Response of layers to ahemeral light cycles incorporating age at application and changes in effective photoperiod

Shanawany, M. M.

doi:10.1079/wps19920015

Cited by 9 publications

(1 citation statement)

References 32 publications

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“…They may help future understanding of the physiological background of a particular feature of long ahemeral LD-cycles, rst noted by Morris (1978) and extended by Shanawany (1982Shanawany ( , 1992. These authors pointed out that the light period in long ahemeral LD-cycles does not need to be as long as in 24-hour cycles in order to stimulate the gonads.…”

Section: Melatonin Rhythmmentioning

confidence: 92%

Oviposition patterns and plasma melatonin rhythms in response to manipulations of the light: Dark cycle

Nøddegaard¹

1998

British Poultry Science

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1. In 2 experiments with Single Comb White Leghorn hens, the effects of different light:dark cycles (LD-cycles) upon oviposition patterns and plasma melatonin rhythms were studied. In experiment 1, a 28-h ahemeral LD-cycle (12L:16D) was used. In experiment 2, a normal 24-h LD-cycle (16L:8D) was applied and the effects of a sudden 8-h forward or backward shift of the 8-h dark period (that is phase-advanced or phase-delayed LD-cycle) were studied. 2. The oviposition patterns as well as the plasma melatonin rhythms were fully synchronised with both LD-cycles (24-h or 28-h). The 2 rhythms were gradually re-synchronised after phase shifts, and the melatonin response phase-led the oviposition response by 2 cycles. Thus, the change of the melatonin rhythm coincided with the change of the (presumed) open period for LH-release. 3. In the unchanged 24-h LD-cycle, ovipositions occurred almost exclusively (98.9%) during light hours, whereas in the 28-h LD-cycle, ovipositions occurred primarily (84.5%) during the last 9 h of the dark period. 4. In both LD-cycles and after changes of the LD-cycle, light always suppressed plasma melatonin, regardless of previous light history. During dark periods, concentrations were elevated but, interestingly, only if darkness had also been experienced during the same time period 24 h earlier. This indicates that light has a direct inhibiting effect upon pineal melatonin release, while actual melatonin release during darkness is controlled by an endogenous clock.

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Section: Melatonin Rhythmmentioning

confidence: 92%

Oviposition patterns and plasma melatonin rhythms in response to manipulations of the light: Dark cycle

Nøddegaard¹

1998

British Poultry Science

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Ahemeral lighting and reproductive efficiency in breeding flocks

Shanawany¹

1993

World's Poultry Science Journal

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The paper addresses all feasible applications of long ahemeral light cycles in breeding flocks and reviews the limited published studies. Long cycles are likely to be most beneficial towards the end of the production cyclewhen eggshell quality is often poorand at the beginning of lay to increase the proportion of eggs exceeding the minimum weight for incubation. Published reports show an improvement in both fertility and hatchability of breeding flocks under long cycles.

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Influence of sequence length on the response to ahemeral lighting late in lay

Shanawany¹,

Morris²,

Pirchner³

1993

British Poultry Science

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1. An experiment is described in which 96 individually-caged SCWL hens in two rooms were used to investigate the response to changing to a 28-h cycle using a reverse treatment design. 2. The application of the 28-h cycle did not affect mean rate of lay but increased mean egg weight and egg output. 3. Grouping the birds according to their preliminary sequence length yielded an interesting outcome. In both rooms, birds with short sequences (< or = 6 eggs) produced significantly more eggs under the 28-h cycle, while those with long sequences (> 6 eggs) produced marginally fewer eggs. The same trend was also evident with egg output. 4. Changing from 24-h to 28-h increased yolk and albumen weights as well as shell quality. However, relative to egg weight, no measurable effect was detected due to light cycle, age or sequence length on yolk and albumen weights. 5. The paper provides new evidence suggesting that long ahemeral cycles could be used to improve egg production as well as shell thickness in flocks with modest rates of lay.

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Response of layers to ahemeral light cycles incorporating age at application and changes in effective photoperiod

Cited by 9 publications

References 32 publications

Oviposition patterns and plasma melatonin rhythms in response to manipulations of the light: Dark cycle

Oviposition patterns and plasma melatonin rhythms in response to manipulations of the light: Dark cycle

Ahemeral lighting and reproductive efficiency in breeding flocks

Influence of sequence length on the response to ahemeral lighting late in lay

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