Parametrization of the Davis Growth Model using data of crossbred Zebu cattle

  • Adriele Giaretta Biase University of São Paulo/ESALQ; Dept. of Exact Sciences
  • Carlos Tadeu dos Santos Dias University of São Paulo/ESALQ; Dept. of Exact Sciences
  • Luís Gustavo Barioni Embrapa Agricultural Informatics
  • Tiago Zanett Albertini University of São Paulo/ESALQ; Dept. of Animal Sciences
  • Lucieta Guerreiro Martorano Embrapa Eastern Amazon
  • James W. Oltjen University of California; Dept. of Animal Science
  • Dante Pazzanese Duarte Lanna University of São Paulo/ESALQ; Dept. of Animal Sciences
  • Patrícia Perondi Anchão Oliveira Embrapa Southeast Livestock
  • Sérgio Raposo de Medeiros Embrapa Beef Cattle
  • Roberto Augusto de Almeida Torres Júnior Embrapa Beef Cattle
Keywords: asymptotic distribution, calibrating, cattle growth, nonparametric bootstrap, ordinary differential equations

Abstract

The system of differential equations proposed by Oltjen et al. [1986, named Davis Growth Model (DGM)] to represent cattle growth has been parameterized with data from Bos taurus (British) and Bos indicus (Nellore) breeds. The DGM has been successfully used for simulation and decision support in the United States. However, the effect of about 30 years of genetic improvement and the use of different breeds may affect the model parameter values, which also may need to be re-estimated for crossbred animals. The aim of this study was to estimate parameter values and confidence intervals for the DGM with growth and body composition data from Zebu crossbred animals. Confidence intervals and asymptotic distribution were generated through nonparametric bootstrap with data from a field experiment conducted in Brazil. The parameters showed normal probability distribution for most scenarios. The rate constant for deoxyribonucleic acid (DNA) synthesis had a minimum increase of 156 % and the maximum of 389 %, compared to the original values and the maintenance requirement had a minimum increase of 126 % and maximum of 160 % compared to the original values. Lower limits of 95 % confidence intervals for the parameters related to maintenance and protein accretion rates were higher than the original estimates of the DGM, evidencing genetic differences of the Zebu crossbred animals in relation to the original DGM parameters.

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Published
2017-02-01
How to Cite
Biase, A., Dias, C., Barioni, L., Albertini, T., Martorano, L., Oltjen, J., Lanna, D., Oliveira, P., Medeiros, S., & Torres Júnior, R. (2017). Parametrization of the Davis Growth Model using data of crossbred Zebu cattle. Scientia Agricola, 74(1), 8-17. https://doi.org/10.1590/1678-992x-2015-0284
Section
Biometry, Modeling and Statistics