| Popis: |
The Cornell Net Carbohydrate and Protein System (CNCPS) model has been increasinglyused in tropical regions for dairy and beef production. However, the lack of appropriate characterizationof the feeds has restricted its application. The objective of this study was to develop and evaluate afeed library containing feeds commonly used in tropical regions with characteristics needed as inputsfor the CNCPS. Feed composition data collected from laboratory databases and from experimentspublished in scientific journals were used to develop this tropical feed library. The total digestiblenutrients (TDN) predicted at 1x intake of maintenance requirement with the CNCPS model agreed withthose predicted by the Weiss et al. (1992) equation (r 2 of 92.7%, MSE of 13, and bias of 0.8%) over allfeeds. However, the regression r 2 of the tabular TDN values and the TDN predicted by the CNCPSmodel or with the Weiss equation were much lower (58.1 and 67.5%, respectively). A thoroughcomparison between observed and predicted TDN was not possible because of insufficient data tocharacterize the feeds as required by our models. When we used the mean chemical compositionvalues from the literature data, the TDN predicted by our models did not agree with the measuredvalues. We conclude using the TDN values calculated using the Weiss equation and the CNCPS modelthat are based on the actual chemical composition of the feeds result in energy values that moreaccurately represent the feeds being used in specific production situations than do the tabular values.Few papers published in Latin America journals that were used in this study reported information needby models such as the CNCPS.Key words: CNCPS, evaluation, feed library, tropical feeds |
