Effect of intermittent light regimens on the performance of intact male turkeys

Abstract

AbstractAn 8-h photoperiod, compared with 12-, 16- or 23-h photoperiods, has been shown to reduce the incidence of injurious pecking and leg problems in intact male turkeys but to result in lower body weights, slower sexual development and less efficient food conversion. The effect of 8 h of illumination given as a solid photoperiod, as eight 1-h periods equally spread through the 24 h or concentrated into a 12-h part of the day on the performance of BUT 8 intact male turkeys was investigated.Fragmentation of the daily illumination increased body weight, improved food conversion efficiency but did not significantly affect food intake. Increased sexual displaying and significantly better food conversion between 16 and 20 weeks by the two intermittently illuminated groups strongly suggested that both regimens were interpreted as stimulatory daylengths. Generally, losses due to mortality and culling were higher in both fragmented groups, while injurious pecking was higher in 8(1L: ID) birds before 5 weeks and in birds given a 12-h ‘subjective day’ after 5 weeks than in 8-h controls. Culling due to leg problems was significantly higher in birds on the 8(1L:2D) regimen but the incidence of leg imperfections was minimal (< 0·037) in all groups. Both intermittent groups but the 8(1L: 2D) in particular, showed a reduced response to hand movement across the eyes compared with 8-h controls. The controls ate proportionately more food during their 16-h dark period than did the intermittent group during their 12-h ‘subjective night’, though both groups increased their ‘nocturnal’ feeding with age.