Abstract
Animal simulation models are sets of equations used to describe biological processes. A non-steady 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.
Highlights
In tropical regions, ruminant production systems are based mainly on forages
The objective of the present study is to extend the model of Dijkstra et al (1996a) to non-steady state feeding conditions and to enable the model to simulate nutrient availability as a response to feed intake patterns and the kinetics of particle size reduction
In contrast to the result obtained under steady state conditions, for non-steady state conditions with varying patterns of feed intake, the inclusion of a mechanism of particle size reduction did affect the availability of nutrients for microbial use in the rumen and resulted in changes in the simulated fluxes and potential milk yield
Summary
Ruminant production systems are based mainly on forages. Among the tropical forages, sugarcane has a high yield of dry matter (DM) and energy (TDN) per unit area, and the forage productivity can reach more than 30 tons of DM per hectare. Laredo & Minson (1973) and Allen (2000) indicated a reduction of the voluntary intake due to low diet digestibility and low passage rate, and it is assumed that low rates of ruminal digestion and passage may lead to physical limitations on daily dry matter intake (DMI) that may be achieved. Such a depression in DMI has been observed by Correa et al (2003) in dairy cows fed sugarcane based diets in comparison to maize
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
