Photoperiod and seasonal influences on the growth of turkey hens

Injurious pecking can be a major cause of mortality in growing turkeys, particularly if given a long photoperiod. Consequently, birds are usually reared under low light intensity (<1 lux) and/or have their beaks trimmed. The influence of an 8, 12, 16 or 23 h photoperiod at an intensity of 1 or 10 lux on the performance of intact (not beak trimmed or de-snooded) BUT8 male turkeys was assessed in a 4 X2 empirical study.Excessive injurious pecking in groups exposed to 10 lux light intensity on >12 h photoperiods necessitated an unscheduled reduction to 1 lux light intensity. Overall, light intensity did not significantly affect food intake, food conversion efficiency, growth or carcass composition. Groups exposed to 10 lux light intensity for all or part of the trial had higher losses and a greater incidence of pecking than birds maintained on al lux light intensity.Growth was inconsistently affected by photoperiod, with birds on 12 h having the highest body weight at 108 days but no significant differences at 136 days. Patterns of food intake were variable but cumulatively to 136 days food intake was not significantly affected by daylength. Overall, but particularly after 108 days, birds on longer photoperiods converted food more efficiently. Mortality and the incidence of injurious pecking was positively correlated with photoperiod and breast meat yield and testicular weight were greater in birds on longer daylengths. There were no significant interactions between photoperiod and illuminance.

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Effect of photoperiod and light intensity on the performance of intact male turkeys

Lewis

Perry

Sherwin

1998

Anim. Sci.

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Photoperiod-Dependent Changes in Melatonin Synthesis in the Turkey Pineal Gland and Retina

Zawilska¹,

Lorenc²,

Berezińska³

et al. 2007

Poultry Science

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The effect of photoperiod on melatonin content and the activity of the melatonin-synthesizing enzymes, namely, serotonin N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase, were investigated in the pineal gland and retina of turkeys. The birds were adapted to 3 different lighting conditions: 16L:8D (long photoperiod), 12L:12D (regular photoperiod), and 8L:16D (short photoperiod). Pineal, retinal, and plasma melatonin concentrations oscillated with a robust diurnal rhythm, with high values during darkness. The duration of elevated nocturnal melatonin levels in the turkey pineal gland, retina, and plasma changed markedly in response to the length of the dark phase, being longest during the short photoperiod with 16 h of darkness. These photoperiodic variations in melatonin synthesis appear to be driven by AANAT, because changes in the activity of this enzyme were closely correlated with changes in melatonin. By contrast, pineal and retinal hydroxyindole-O-methyltransferase activities failed to exhibit any significant 24-h variation in the different photoperiods. A marked effect of photoperiod on the level of melatonin production was also observed. Peak values of melatonin and AANAT activity in the pineal gland (but not in the retina) were highest during the long photoperiod. During the light phase, mean melatonin concentrations in the pineal gland and retina of turkeys kept under the long photoperiod were significantly higher compared with those from birds maintained under the regular and short photoperiods. In addition, mean circulating melatonin levels were lowest in the short photoperiod. Finally, the magnitude of the light-evoked suppression of nighttime pineal AANAT activity was also influenced by photoperiod, with suppression being smallest under the long photoperiod. These findings show that in the turkey, photoperiod plays an important role in regulating the melatonin signal.

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Photoperiod and seasonal influences on the growth of turkey hens

Cited by 2 publications

References 13 publications

Effect of photoperiod and light intensity on the performance of intact male turkeys

Effect of photoperiod and light intensity on the performance of intact male turkeys

Photoperiod-Dependent Changes in Melatonin Synthesis in the Turkey Pineal Gland and Retina

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