The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform

Fernando F. Cardoso - One of the best experts on this subject based on the ideXlab platform.

  • Linkage disequilibrium, persistence of phase and effective population size estimates in Hereford and Braford cattle
    BMC Genetics, 2016
    Co-Authors: Patrícia Biegelmeyer, Claudia C. Gulias-gomes, Alexandre R. Caetano, Juan P. Steibel, Fernando F. Cardoso
    Abstract:

    Background The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes ( N _ e ), and can provide insights into the genetic diversity history of populations. Estimates of the consistency of linkage phase across breeds ( R _ H,B ) can be used to determine if there is sufficient relationship to use pooled reference populations in multi-breed GS programs. The objective of this study was to estimate LD levels, persistence of phase and effective population size in Hereford and Braford cattle populations sampled in Brazil. Results Mean LD estimates, measured using the squared correlation of alleles at two loci ( r ^ 2 ), obtained between adjacent SNP across all chromosomes were 0.21 ± 0.27 for Herefords (391 samples with 41,241 SNP) and 0.16 ± 0.22 for Brafords (2044 samples and 41,207 SNP). Estimated r ^ 2 was > 0.2 and 0.3, respectively, for 34 and 25 % of adjacent markers in Herefords, and 26 and 17 % in Brafords. Estimated N _ e for Brafords and Herefords at the current generation was 220 and 153 individuals, respectively. The two breeds demonstrated moderate to strong persistence of phase at all distances ( R _ H,B  = 0.53 to 0.97). The largest phase correlations were found in the 0 to 50 Kb bins ( R _ H,B  = 0.92 to 0.97). Estimated LD decreased rapidly with increasing distance between SNP, however, useful linkage for GWAS and GS ( r ^ 2  > 0.2) was found spanning to ~50 Kb. Conclusions Panels containing about 50,000 and 150,000 SNP markers are necessary to detect minimal levels of LD between adjacent markers that would be useful for GWAS and GS studies to Hereford and Braford breeds, respectively. Markers are expected to be linked to the same QTL alleles in distances 

  • linkage disequilibrium persistence of phase and effective population size estimates in Hereford and braford cattle
    BMC Genetics, 2016
    Co-Authors: Patrícia Biegelmeyer, Alexandre R. Caetano, Juan P. Steibel, Fernando F. Cardoso, Claudia Cristina Guliasgomes
    Abstract:

    The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes (N e ), and can provide insights into the genetic diversity history of populations. Estimates of the consistency of linkage phase across breeds (R H,B ) can be used to determine if there is sufficient relationship to use pooled reference populations in multi-breed GS programs. The objective of this study was to estimate LD levels, persistence of phase and effective population size in Hereford and Braford cattle populations sampled in Brazil. Mean LD estimates, measured using the squared correlation of alleles at two loci (r 2 ), obtained between adjacent SNP across all chromosomes were 0.21 ± 0.27 for Herefords (391 samples with 41,241 SNP) and 0.16 ± 0.22 for Brafords (2044 samples and 41,207 SNP). Estimated r 2 was > 0.2 and 0.3, respectively, for 34 and 25 % of adjacent markers in Herefords, and 26 and 17 % in Brafords. Estimated N e for Brafords and Herefords at the current generation was 220 and 153 individuals, respectively. The two breeds demonstrated moderate to strong persistence of phase at all distances (R H,B  = 0.53 to 0.97). The largest phase correlations were found in the 0 to 50 Kb bins (R H,B  = 0.92 to 0.97). Estimated LD decreased rapidly with increasing distance between SNP, however, useful linkage for GWAS and GS (r 2  > 0.2) was found spanning to ~50 Kb. Panels containing about 50,000 and 150,000 SNP markers are necessary to detect minimal levels of LD between adjacent markers that would be useful for GWAS and GS studies to Hereford and Braford breeds, respectively. Markers are expected to be linked to the same QTL alleles in distances < 50 Kb in both populations due to observed high persistence of phase levels.

