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  • 1
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    Online Resource
    Aspectos genéticos e ambientais da curva de lactação de vacas da raça Guzerá
    FapUNIFESP (SciELO) ; 2001
    In:  Revista Brasileira de Zootecnia Vol. 30, No. 4 ( 2001-07), p. 1204-1211
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 30, No. 4 ( 2001-07), p. 1204-1211
    Abstract: The knowledge of the genetic relationships between the parameters of lactation curve and the milk yield is important for the selection of cows and sire. The records milk yield from 583 cows of the Guzerá breed, daughters of 165 sire, were used to estimate the lactation curve parameters by two mathematical models. Milk productions were obtained from the extracted base of data from National Animal Science Archive maintained by National Center for Dairy Research (Embrapa Gado de Leite). The analyses were performed by the MTDFREML system, under animal model containing herd-year-season of calving, the linear and quadratic age effects of calving, as fixed effects animal, permanent environment and error included as random effects. The estimates of genetic correlations between the total milk yield and the initial milk yield, and the rate of decline of milk yield were 0.55 and 0.86, and -0.19 and 0.38, respectively, for each mathematical model. For last two characteristics, these estimates were 0.45 and 0.75, indicating that cows with larger initial milk yield presented accentuated milk yield declines along the lactation period. The genetic correlations among 305-days yield and the parameters of model followed the same tendency, in magnitude and sign, to the one of the total milk yield. In agreement with the results, it can be inferred that the selection for the total milk yield results in increment in the initial milk yield, and in inexpressive changes in the rate of decline of the milk yield, not altering the form of the lactation curve. The rank correlations among the classifications of the predicted genetic values were high and positive (0.68 and 0.74), suggesting that the individuals with the highest genetic values for initial milk yield, would be also those with higher values for total milk yield.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982001000500011
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2001
    detail.hit.zdb_id: 2078814-9
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  • 2
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    Interação reprodutor x rebanho na produção de leite da raça Holandesa no Brasil
    FapUNIFESP (SciELO) ; 2001
    In:  Revista Brasileira de Zootecnia Vol. 30, No. 3 suppl 1 ( 2001-06), p. 992-999
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 30, No. 3 suppl 1 ( 2001-06), p. 992-999
    Abstract: Milk yield adjusted for 305 days and for age of Holtein cows were used to verify the effectiveness of including sire-by-herd interaction in the model of analysis as an adjustment factor for heterogeneous variances between herds. The herds were classified in three classes of phenotypic standard deviation: high, medium and low. Variance component estimates were obtained by Restricted Maximum Likelihood methodology, for classes of phenotypic standard deviation, considering each one as a different trait, using a multiple trait analysis. Two different animal models were used, either fitting or not fitting sire-by-herd interaction effect.The effectiveness of including this interation in the model was tested by Likelihood ratio test. Averages and variance components for milk yield increased from low to high phenotypic standard deviation classes. Variance component estimates were smaller, when sire-by-herd interaction was fitted, however, residual variance components were similar for both models. Heritability estimates for milk yield obtained by fitting or not fitting the interaction term in the model, were similar. Genetic correlation between classes of phenotypic standard deviation were close to unity. The proportion of the phenotypic variance due to sire-by-herd interaction variance fluctuated from 2.2 to 4.4 percent. The logarithms of the likelihood functions were higher when fitting a sire-by-herd interaction than for the model not including the interaction, for all classes.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982001000400012
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2001
    detail.hit.zdb_id: 2078814-9
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  • 3
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    Maternal effects on the genetic evaluation of Tabapuã beef cattle
    FapUNIFESP (SciELO) ; 2004
    In:  Genetics and Molecular Biology Vol. 27, No. 4 ( 2004), p. 517-521
    Details
    In: Genetics and Molecular Biology, FapUNIFESP (SciELO), Vol. 27, No. 4 ( 2004), p. 517-521
    Type of Medium: Online Resource
    ISSN: 1415-4757
    URL: Article
    DOI: 10.1590/S1415-47572004000400009
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2004
    detail.hit.zdb_id: 2126947-6
    SSG: 12
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  • 4
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    Curva de lactação na raça Guzerá
    FapUNIFESP (SciELO) ; 2000
    In:  Revista Brasileira de Zootecnia Vol. 29, No. 5 ( 2000-10), p. 1332-1339
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 29, No. 5 ( 2000-10), p. 1332-1339
    Abstract: The objectives of this work were to identify the mathematical functions that better fitted the milk production of Guzera breed cows, to evaluate the effects of the environmental factors on the lactation curve format and to estimate the genetic parameters for the milk production and for the dependable components of the lactation curve format. A total of 1130 lactations from 583 Guzera breed cows, daughters of 165 bulls, with production over the period from 1983 to 1997 were used. The models y = a n e-cn, y = a - cn + ln (n), y=a -cn e y =a e-c n were the ones that best fitted the milk production of the cows. By the analysis of variance, it was observed that the effects of cow herd, calving year and cow age at calving influenced the total milk production, initial milk production and milk decline production rate characteristics. The coefficients of heritability and repeatability estimates were obtained by means of one and two characteristic analyses. The animal selection, based only on the of the lactation curve format, would be of low efficiency.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982000000500011
