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O objetivo deste estudo foi analisar modelos não-lineares para descrever o crescimento em animais da raça Indubrasil no Estado do Sergipe. Após a definição do modelo de melhor ajuste, calculou-se a taxa de crescimento absoluto e avaliou-se a influência de fatores ambientais (sexo, fazenda, mês e ano de nascimento) sobre os parâmetros da curva. Utilizaram-se dados de, no mínimo, 8 pesagens, obtidas a intervalos de aproximadamente 90 dias, do nascimento aos 2 anos de idade de 1.201 bovinos, provenientes da Associação Brasileira dos Criadores de Zebu (ABCZ). Os modelos não-lineares utilizados foram: Brody, Von Bertalanffy, Richards, Logístico e Gompertz. O modelo Logístico apresentou melhor ajuste seguido dos modelos Gompertz e Von Bertalanffy. O peso assintótico (A) e a taxa de maturidade (K) estimada pelo modelo Logístico foram 427,87 kg e 0,0052, respectivamente. Constatou-se acentuado decréscimo da taxa de crescimento absoluto na fase pós-desmama, devendo ser adotado um regime alimentar adequado para acompanhar as exigências de nutrientes dos animais nessa fase. Os efeitos de ambiente influenciaram significativamente (P < 0,05) os parâmetros A e k . A correlação estimada entre os parâmetros A e k foi negativa (-0,62), indicando que os animais mais precoces possuem menor probabilidade de atingir pesos elevados à idade adulta.The objective of this study was to analyze nonlinear models to describe growth of Indubrazil cattle raised in Sergipe State. After defining the best adjusted model, it was evaluated the influence of environmental effects (sex, farm, month and year of birth) over mature weight (A) and maturation rate (K). Data from 1,201 animals weighed in nearly 90-day intervals from birth up to two years of age were used, based on records from the Brazilian Association of Zebu Breeders (ABCZ). The models utilized were Brody, Von Bertalanffy, Richards, Logistic and Gompertz. The Logistic model presented best adjustment followed by Gompertz and Von Bertalanffy models. The parameters A (weight at maturity) and k (maturation rate), obtained by the Logistic model were 427.87 and 0.0052, respectively. An accentuated decrease in the absolute growth rate was observed after weaning and nutritional strategies should be performed to avoid the low weight gain at this stage. Environmental factors affected significantly the parameters A and k. The correlation estimated between the parameter A and k was negative (-0.62), indicating that fast-growing young animals are less likely to reach higher weights when adults.

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