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Abstract: The method of Boisen and Fernandez [Boisen, S., Fernandez, J.A., 1997. Prediction of total tract digestibility of energy in feedstuffs and pig diets by in vitro analyses, Anim. Feed Sci. Technol. 68, 277–286] for measuring in vitro fecal digestibility of organic matter (OMdv) or in vitro digestible organic matter content (DOMv, g/kg) was used on 113 compound feeds (79 as mash and 34 as pellets) and 66 ingredients (as mash) whose digestibility of organic matter (OMd) and energy (Ed) and digestible energy content (DE, MJ/kg) had been measured in 60kg growing pigs for all compound feeds and ingredients, and in adult sows for about 2/3 of the compound feeds (as mash); net energy (NE, MJ/kg) of these feeds were estimated from digestibility information. The repeatability and accuracy of the method were evaluated. Data obtained on compound feeds fed as mash were used to establish prediction equations of OMd, Ed, DE NE from OMdv or DOMv and chemical criteria. The levels of accuracy and repeatability of OMdv measurement were satisfactory and values for OMdv and OMd of mash compound feeds were very close and highly correlated (r =0.91). Apart from OMdv, the best prediction equations of OMd or Ed included ash content and a cell wall criterion (ADF or crude fiber); for prediction of DE, fat content had also to be considered. The coefficient of variation of all equations was below 0.02. The equations allow a satisfactory prediction of OMd, Ed or DE of the 66 ingredients fed as mash. However, the equations established on data obtained on mash feeds underestimate the in vivo nutritional value of pelleted feeds and are not applicable to prediction of energy value of feeds for adult pigs. [Copyright &y& Elsevier]

Abstract: Animal production is facing new challenges that call for a more integrative approach towards nutrition. Although considerable research progress has been made by the development of mathematical models of nutrient utilisation in farm animals, practical application of these models has been rather limited. The objective of the InraPorc® project is to integrate the current state of knowledge in a nutritional model for growing pigs and sows, and make it available as a decision support tool to end-users. The objective for the growing pig (15–150kg BW) model is to analyse nutrient utilisation for characterised pig types and to evaluate the effects of using different nutritional strategies in terms of nutrient utilisation, performance and carcass characteristics. As model parameters related to feed intake and growth potential are adjusted by the model user, growth (in an absolute sense) is not predicted. The model is based on the transformation of dietary nutrients to body protein and lipid, which are then used to predict body weight, lean body mass and backfat thickness. The representation of nutrient utilisation is mostly based on concepts used in net energy and ideal protein systems. Driving forces of the model include feed intake, the partitioning of energy between protein and lipid deposition, and availability of dietary protein and amino acids. Using literature data, the model appeared reasonably well capable of predicting the consequence of a nutrient intake restriction. The decision support tool is available at http://www.rennes.inra.fr/inraporc/. Through a user-friendly interface, the tool can be used to visualise different aspects of nutrient utilisation and excretion. [Copyright &y& Elsevier]