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2000
    detail.hit.zdb_id: 2078814-9
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  • 5
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    Análises da persistência na lactação de vacas da raça Holandesa, usando produção no dia do controle e modelo de regressão aleatória
    FapUNIFESP (SciELO) ; 2004
    In:  Revista Brasileira de Zootecnia Vol. 33, No. 3 ( 2004-06), p. 546-554
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 33, No. 3 ( 2004-06), p. 546-554
    Abstract: A total of 87,045 milk yield records of 11,023 first-parity Holstein cows was utilized, obtained from 1997 to 2001 from different herds of 10 Minas Gerais locations. Six types of persistency measures in lactation were evaluated using milk yield breeding values, obtained by means of Random Regression Model - RRM. The Wilmink function was used to describe the random and fixed effects by RRM. Heritability estimates and genetic correlations for various persistency measures in lactation were dependent on the definition of persistency. The heritability estimates for persistency in lactation ranged from 0.11 to 0.27 and the genetic variations among persistency measures in lactation and milk yield up to d 305 ranged from -0.31 to 0.55, showing that persistency in lactation is a trait of moderate heritability showing little correlation with milk yield up to d 305. The selection of animals for persistency in lactation aiming to alter the lactation curve may be effective.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982004000300004
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2004
    detail.hit.zdb_id: 2078814-9
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  • 6
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    Efeito da interação reprodutor x rebanho na acurácia da avaliação genética de reprodutores da raça Holandesa no Brasil
    FapUNIFESP (SciELO) ; 2001
    In:  Revista Brasileira de Zootecnia Vol. 30, No. 3 suppl 1 ( 2001-06), p. 1000-1006
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 30, No. 3 suppl 1 ( 2001-06), p. 1000-1006
    Abstract: Yield records of Holstein cows were used to verify the interaction effect on accuracy of sire breeding values. The records of milk yield were adjusted to 305 days of lactation and age of the cow. Variance components for milk yield were estimated using restricted maximum likelihood methodology through two animal models, either not fitting or fitting a sire-by-herd interaction term. Likelihood ratio test was used to verify the effectiveness of including a sire-by-herd interaction effect in the model. Average milk yield was 6,936.13 ± 1,508.36 kg. The variance components estimates were smaller, when the sire-by-herd interaction was fitted, however, residual variance component, were similar for both models. Heritability estimates for milk yield obtained not fitting and fitting the interaction term in the model, were 0.247 ± 0.021 e 0.237 ± 0.021, respectivelly. The proportion of the phenotypic variance due to the sire-by-herd interaction variance, was equal to 0.034±0,005 percent. The logarithm of the likelihood function was highest fitting a sire-by-herd interaction. The breeding values of the sires for 305 day mature milk yield were lower using the model with sire by herd interaction, being of the Spearman correlation value close to unity.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982001000400013
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2001
    detail.hit.zdb_id: 2078814-9
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  • 7
    Online Resource
    Online Resource
    Avaliação de modelos para estimação de componentes de (co)variância em características de desempenho e reprodutivas em suínos
    FapUNIFESP (SciELO) ; 2004
    In:  Revista Brasileira de Zootecnia Vol. 33, No. 2 ( 2004-04), p. 350-357
    Details
    In: Revista Brasileira de Zootecnia, FapUNIFESP (SciELO), Vol. 33, No. 2 ( 2004-04), p. 350-357
    Abstract: Large White data set with performance and reproductive traits for a development line were analyzed in order to verify the importance of including maternal and common litter effects in genetic evaluation models, using four different models: model 1 - direct genetic effect; model 2 - the direct and maternal genetic effects; model 3 - the direct and common litter effects; and the model 4 - the direct, maternal and common litter effects. The traits were analyzed by Restricted Maximum Likelihood method (REML). The Likelihood ratio test was applied in order to verify which model was more adapted to the genetic evaluation. Pearson and Spearman correlation among predicted values for each trait in different models were obtained, in order to verify ranking alterations when the most adapted model was not used. The model 4 was the most adapted to performance traits and age at first farrowing and, for the litter traits, the model 1. For some traits, in which the model 4 was the most adapted, the correlations between predicted values, by the model 4 and the remaining, were close to unit, indicating that with limited computational conditions, models less parameterized could be used without prejudice to the real genetic gain.
    Type of Medium: Online Resource
    ISSN: 1516-3598
    URL: Article
    DOI: 10.1590/S1516-35982004000200011
    Language: Unknown
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2004
    detail.hit.zdb_id: 2078814-9
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