A total of 49 sows and their 722 piglets were followed from birth
until weaning in 3 successive replicates (16 sows in replicate 1, 17 in
replicate 2, and 16 in replicate 3). Sows had on average 14.7 live
born piglets. Hybrid piglets (Piétrain [English Landrace Large
White]), heterozygous for the halothane gene, were used. They
were individually marked with an ear tag within the first 24 hours
after birth and weaned all on the same day at approximately
22 days of age. Cross fostering was applied during the week of birth
to balance litters for body weight and number of piglets. Painful
interventions, such as castration, tail docking, ear tagging, and iron
injection, were standardized for each piglet and applied within the
first 5 days of life. Castration on male piglets was carried out after
administering an analgesic (meloxicam, im). Piglets were raised in
the same housing conditions at a commercial pig farm in Belgium.
Management of this system was based on the “all ineall out”
principle for each room. During gestation, sows were kept in groups
of 10 and part of the housing facility was littered with straw. Five to
7 days before the expected farrowing date, sows were moved to the
farrowing house. The farrowing crates (160 cm [W] 230 cm [L]
60 cm [H]) had a creep area for the piglets and a sow lying/suckling
area provided with lateral rails for piglet protection. Sows were
restrained (60 cm [W] 200 cm [L] 110 cm [H]) and had no access
to any environmental enrichment, as is common practice in the
farrowing phase. The flooring in the piglet area consisted of plastic
slatted floors with solid plastic floor in the piglet creep area. The
flooring in the sow area was fully slatted. Piglets had ad libitum
access to water throughout the study.