The Effect of Ahemeral Light and Dark cycles on the Performance of Laying Hens— (A Review)

Section: Discussionmentioning

confidence: 98%

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

Triyuwanta¹,

Nys²

1990

“…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: 99%

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

Nøddegaard¹

1998

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.

“…In general, however, longer formation times for whole eggs are associated with increases in 222 the three different components (reviews by Shanawany, 1982Shanawany, , 1990; see also Siopes and third of the initial reserves of water-soluble proteins (Edwards et al, 1976).…”

mentioning

confidence: 99%

Double-yolked pheasant eggs provide an insight into the control of albumen secretion in bird eggs

Deeming¹

2011

International audience1. The possible role of the presence of the yolk in stimulating secretion of albumen was investigated. 2. Double-yolked and single-yolked pheasant (Phasianus colchinus) eggs were opened to determine the masses of the shell, albumen and yolk(s). 3. In double-yolked eggs, the two yolk masses were not significantly different. Albumen mass was increased above that expected from an egg with a single-yolk of comparable size but below that expected from an egg having a mass of the combined yolks. The mass of shell per unit area reflected the mass of the initial mass of the egg irrespective of the number of yolks. 4. The additional mass of albumen is unrelated to yolk or initial egg mass. It is postulated that in double-yolked eggs the oviduct is mechanically stimulated by the presence of both yolks, which empties the stores of water-soluble albumen proteins in the magnum wall. Such stores are insufficient to provide the same amount of protein for the two yolks