Understanding body composition and efficiency in ruminants: a non-linear approach

ion of the model. The approach to estimation of efficiency differs to previous feeding systems. Traditional feeding systems utilise empirically derived linear (additive) relationships between feed, weight (and through weight, body composition) and heat production. Our approach uses empirically derived dynamic relationships which encompass simultaneous interactions between feed intake, body components (protein and fat and hence weight), and heat production. In this construction, efficiency ofenergyuse for maintenance and is an outcome rather than an input. The system we are working with can be described by the following five coupled non-linear differential equations written here in general form: Each equation contains functions of terms from other coupled equations. Unlike models derived directly Corn experimental data, the equations are built from behavioural analysis of the system of equations to ensure that they have properties that include and mimic the observed (experimental) behaviours of the system. This is an iterative process between the mathematicians and biologists and takes place before any numerical solutions are derived. Our simple notions of cause and effect have come under close scrutiny during this process, including the idea that complex behaviours can arise tiom simple laws. The first step in the model building process is to look at the behaviour of the components of the system that the model will ultimately capture. The difference in approach to that used in development of previous feeding systems is that a qualitative analysis of the system’s behaviour is conducted before numerical solutions are sought. This is to ensure that the equations will generate realistic solutions. Some of the qualitative and quantitative characteristics that influence our thinking about the form of the separate equations for protein (muscle and viscera), fat, heat production and feed intake are shown below.