Use of nonlinear models to evaluate the growth curve of lambs

Authors

  • Mylena Cristina Ribeiro Borges Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária, Zootecnista. Uberlândia, MG. Brasil. https://orcid.org/0009-0005-1906-1246
  • Gustavo Roberto Dias Rodrigues Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária, Zootecnista. Uberlândia, MG. Brasil. https://orcid.org/0000-0001-9438-3724
  • Camila Raineri Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária, Docente do curso de Zootecnia. Uberlândia, MG. Brasil. https://orcid.org/0000-0002-6398-5033
  • Gilberto de Lima Macedo Júnior Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária, Docente do curso de Zootecnia. Uberlândia, MG. Brasil https://orcid.org/0000-0001-5781-7917
  • Natascha Almeida Marques da Silva Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária, Docente do curso de Zootecnia. Uberlândia, MG. Brasil. https://orcid.org/0000-0003-2318-1791

DOI:

https://doi.org/10.35699/2447-6218.2023.45002

Keywords:

Adult weight, Logistic model, Mean square error, Quality evaluators

Abstract

The objective was to use non-linear regression models to evaluate the growth curve of lambs. For this, data regarding the weight and age of 70 crossbred Dorper x Santa Inês lambs born between the years 2016 to 2019 were used. The production system was intensive and semi-confined. The animal data were adjusted using non-linear Brody, Von Bertalanffy, logistic and Gompertz models. To compare the fit of the models, the adjustment quality evaluators were used: mean square error (MSE), coefficient of determination (R2) and percentage of convergence (%conv). The growth curves were made by individual adjustments. All analyzes were performed using the RStudio software, version R 4.1.2. The Logistic model was the one that best estimated the parameter a (adult weight) with 48.09 kg, while the others overestimated the biological reality of the parameter. Likewise, it presented the highest value for parameter k (maturity rate) with 0.0219. All models obtained a coefficient of determination (R²) greater than 96%. Von Bertalanffy's model had the lowest SMQ (1.61), followed by Gompetz (2.27), Logistic (2.76) and Brody (3.36). The Logistic model had the highest percentage of data convergence (87.14%), followed by Gompertz (71.43%), Von Bertalanffy (35.71%) and Brody (10%). Therefore, the logistic model showed the best fit compared to the others with adequate R², low MSE, high percentage of convergence and adequate asymptotic value, not tending to overestimate adult weight.

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References

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Published

2023-05-17

How to Cite

Borges, M. C. R., Rodrigues, G. R. D., Raineri, C., Macedo Júnior, G. de L., & Silva, N. . A. M. da. (2023). Use of nonlinear models to evaluate the growth curve of lambs. Agrarian Sciences Journal, 15, 1–6. https://doi.org/10.35699/2447-6218.2023.45002

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Research Papers
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