Banca de DEFESA: LUCAS SILVA DO AMARAL

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCAS SILVA DO AMARAL
DATE: 13/02/2025
TIME: 14:00
LOCAL: Auditório do Deinfo
TITLE:

APPLICATION OF CRITICAL POINTS OF CURVES AND SYMMETRIC NONLINEAR MODELS IN THE EVALUATION OF ANIMAL GROWTH

KEY WORDS:

Statistical Modeling; Diets; Probability Distributions.

PAGES: 96
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUMMARY:

This study aimed to model growth curves of Lionhead rabbits and Zebu x Taurine cattle subjected to diets with different protein levels and feeding regimes, respectively. For the rabbits, 32 animals were distributed into four groups with diets containing 13%, 16%, 19%, and 22% crude protein, evaluated weekly between 73 and 192 days of age. Five nonlinear models (Brody, Gompertz, Logistic, Richards, and von Bertalanffy) were fitted to the data. According to evaluation criteria combined with cluster analysis, the von Bertalanffy model was deemed the most appropriate. Subsequently, a curve identity test and an analysis of critical points (inflection point (IP), maximum acceleration point (MAP), maximum deceleration point (MDP), and asymptotic deceleration point (ADP)) were performed. The curve identity test indicated significant differences between the diets (p < 0.05), except for performance between the 16% and 19% protein diets. The analysis of critical points revealed that rabbits fed the 13% protein diet exhibited slower development, whereas those on the 22% protein diet reached growth stabilization more quickly. The comparison of treatments demonstrated that the 16% protein diet provided the best performance in terms of animal health. In the study with cattle, symmetric nonlinear models were fitted to the accumulated weight gain of 24 animals, which were divided into three feeding regimes: no adaptation protocol (CON), with adaptation protocol (ADP), and extruded diet (EXT). Weight gain was monitored daily over 144 days. The fitted models included Brody, Gompertz, Logistic, Santos, and von Bertalanffy, and the distributions analyzed were Normal, t-Student, Exponential Power, Cauchy, Logistic I, and Logistic II. The von Bertalanffy model fitted with a t-Student distribution with 3 degrees of freedom proved to be the most effective from both statistical and biological perspectives. Regarding feeding regimes, the ADP diet stood out, showing higher absolute growth rates and greater growth acceleration, outperforming the CON and EXT diets. In summary, the analysis of critical points of the growth curves provided valuable insights for more precise nutritional interventions, and the application of symmetric distributions was crucial for handling data with outliers, enhancing the robustness of the analyses. These findings can contribute to more effective nutritional management practices, with implications for both companion animals and meat production.

COMMITTEE MEMBERS:
Interno - ANTONIO SAMUEL ALVES DA SILVA
Externo à Instituição - CICERO CARLOS RAMOS DE BRITO - IFPE
Externo à Instituição - DAMOCLES AURELIO NASCIMENTO DA SILVA - UPE
Interno - FRANK SINATRA GOMES DA SILVA
Presidente - GUILHERME ROCHA MOREIRA