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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), 452-458

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See detailA homologous radioimmunoassay for quantification of insulin-like growth factor-binding protein-2 in blood from cattle.
Vleurick, L.; 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 ▲]

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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

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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

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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

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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 ▲]

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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

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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

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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

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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 ▲]

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See detailApplication of canonical transformation with missing values to multitrait evaluation of Jersey type
Gengler, Nicolas ULg; Wiggans, G. R.; Wright, J. R. et al

in Journal of Dairy Science (1997), 80(10), 2563-2571

A multitrait animal model was used to calculate predicted transmitting ability and reliabilities for final score and 15 linear type traits of 225,632 US Jersey cows. Records were adjusted for age and ... [more ▼]

A multitrait animal model was used to calculate predicted transmitting ability and reliabilities for final score and 15 linear type traits of 225,632 US Jersey cows. Records were adjusted for age and stage of lactation before analysis. The model contained effects for interactions of herd and date scored; year scored, parity, and age; and herd and sire; effects of permanent environment and additive genetics were also included. Of the 381,511 records included, some observations were missing for final score (8%), body depth (43%), and teat length (33%). The evaluation system used a canonical transformation, included several random effects, and estimated missing values with each iteration. Inbreeding was considered in the computations. Convergence was achieved in approximately 50 rounds of iteration. Correlations between animal and sire model predicted transmitting ability ranged from 0.56 to 0.95 and generally were higher for bulls than for cows and for more recent birth years. Genetic trend was strongly positive for dairy form, final score, and rear udder traits (height and width) and negative for udder depth. For other traits, genetic trend was small. This methodology should improve the accuracy of genetic evaluations for type traits of US Jerseys. [less ▲]

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See detailEstimation of (co)variance components for Jersey type traits using a repeatability model
Gengler, Nicolas ULg; Wiggans, G. R.; Wright, J. R. et al

in Journal of Dairy Science (1997), 80(8), 1801-1806

(Co)variance components for final score and 15 linear type traits of Jersey cows were estimated by multitrait REML using multiple diagonalization and a repeatability model with 34,999 records of 22,354 ... [more ▼]

(Co)variance components for final score and 15 linear type traits of Jersey cows were estimated by multitrait REML using multiple diagonalization and a repeatability model with 34,999 records of 22,354 cows. Multiple diagonalization gave relative off-diagonals (ratio of squared off-diagonals to the product of diagonals) of <0.1%. Heritabilities and repeatabilities, respectively, were estimated as 0.29 and 0.48 for final score, 0.40 and 0.57 for stature, 0.26 and 0.39 for strength, 0.28 and 0.43 for dairy form, 0.13 and 0.25 for foot angle, 0.13 and 0.25 for rear legs (side view), 0.27 and 0.41 for body depth, 0.31 and 0.52 for rump angle, 0.22 and 0.33 for thurl width, 0.22 and 0.36 for fore udder attachment, 0.28 and 0.46 for rear udder height, 0.26 and 0.42 for rear udder width, 0.32 and 0.48 for udder depth, 0.20 and 0.36 for udder cleft, 0.29 and 0.46 for front teat placement, and 0.31 and 0.48 for teat length. Estimates of heritability generally were higher, and estimates of repeatability were lower, than values used previously for USDA genetic evaluations, which were based on data from the 1970s and early 1980s. Final score was highly correlated both genetically and phenotypically with dairy form and rear udder traits. These estimates of heritabilities and (co)variance components are necessary for multitrait genetic evaluation of linear type traits of US Jerseys. [less ▲]

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See detailEffect of diet and bST on mRNA for IGF-I binding proteins (BP)-2 and -3 in dairy cattle
Sharma, B. K.; Vandehaar, M. J.; Tucker, H. A. et al

in Journal of Dairy Science (1997), 80(suppl 1), 176

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See detailPit-1 gene polymorphism, milk yield, and conformation traits for Italian Holstein-Friesian bulls
Renaville, Robert ULg; Gengler, Nicolas ULg; Vrech, E. et al

in Journal of Dairy Science (1997), 80(12), 34313438

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See detailApproximation of reliability for multiple-trait animal models with missing data by canonical transformation
Gengler, Nicolas ULg; Misztal, I.

in Journal of Dairy Science (1996), 79(2), 317-328

An algorithm for approximation of reliability for multiple traits by multiple diagonalization was modified to support missing data by weighting transformed contributions of records based on the pattern of ... [more ▼]