R Barlow - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of Hereford and first-cross cows on three pasture systems. II. Growth of Hereford and Brahman sired calves out of mature cows
    The Journal of Agricultural Science, 1994
    Co-Authors: H. Hearnshaw, P. F. Arthur, P. J. Kohun, R Barlow
    Abstract:

    SUMMARYThe preweaning growth of the progeny of mature cows grazing high, medium or low quality pasture was evaluated. The cows were 5–9 years of age at the beginning of the study and were either purebred Hereford (H x H), first-cross Brahman x Hereford (B x H), Simmental x Hereford (S x H) or Friesian x Hereford (F x H). Hereford and Brahman bulls were mated to these cows for three mating seasons commencing in 1982, at Grafton, New South Wales, Australia. Records on 634 calves born over three consecutive years were used.Most traits were subject to significant sire breed or dam breed effects or their interactions with one or more of the other main effects (pasture, year of birth of calf, cow age and sex of calf). The incidences of calving difficulty and stillbirths were exceptions. Stillbirths (mean of 3·8%) were not affected by any of the effects studied, while calving difficulty was affected only by sex of calf effect (males, 3·9%; females, 0·8%). The mean calving date of Brahman-sired calves was 11·4 days later (P < 0·05) than that of Hereford-sired calves. Differences between Brahman-sired and Hereford-sired calves for weaning weight were not significant for S x H (Brahman, 237 kg; Hereford, 232 kg) and FxH (Brahman, 238kg; Hereford, 238kg) dams. For HxH dams however, calves sired by Brahman were heavier at weaning (205 kg) than those sired by Hereford (193 kg) bulls, while for B x H dams the reverse was true (Brahman, 222 kg; Hereford, 231 kg). For calves with B x H dams average daily gain (ADG) was the same (957 g/day) for each sire breed, while for the other dam breeds, Brahman-sired calves had a higher ADG than Hereford-sired calves (862 v. 779, 1014 v. 946 and 1022 v. 950 g/day for H x H, S x H and FxH, respectively). Calves sired by Brahman bulls had > 90% eyelid pigmentation while Hereford-sired calves had 44–74%. On high quality pasture, the weaning weights and ADG of calves of F x H and S x H dams were higher than those of B x H and HxH dams. On medium quality pasture, weaning weight of calves of crossbred dams (B x H, S x H and FxH) were similar but higher than those of H x H dams. On low quality pasture, mean weaning weight of calves of B x H was higher than those of S x H and F x H dams, which in turn, were higher than that of H x H dams.

Alexandre R. Caetano - One of the best experts on this subject based on the ideXlab platform.

  • Linkage disequilibrium, persistence of phase and effective population size estimates in Hereford and Braford cattle
    BMC Genetics, 2016
    Co-Authors: Patrícia Biegelmeyer, Claudia C. Gulias-gomes, Alexandre R. Caetano, Juan P. Steibel, Fernando F. Cardoso
    Abstract:

    Background The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes ( N _ e ), and can provide insights into the genetic diversity history of populations. Estimates of the consistency of linkage phase across breeds ( R _ H,B ) can be used to determine if there is sufficient relationship to use pooled reference populations in multi-breed GS programs. The objective of this study was to estimate LD levels, persistence of phase and effective population size in Hereford and Braford cattle populations sampled in Brazil. Results Mean LD estimates, measured using the squared correlation of alleles at two loci ( r ^ 2 ), obtained between adjacent SNP across all chromosomes were 0.21 ± 0.27 for Herefords (391 samples with 41,241 SNP) and 0.16 ± 0.22 for Brafords (2044 samples and 41,207 SNP). Estimated r ^ 2 was > 0.2 and 0.3, respectively, for 34 and 25 % of adjacent markers in Herefords, and 26 and 17 % in Brafords. Estimated N _ e for Brafords and Herefords at the current generation was 220 and 153 individuals, respectively. The two breeds demonstrated moderate to strong persistence of phase at all distances ( R _ H,B  = 0.53 to 0.97). The largest phase correlations were found in the 0 to 50 Kb bins ( R _ H,B  = 0.92 to 0.97). Estimated LD decreased rapidly with increasing distance between SNP, however, useful linkage for GWAS and GS ( r ^ 2  > 0.2) was found spanning to ~50 Kb. Conclusions Panels containing about 50,000 and 150,000 SNP markers are necessary to detect minimal levels of LD between adjacent markers that would be useful for GWAS and GS studies to Hereford and Braford breeds, respectively. Markers are expected to be linked to the same QTL alleles in distances 

