MATERIAL AND METHODS
Animals and fattening trial
The experiment took place in a commercial pig
farm. Initially, seventy two male crossbred (progeny
of Large White Landrace dams sired by Duroc
boars) pigs were selected from 34 litters farrowed
within two weeks. Within each litter, male pigs
were either left entire or surgically castrated (SC,
n = 24) during the first week of life. At the average
age of 79.2 ± 3.3 days, when pigs entered the fattening
unit, half of the entire male pigs (IC, n = 24)
received the first vaccination against GnRH (2 ml
of Improvac® vaccine per animal, Pfizer Animal
Health), whereas the remaining half (EM, n = 24)
was untreated. Pigs of each treatment group were Table 1. Performance traits (mean ± standard deviation)
in entire males, immunocastrates, and surgical castrates
according to the phase of experiment