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History:

The two large chambers were constructed in 1980, one year after the construction of the research unit in Saint Gilles. Their design was largely based on the large respiration chamber of Inra in Theix used for studies in cattle (Vermorel et al., 1973). The physical dimensions of the respiration chamber were chosen so that studies on gestating and lactating sows could be carried out. In 2000, the climate control system was redesigned and the system of direct cool air production was replaced by a water-glycol system, allowing for a more flexible and powerful regulation.
In 1985, a 2 m3 chamber used at INRA at Jouy-en-Josas (Charley et al) was adapted to become an open-circuit system and this system was used for approximately 10 years. In 1999, the system was replaced by a new open-circuit respiration chamber (1.7 m3) using a water-glycol climate control system.
Along with the evolution of electronics and computers and to respond to different experimental protocols, the measurement system was further changed:

• Depending on the types of measurement and to improve reliability : the use of infrared beams to detect the posture of the animal, electronic ear tags to identify animals in a group, estimation of physical activity through force sensors, weight sensor to measure feeding and drinking behavior, renewal of the gas analyzers
• With the performances of data acquisition systems and data treatment: Use of a computer–controlled data acquisition systems, connection to computer networks for data transfer and remote supervision of the system and, since 1995, the use of modeling techniques to analyze the within-day dynamics of energy expenditure and to quantify the components of heat production related to the basal metabolism, physical activity and the metabolic utilization of feed (van Milgen et al., 1997).

Description of the installation

The respiration chambers laboratory is composed of three open-circuit respiration chambers.
Two identical 12 m3 chambers (useful inner space LxHxD = 1.8 m x 1.8 m x 2.5 m), linked by a gateway, for studies in animals or groups of animals ranging between 10 and 80 kg metabolic body weight (BW0.75). For example, 50 to 100 kg pigs can be kept individually or in small groups in these chambers, just like 8 to 10 piglets, or 10 turkeys at 8 weeks of age or a veal calf up to 250kg body weight.

One 1.7 m3 chamber (useful inner space LxHxD = 0.9 m x 1.1 m x 1.5 m) for individually-housed animals between 10 and 50 kg BW or for group-housed animals (e.g., 3-4 weaned piglets, 10 broilers at 3 weeks of age).

• The temperature and humidity level can be controlled in the respiration chambers. These parameters can be set between 5 and 35°C for temperature, and between 50 and 90% for relative humidity. The air renewal rate in the respiration chamber is approximately 100 times per hour.
• Air is extracted from the chambers by an air extraction pump, which is then directed towards a mass gas flow meter. The extraction rate can be varied between 4 and 20 m3/h for the large chambers and between 1 and 6 m3/h for the small chamber.
• Each respiration chamber is linked to a gas analysis system allowing the continuous measurement of O2, CO2 and CH4.
• Each chamber is equipped with a data acquisition system. Controlled by a computer, this system allow to save (several times per second) the different parameters of the system such as temperature, atmospheric pressure, humidity, gas extraction rate, concentrations of O2, CO2 and CH4, weights of the feeder and drinking systems, force sensors, sensor indicating the standing or lying position of the animal.
• Specific equipment can be used in the chamber for animal housing (e.g., slats), solid or liquid (programmable) feeding systems, the separate collection of urine and feces while ensuring the well-being of the individual or group-housed animal and measurement of the energy cost of horizontal movement in pigs ("home-trainer").

Additional facilities

• A experimental pig production unit for providing the animals; miniature pigs are also available.
• An animal physiology laboratory with infrastructure and personnel authorized to carry out animal experiments.
• Facilities for surgery.
• An experimental feed production unit.
• A laboratory for (bio)chemical analysis of feed, feces and urine, blood and animal tissues.
• An experimental slaughterhouse.
• A mass-spectrometry laboratory (if stable isotope are used).
• Facilities for imaging: scanner, tomograph, gamma camera.
• Expertise in electricity, plumbing, electronics, mechanics and computer programming for the maintenance and to develop prototypes designed for experimental studies. For example, the individual identification of pigs in a group-housed system and a system for automatic distribution of milk and solid feeds for veal calves have been developed.

To carry out research program with the respiration chamber, additional facilities available at the research unit can be used, such as: