INCUBATION IN MALLARDS (ANAS PLATYRHYNCHOS): CHANGES IN PLASMA LEVELS OF PROLACTIN AND LUTEINIZING HORMONE

1980 ◽  
Vol 86 (2) ◽  
pp. 371-379 ◽  
Author(s):  
A. R. GOLDSMITH ◽  
D. M. WILLIAMS
Keyword(s):  
Luteinizing Hormone ◽  
Breeding Season ◽  
Reproductive Cycle ◽  
Plasma Levels ◽  
Fixed Time ◽  
Prolactin Secretion ◽  
Egg Laying ◽  
Breeding Period ◽  
Male And Female ◽  
Incubation Behaviour

The concentrations of prolactin and LH were measured in the plasma of male and female mallards (Anasplatyrhynchos) during the breeding season. The concentration of prolactin in the female birds was low before and during egg-laying, increased threefold (P < 0·001 ) during incubation and returned to basal levels immediately after the young were hatched. The drakes, which do not participate in incubation in this species, had fairly low prolactin levels throughout the breeding period; levels being slightly higher during the incubation phase than at other times but still much lower (P < 0·001) than in the incubating females. Concentrations of LH in the females were high during egg-laying but declined at the onset of incubation. In the drakes levels of LH remained high for much longer and did not appear to decline at a fixed time relative to the reproductive cycle of the female birds. These observations support the view that prolactin is associated with incubation in birds, though the data do not permit a conclusion as to whether an increase in prolactin secretion causes incubation behaviour or is stimulated by it.

Reproductive cycle and energetic cost of reproduction of the neogastropod Buccinum undatum in the Irish Sea

1993 ◽  
Vol 73 (2) ◽  
pp. 391-403 ◽  
Author(s):  
A. E. Kideys ◽  
R. D. M. Nash ◽  
R. G. Hartnoll
Keyword(s):  
Reproductive Cycle ◽  
Cost Of Reproduction ◽  
Egg Laying ◽  
Irish Sea ◽  
Energetic Cost ◽  
Ovary Development ◽  
Breeding Period ◽  
Laboratory Observation ◽  
Buccinum Undatum ◽  
The Irish Sea

The annual reproductive cycle and cost of reproduction of the common whelk, Buccinum undatum L. (Gastropoda: Prosobranchia) were studied off Douglas, south-east of the Isle of Man. Sexual maturity was reached at 60–70 mm shell length. Two years of laboratory observation and field data indicated an autumn to mid-winter breeding season. Egg-laying occurred in the laboratory mainly between December and January, and hatching of juveniles between April and early May, 3–5 months after spawning. The cycles of testis and ovary development were very similar, especially during the breeding period. The annual energy invested in reproduction was estimated to be at least 4.1 kj m-2. The investment by females (3.84 kj m-2 y-1) was much greater than by males (0.26 kj m-2 y-1).

Melatonin feeding decreases prolactin levels in the ewe

1983 ◽  
Vol 99 (1) ◽  
pp. 41-46 ◽  
Author(s):  
A. M. Symons ◽  
Josephine Arendt ◽  
C. A. Laud
Keyword(s):  
Breeding Season ◽  
Plasma Levels ◽  
Early Onset ◽  
Prolactin Secretion ◽  
Dark Phase ◽  
Natural Light

Three groups of Suffolk-cross ewes were kept in (A) summer photoperiod plus melatonin feeding in such a way as to mimic the plasma levels found in winter photoperiod, (B) winter photoperiod or (C) natural light/dark from mid-June onwards. Prolactin levels remained high in group C throughout July and August but were dramatically reduced in both groups A and B. The rise in prolactin levels associated with dusk, however, was still apparent in all three groups. Appropriate administration of melatonin can thus influence prolactin secretion in the same way as an extension of the dark phase. This effect is associated with an early onset of the breeding season in the ewe.

Levels of alpha2 pregnancy-associated glycoprotein in maternal circulation during pregnancy in the mink

1993 ◽  
Vol 27 (2) ◽  
pp. 161-163
Author(s):  
J. Hau ◽  
Lise Lotte I. Andersen ◽  
H. Bohn
Keyword(s):  
Breeding Season ◽  
Plasma Levels ◽  
Local Minimum ◽  
Local Maximum ◽  
Peripheral Circulation ◽  
Breeding Period ◽  
Plasma Samples ◽  
Maternal Circulation ◽  
Heparin Plasma ◽  
Immunological Cross Reaction

This is the first demonstration of α2-pregnancy-associated glycoprotein ( α2-PAG) in the mink. Mink α2-PAG exhibits complete immunological cross reaction with dog α2-PAG when analysed in assays employing antisera against canine α2-PAG raised in rabbits. Alpha2-PAG was quantitated by rocket immunoelectrophoresis in heparin plasma samples obtained from the peripheral circulation of mink during the breeding season. The plasma levels recorded in male mink were significantly lower (23 AU/ml) than the levels recorded in females at any stage of the breeding period. Very early in the breeding season and 2 weeks after delivery the α2-PAG levels were high (>200 AU/ml) in the circulation of the female mink. Like α2-PAG in the pregnant bitch, mink α2-PAG concentrations reach a local maximum in mid-pregnancy, and a local minimum at term.

scholarly journals The annual reproductive cycle of the snail Megalobulimus abbreviatus (Bequaert, 1948) (Gastropoda, Pulmonata)

2005 ◽  
Vol 65 (3) ◽  
pp. 459-467 ◽  
Author(s):  
A. C. M. Horn ◽  
A. Achaval ◽  
D. M. Zancan
Keyword(s):  
Breeding Season ◽  
Reproductive Cycle ◽  
Reproductive System ◽  
Morphological Changes ◽  
Reproductive Organ ◽  
Early Summer ◽  
Egg Laying ◽  
Annual Reproductive Cycle ◽  
Organ Weights ◽  
Maturation Index

Morphological changes in the sexual organs of the pulmonates were observed throughout a year and correlated with reproductive-cycle periods. Reproductive-organ weights of the snail Megalobulimus abbreviatus were recorded seasonally and gonad sections were analyzed morphologically. The weights were used to obtain the organosomatic index. Mean oocytic diameter and oocytic maturation index were based on gonad sections. It was concluded that M. abbreviatus is an iteroparous snail whose annual reproductive cycle is characterized by mating and egg laying throughout spring and early summer, and also by reproductive system preparation, occurring over the remainder of the summer until the end of winter, for a new breeding season.

