections of 1 i.u. oxytocin were given to remove the remaining milk. Milk flow was recorded continuously and blood samples were taken every minute during milking and 10 min after milking. During the first milking in unfamiliar surroundings, no oxytocin was released. Thereby, only 13% of the total milk yield, the cisternal milk, was available and the alveolar milk fraction could only be removed after injection of oxytocin. During subsequent relocations oxytocin release steadily increased toward the control level, although the timing of oxytocin release remained delayed as compared with controls. However, the milk fraction available before oxytocin injection increased with increasing number of removals, following an asymptotic approach to control levels. The concentrations of β-endorphin, cortisol (and perhaps also of prolactin) gradually declined with the number of times the animal was moved to unfamiliar surroundings, i.e. hormone concentrations gradually adjusted to control level. During milking, concentrations of prolactin and cortisol increased, while β-endorphin concentrations decreased (except for the first relocation). We conclude that milking-related oxytocin release and therefore milk ejection adapted gradually to repeated relocations to unfamiliar surroundings. This adaptation was inversely related to β-endorphin concentrations, so it is possible that oxytocin release was suppressed by high circulating β-endorphin concentrations.
Leucine and protein metabolism in the lactating dairy cow mammary gland: responses to supplemental dietary crude protein intake
Authors: Bequette Brian J. , Metcalf John A. , Wray-Cahen Diane , Backwell F. R. Colette , Sutton John D. , Lomax Michael A. , Macrae John C. , Lobley Gerald E. 
Published: June 2009

SummaryMammary gland protein metabolism, determined by an arteriovenous difference technique, was monitored in four Holstein-Friesian dairy cows in response to supplemental dietary protein (provided as rumen-protected soyabean meal) during late lactation (weeks 24–30). Each cow was offered two isoenergetic diets composed of grass silage (170 g crude protein/kg dry matter) plus either a low (108 g/kg) or medium (151 g/kg) crude protein concentrate in a single crossover design involving two 21 d periods. On day 21, arteriovenous measurements across the mammary gland were made during a 13 h continuous i.v. infusion of [1-13C]leucine and with frequent (2 hourly) milk sampling during the final 6 h. Although total milk yield was slightly increased (+1 kg/d) by protein supplementation, milk protein yield was not significantly affected. Whole body protein flux (protein synthesis plus oxidation) was not significantly affected by supplementation. Total mammary gland protein synthesis (milk plus non-milk protein) was also not affected by supplementation but on both diets gland synthesis was always greater (by 20–59%) than milk protein output. The fractional oxidation rate of leucine by the mammary gland was significantly increased by protein supplementation (0·047 v. 0·136). Although the enrichment of leucine in secreted milk protein continued to increase, the final value (at 13 h) was 0·94 of the arterial plasma free leucine plateau value (not significantly different), suggesting almost exclusive use of plasma free leucine for milk protein synthesis. Based on current feeding schemes for dairy cattle, a fixed proportion (0·65–0·75) of the additional protein intake (+490 g/d) should have been partitioned into milk protein. Instead, leucine oxidation by the mammary gland was increased. Whether oxidation of other amino acids was also enhanced is unknown but if amino acid oxidation and the ‘additional’ non-milk protein synthesis occurring in the gland are not crucial to milk synthesis, then by reducing such activities improvements in the efficiency of converting absorbed amino acid into milk protein can be achieved.
Detection and localization of peptidases inLactococcus lactiswith monoclonal antibodies
Authors: Laan Harry , Haverkort Roel E. , Leij Loe De , Konings Wil N. 
Published: June 2009

SummaryMonoclonal antibodies against peptidases ofLactococcus lactiswere isolated and characterized: PEPN1–4 against a lysyl aminopeptidase PepN, PEPT1–5 against a tripeptidase PepT and PEPD1–3 against a dipeptidase PepD. These monoclonal antibodies reacted specifically with their respective antigens in crude cell extracts ofLc. lactissubspp.cremorisandlactis. A number of monoclonal antibodies cross reacted with proteins of other (lactic acid) bacteria. PEPT1, 2, 4 and 5 cross reacted weakly with a 35 kDa protein inLactobacillus delbrueckii, while PEPT1 and PEPT2 reacted with proteins in the cell-free extract ofStreptococcus thermophilusandClostridium fervidus. Of the four isolated monoclonal antibodies against PepN, only PEPN3 cross reacted weakly with a 90 kDa protein inEscherichia colicell-free extract, and the other three antibody species against PepN cross reacted with 80 kDa proteins ofLb. casei, Lb. delbrueckii, andStr. bovis, but not ofEsch. coli. Of the three monoclonal antibodies against PepD, only PEPD1 and PEPD2 cross reacted with 40 kDa proteins ofLb. casei, Lb. delbrueckiiandStr. bovis. All PEPN, PEPD and PEPT antibodies reacted with components in cell-free extracts of eleven differentLc. lactisstrains, indicating that the peptidases of these strains were very similar to those ofLc. lactissubsp.cremorisWG2. However,Lc. lactissubsp.hordniaeappeared to differ from the otherLc. lactissubspecies since only PEPT1, 2 and 5 reacted with a protein in the cell-free extract. Immunogold labelling ofLc. lactisWG2 with the isolated monoclonal antibodies revealed that PepN, PepD and PepT were located intracellularly. The intracellular location of these peptidases is discussed in relation to the supply of essential amino acids and peptides.