References of "Journal of Dairy Science"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailIncreased nuclear factor kappa B activity in Milk Cells of Mastitis-Affected Cows
Boulanger, D.; Bureau, Fabrice ULg; Melotte, D. et al

in Journal of Dairy Science (2003), 86(4), 1259-1267

Bacterial mastitis is accompanied by a drastic increase in milk somatic cell count (SCC), with neutrophils being the predominant cell type found in the infected quarters. Accumulation and activation of ... [more ▼]

Bacterial mastitis is accompanied by a drastic increase in milk somatic cell count (SCC), with neutrophils being the predominant cell type found in the infected quarters. Accumulation and activation of neutrophils at the site of infection require local expression of many inflammatory genes encoding adhesion molecules, chemokines and cytokines. Most of the inflammatory genes contain binding sites for the nuclear factor kappaB (NF-kappaB) within their promoter and therefore partly depend on NF-kappaB for their expression. We thus hypothesized that an increase in NF-kappaB activity in the mammary gland could contribute to development of the neutrophilic inflammation that characterizes mastitis. In an attempt to verify this hypothesis, we first assessed milk cells from healthy and acute and chronic mastitis-affected cows for NF-kappaB activity using electrophoretic mobility shift assays. We next studied the relationships between the intensity of NF-kappaB activity in these cells and the degree of udder inflammation. Active NF-kappaB complexes were undetectable in milk cells from healthy cows, whereas high levels of NF-kappaB activity were always found in cells from cows with acute mastitis. In milk cells obtained from chronic mastitis-affected cows, NF-kappaB activity varied from low to high. Finally, the level of NF-kappaB activity measured in milk cells from chronic mastitis-affected cows was not correlated to SCC or to the proportion of neutrophils present in milk samples, but was highly correlated with the expression level of interleukin-8 and granulocyte/macrophage colony-stimulating factor, two NF-kappaB-dependent cytokines crucially involved in initiation and perpetuation of neutrophilic inflammation. These results suggest that NF-kappaB might play a role in mastitis pathogenesis. [less ▲]

Detailed reference viewed: 47 (25 ULg)
Full Text
Peer Reviewed
See detailModeling lactation curves and estimation of genetic parameters for first lactation test-day records of French Holstein cows.
Druet, Tom ULg; Jaffrezic, F.; Boichard, D. et al

in Journal of Dairy Science (2003), 86(7), 2480-90

Several functions were used to model the fixed part of the lactation curve and genetic parameters of milk test-day records to estimate using French Holstein data. Parametric curves (Legendre polynomials ... [more ▼]

Several functions were used to model the fixed part of the lactation curve and genetic parameters of milk test-day records to estimate using French Holstein data. Parametric curves (Legendre polynomials, Ali-Schaeffer curve, Wilmink curve), fixed classes curves (5-d classes), and regression splines were tested. The latter were appealing because they adjusted the data well, were relatively insensitive to outliers, were flexible, and resulted in smooth curves without requiring the estimation of a large number of parameters. Genetic parameters were estimated with an Average Information REML algorithm where the average information matrix and the first derivatives of the likelihood functions were pooled over 10 samples. This approach made it possible to handle larger data sets. The residual variance was modeled as a quadratic function of days in milk. Quartic Legendre polynomials were used to estimate (co)variances of random effects. The estimates were within the range of most other studies. The greatest genetic variance was in the middle of the lactation while residual and permanent environmental variances mostly decreased during the lactation. The resulting heritability ranged from 0.15 to 0.40. The genetic correlation between the extreme parts of the lactation was 0.35 but genetic correlations were higher than 0.90 for a large part of the lactation. The use of the pooling approach resulted in smaller standard errors for the genetic parameters when compared to those obtained with a single sample. [less ▲]

Detailed reference viewed: 25 (5 ULg)
Full Text
Peer Reviewed
See detailImbalance between lipoxin A(4) and leukotriene B-4 in chronic mastitis-affected cows
Boutet, Philippe ULg; Bureau, Fabrice ULg; Degand, Guy ULg et al

in Journal of Dairy Science (2003), 86(11), 3430-3439

Persistent accumulation of inflammatory cells in the udder, with neutrophils being the predominant cell type, is a characteristic feature of chronic mastitis in dairy cows. Leukotriene (LT) B-4 is a ... [more ▼]

