A novel indirect calorimeter system for measuring gas exchange and determining digestibility, nutrient retention, and net energy in diets fed to group-housed pigs: technical note

A novel indirect calorimeter chamber system has been built at the University of Illinois Urbana-Champaign (IL, USA). The unit consists of 6 respiration-metabolism chambers where temperature and humidity are controlled, gas analysis units, a data management unit, a mechanical room, and an air-conditioned feed storage room. The chambers are airtight and each chamber has the capacity to hold more than 1 pig depending on size. Using the system, concentrations of digestible energy, metabolizable energy, and net energy, and digestibility and retention of nutrients can be determined in diets fed to pigs on an ad libitum basis. A recovery test was performed using propane combustion. The recovery rate of oxygen ranged from 86.7% to 108.7% with a mean of 99.0% and a coefficient of variation of 6.27%. The recovery rate of carbon dioxide ranged from 100.0% to 101.0% with a mean of 100.6% and a coefficient of variation of 0.29%. In summary, a novel calorimeter unit allows for pigs to be group-housed and given ad libitum access to feed and water. This system is believed to be representative of commercial settings, and therefore, net energy can be determined in diets fed to pigs under conditions similar to those used in commercial production.