An extant dynamic model of digestion and absorption of nutrients in cattle fed sugarcane was adapted for non-steady state feeding conditions. This modified model includes mechanisms of particle size reduction and delay in availability of particles and intracellular contents for microbial fermentation after ingestion. Two trials (one with beef cattle and the other with dairy cattle) were used to evaluate the non-steady state model. In general, predicted values were close to observed values for duodenal neutral detergent fibre (NDF) and nitrogen flows (mean squared prediction error (MSPE) of 14% and 15% of observed mean, respectively). There was no indication of over- or underprediction of NDF and nitrogen flows. An overestimation of rumen volume observed in steers suggests that the equation to calculate rumen volume needs to be adapted for low feed intake. Overall mean of milk production was predicted accurately. Predictions under non-steady state conditions showed higher accuracy when real intake behaviour was simulated. The model can be used to select strategies of supplementation of dairy cows fed sugarcane-based diets.
|Title of host publication||Nutrient Digestion and Utilization in Farm Animals: Modelling Approaches|
|Editors||E. Kebreab, J. Dijkstra, A. Bannink, W.J.J. Gerrits, J. France|
|Place of Publication||Wallingford|
|Publication status||Published - 2006|