Plasma prolactin concentrations were higher (P < 0.001) in newborn red deer calves whose mothers had been maintained for the last 14 weeks of gestation in long days (18 h light)(group L, n = 9) than in those whose mothers had been kept over the same period in short days (6 h light)(group S, n = 5). After transfer of all hinds and suckled calves on the day of birth to constant intermediate daylength (12 h light), prolactin concentrations decreased exponentially (P < 0.001) in group L calves, but not in group S, during the first 21 days. Thereafter, prolactin fell to a nadir in group L calves and rose to peak values in group S calves at 8-12 weeks post partum (P = 0.003), before converging again by 14 weeks. The pattern of prolactin secretion over the first 14 weeks of life was therefore significantly affected by prenatal photoperiod.
Plasma prolactin concentrations in the adult hinds were higher (P < 0.001) in group L than group S at 4-10 weeks before parturition; they were similarly high around parturition and fell thereafter to baseline values after 7 weeks.
These results provide evidence that deer fetuses respond to photoperiodic information, thereby acquiring a photoperiodic history in utero that influences postnatal responses to photoperiod.
|Number of pages||6|
|Journal||Journal of Reproduction and Fertility|
|Publication status||Published - Aug 1992|
- PLASMA MELATONIN CONCENTRATIONS
- PREGNANT EWE
- LATE GESTATION
- FETAL SHEEP
- plasma melatonin concentrations
- pregnant ewe
- late gestation
- fetal sheep