Persistent accumulation of inflammatory cells in the udder, with neutrophils being the predominant cell type, is a characteristic feature of chronic mastitis in dairy cows. Leukotriene (LT) B-4 is a potent chemotactic agent, known to induce recruitment and accumulation of neutrophils in the bovine mammary gland. The LTB4-stimulated neutrophil functional responses are closely opposed by lipoxin (LX) A(4), which promotes the resolution of inflammation. We thus hypothesized that the chronic inflammation of the udder could be associated with an unfavorable ratio between these two eicosanoids and that the persistence of neutrophil accumulation could be due to an increase in LTB4 synthesis and/or an impaired LXA(4) production. In an attempt to verify this hypothesis, we first measured LXA(4), LTB4, and their ratio in the milk of healthy and acute and chronic mastitis-affected quarters. Next, we studied the relationships between these variables and the degree of udder inflammation as assessed by somatic cell count measurement. The LTB4 concentration was low in healthy quarters, drastically increased in acute mastitis, and reached intermediate levels in chronic mastitis-affected quarters. However, whereas LXA(4) concentration was highly increased in acute mastitis, healthy and chronic quarters had similarly low values. The LXA(4):LTB4 ratio was thus significantly lower in chronic mastitis-affected cows. The LTB4 concentrations measured in chronic quarters were highly correlated to somatic cell count and to milk neutrophil and macrophage numbers. A weaker correlation was observed between LXA(4) and these variables. For both eicosanoids, the highest correlation was observed with the number of neutrophils. These results show the existence of an LXA(4):LTB4 imbalance in chronic mastitis-affected cows because of low LXA(4) concentrations. Further studies are needed to determine whether administration of LX or stable analogs could have therapeutic potential in the control of chronic bovine mastitis. [less ▲]

Detailed reference viewed: 39 (4 ULg)
Full Text
Peer Reviewed
See detailWithin-herd effects of age at test day and lactation stage on test-day yields
Bormann, J.; Wiggans, G. R.; Druet, Tom ULg et al

in Journal of Dairy Science (2003), 86(11), 3765-3774

Variance ratios were estimated for random within-herd effects of age at test day and lactation stage, on test-day yield and somatic cell score to determine whether including these effects would improve ... [more ▼]

Variance ratios were estimated for random within-herd effects of age at test day and lactation stage, on test-day yield and somatic cell score to determine whether including these effects would improve the accuracy of estimation. Test-day data starting with 1990 calvings for the entire US Jersey population and Holsteins from California, Pennsylvania, Wisconsin, and Texas were analyzed. Test-day yields were adjusted for across-herd effects using solutions from a regional analysis. Estimates of the relative variance ( fraction of total variance) due to within-herd age effects were small, indicating that regional adjustments for age were adequate. The relative variances for within-herd lactation stage were large enough to indicate that accuracy of genetic evaluations could be improved by including herd stage effects in the model for milk, fat, and protein, but not for somatic cell score. Because the within-herd lactation stage effect is assumed to be random, the effect is regressed toward the regional effects for small herds, but in large herds, lactation curves become herd specific. Model comparisons demonstrated the greater explanatory power of the model with a within-herd-stage effect as prediction error standard deviations were greater for the model without this effect. The benefit of the within-herd-stage effects was confirmed in a random regression model by comparing variance components from models with and without random within-herd regressions and through log-likelihood ratio tests. [less ▲]

Detailed reference viewed: 21 (1 ULg)
Full Text
Peer Reviewed
See detailEstimating effects of permanent environment, lactation stage, age, and pregnancy on test-day yield.
Bormann, J.; Wiggans, G. R.; Philpot, J. C. et al

in Journal of Dairy Science (2002), 85(1), 2631-26321

Detailed reference viewed: 10 (2 ULg)
Full Text
Peer Reviewed
See detailDeriving lactation yields from test-day yields adjusted for lactation stage, age, pregnancy, and herd test date
Wiggans, G. R.; VanRaden, P. M.; Bormann, J. et al

in Journal of Dairy Science (2002), 85

Detailed reference viewed: 7 (5 ULg)
Peer Reviewed
See detailAdditive and dominance genetic variance of fertility by method R and preconditioned conjugate gradient
Druet, Tom ULg; Solkner, J.; Groen, A. F. et al

in Journal of Dairy Science (2001), 84(4), 9871-98716

The objectives of this study were threefold: 1) estimation of additive and dominance genetic variances for fertility traits for Austrian Simmental and Brown Swiss dairy cattle; 2) use of method R and the ... [more ▼]