  • linkage disequilibrium persistence of phase and effective population size estimates in Hereford and braford cattle
    BMC Genetics, 2016
    Co-Authors: Patrícia Biegelmeyer, Alexandre R. Caetano, Juan P. Steibel, Fernando F. Cardoso, Claudia Cristina Guliasgomes
    Abstract:

    The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes (N e ), and can provide insights into the genetic diversity history of populations. Estimates of the consistency of linkage phase across breeds (R H,B ) can be used to determine if there is sufficient relationship to use pooled reference populations in multi-breed GS programs. The objective of this study was to estimate LD levels, persistence of phase and effective population size in Hereford and Braford cattle populations sampled in Brazil. Mean LD estimates, measured using the squared correlation of alleles at two loci (r 2 ), obtained between adjacent SNP across all chromosomes were 0.21 ± 0.27 for Herefords (391 samples with 41,241 SNP) and 0.16 ± 0.22 for Brafords (2044 samples and 41,207 SNP). Estimated r 2 was > 0.2 and 0.3, respectively, for 34 and 25 % of adjacent markers in Herefords, and 26 and 17 % in Brafords. Estimated N e for Brafords and Herefords at the current generation was 220 and 153 individuals, respectively. The two breeds demonstrated moderate to strong persistence of phase at all distances (R H,B  = 0.53 to 0.97). The largest phase correlations were found in the 0 to 50 Kb bins (R H,B  = 0.92 to 0.97). Estimated LD decreased rapidly with increasing distance between SNP, however, useful linkage for GWAS and GS (r 2  > 0.2) was found spanning to ~50 Kb. Panels containing about 50,000 and 150,000 SNP markers are necessary to detect minimal levels of LD between adjacent markers that would be useful for GWAS and GS studies to Hereford and Braford breeds, respectively. Markers are expected to be linked to the same QTL alleles in distances < 50 Kb in both populations due to observed high persistence of phase levels.

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

  • Body and carcass characteristics of newborn Piedmontese x Hereford and Wagyu x Hereford female calves.
    2001
    Co-Authors: Pl Greenwood, H. Hearnshaw, D. W. Hennessy, J. M. Thompson, Gs Harper
    Abstract:

    Newborn (≤ 10 h post-partum) female calves of Hereford dams mated to extreme sire genotypes for marbling (Wagyu, n = 8 calves) and muscle growth (Piedmontese, n = 10 calves) were studied to provide base-line data for studies aimed at elucidating the cellular basis and regulation of growth and development of carcass tissues. As a proportion of empty body weight (EBW), Piedmontese × Hereford calves had higher (P 0.10). On a carcass weight-specific basis, Piedmontese × Hereford calves had more lean (75.1 ± 0.4% vs 72.9 ± 0.6%) and less fat (4.8 ± 0.1% vs 5.2 ± 0.1%) and bone (20.1 ± 0.4% vs 21.9 ± 0.5%). The results demonstrate differences at birth in the distribution of body and carcass tissues between the Wagyu × Hereford and Piedmontese × Hereford cattle investigated.

  • Evaluation of Hereford and first-cross cows on three pasture systems. II. Growth of Hereford and Brahman sired calves out of mature cows
    The Journal of Agricultural Science, 1994
    Co-Authors: H. Hearnshaw, P. F. Arthur, P. J. Kohun, R Barlow
    Abstract:

