Sensitivity analysis of 1996 National Research Council model for supplemented grazing beef cattle


The National Research Council (NRC) published in 1996 the Seventh Edition of the Nutrient Requirement of Beef Cattle (NRC 1996), which includes a software to evaluate diets. However, it is unknown the sensitivity of its outputs according to the changing values of its inputs. This is particularly important during the evaluation of the software performance in the presence of new scenarios. In order to evaluate this, an analysis of sensitivity was performed using the one at a time and multi-way procedures. The results showed inconsistencies between the values from the sensitivity in the level one (L1) and the level two (L2) of the software. The inputs that had higher response to the change in the prediction of daily weight gain (DWG) in the L1, compared to the L2, were herbage intake, enriched sugar cane intake, supplement intake, initial body weight, mature weight, and animal breed. The inputs that did not have changes for both levels (L) were age of the animal, heat stress, wind speed, night cooling, hide, hair depth, grazing unit size, days on pasture, and number of animals grazing. It is necessary to carry out evaluations using real data to know the performance of the software in frequent commercial situations.
Key words: NRC software, input sensitivity, Bos taurus, tropical Mexican conditions.

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