Agriculture Reference
In-Depth Information
2
InraPorc: Where Do We Come From
and Where Do We Want to Go?
J. van Milgen,* J.Y. Dourmad, J. Noblet, E. Labussière, F. Garcia-Launay,
S. Dubois, A. Valancogne and L. Brossard
INRA, Saint-Gilles, France
Abstract
The first nutritional models for pig growth were published in the mid-1970s. Although modelling has
been seen for a long time as a very promising approach in animal nutrition, widespread use of models
has been limited. We hold the opinion that models should be user-friendly to ensure that they will be
adopted by users other than the model developers. It is with this in mind that we started the develop-
ment of the InraPorc model and software tool. One of the main challenges we encountered was to capture
the phenotypic variation among pigs in a limited number of user-accessible model inputs. Feed intake,
protein deposition and energy expenditure are model inputs, while lipid deposition is an energy sink.
An inappropriate description of the feed intake, protein deposition or energy expenditure will therefore
result in a very fat or very lean pig when the simulation is carried out for a long period of time. We in-
cluded a function in the model where feed intake is described as a Gamma function of the maintenance
energy expenditure. This function ensures that, as the pig matures, feed intake attains the maintenance
energy expenditure so that energy retention and growth cease. Deterministic growth models such as
InraPorc simulate the performance of a single 'average' pig. However, nutritional recommendations for
the average pig should not be applied to a population of pigs because the performance of the population
would then be less than that of the average pig. To include variation among pigs in simulation models,
the variance-covariance structure of model parameters should be taken into account because variation
among animals is only partly random. For example, a pig that eats more than average will probably also
grow faster than average. Including stochastic aspects in simulation models is currently a research topic
in our group, and results of this will be included in a future release of the InraPorc software tool.
Introduction
intended to be a
3-
year project with an an-
ticipated delivery in 2001. However, the first
software version was released in 2006 and
the model description was published in
2008 (Dourmad
et al
., 2008; van Milgen
et al
., 2008). What went wrong? Not much
in terms of model development. This is not
too surprising because the InraPorc model
(at least the growing pig model) is a rather
The InraPorc project started in 1998 with the
goal of developing a nutritional model for
growing pigs and sows that could be ac-
cessed through a user-friendly interface.
InraPorc is a model and a software tool that
allows users to work with the model. Devel-
opment of the model and the tool was