The objectives of this study were threefold: 1) estimation of additive and dominance genetic variances for fertility traits for Austrian Simmental and Brown Swiss dairy cattle; 2) use of method R and the preconditioned conjugate gradient compared to solving for method R by second-order Jacobi iteration; and 3) study of the impact of inclusion of parental subclass effects on solutions for other random effects. Dominance variances were modeled for the inseminated cow and ranged from 0.32 to 1.36% of total variance. These values were similar to values for additive effects, which were approximately 1% of total variance. Convergence was clearly improved with preconditioned conjugate gradient and number of extrapolations reduced. Variance for permanent environment under a model without dominance could be split into a new estimate of permanent environmental variance and parental subclass variance. Solutions for parental subclass dominance effects were approximately proportional to permanent environment effects, but highly dependent on the number of animals contributing dominance relationships, especially full-sibs and three-quarter-sibs. For animals with a lot of dominance information (full-sibs, three-quarter-sibs, cousins), permanent environment and parental subclass dominance effects were nearly independent. Changes in additive effects were negligible, probably because both variances for parental subclass dominance effects and additive genetic effects were very small compared with residual variance. [less ▲]

Detailed reference viewed: 34 (3 ULg)
Full Text
Peer Reviewed
See detailHeterogeneity of (co)variance components for Jersey type traits
Gengler, Nicolas ULg; Dusseldorf, T.; Wiggans, G. R. et al

in Journal of Dairy Science (2001), 84

Detailed reference viewed: 3 (0 ULg)
Full Text
Peer Reviewed
See detailAssociations between casein haplotypes and first lactation milk production traits in Finnish Ayrshire cows
Ikonen, T.; Bovenhuis, H.; Ojala, M. et al

in Journal of Dairy Science (2001), 84(2), 507-514

The objective of this study was to estimate the effects of ß--casein (CN) haplotypes on first-lactation milk production traits. The ß--CN haplotypes were deduced using information on ß- and -CN genotypes ... [more ▼]

The objective of this study was to estimate the effects of ß--casein (CN) haplotypes on first-lactation milk production traits. The ß--CN haplotypes were deduced using information on ß- and -CN genotypes of cows and their sires for 16,973 Finnish Ayrshire cows that had at least nine paternal half sibs. Effects of CN haplotypes on milk production traits were estimated for one haplotype at a time using an animal model, which included the fixed effects for calving year and month, age at calving, days open, ß-lactoglobulin, and a ß--CN haplotype. Differences in milk production traits were also estimated between haplotype combinations A1A+A2B and A1B+A2A within ß--CN genotype A1A2AB and between combinations A1E+A2A and A1A+A2E within genotype A1A2AE. The ß--CN haplotypes A2A and A2B were associated with high milk and protein yields and low fat content, and those that included the ß-CN A1 allele were associated with low yields and high fat content. Protein content was affected by the -CN locus; haplotype A1B was associated with high protein content and A1E was with low protein content. The haplotype combination A1A+A2B was associated with 140 kg more milk yield (P = 0.045) and 0.03 percentage units less protein content (P = 0.055) than combination A1B+A2A, and combination A1A+A2E showed 0.02 percentage units greater protein content (P = 0.098) than A1E+A2A. These results indicate that genes linked to the CN loci contribute to the variation in milk yield and protein content. [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailEstimation of (co)variance functions for test-day yields during first and second lactations in the United States
Gengler, Nicolas ULg; Tijani, A.; Wiggans, G. R. et al

in Journal of Dairy Science (2001), 82

(Co)variance components for milk, fat, and protein yields during first and second lactations were estimated from test-day data from 23,029 Holstein cows from 37 herds in Pennsylvania and Wisconsin using a ... [more ▼]

(Co)variance components for milk, fat, and protein yields during first and second lactations were estimated from test-day data from 23,029 Holstein cows from 37 herds in Pennsylvania and Wisconsin using a multitrait test-day model. Canonical transformation was used with an expectation-maximization algorithm. To allow description of (co)variances within and across yield traits and parities, four lactation stages of 75 d were defined6 for each parity, and the test day nearest the center of each interval was used. Prior to analysis, data were adjusted for lactation curves within lactation stages using all records from all available cows. Data from cows with missing values were excluded to allow a canonical transformation to be used for estimation of (co)variance matrices. Data from 9110 cows were available for canonical analysis of lactations with test days in all lactation stages. (Co)variance functions were used to describe (co)variance structure within and across yield trait and parity. (Co)variance components of biological functions (305-d yield, persistency defined as difference between yields on d 280 and 60, and maturity rate defined as difference between second- and first-lactation yields) were developed from (co)variance functions. Heritabilities ranged from 0.09 to 0.22 for test-day yields, from 0.21 to 0.23 for 305-d yields, from 0.03 to 0.11 for persistencies, and from 0.05 to 0.07 for maturity rates. Phenotypic correlations between first- and second-lactation persistencies were low, but genetic correlations were high. Genetic correlations with maturity rate ranged from 0.11 to 0.61 for 305-d yields and persistencies. [less ▲]

