This book contains the papers presented as either posters or oral presentations at the 7th International Workshop on ‘Modelling Nutrient Digestion and Utilisation in Farm Animals’. The workshop was 
co-organised by INRA (the French National Institute of Agricultural Research) and AgroParisTech 
and was held at AgroParisTech in Paris on 10-12 September 2009. Previous modelling workshops 
in this series were held at: Grassland Research Institute (1979, Hurley, United Kingdom), Universiy 
of California (1984, Davis, USA), Lincoln University (1989, Canterbury, New Zealand), Research 
Center Foulum (1994, Denmark), Capetown (1999, South Africa), Wageningen University (2004, 
the Netherlands). All workshops were held in conjunction with the International Symposium on 
Ruminant Physiology.
The major purpose of this workshop was to present the ‘state of art’ in modelling digestion and 
nutrient utilization in farm animals. It was attended by scientists, modellers, PhD students, and 
non-modellers to discuss and exchange new ideas and methods. The contributions covered a large 
range of topics within modelling activities applied to animal nutrition. The Workshop (and this 
book) were organised in the following six sessions:
1. Advances in methodological aspects of modelling
2. Modelling feeding behaviour and regulation of feed intake
3. Modelling fermentation, digestion and microbial interactions in the gut
4. Modelling interactions between nutrients and physiological functions: consequence on product quality and animal health
5. Extrapolating from the animal to the herd
6. Modelling the environmental impact of animal production
Approximately 110 participants from 18 different countries made this workshop an exciting event. 
A total of 212 colleagues contributed as author or co-author to the 67 oral (36) or poster (31) presentations, resulting in a total of 45 papers in this book. This is a considerable increase compared 
with previous workshops, and illustrates the increasing role of modelling in research programs.
To give an idea of the range of topics covered, a rapid overview of more than 300 keywords of 
the titles of workshops held since the second workshop (Davis, USA) indicates that the studies 
presented mainly concerned ruminants (23.8% of the keywords), most of which deal with dairy 
cattle (14.5%). Fewer studies deal with monogastrics (5.6%). With regard to digestion, rumen 
function (11.9%) was also more frequently modelled than the digestion processes in monogastrics 
(1.6%). The dominance of ruminants is mainly the result of the fact that the first 2 workshop 
essentially focused on these animals. In terms of physiological functions, lactating animals were 
more frequently studied than growing animals (7.3%). The 3 other major topics of presentation 
focused on metabolism (11.5%), farm systems and herd management (9.9%) and methodological 
aspect of on modelling (8.2%). For metabolism, there is an approximate balance between energy 
(3.3%), protein (3.0%) and mineral studies (2.6%). Surprisingly, only few models presented concern 
some important topics of research in animal nutrition, this is particularly the case for intake and 
behaviour (2.0%) and the regulation of metabolism (1.0%). Moreover, disciplines other than nutrition 
were only rarely considered: pathology (1.3%), genetics (0.7%). Concerning the range of topics 
in the current workshop, there were no marked changes in comparison with previous workshops. 
The biggest change was that there was an increase in the proportion of communications focussing 
on the farm and environmental aspects of animal production (20.5% in the present workshop vs. 
12.7% for workshops 5 and 6, and 6.9% for workshops 2, 3 and 4).