AVALIAÇÃO DE SISTEMAS ENERGÉTICOS PARA VACAS LEITEIRAS

Objetivou-se avaliar a qualidade da predicao das exigencias de energia para vacas leiteiras do sistema de Oliveira (2015) para condicoes tropicais, em comparacao aos sistemas AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2004), INRA (2007), CSIRO (2007) e Moraes et al. (2015). Utilizou-se observacoes de quatro experimentos de alimentacao de vacas leiteiras do tipo rotativo, totalizando 181 observacoes de consumo de nutrientes digestiveis totais (NDT) de 16 dietas experimentais. O conjunto de dados construidos apresentou uma ampla variacao nas caracteristicas dos animais (producao de leite entre 6,1 a 36,5 kg/dia), dieta e consumo de NDT (4,0 a 16,6 kg/dia). O sistema energetico de Oliveira (2015) explicou 83% do consumo de NDT observado, superestimou o consumo de NDT em media 0,35 kg/dia e apresentou raiz quadrada do erro medio de predicao (RQEMP) de 12,2% do valor observado. Os sistemas AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2014) e Moraes et al (2015) apresentaram RQEMP similares (P > 0,05) ao sistema de Oliveira (2015), indicando similaridade na acuracia para predizer as exigencias de energia para vacas leiteiras em condicoes tropicais. Recomenda-se ainda investigar a adequacao destes sistemas energeticos em experimentos de longa duracao.Palavras-chave: acuracia; energia; sistemas nutricionais. EVALUATION OF ENERGETICS SYSTEMS FOR DAIRY COWS ABSTRACT: The objective was evaluate accuracy and precision of the estimated energy requirements for lactating dairy of the Oliveira (2015) system to tropical condition, compared to AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2004), INRA (2007), CSIRO (2007) and proposed by Moraes et al. (2015). Four rotative feeding trials were used as dataset, totalizing 181 observations of total digestible nutrient (TDN) intake from 16 diets. Dataset had wide variation in animal performance (milk yield between 6.1 to 36.5 kg/day), diet and TDN intake (4.0 to 16.6 kg/day). The Oliveira (2015) system explained 83% of the observed TDN intake, over-predicted TDN intake by 0.34 kg/day and presented root mean square error of prediction (RMSPE) of the 12.2% of the observed TDN intake. AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2014) e Moraes et al (2015) systems had similar RMSPE (P > 0.05) to Oliveira (2015) system, indicating similar accuracy to predict energy requirement for dairy cows under tropical conditions. We recommended to investigate the adequacy these systems in long term feeding trials.Keywords: accuracy; energy; nutritional systems.