Data/hora: 01/06/2024 04:41:22

Provedor de dados: | 96
País: | Brazil
Título: | Validation of models for predicting milk urea nitrogen concentrations, estimating dry matter intake by the NRC (2001)
Autores: | Meyer,Paula Marques; Machado,Paulo Fernando; Coldebella,Arlei; Cassoli,Laerte Dagher; Coelho,Karyne Oliveira; Rodrigues,Paulo Henrique Mazza.
Data: | 2012-05-01
Ano: | 2012
Palavras-chave: | Dairy cow; Milk urea nitrogen; Nitrogen excretion; Protein utilization.
Resumo: | The objective of this study was to validate three different models for predicting milk urea nitrogen using field conditions, attempting to evaluate the nutritional adequacy diets for dairy cows and prediction of nitrogen excreted to the environment. Observations (4,749) from 855 cows were used. Milk yield, body weight (BW), days in milk and parity were recorded on the milk sampling days. Milk was sampled monthly, for analysis of milk urea nitrogen (MUN), fat, protein, lactose and total solids concentration and somatic cells count. Individual dry matter intake was estimated using the NRC (2001). The three models studied were derived from a first one to predict urinary nitrogen (UN). Model 1 was MUN = UN/12.54, model 2 was MUN = UN/17.6 and model 3 was MUN = UN/(0.0259 × BW), adjusted by body weight effect. To evaluate models, they were tested for accuracy, precision and robustness. Despite being more accurate (mean bias = 0.94 mg/dL), model 2 was less precise (residual error = 4.50 mg/dL) than model 3 (mean bias = 1.41 and residual error = 4.11 mg/dL), while model 1 was the least accurate (mean bias = 6.94 mg/dL) and the least precise (residual error = 5.40 mg/dL). They were not robust, because they were influenced by almost all the variables studied. The three models for predicting milk urea nitrogen were different with respect to accuracy, precision and robustness.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982012000500026
Editor: | Sociedade Brasileira de Zootecnia
Relação: | 10.1590/S1516-35982012000500026
Formato: | text/html
Fonte: | Revista Brasileira de Zootecnia  v.41 n.5 2012
Fonte: | info:eu-repo/semantics/openAccess