The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform

Johanna Vilkki - One of the best experts on this subject based on the ideXlab platform.

  • Marker-assisted breeding value estimation for mastitis resistance in Finnish Ayrshire Cattle
    Journal of dairy science, 2011
    Co-Authors: Han A. Mulder, Martin Lidauer, Johanna Vilkki, Ismo Strandén, Roel F. Veerkamp
    Abstract:

    Marker-assisted breeding value estimation is expected to increase the accuracy of estimated breeding values, especially for traits with low heritability. Several quantitative trait loci (QTL) have been found for somatic cell score and clinical mastitis. The objective of this study was to demonstrate marker-assisted breeding value estimation, combining data of genotyped and ungenotyped animals in a large pedigree population using either identical-by-descent (IBD) or identical-by-state (IBS) haplotypes for some previously identified QTL regions for somatic cell score and clinical mastitis in Finnish Ayrshire Cattle. For both methods, QTL variances were estimated based on daughter yield deviations of genotyped bulls. The QTL explained only a small proportion of genetic variance, especially with IBS haplotypes. Using IBD haplotypes gave more reranking of bulls and cows than using IBS haplotypes. Cross-validation showed no increase in predictive ability when using IBS haplotypes compared with conventional breeding value estimation, whereas a decrease in predictive ability was observed with IBD haplotypes. Furthermore, computing time was lower and convergence was better with IBS haplotypes than with IBD haplotypes. In this study on mastitis resistance in Finnish Ayrshire, conventional breeding value estimation would be advocated because of the lack in improvement of accuracy and predictive ability when using marker-assisted breeding value estimation. However, in situations where IBS haplotypes would explain 10 to 20% or more of the genetic variance, marker-assisted breeding value estimation with IBS haplotypes may yield greater accuracy and predictive ability than conventional breeding value estimation.

  • Casein haplotypes and their association with milk production traits in the Finnish Ayrshire Cattle
    Animal genetics, 2009
    Co-Authors: Riikka Velmala, Johanna Vilkki, Kari Elo, Asko Mäki-tanila
    Abstract:

    Polymorphism of casein genes was studied in half-sib families of artificial insemination bulls of the Finnish Ayrshire dairy breed. Ten grand-sires and 300 of their sons were genotyped for the following polymorphisms : α s1 -casein (B, C), β-casein (A 1 , A 2 ), the microsatellite within the κ-casein gene (ms 5 , ms 4 ) and K-casein (A, B, E). Nine different combinations of these alleles, casein haplotypes, were found. Associations between casein haplotypes and milk production traits (milk and protein yield, fat and protein percentage and milking speed) were studied with ordinary least-squares analysis to find a direct effect of the haplotypes or an association within individual grandsire families using the granddaughter design. Estimated breeding values of sons were obtained from cow evaluation by animal model. No direct effect of the casein haplotypes on the traits was found. Within grandsire families, in one out of four families the chromosomal segment characterized by haplotype 3 (B-A 2 -ms 4 -A) was associated with an increase in milk yield (P

  • casein haplotypes and their association with milk production traits in the finnish Ayrshire Cattle
    Animal Genetics, 2009
    Co-Authors: Riikka Velmala, Johanna Vilkki, Kari Elo, Asko Makitanila
    Abstract:

    Polymorphism of casein genes was studied in half-sib families of artificial insemination bulls of the Finnish Ayrshire dairy breed. Ten grand-sires and 300 of their sons were genotyped for the following polymorphisms : α s1 -casein (B, C), β-casein (A 1 , A 2 ), the microsatellite within the κ-casein gene (ms 5 , ms 4 ) and K-casein (A, B, E). Nine different combinations of these alleles, casein haplotypes, were found. Associations between casein haplotypes and milk production traits (milk and protein yield, fat and protein percentage and milking speed) were studied with ordinary least-squares analysis to find a direct effect of the haplotypes or an association within individual grandsire families using the granddaughter design. Estimated breeding values of sons were obtained from cow evaluation by animal model. No direct effect of the casein haplotypes on the traits was found. Within grandsire families, in one out of four families the chromosomal segment characterized by haplotype 3 (B-A 2 -ms 4 -A) was associated with an increase in milk yield (P<0.01) and a decrease in fat percentage (P<0.01) when contrasted with haplotype 8 [B-A 1 -ms 4 -E). The results provide evidence that in the Finnish Ayrshire breed at least one quantitative trait locus affecting the genetic variation in yields traits is segregating linked to either haplotype 3 (B-A 2 -ms 4 -A) or 8 (B-A 1 -ms 4 -E).

  • Quantitative trait loci for udder conformation and other udder traits in Finnish Ayrshire Cattle
    Agricultural and Food Science, 2008
    Co-Authors: Nina Schulman, Sirja M. Viitala, Johanna Vilkki
    Abstract:

    Udder traits are important due to their correlation with clinical mastitis which causes major economic losses to the dairy farms. Chromosomal areas associated with udder conformation traits, milking speed and leakage could be used in breeding programs to improve both udder traits and mastitis resistance. Quantitative trait loci (QTL) mapping for udder traits was carried out on bovine chromosomes (BTA) 9, 11, 14, 18, 20, 23, and 29, where earlier studies have indicated QTL for mastitis. A granddaughter design with 12 Ayrshire sire families and 360 sons was used. The sires and sons were typed for 35 markers. The traits analysed were udder depth, fore udder attachment, central ligament, distance from udder to floor, body stature, fore teat length, udder balance, rear udder height, milking speed, and leakage. Associations between markers and traits were analysed with multiple marker regression. Five genome-wise significant QTL were detected: stature on BTA14 and 23, udder balance on BTA23, rear udder height on BTA11, and central ligament on BTA23. On BTA11 and 14 the suggested QTL positions for udder traits are at the same position as previously detected QTL for mastitis and somatic cell count.;

  • Quantitative Trait Loci for Health Traits in Finnish Ayrshire Cattle
    Journal of dairy science, 2004
    Co-Authors: Nina Schulman, Dirk-jan De Koning, Asko Mäki-tanila, Sirja M. Viitala, Jouni Virta, Johanna Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mor- tality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a vari- ance component based approach for the chromosomes and trait combinations, which were ob- served significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where aQ TL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treat- ments. QTL / fertility / dairy cow

Sirja M. Viitala - One of the best experts on this subject based on the ideXlab platform.

