Número de coletas da produção de leite na predição de modelos para estimativa da produção média diária de leite de vacas nelore
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Data
2009-03
Título da Revista
ISSN da Revista
Título de Volume
Editor
José Henrique Stringhini
Resumo
The objective of the experiment was to evaluate
models with different number of collections of milk yield
to estimate average daily milk yield in Nellore beef cows
until 217 days of lactation. The eight evaluations of milk
yield were taken from 29 cows, by direct method through
milking, at 14, 42, 70, 98, 126, 154, 182 days and weaning
(217 days). For the selection of multiple linear regression
models, with objective of estimate the average daily milk
yield according to number of milk collects, Stepwise
procedure of SAS was used. The data were submitted to residual analysis by tests of heterocedasticity of variance
(χ² statistic), normality (W statistic of Shapiro-Wilk) and
diagnosis of outliers (three observations were excluded
from original n=30), beyond multicolinearity diagnosis.
For validation of the selected regression models, the
prediction error sum of squares statistic (PRESS), was used.
The selected days of milk yield collections were: 98 for 1
collection; 70 and 98 for 2 collections; 14, 70, and 98 for
3 collections; 14, 70, 98 and 154 for 4 collections; 14, 70,
98, 154 and 182 for 5 collections; 14, 42, 70, 98, 154 and
182 days for 6 collections and 14, 42, 70, 98, 126, 154 and
182 days for 7 collections. The adjusted R² for models with
1; 2; 3; 4; 5; 6 and 7 collections were, respectively, 0.7900;
0.8718; 0.9064; 0.9596; 0.9698; 0.9875 and 0.9972. All
the predicted models were satisfactory to estimate average
daily milk yield. In a possibility of to execute various
collections of milk yield during lactation period, three milk
collections chosen in strategic dates during lactation period
were sufficient to estimate with high precision the average
daily milk yield.
Descrição
Palavras-chave
Análise residual, Fase de cria, Lactação, Regressão linear múltipla, Seleção de variáveis independentes, Técnicas de validação de modelos de regressão, Lactation, Maternal phase, Multiple linear regression, Selection of independent variables, Residual analysis, Techniques of validation of regression models
Citação
PACHECO, Paulo Santana; RESTLE, João; BRONDANI, Ivan Luiz; SILVA, José Henrique Souza da; MIOTTO, Fabrícia Rocha Chaves; NEIVA, José Neuman Miranda. Número de coletas da produção de leite na predição de modelos para estimativa da produção média diária de leite de
vacas nelore. Ciência Animal Brasileira, Goiânia, v. 10, n. 1, p. 146-156, jan./mar. 2009. Disponível em: <https://www.revistas.ufg.br/vet/article/view/4263/4581>.