Housing and nutrition
The rabbits were housed individually in metabolic wire cages that allowed the faeces separation. A cycle of 16 h of light and 8 h of dark was used throughout the experiment. Temperature and humidity in the building were recorded continuously by a digital thermograph positioned at the same level as the cages. Heating and forced ventilation systems allowed the building air temperature to be maintained within 18 ± 4 C throughout the experiment. Relative humidity was about 70 ± 5 %. The rabbits were fed a commercial diet (pellets of 3.5 mm in diameter). The ingredients and chemical composition