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Scientia Agricola

On-line version ISSN 1678-992X

Abstract

PINHO, Sheila Zambello de; CARVALHO, Lídia Raquel de; MISCHAN, Martha Maria  and  PASSOS, José Raimundo de Souza. Critical points on growth curves in autoregressive and mixed models. Sci. agric. (Piracicaba, Braz.) [online]. 2014, vol.71, n.1, pp.30-37. ISSN 1678-992X.  http://dx.doi.org/10.1590/S0103-90162014000100004.

Adjusting autoregressive and mixed models to growth data fits discontinuous functions, which makes it difficult to determine critical points. In this study we propose a new approach to determine the critical stability point of cattle growth using a first-order autoregressive model and a mixed model with random asymptote, using the deterministic portion of the models. Three functions were compared: logistic, Gompertz, and Richards. The Richards autoregressive model yielded the best fit, but the critical growth values were adjusted very early, and for this purpose the Gompertz model was more appropriate.

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