THE EFFECTS OF FEEDING SYSTEM, LYSINE LEVEL AND GILT CONTACT ON PERFORMANCE, SKATOLE LEVELS AND ECONOMY OF ENTIRE MALE PIGS

The study embracing 1528 crossbred entire male (EM), female (F) and ca strated (C) pigs (26-105 kg live weight, LW) was aimed at studying the effects of different environmental factors such as feeding system, di et composition, raising in single-sex and mixed groups, and feeding an d grouping routines prior to slaughter on performance and backfat skat ole levels. Furthermore, the profitability of the different sexes was calculated. The pigs were fed restrictedly a dry or a wet (whey or wat er) diet containing either 0.85, 0.95 or 1.05% lysine. The evening bef ore slaughter the pigs were either fed or not. During transport and la irage before slaughter, one half of the pigs were mixed with unfamilia r pigs of all sexes, while the other half were handled pen-wise. In co mparison with C, EM pigs had superior daily weight gain (DWG, +23 g/d) and feed efficiency (-0.15 kg feed/kg weight gain). In the LW range f rom 60 kg to slaugther EM raised in groups together with F had a tende ncy to exhibit a lower DWG, compared with raising in single-sex groups . Carcass lean meat percentage in EM exceeded that of C by 4.1 units w hen estimated by partial dissection. In the LW range from start to 60 kg, pigs fed the highest lysine level (1.05%) had a higher DWG than pi gs fed lower lysine levels (0.85 and 0.95%). Lysine level had no effec t on carcass lean meat percentage. Wet feeding with whey, but not with water, reduced backfat skatole levels, in comparison with dry feeding . Pigs fed the higher vis-a-vis the lower lysine level had higher skat ole levels in trial 1, whereas in trial 2 there was no effect. Contact with F pigs in the pen tended to reduce fat skatole level in EM. Neit her feeding routines nor mixing with unfamiliar pigs prior to slaughte r affected skatole level in backfat, except for a reduction in nonfed pigs, mixed with unfamiliar pigs prior to slaughter. Gross margin per pig place and year did not distinguish EM from C when graded commercia lly, but was significantly superior for EM when payment was based on d issected carcass lean meat percentage. (C) 1997 Elsevier Science B.V.