Detailed reference viewed: 15 (3 ULg)
Full Text
Peer Reviewed
See detailApplication of a Mixed Normal Mixture Model for the Estimation of Mastitis-Related Parameters
Detilleux, Johann ULg; Leroy, P. L.

in Journal of Dairy Science (2000), 83(10), 2341-9

The current methodology for estimating genetic parameters for SCC (SCS) does not account for the difference in SCS between healthy cows and cows with an intramammary infection (IMI). We propose a two ... [more ▼]

The current methodology for estimating genetic parameters for SCC (SCS) does not account for the difference in SCS between healthy cows and cows with an intramammary infection (IMI). We propose a two-component finite mixed normal mixture model to estimate IMI prevalence, separate SCS subpopulation means, individual posterior probabilities of IMI, and SCS variance components. The theory is presented and the expectation-conditional maximization algorithm is utilized to compute maximum likelihood estimates. The methodology is illustrated on two simulated data sets based on the current knowledge of SCS parameters. Maximum likelihood estimates of IMI prevalence and SCS subpopulation means were close to simulated values, except for the estimate of IMI prevalence when both subpopulations were almost confounded. Individual posterior probabilities of IMI were always higher among infected than among healthy cows. Error and additive variance components obtained under the mixture model were closer to simulated values than restricted maximum likelihood estimates obtained assuming a homogeneous SCS distribution, especially when subpopulations were completely separated and when mixing proportion was highest. Convergence was linear and rapid when priors were chosen with caution. The advantages of the methodology are demonstrated, and its feasibility for large data sets is discussed. [less ▲]

Detailed reference viewed: 26 (9 ULg)
Peer Reviewed
See detailAnalysis of plasma IGF-I hormone levels in Holstein-Friesian Heifers
Horvai-Szabo, M.; Renaville, Robert ULg; Dohy, J.

in Journal of Dairy Science (2000), 83(suppl 1), 48

Detailed reference viewed: 5 (0 ULg)
Peer Reviewed
See detailUse of sequential estimation of regressions and effects on regressions to solve large multitrait test-day models
Gengler, Nicolas ULg; Tijani, A.; Wiggans, G. R.

in Journal of Dairy Science (2000), 83(2), 3691-36918

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailA homologous radioimmunoassay for quantification of insulin-like growth factor-binding protein-2 in blood from cattle.
Vleurick, Lieve; Renaville, Robert ULg; VandeHaar, M. et al

in Journal of Dairy Science (2000), 83(3), 452-8

Insulin-like growth factor-I and -II (IGF-I, IGF-II) circulate in biological fluids bound to six different IGF-binding proteins that regulate IGF bioactivity. The IGF-binding protein-2 is regulated by ... [more ▼]

Insulin-like growth factor-I and -II (IGF-I, IGF-II) circulate in biological fluids bound to six different IGF-binding proteins that regulate IGF bioactivity. The IGF-binding protein-2 is regulated by growth hormones, and its concentration depends on nutrition and physiological state. Specific antibodies directed against bovine IGF-binding protein-2 were produced, and IGF-binding protein-2 levels in bovine blood samples were quantified by radioimmunoassay. Parallel displacement curves showed strong cross-reactivity with bovine and ovine plasma, were low with porcine plasma, and no cross-reactivity with rat or chicken plasma. Addition of IGF-I or -II to a control pool of bovine plasma did not significantly alter control IGF-binding protein-2 values in a radioimmunoassay. Six nycthemeral periods, determined for three young bulls bled on two occasions, showed that IGF-binding protein-2 plasma levels were stable throughout the day; two or three samples were sufficient to characterize the animal. Cows treated with recombinant bovine somatotropin (bST) had significantly lower serum levels of IGF-binding protein-2 than did control cows. Furthermore, IGF-binding protein-2 levels were dramatically increased at the onset of lactation. This radioimmunoassay for bovine IGF-binding protein-2, which enables quantitative assessment of IGF-binding protein-2 concentration in cattle, confirmed that IGF-binding protein-2 concentrations are depressed by administration of bST, enhanced after calving, and showed absence of diurnal variation. [less ▲]

