Traditional and alternative nonlinear models for estimating the growth of Morada Nova sheep

Abstract

In the present study, alternative and traditional nonlinear models to describe growth curves of Morada Nova sheep reared in the state of Bahia, Brazil, were applied. The nonlinear models were: Schnute, Mitscherlich, Gompertz, Logistic, Meloun I Meloun II, III Meloun, Gamito and Meloun IV. The model adjustment was evaluated by using: Adjusted Coefficient of Determination (R 2 aj), Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), Mean Squared Error of Prediction (MEP) and Coefficient of Determination of Prediction (R 2 p). The selection of the best model was based on cluster analysis, using the evaluators as variables. Six out of the nine tested models converged, while Meloun I and Meloun IV were equally effective in explaining animal growth, without significant influence of sex or type of parturition over the curve parameters. The models Meloun I and IV have the best adjustment and reveal a remarkable reduction of weight gain after 150 days of age, which indicates special attention should be given to feeding at this stage.

Descrição do crescimento de ovinos Santa Inês utilizando modelos não-lineares selecionados por análise multivariada

“…A identificação do ponto de inflexão imediatamente após o desmame sugere a necessidade de ajuste no manejo nutricional para reduzir os efeitos da mudança de dieta sobre a TCA. Segundo Souza et al (2013), esta informação é de importância estratégica para os produtores, auxiliando na determinação da idade mais econômica para abate, oferecendo a melhor relação custo / benefício. As informações sobre o desempenho animal expressas pelo TCA torna possível a determinação da idade ideal de abate.…”

Modeling the growth curve of Iranian Shall sheep using non-linear growth models

“…Analysis of the animal growth 59 performance through their life span is helpful to establish appropriate feeding strategies and the 60 best slaughter age. Studies focusing on growth curves have increased at recent years due to the 61 development of new computational methods for faster and more accurate analyses as well as the 62 availability of new models to be tested (Souza et al, 2013). In order to increase farmers' income, 63 there needs to be improvement in the production of these animals.…”

Longitudinal data assessment of global stability index in kale leaves

“…A good fit for the Brody model with the lowest AIC (26.238) was found, with the highest R 2 value (0.985) and 99 % of convergence; however, The best model was considerd to be the Melow I (yi = β 1 -β 2 e (-β 3 x i ) + ε i ), since in this model there was 100 % convergence with values around 26.285 for AIC and 0.984 for R 2 . According to Souza et al (2013), the coefficients adjusted by the Melow I model garner greater importance when the biological significance is taken into account, in which, β 1 reflects the individual final performance, and β 3 the progress rate of curves. These coefficients were used for multivariate variance analysis, when a significant effect (p small or equal to 0.01) of accessions was detected in vectors of the coefficients studied by Wilks' lambda, Pillai's trace, Hotelling-Lawley and Roy's root tests.…”