@article{lien_siopes_1993, title={EFFECTS OF SHORT-TERM THYROXINE ADMINISTRATION DURING THE LAYING PERIOD ON EGG-PRODUCTION AND MOLTING BY TURKEYS}, volume={34}, ISSN={["0007-1668"]}, DOI={10.1080/00071669308417595}, abstractNote={1. Effects of thyroxine (T4) administration on egg production, moulting and photorefractoriness in laying turkeys were determined. Thyroxine dosages of 0.075 to 2 mg/bird/d were injected IM for periods of either 2 or 3 weeks following 10 weeks of photostimulation. Control groups were administered saline vehicle. 2. Plasma T4 concentrations were increased in a dose dependent manner by T4 administration, while triiodothyronine (T3) was decreased. 3. Egg production and percentage of hens in production were transiently decreased in a dose dependent manner by T4 administration, but returned to levels similar to controls within 4 weeks of T4 treatment termination. Moulting was stimulated in a dose-dependent manner by T4 administration, but was similar to controls after T4 treatment termination. Only dosages of 2 mg/bird/d resulted in cessation of egg production and complete moulting. 4. Results indicate that although short term elevation of plasma T4 causes cessation of egg production and moulting these effects are transient and not indicative of photorefractoriness.}, number={2}, journal={BRITISH POULTRY SCIENCE}, author={LIEN, RJ and SIOPES, TD}, year={1993}, month={May}, pages={405–416} }
 @article{lien_siopes_1993, title={THE RELATIONSHIP OF PLASMA THYROID-HORMONE AND PROLACTIN CONCENTRATIONS TO EGG-LAYING, INCUBATION BEHAVIOR, AND MOLTING BY FEMALE TURKEYS EXPOSED TO A ONE-YEAR NATURAL DAYLENGTH CYCLE}, volume={90}, ISSN={["0016-6480"]}, DOI={10.1006/gcen.1993.1075}, abstractNote={To determine relationships to egg laying, incubation behavior and molting, plasma thyroxine (T4), triiodothyronine (T3), and prolactin levels of 20 female domestic turkeys were determined throughout a one-year cycle of natural daylengths. Endocrine changes were analyzed relative to periods of reproductive and molting cycles. Data were also analyzed relative to termination of lay after division into two groups based on the presence (I, n = 7) or absence (NI, n = 13) of incubation behavior. Plasma T4 levels of the flock increased to a peak and subsequently decreased during the onset of lay period from February to April. Plasma T4 generally increased throughout the decline of lay period from April to July and molting period from July to October, and then reached greatest levels at the end of the molting period. Plasma T3 reached a peak early in the onset of lay and decreased rapidly during the remainder of that period. Plasma T3 remained depressed during the decline of lay, increased throughout molting, and attained greatest levels as molt was completed. Prolactin was low throughout the prelay period and sharply increased midway through the onset of lay. Prolactin increased to a marked peak during the decline of lay, and then rapidly decreased as egg laying was terminated. Relative to NI birds, egg laying was terminated earlier and prolactin levels were markedly greater during and following the termination of lay in I birds. Plasma T4 and T3 were generally lower in I birds during the molting period which followed the termination of lay and their molt was delayed.(ABSTRACT TRUNCATED AT 250 WORDS)}, number={2}, journal={GENERAL AND COMPARATIVE ENDOCRINOLOGY}, author={LIEN, RJ and SIOPES, TD}, year={1993}, month={May}, pages={205–213} }
 @article{lien_siopes_1991, title={INFLUENCE OF THYROIDECTOMY ON REPRODUCTIVE RESPONSES OF MALE DOMESTIC TURKEYS (MELEAGRIS-GALLOPAVO)}, volume={32}, ISSN={["0007-1668"]}, DOI={10.1080/00071669108417366}, abstractNote={1. The influence of age at thyroidectomy on reproductive activity of male turkeys was investigated. 2. Thyroidectomy of 53-week-old male domestic turkeys that had been reproductively active for 25 weeks resulted in undetectable plasma thyroxine concentrations, termination of semen production and testicular regression. Daily light-dark treatment was 14L:10D before and after thyroidectomy. 3. Thyroidectomy of 28-week-old, reproductively inactive, males maintained on a daily light-dark cycle of 8L:16D resulted in increased semen volumes following photostimulation with 14L:10D at 32 weeks of age. Semen quality was not affected, while plasma thyroid hormone concentrations were undetectable. The moult and termination of semen production that occurred in response to changing the daily light-dark cycle from 14L:10D to 8L:16D near the end of the study were inhibited by thyroidectomy. 4. The requirement for the thyroid glands in the reproductive processes of male turkeys changes either with age or after an extended period of reproductive activity.}, number={2}, journal={BRITISH POULTRY SCIENCE}, author={LIEN, RJ and SIOPES, TD}, year={1991}, month={May}, pages={405–415} }
 @article{lien_siopes_1989, title={TURKEY PLASMA THYROID-HORMONE AND PROLACTIN CONCENTRATIONS THROUGHOUT AN EGG-LAYING CYCLE AND IN RELATION TO PHOTOREFRACTORINESS}, volume={68}, ISSN={["0032-5791"]}, DOI={10.3382/ps.0681409}, abstractNote={Plasma concentrations of thyroxine (T4), triiodothyronine (T3), and prolactin were determined weekly through an egg laying cycle induced with 30 wk of 14 h light:10 h dark. Egg production, primary remige molting, and occurrence of photorefractoriness were monitored. Hens were assigned to one of two groups; those that exhibited photorefractoriness (PR) and those that remained photosensitive (PS). Weekly plasma T4 concentrations relative to the time of initiation of photostimulation did not differ between PR and PS groups; concentrations peaked prior to the onset of egg production, were lowest during peak egg production, and increased between Weeks 6 and 30 of photostimulation. Plasma T4 levels of PR hens peaked 3 wk prior to the onset of photorefractoriness. Plasma T3 concentrations of PS and PR hens were similar until increases occurred in PR hens at the onset of photorefractoriness. Plasma prolactin levels in PS and PR hens increased after photostimulation, declined sooner in PR hens, and were generally greater in PS than PR hens during the last 20 wk of the study. Mean time of onset of photorefractoriness in PR hens was 23.0 wk (range = 18 to 28 wk) after initiation of photostimulation. Egg production of PS hens was greater than that of PR hens after 20 wk of photostimulation, and PR hens molted a greater number of primary remiges than PS hens. Results indicated that 1) elevated plasma T4 may be involved in development of photorefractoriness in turkey hens, 2) increases in plasma T3 may be involved in gonadal regression and molting, and 3) elevated plasma prolactin was associated with persistence of photosensitivity.}, number={10}, journal={POULTRY SCIENCE}, author={LIEN, RJ and SIOPES, TD}, year={1989}, month={Oct}, pages={1409–1417} }