Detailed reference viewed: 69 (15 ULg)
Peer Reviewed
See detailEstimation of (co)variances of test day yields for first lactation Holsteins in the United States
Gengler, Nicolas ULg; Tijani, A.; Wiggans, G. R. et al

in Journal of Dairy Science (1999), 82(1), 2251-22514

Detailed reference viewed: 13 (3 ULg)
Peer Reviewed
See detailUse of multitrait evaluation procedures to improve reliability of early prediction of survival
Druet, Tom ULg; Solkner, J.; Gengler, Nicolas ULg

in Journal of Dairy Science (1999), 82(9), 20541-205416

Multitrait, across-country evaluation procedures were adapted to improve reliability of survival breeding values by combining direct information with yield and functional traits: milk persistency, somatic ... [more ▼]

Multitrait, across-country evaluation procedures were adapted to improve reliability of survival breeding values by combining direct information with yield and functional traits: milk persistency, somatic cell count, fertility (male and female), and calving ease (direct and maternal). A set of bulls was selected from the Austrian Simmental population based on mean original reliabilities of at least 0.50 for yield traits or of at least 0.20 for functional traits. Only breeding values above these limits were retained. The breeding values were deregressed, assuming that they were obtained by single-trait, sire-maternal grandsire models. An expectation maximization restricted maximum likelihood algorithm based on the multitrait, across-country evaluation equations was used to compute genetic correlations among all of these traits. These equations were solved, and the reliabilities of the solutions were also estimated. Mean rank correlation between direct and combined breeding values was 0.85 with values as low as 0.67 for the group of youngest bulls, Direct (original), indirect, and combined reliabilities were compared to appreciate the impact of our procedures on improvement of reliability of survival breeding values; This improvement, dependent on the level of reliability of direct and indirect information, could be up to 0.24 for animals with low direct reliability and high indirect reliability. For young bulls born in 1992 without reliable direct survival information but with already reliable information on yield and functional traits, mean reliability improvement was 0.13. For all bulls this value was still 0.06. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Peer Reviewed
See detailAnimal model genetic evaluation of type traits for five dairy cattle breeds
Gengler, Nicolas ULg; Wiggans, G. R.; Wright, J. R.

in Journal of Dairy Science (1999), 82(6), 13501-135022

Detailed reference viewed: 9 (0 ULg)
Peer Reviewed
See detailEstimation of (co)variance function coefficients for test day yield with a expectation-maximization restricted maximum likelihood algorithm
Gengler, Nicolas ULg; Tijani, A.; Wiggans, G. R. et al

in Journal of Dairy Science (1999), 82(8), 18491-184923

Detailed reference viewed: 13 (2 ULg)
Peer Reviewed
See detailUse of (co)variance functions to describe (co)variances for test day yield
Tijani, A.; Wiggans, G. R.; Van Tassell, C. P. et al

in Journal of Dairy Science (1999), 82(1), 2261-22614

Detailed reference viewed: 7 (1 ULg)
Peer Reviewed
See detailDynamic surface properties of the proteose-peptone fraction of bovine milk
Innocente, N.; Corradini, C.; Blecker, Christophe ULg et al

in Journal of Dairy Science (1998), 81(7), 1833-1839

Proteose-peptone is a heat-stable and acid-soluble protein fraction of milk that has important functional properties. Component 3, which is the most hydrophobic fraction, appears to be largely responsible ... [more ▼]

Proteose-peptone is a heat-stable and acid-soluble protein fraction of milk that has important functional properties. Component 3, which is the most hydrophobic fraction, appears to be largely responsible for the physicochemical properties of proteose-peptones and for their important biological role in milk. In this study, total proteose-peptone was prepared from bulk skim milk by precipitation with ammonium sulfate, and the hydrophobic fraction was purified by FPLC(R) (Pharmacia Fine Chemicals, Uppsala, Sweden). The drop volume method was used to investigate the dynamic surface activity of total proteose-peptone and component 3 of proteose-peptone at the air-water interface and at the oil-water interface. In general, proteose-peptones are good surfactants at both interfaces. Of all proteose-peptones, component 3 causes a more rapid reduction of interfacial tension in both interfaces. A system for measuring film balance was used to obtain more information about the surface and mechanical properties of proteose-peptone monolayers. We deduced from the compression isotherms that component 3 of proteose-peptone and total proteose-peptone films spread at the air-water interface present different mechanical properties. [less ▲]

Detailed reference viewed: 28 (2 ULg)