Evaluation of mathematical models to describe growth of grazing young bulls
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abstract
The objective of this study was to evaluate the use of different mathematical models to describe growth of grazing beef cattle. Data of 20 Nellore bulls with initial weight of 12928.1 kg and final weight of 40562.0 kg were used. The animals were randomly divided into four plots and placed on B. decumbens Stapf pastures. Three plots received concentrate supplement with different protein profiles and the fourth plot received only mineral supplement. Animals were weighed every 28 days to design growth curve of full body weight. Five mathematical models were evaluated to describe animal growth: Multiphase, Linear, Logarithmic, Gompertz and Logistic models. Assessment of adequacy of the models was performed by using coefficient of determination, simultaneous F-test for identity of parameters, concordance correlation coefficient, root of the mean square error of prediction and partition of the mean square error of prediction. The analysis of the pairwise mean square error of prediction and the delta Akaike's information criterion were used to compare the models for accuracy and precision. Evaluation of all the tested models showed that all of them were able to predict variability among animals. However, Gompertz, Logarithmic and Logistic models created individual predictions that were not satisfactory. Models differed from each other concerning accuracy and precision; the best were in the following order: Multiphase, Linear, Gompertz, Logarithmic and Logistic. The Multiphase model was more efficient than the others for description of grazing beef cattle growth. 2012 Sociedade Brasileira de Zootecnia.
REVISTA BRASILEIRA DE ZOOTECNIA-BRAZILIAN JOURNAL OF ANIMAL SCIENCE
author list (cited authors)
Fernandes, H. J., Tedeschi, L. O., Paulino, M. F., Detmann, E., Paiva, L. M., Valadares Filho, S., da Silva, A. G., & Gomes Azevedo, J. A.
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5
complete list of authors
Fernandes, Henrique Jorge||Tedeschi, Luis Orlindo||Paulino, Mario Fonseca||Detmann, Edenio||Paiva, Luisa Melville||Valadares Filho, Sebastiao de Campos||da Silva, Aline Gomes||Gomes Azevedo, Jose Augusto