Seasonal endocrine changes in male and female Arctic charr (Salvelinus alpinus). I. Plasma levels of three androgens, 17α-hydroxy-20β-dihydroprogesterone, and 17β-estradiol

1992 ◽  
Vol 70 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Ian Mayer ◽  
Monika Schmitz ◽  
Bertil Borg ◽  
Rüdiger Schulz
Keyword(s):  
Breeding Season ◽  
Adult Male ◽  
Annual Cycle ◽  
Plasma Levels ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Male And Female ◽  
17Β Estradiol ◽  
Males And Females

Plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), and 11-ketoandrostenedione (OA), the progestin 17α-hydroxy-20β-dihydroprogesterone (17,20-P), and 17β-estradiol (E2) were measured by radioimmunoassay over the annual cycle in both adult male and female Arctic charr (Salvelinus alpinus). In both males and females plasma T, OT, and OA all reached their highest levels during the early breeding season in September. The dominant androgen in maturing males was OT, which reached levels of ca. 90 ng/mL. Plasma levels of OT and OA, but not T, were considerably higher in males than in females; 17,20-P peaked later than the androgens, in November in males (14 ng/mL) and October in females (0.8 ng/mL). E2 was always low or nondetectable in males. In maturing females E2 peaked in August (3.5 ng/mL) before falling concomitantly with rising T levels. From January to April plasma levels of all measured steroids were low in both males and females.

scholarly journals Seasonality of Reproduction in Sheep and its Control by Photoperiod

1988 ◽  
Vol 41 (1) ◽  
pp. 69 ◽  
Author(s):  
R Ortavant ◽  
F Bocquier ◽  
J Pelletier ◽  
JP Ravault ◽  
J Thimonier ◽  
...  
Keyword(s):  
Breeding Season ◽  
Reproductive Cycle ◽  
Distal Part ◽  
Proximal Part ◽  
General Phenomenon ◽  
Dependent Effect ◽  
Male And Female ◽  
Annual Variations ◽  
Steroid Dependent ◽  
Effect Of Light

Seasonality of the reproductive cycle in sheep is a general phenomenon for mid-latitude breeds. The proximal part (breeding season) and also partially distal part (end of gestation and beginning of lactation) of this cycle is controlled by photoperiod, whatever the form of light regimens. Data are presented which indicate that male and female do not necessarily have the same photoperiodic sensitivity. Gonadal stimulation in the ram starts 1'5-2 months earlier than in the ewe under annual variations. Photoperiod controls the reproductive cycle by the intermediary of the hypothalamo-pituitary axis. There are both a steroidindependent and a steroid-dependent effect of light, depending on both decreasing and increasing daylength in mid-latitudes.

PLASMA LEVELS OF LUTEINIZING HORMONE, PROGESTERONE, TESTOSTERONE AND 5α-DIHYDROTESTOSTERONE IN MALE AND FEMALE PIGS DURING SEXUAL MATURATION

1976 ◽  
Vol 68 (2) ◽  
pp. 347-348 ◽  
Author(s):  
F. ELSAESSER ◽  
F. ELLENDORFF ◽  
D. K. POMERANTZ ◽  
N. PARVIZI ◽  
D. SMIDT
Keyword(s):  
Luteinizing Hormone ◽  
Sexual Maturation ◽  
Plasma Levels ◽  
Male And Female

CONCENTRATIONS OF PROLACTIN AND LUTEINIZING HORMONE IN PLASMA OF DOVES IN RELATION TO INCUBATION AND DEVELOPMENT OF THE CROP GLAND

1981 ◽  
Vol 90 (3) ◽  
pp. 437-443 ◽  
Author(s):  
A. R. GOLDSMITH ◽  
C. EDWARDS ◽  
M. KOPRUCU ◽  
R. SILVER
Keyword(s):  
Luteinizing Hormone ◽  
Rapid Growth ◽  
Prolactin Secretion ◽  
Breeding Cycle ◽  
Plasma Prolactin ◽  
Male And Female ◽  
Streptopelia Risoria ◽  
Ring Doves

The concentrations of prolactin and LH were measured in the plasma of male and female ring doves (Streptopelia risoria) during the breeding cycle. Prolactin concentrations were low during courtship and early incubation but increased markedly (P<0·01 in both sexes) between days 7 and 15 of incubation, during the period of rapid growth of the crop sac. Levels remained raised for 4 days after the young had hatched but then declined as the crop sacs gradually regressed. These observations showed that concentrations of prolactin were high at the time when the crop sacs were proliferating and producing 'milk' for feeding the young, but that there was no increase in prolactin secretion at the onset of incubation as occurs in ducks, hens and other birds. In samples taken from doves at various times of the day and night there was no increase in plasma prolactin during the first few days of incubation. Concentrations of LH in plasma were generally higher in male doves than in females, but in both sexes were significantly higher during courtship than during incubation and brooding the young. Concentrations increased again when the young were independent and the parents began a second round of courtship.

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