    SUMMARYThe preweaning growth of the progeny of mature cows grazing high, medium or low quality pasture was evaluated. The cows were 5–9 years of age at the beginning of the study and were either purebred Hereford (H x H), first-cross Brahman x Hereford (B x H), Simmental x Hereford (S x H) or Friesian x Hereford (F x H). Hereford and Brahman bulls were mated to these cows for three mating seasons commencing in 1982, at Grafton, New South Wales, Australia. Records on 634 calves born over three consecutive years were used.Most traits were subject to significant sire breed or dam breed effects or their interactions with one or more of the other main effects (pasture, year of birth of calf, cow age and sex of calf). The incidences of calving difficulty and stillbirths were exceptions. Stillbirths (mean of 3·8%) were not affected by any of the effects studied, while calving difficulty was affected only by sex of calf effect (males, 3·9%; females, 0·8%). The mean calving date of Brahman-sired calves was 11·4 days later (P < 0·05) than that of Hereford-sired calves. Differences between Brahman-sired and Hereford-sired calves for weaning weight were not significant for S x H (Brahman, 237 kg; Hereford, 232 kg) and FxH (Brahman, 238kg; Hereford, 238kg) dams. For HxH dams however, calves sired by Brahman were heavier at weaning (205 kg) than those sired by Hereford (193 kg) bulls, while for B x H dams the reverse was true (Brahman, 222 kg; Hereford, 231 kg). For calves with B x H dams average daily gain (ADG) was the same (957 g/day) for each sire breed, while for the other dam breeds, Brahman-sired calves had a higher ADG than Hereford-sired calves (862 v. 779, 1014 v. 946 and 1022 v. 950 g/day for H x H, S x H and FxH, respectively). Calves sired by Brahman bulls had > 90% eyelid pigmentation while Hereford-sired calves had 44–74%. On high quality pasture, the weaning weights and ADG of calves of F x H and S x H dams were higher than those of B x H and HxH dams. On medium quality pasture, weaning weight of calves of crossbred dams (B x H, S x H and FxH) were similar but higher than those of H x H dams. On low quality pasture, mean weaning weight of calves of B x H was higher than those of S x H and F x H dams, which in turn, were higher than that of H x H dams.

Odis Wayne Robison - One of the best experts on this subject based on the ideXlab platform.

  • EVALUATION OF CROSSBRED CALF AND COW TYPES; SUBJECTIVE TRAITS
    2015
    Co-Authors: Akin Pala, Roger Mccraw, Odis Wayne Robison
    Abstract:

    Data in this experiment consisted of birth weight, calving score, thickness and grade records of 600 crossbred calves. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows. Yearling and 2-yr-old Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters then were bred to Polled Hereford bulls (Data Set 2). Later-parity Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters were mated to Salers or Simmental sires (Data Set 3). The traits evaluated were birth weight, thickness and feeder grade of calves and degree of calving diffi culty. Calving diffi culty, grade, muscling or thickness evaluation is a subjective assessment. Progeny of Angus cattle were lighter at birth and were born easier than progeny of Brangus and Gelbvieh cattle. Angus-Hereford cows were more likely to have medium grade calves than Brangus-Hereford cows (odds ratio=1.69) and that was the only signifi cant difference for grade in all data sets. Brangus calves had thicker muscles than Angus and Gelbvieh calves. Adding Bos Indicus genes to a cross may increase birth weight, calving diffi culty and muscle thickness

  • EVALUATION OF CROSSBRED CALF AND COW TYPES; SUBJECTIVE TRAITS
    Faculty of Agriculture University of Zagreb, 2006
    Co-Authors: Pala Akin, Mccraw Roger, Odis Wayne Robison
    Abstract:

    Data in this experiment consisted of birth weight, calving score, thickness and grade records of 600 crossbred calves. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows. Yearling and 2-yr-old Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters then were bred to Polled Hereford bulls (Data Set 2). Later-parity Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters were mated to Salers or Simmental sires (Data Set 3). The traits evaluated were birth weight, thickness and feeder grade of calves and degree of calving diffi culty. Calving diffi culty, grade, muscling or thickness evaluation is a subjective assessment. Progeny of Angus cattle were lighter and born easier than progeny of Brangus and Gelbvieh cattle. Gelbvieh crosses had the highest frequency of thickness 1 calves and Brangus crosses had the highest frequency of medium size calves. Angus calves were lighter than Brangus calves in all the data sets but they had thicker muscles. Adding Bos Indicus genes to a cross may increase birth weight while decreasing muscling and calving ease

  • Evaluation of crossbred calf and cow types for the coastal plain of North Carolina.
    Journal of animal science, 2000
    Co-Authors: Akin Pala, Odis Wayne Robison, Roger Mccraw
    Abstract:

    Data in this experiment consisted of 418 lactation records, and weaning and birth weight records from 600 crossbred calves. The traits evaluated included birth weight, weaning weight, weaning weight per cow exposed, weaning weight per weight of cow, weaning weight per weight of cow exposed, and pre- dicted milk yield. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows. Yearling and 2-yr-old Angus-Hereford, Brangus-Hereford, and Gelb- vieh-Hereford daughters then were bred to Polled Here- ford bulls (Data Set 2). Later-parity Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters