Rate of Testicular Maturation, in Relation to Gonadotrophin and Testosterone Levels, in Quail Exposed to Various Artificial Photoperiods and to Natural Daylengths

Follett, B. K.; Maung, Shwe Lu

doi:10.1677/joe.0.0780267

Cited by 168 publications

(90 citation statements)

References 15 publications

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“…The results from experiment 1 are consistent with previous findings on this [12] and other species ( [13,15]; see reviews [7,23]), and suggest that the blackheaded bunting possesses a highly dynamic photoperiodic response system, which can selectively respond to externally imposed environmental light conditions. The following observations are of interest.…”

Section: Discussionsupporting

confidence: 89%

“…How dynamic the photoperiodic response system is can be studied experimentally by subjecting individuals to a range of photoperiods and light intensities. In one such study on Japanese quail (Coturnix c. japonica), Follett and Maung [15] found a relationship between the length of photoperiod and rate of photoperiodic induction. The rate of testicular growth was slower by 50% in birds exposed to 12L:12D (12 h of light:12 h of darkness) compared to 14L:10D, 16L:8D and 20L:4D in which full growth had occurred; a near full growth occurred in 13L:11D.…”

Section: Introductionmentioning

confidence: 99%

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Regulation of seasonality in the migratory male blackheaded bunting (Emberiza melanocephala)

et al. 2004

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-The present study was carried out on a Palearctic-Indian migratory species, the blackheaded bunting (Emberiza melanocephala), to understand the importance of photoperiodism and circannual rhythms in determining seasonality in changes in body mass and testis size in birds. An initial experiment determined the effects of duration and intensity of light on photoperiodic induction. The birds were exposed to different photoperiods (hours of light:hours of darkness; 11.5L:12.5D, 12L:12D, 12.5L:11.5D and 13L:11D) at the same (~ 450 lux) light intensity, and to 13L:11D at different light intensities (50-, 100-, 400-, 800-and 1000-lux). The induction and subsequent regression of photoperiodic responses were dependent upon duration and intensity of the light period until these reached threshold. A second experiment investigated if an endogenous seasonal rhythm underlies photoperiodism in buntings. Birds maintained since February on a 8L:16D photoperiod (a non-inductive short day length invariably used to ensure photosensitivity in photoperiodic species) were subjected periodically to 16L:8D (a long day length), one group every month from mid-March to mid-August. The magnitude of long day response in body mass and testes decreased as the duration of the short days progressed, but testicular response was restored in birds that were exposed to long days in July and August. The birds exposed simultaneously to short, long, and natural day lengths for 32 weeks underwent an induction-regression cycle under long days and natural day lengths, but not under short days in which a decrease in body mass occurred after about 20 weeks. The last experiment examined the importance of latitudinal migration on photoperiodism, by comparing the response to long days of three groups which included birds from populations those were held in the outdoor aviary for 1 or 2 years at 27° N and those immediately arrived from their breeding grounds (~ 40° N). There was no difference in the photoperiodic induction among the three groups, indicating that neither experience to changing photoperiods during a migratory journey, nor to long photoperiods at breeding grounds, were critical for a subsequent response (initiationtermination-reinitiation) cycle. Taken together, these findings suggest that (1) the blackheaded bunting has its own endogenous timing program, which is regulated by the photoperiod, and (2) the photoperiodic programs of bunting are flexible enough to accommodate variations in the amplitude of environmental cycles. Thus, it appears that photoperiodism has evolved independently of the evolution of migration in this species.bunting / intensity / photoperiod / photoperiodic response system / photosensitivity / seasonality

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Regulation of seasonality in the migratory male blackheaded bunting (Emberiza melanocephala)

et al. 2004

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“…We did not distinguish if this anticipatory rise in O 2 consumption was due to anticipation to light or feeding. However, in pigeons, the rise in O 2 consumption also appeared before a meal when this did not coincide with lights on, indicating that birds are able to anticipate feeding times irrespective of light [10].…”

Section: Discussionmentioning

confidence: 95%

Effect of photoperiod on body weight gain, and daily energy intake and energy expenditure in Japanese quail (Coturnix c. Japonica)

Boon

2000

Physiology &Amp; Behavior

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“…The system is never completely insensitive in cockerels, however, since testicular development has been described in animals exposed to half an hour of light per day (Nalbandov, 1970). The notion of a minimum threshold daylength cannot be true of the cockerel, unlike the Japanese quail (Sharp and Follett, 1969 ;Follett and Maung, 1978 …”

Section: Introductionmentioning

confidence: 99%

Variations in the plasma levels of luteinizing hormone and androstenedione and their relationship with the adult daily sperm output in cockerels raised under different photoschedules

Williams¹,

Reviers²

1981

Reprod. Nutr. Dévelop.

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Summary. Circulating levels of LH and androstenedione were measured in 4 groups of 30 cockerels from 3 to 26 weeks of age. Each group was submitted to a different programme of artificial lighting, either a long (16 h) photoperiod, a short (8 h) photoperiod, an increasing (8 h to 16 h) photoperiod or a night-interruption regimen. Measurements were also made of the numbers of spermatozoa ejaculated on a daily basis between 22 and 24 weeks of age, and these data were then compared with data on the hormone levels in plasma.Certain differences in mean plasma hormone levels between groups subjected to different photoperiodic treatments were observed. Adult plasma levels of LH were lowest in birds exposed to 16 h of light per day while they were attained later in animals exposed to only 8 h of light per day. Similarly, adult plasma levels of androstenedione were attained at a later age in birds subjected to 8 h light per day than in the other treatment groups while the highest peak values, around the time of puberty, were found in cockerels receiving 8 h light in two blocks of 7 h and 1 h. Although some differences in hormone parameters were found between the best and the poorest sperm producers under certain of the lighting programmes, no relationship could be found between either the mean plasma level of LH, the duration ofthe pre-pubertal plateau of LH, the age at the pre-pubertal rise in LH or the age at the pre-pubertal rise in androstenedione and the level of adult fertility.Introduction.

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Rate of Testicular Maturation, in Relation to Gonadotrophin and Testosterone Levels, in Quail Exposed to Various Artificial Photoperiods and to Natural Daylengths

Cited by 168 publications

References 15 publications

Regulation of seasonality in the migratory male blackheaded bunting (Emberiza melanocephala)

Regulation of seasonality in the migratory male blackheaded bunting (Emberiza melanocephala)

Effect of photoperiod on body weight gain, and daily energy intake and energy expenditure in Japanese quail (Coturnix c. Japonica)

Variations in the plasma levels of luteinizing hormone and androstenedione and their relationship with the adult daily sperm output in cockerels raised under different photoschedules

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