2.2. Animals, housing, transport and slaughter
All 1040 pigs (Piétrain × Hypor = nN) were born and raised at the same farm. Housing conditions of all pigs were standardized according to Council Directive 2010/63/EU. All experimental procedures were approved by the Ethical Committee on the use of experimental animals (KU Leuven).
Water and a commercial diet (corn, barley, wheat, soybean) were available ad libitum. At birth, piglets were individually marked with a unique numbered ear tag, assuring total traceability from birth to slaughter. Male piglets were castrated one week after birth, in accordance to current legislation (Belgian law 14 August 1986). At four weeks of age, pigs were weaned and group housed, making weight groups according to average body weight. The number of pigs ranged between 12 and 15 per pen depending on the availability of pigs per batch. Barrows and gilts were mixed per pen in a fixed ratio. The number of pigs per pen complied with European legislation (EU 2008/120/EC). Flooring was slats without bedding, i.e. plastic for weaners and concrete afterwards.
Ventilation with fans and heating were computer-controlled and set to assure the required minimal ventilation rate and to keep dry air temperature between 16 °C and 26 °C depending on age and outside temperature.
All pigs (± 110 kg) were transported with the same driver and vehicle to the same slaughterhouse, following the same route (160 km) during ± 2.25 h. Feed was withdrawn about 12 h before loading. Loading, stocking density and unloading were standardized. Lairage time was about 2 h. Head to chess electro-stunning was applied.