Número de amostragens da produção de leite para estimativa da produção média diária de leite em vacas charolês
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Data
2009-03
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Editor
Jose Henrique Stringhini
Resumo
The objective of the experiment was to evaluate
different number of collections of milk yield to prediction
of models to estimate average daily milk yield of Charolais
beef cows until 217 days of lactation. The eight evaluations
of milk yield were taken from 27 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 the objective to estimate the average
daily milk yield according to number of milk collections,
Stepwise procedure 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: day 98 for 1 collection; days 70 and 98 for 2 collections; days 14, 70, and 98 for 3 collections; days 14, 70, 98 and 154 for 4 collections; days 14, 70, 98, 154 and 182 for 5 collections; days 14, 42, 70, 98, 154 and 182 for 6 collections and days 14, 42, 70, 98, 126, 154 and 182 for 7 collections. The adjusted R² for models with 1; 2; 3; 4; 5; 6 and 7 collections were, respectively, 0.72; 0.87; 0.97; 0.97; 0.99; 0.99 and 0.99. All the predicted models with different number of collections of milk yield 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, Lactação, Regressão linear múltipla, Seleção de variáveis independentes, Técnicas de validação de modelos de regressão, Lactation, Multiple linear regression, Selection of independent variables, Residual analysis, Techniques of validation of regression models
Citação
PACHECO, Paulo Santana; RESTLE, João; FREITAS, Aline Kellermann de; BRONDANI, Ivan Luiz; SILVA, José Henrique Souza da; ALVES FILHO; Dari Celestino. Número de amostragens da produção de leite para estimativa da produção média diária de leite em vacas charolês. Ciência Animal Brasileira, Goiânia, v. 10, n. 1, p. 135-145, jan./mar. 2009. Disponível em: <https://www.revistas.ufg.br/vet/article/view/4262/4580>.