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 castrated (C) pigs (26-105 kg live weight, LW) was aimed at studying the effects of different environmental factors such as feeding system, diet composition, raising in single-sex and mixed groups, and feeding and grouping routines prior to slaughter on performance and backfat skatole levels. Furthermore, the profitability of the different sexes was calculated. The pigs were fed restrictedly a dry or a wet (whey or water) diet containing either 0.85, 0.95 or 1.05% lysine. The evening before slaughter the pigs were either fed or not. During transport and lairage before slaughter, one half of the pigs were mixed with unfamiliar pigs of all sexes, while the other half were handled pen-wise. In comparison 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 from 60 kg to slaugther EM raised in groups together with F had a tendency 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 when 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 pigs fed lower lysine levels (0.85 and 0.95%). Lysine level had no effect 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 skatole 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. Neither feeding routines nor mixing with unfamiliar pigs prior to slaughter 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 commercially, but was significantly superior for EM when payment was based on dissected carcass lean meat percentage. (C) 1997 Elsevier Science B.V.