Utilização de modelos não-lineares para descrever o crescimento do perímetro escrotal em ruminantes.

Growth follows a definite pattern in animal populations in relation to age. In early life, growth is faster than that which occurs close to maturity, showing an increasing sigmoid evolution curve. When a set of measures is taken in the same individual, from birth to maturity, it can represent the growth through a "growth curve". The non-linear models allow the description of series of data by age and size and allow to condense the information into a few parameters with biological interpretation. The scrotal circumference is an important feature in the selection of reproducers by presenting a moderate to high heritability, high repeatability and for being associated with important reproductive traits in both, males and females genetically related with these males. Thus, the nonlinear models arise as a tool to characterize the relationship between age and scrotal circumference growth and use their parameters for the identification of animals with desirable characteristics in testicular development. [ABSTRACT FROM AUTHOR]