MATERIALS AND METHODS
Animals and housing
The study was performed on two farrow-tofinish
farms (I and II) of capacities of 2500 and 900
sows, respectively. On both farms, the production
technology was based on a weekly rota management
system. Every week, 110 (farm I) or 40 (farm II) sows
gave birth to piglets. Sows, 3-7 days before their due
date, were moved into the farrowing facility, at which
time they were washed and bathed. Lactation on farm
I lasted 28 ± 3 days, and on farm II, 26 ± 2 days, after
which the piglets were transferred to nursery, and sows
to mating facilities. Production data for both farms are
shown in Table 1. Sows were Yorkshire, Landrace and F1 (Yorkshire × Landrace) while boars are of Duroc
race. On farm I, vaccination of sows was implemented
against classical swine fever, atrophic rhinitis [16],
colibacilosis and clostridial necrotizing enteritis, and
on farm II, sows were vaccinated against porcine
parvovirus and classical swine fever. Piglets on farm I
were vaccinated against enzootic pneumonia (7th day
of life), porcine circovirus type 2 (21st day of life) and
classical swine fever (45th and 90th day of life), and on
farm II against enzootic pneumonia (7th day of life) and
classical swine fever (45th and 90th day of life).
Sows were kept in individual compartments
during farrowing and the same nutrition technology for
both sows and piglets was implemented on both farms.
Sows were fed twice per day, and in the last week of
lactation before weaning, three times per day. Water
was available to sows and piglets ad libitum. Sows
drank water from mechanical nipples positioned at a
height of 50 cm, while water nipples for piglets were
at a height of 10 cm. Additional feed was introduced
to the piglets on the 5th day of life; pre-starter feed was
put on the floor and in small feeders. On farm I there
were 22 compartments in a farrowing room, while on
farm II, one farrowing room had 40 compartments