  • Quantitative trait loci for udder conformation and other udder traits in Finnish Ayrshire Cattle
    Agricultural and Food Science, 2008
    Co-Authors: Nina Schulman, Sirja M. Viitala, Johanna Vilkki
    Abstract:

    Udder traits are important due to their correlation with clinical mastitis which causes major economic losses to the dairy farms. Chromosomal areas associated with udder conformation traits, milking speed and leakage could be used in breeding programs to improve both udder traits and mastitis resistance. Quantitative trait loci (QTL) mapping for udder traits was carried out on bovine chromosomes (BTA) 9, 11, 14, 18, 20, 23, and 29, where earlier studies have indicated QTL for mastitis. A granddaughter design with 12 Ayrshire sire families and 360 sons was used. The sires and sons were typed for 35 markers. The traits analysed were udder depth, fore udder attachment, central ligament, distance from udder to floor, body stature, fore teat length, udder balance, rear udder height, milking speed, and leakage. Associations between markers and traits were analysed with multiple marker regression. Five genome-wise significant QTL were detected: stature on BTA14 and 23, udder balance on BTA23, rear udder height on BTA11, and central ligament on BTA23. On BTA11 and 14 the suggested QTL positions for udder traits are at the same position as previously detected QTL for mastitis and somatic cell count.;

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mortality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a variance component based approach for the chromosomes and trait combinations, which were observed significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where a QTL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treatments.

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    v2008okBEL/EG

  • Quantitative Trait Loci for Health Traits in Finnish Ayrshire Cattle
    Journal of dairy science, 2004
    Co-Authors: Nina Schulman, Dirk-jan De Koning, Asko Mäki-tanila, Sirja M. Viitala, Jouni Virta, Johanna Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mor- tality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a vari- ance component based approach for the chromosomes and trait combinations, which were ob- served significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where aQ TL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treat- ments. QTL / fertility / dairy cow

Johanna H. Vilkki - One of the best experts on this subject based on the ideXlab platform.

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mortality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a variance component based approach for the chromosomes and trait combinations, which were observed significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where a QTL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treatments.

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    v2008okBEL/EG

Nina Schulman - One of the best experts on this subject based on the ideXlab platform.

  • Quantitative trait loci for udder conformation and other udder traits in Finnish Ayrshire Cattle
    Agricultural and Food Science, 2008
    Co-Authors: Nina Schulman, Sirja M. Viitala, Johanna Vilkki
    Abstract:

    Udder traits are important due to their correlation with clinical mastitis which causes major economic losses to the dairy farms. Chromosomal areas associated with udder conformation traits, milking speed and leakage could be used in breeding programs to improve both udder traits and mastitis resistance. Quantitative trait loci (QTL) mapping for udder traits was carried out on bovine chromosomes (BTA) 9, 11, 14, 18, 20, 23, and 29, where earlier studies have indicated QTL for mastitis. A granddaughter design with 12 Ayrshire sire families and 360 sons was used. The sires and sons were typed for 35 markers. The traits analysed were udder depth, fore udder attachment, central ligament, distance from udder to floor, body stature, fore teat length, udder balance, rear udder height, milking speed, and leakage. Associations between markers and traits were analysed with multiple marker regression. Five genome-wise significant QTL were detected: stature on BTA14 and 23, udder balance on BTA23, rear udder height on BTA11, and central ligament on BTA23. On BTA11 and 14 the suggested QTL positions for udder traits are at the same position as previously detected QTL for mastitis and somatic cell count.;

  • Quantitative Trait Loci for Health Traits in Finnish Ayrshire Cattle
    Journal of dairy science, 2004
    Co-Authors: Nina Schulman, Dirk-jan De Koning, Asko Mäki-tanila, Sirja M. Viitala, Jouni Virta, Johanna Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mor- tality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a vari- ance component based approach for the chromosomes and trait combinations, which were ob- served significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where aQ TL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treat- ments. QTL / fertility / dairy cow

Nina F. Schulman - One of the best experts on this subject based on the ideXlab platform.

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire Cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mortality and paternal non-return rate were used as phenotypic data. In a granddaughter design, 171 markers were typed on all 29 bovine autosomes. Associations between markers and traits were analysed by multiple marker regression. Multi-trait analyses were carried out with a variance component based approach for the chromosomes and trait combinations, which were observed significant in the regression method. Twenty-two chromosome-wise significant QTL were detected. Several of the detected QTL areas were overlapping with milk production QTL previously identified in the same population. Multi-trait QTL analyses were carried out to test if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where a QTL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treatments.

  • Quantitative trait loci for fertility traits in Finnish Ayrshire Cattle
    Genetics Selection Evolution, 2008
    Co-Authors: Nina F. Schulman, Goutam Sahana, Mogens S. Lund, Sirja M. Viitala, Johanna H. Vilkki
    Abstract:

    v2008okBEL/EG