Simulation model for particle dynamics in rumen of cattle fed sugarcane diet

Abstract

Animal simulation models are sets of equations used to describe biological processes. A nonsteady state simulation model of cattle digestion is presented in order to represent nutrient availability as a response to feed intake pattern and the kinetics of particle size reduction. Variables representing the particle size reduction and discontinuous voluntary feed intake were included in a mechanistic model created to optimize the supplementation of sugarcane based diets. In general the predicted values were very close to observed values for fibre and nitrogen flows. The model has not shown consistent bias in relation to the behavior of the observed data of duodenal flow of neutral detergent fiber and non-ammonia nitrogen. Milk production simulations were quite close to actual values. Predictions were improved by the non steady-state model, taking into account variable intake rate in relation to the previous steady-state model. The model can be used to select strategies for supplementation of cattle fed sugarcane based diets.

Recent advances in modeling nutrient utilization in ruminants1

“…Thus, this representation will greatly affect the diurnal pattern of rumen pool sizes and flows to the duodenum, but its effect on the simulated average extent of degradation compared with continuous feed intake is likely to be small (Bannink et al, 1997a). Collao-Saenz et al (2005) adopted this representation as developed by Baldwin (1995) but included a representation of increased microbial death rate when substrate availability was decreased several hours after feeding. Moreover, rumen volume was assumed to be related to size of the meals and DM content.…”

<i>In sacco</i> kinetics disappearance of NDF of small and large particles of the rumen contents in grazing dairy cows

“…In the model of Sauvant et al (1996), the degradation rate of digestible NDF in LP was 0.8 times that in SP and in the model of Baldwin et al (1987) and Collao-Saenz et al (2005), the degradation rate of LP was considered negligible compared to that of SP. Sauvant et al (1996) calculated that a variation of 20% of the ratio between degradation rates of SP and LP had a limited impact on dry matter intake prediction in their model.…”