Autores

Elisa Junqueira Oliveira, Anielly De Paula Freitas, Roana Lourenço Ferreira, Flavia Fernanda Simili, Lenira El Faro, Maria Lucia Pereira Lima, Ricardo Lopes Dias Costa, Claudia Cristina Paro de Paz

Analysis of growth curve in Santa Ines females sheep

Resumo

Análise da curva de crescimento em fêmeas da raça Santa Inês

Abstract

In a sheep production system, the growth-related
characteristics have direct relationship to both, quantity and quality of meat.
The objective of this study was to evaluate the application of non-linear
models to report the growth curve of Santa Inês sheep. Weights of 140 females,
born from2010 to 2012, from a single herd at Cravinhos- SP were used. The
weights were measured from birth to about one year of age and the ages were
grouped together in biweekly classes. The average weight observed at birth was
of 3.77±0.92 kg.
The non-linear models utilized in the data adjustment were the Brody, Gompertz,
Logistic and Von Bertalanffy models, adjusted by the Gauss-Newton method by
means of NLIN procedure, available in SAS software. The parameters which
compose the functions, Wt (kg) is the weight in time t (days); A (kg) is the
asymptotic weight when age tends to infinity; b is an integration constant,
related to the initial weights of the animals and not well defined biological
interpretation, and k is the maturity rate. The average estimates for A and k, are the
most important from an zootechnical
parameters point of view, mainly
because heavier females tend to create faster growing sheep. All the models evaluated reached convergence. The
quality of the models adjustment was done by error mean square (EMS) means. From the EMS results , the Gompertz model
showed the best adjustment, which indicates increased association between the
observed and estimated weights, in
spite of the EMS values being quite close in
all models, pointing out that all were adequate to report the growth curve from
birth to one year of age in females of Santa Inês breed.

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