EFFECT OF LIGHTING TREATMENT ON THE PRODUCTIVITY, HEALTH, BEHAVIOR AND SEXUAL MATURITY OF HEAVY MALE TURKEYS

1. Turkey poults (1620) were used to compare the effects of three ligh ting programmes on heavy strain males reared to 188 d: constant light (24L:OD, CON); increasing light (6L: 18D at 7 d gradually increasing t o 20L:4D by 63 d, INC); a pattern identical to INC followed by a decre ase in daylength from 84 d to 10L: 14D at 112 d (DID). 2. Lighting aff ected growth pattern but had no effect on body weight at 118 d or over all food to gain ratio. 3. Both INC and DID lighting reduced overall m ortality in comparison to CON light primarily because of a reduction i n the incidence of skeletal disease and spontaneous cardiomyopathy. IN C and DID lighting increased the incidence of cannibalism. 4. Turkeys given INC or DID lighting had a superior ability to walk in comparison to those birds given CON light. 5. INC and DID males stood, ate and d rank more frequently, and sat less often than CON turkeys during behav ioural observation. 6. There were no lighting effects on carcase compo sition except that INC and DID birds had heavier keel bones. The ultim ate force per cm2 (stress) required to break femora was greater for tu rkeys given INC and DID lighting (P=0.065). 7. Plasma testosterone con centrations at 117 d were 272.5, 115.2 and 29.5 pg/ml for turkeys give n CON, INC and DID lighting, respectively (P=0.072). Testosterone conc entration was not related to growth rate.