ADJUSTMENT OF NONLINEAR MODELS AND ESTIMATION OF GROWTH PARAMETERS IN TROPICARNE CATTLE

作者：Dominguez Viveros Joel; Alonso Rodriguez Almeida F; Nunez Dominguez Rafael; Ramirez Valverde Rodolfo; Angel Ortega Gutierrez J; Ruiz Flores Agustin

来源：Agrociencia, 2013, 47(1): 25-34.

• model selection
• Brody
• Bertalanffy
• tropical cattle
• growth curve

Growth analysis with non-linear regression models (NLM) allows deriving parameters (GP) and indicators (GI) of growth under specific production conditions that can be taken into account in genetic improvement programs. The objectives of this study were to select and adjust a NLM to the growth of Tropicarne cattle raised in the Gulf of Mexico coastline. The NLM evaluated were Brody, Logistic, Bertalanffy and Gompertz. The growth information analyzed corresponded to 12 890 monthly weigh-ins, from birth to 24 months of age, in 1787 animals. The GP estimated were adult weight (AW) and maturity rate (MR); and the GI, age (API) and weight (WPI) at point of inflection, age at 50 % of maturity (A50M) and percentage of maturity at 18 months of age (PM18). The analyses were carried out with the NLIN procedure of SAS. The selection of models was done based on the average prediction error, variance of the prediction error, multiple and adjusted determination coefficient, the Durbin-Watson statistic, and the Akaike information criterion. The Brody model, followed by the Bertalanffy model, showed a better adjustment with estimations of 467.5 and 378.8 kg for AW, and 0.0612 and 0.132 kg kg(-1) month(-1) for MR. Derivations of the API, WPI, A50M and PM18 were 3.8 months, 112.2 kg, 7.4 months and 85 %. The Brody model allowed a better description of the growth of Tropicarne cattle, which implies slow MR, characteristic of the growth of bovines in the tropics, in contrast with the typical sigmoid curve for some breeds in temperate climates.

• 出版日期2013-2