An algorithm for approximation of reliability for multiple traits by multiple diagonalization was modified to support missing data by weighting transformed contributions of records based on the pattern of missing data. The accuracy of approximation was assessed with simulated and field data by comparing approximate reliabilities with those from direct inversion. Simulated data had several levels of missing data and covariances between traits; correlations were close to those for linear type traits of dairy cattle. Field data were 1) dairy records for milk, fat, and protein yields with 26% of the observations for fat and protein removed and 2) beef records for birth weight, weaning weight, and mean gain after weaning with 43% of observations missing. These files also contained empty fixed effect classes. The algorithm worked best for simulated data, and, when covariances between traits decreased, proportion of missing traits decreased and the number of empty fixed classes decreased. For dairy data, improvement over single-trait reliability occurred only for traits with missing data; for beef data, little or no improvement occurred. The method is useful with multiple diagonalization if the proportion of missing records or number of empty fixed effect classes or covariances between traits is moderate. [less ▲]

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See detailRelationships of polymorphisms for growth hormone and growth hormone receptor genes with milk production traits for Italian Holstein-Friesian bulls
Falaki, M.; Gengler, Nicolas ULg; Sneyers, M. et al

in Journal of Dairy Science (1996), 79(8), 1446-1453

Allelic variation in the structural or regulatory sequences of growth hormone and its receptor genes might directly or indirectly affect milk traits. This possibility prompted us to investigate the ... [more ▼]

Allelic variation in the structural or regulatory sequences of growth hormone and its receptor genes might directly or indirectly affect milk traits. This possibility prompted us to investigate the eventual relationships of restriction fragment length polymorphisms at the locus of bovine growth hormone (using TagI and MspI restriction enzymes) and its receptor (using TaqI restriction enzyme) production traits of bulls. Holstein-Friesian bulls were used in this experiment, and data were analyzed with a fixed linear model. The restriction fragment length polymorphisms at the growth hormone locus did not affect the milk traits studied. Six restriction enzyme TaqI bands of 7.1, 6.2, 5.7, 5.4, 4.2, and 3.3 kb with nine patterns were observed after hybridization by a cDNA probe containing the coding sequences for the intracellular C-terminal part of the receptor. The effect of this polymorphism on PTA for milk protein percentage was highly significant and was favorable for the rare (6.6%) 5.7- and 5.4-kb pattern. Our results indicate that further study is needed to explain the DNA polymorphism and to obtain more definite conclusions about effects on milk traits. [less ▲]

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See detailInfluence of breed of fetus on periparturient endocrine responses and subsequent milk production of Ayrshire dams
Guilbault, L. A.; Roy, G. L.; Beckers, Jean-François ULg et al

in Journal of Dairy Science (1990), 73(10), 2766-2773

Purebred Ayrshire females were assigned to two groups based on the breed of fetus carried during gestation. In group 1, Limousin embryos were transferred nonsurgically into Ayrshire recipients (10 heifers ... [more ▼]

Purebred Ayrshire females were assigned to two groups based on the breed of fetus carried during gestation. In group 1, Limousin embryos were transferred nonsurgically into Ayrshire recipients (10 heifers and 1 cow), and in group 2, 11 Ayrshire heifers and 1 cow were inseminated artificially to Ayrshire bulls. Blood samples were collected daily from d 265 of gestation until d 15 postpartum from 5 heifers of each group. Milk yield was recorded on alternate weeks during the first 20 wk postpartum. Calf birth weight was higher (44.2 vs. 35.4 kg) and gestation was longer (297.4 vs. 280.2 d) in Ayrshire dams bearing Limousin fetuses than in those bearing Ayrshire fetuses. Daily milk production for the first 20 wk was lower (18.1 vs. 20.8 kg) in Ayrshire dams bearing Limousin fetuses than in those bearing Ayrshire fetuses. Prepartum decrease in progesterone concentrations and increase in estrone concentrations were faster in Ayrshire heifers bearing Limousin fetuses than in those bearing Ayrshire fetuses. Profiles of peripartum concentrations of bovine placental lactogen differed between Ayrshire dams carrying different families of Limousin fetuses but were similar in those carrying families of Ayrshire fetuses. The concentrations of 15-keto-13,14-dihydroprostaglandin F2 were lower during the postpartum period in heifers that gave birth to Limousin calves than in those that had Ayrshire calves. In conclusion, the breed of fetus influences physiological and endocrine responses of the dam, which might have some effect on milk production of the dam. [less ▲]

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