Avian Molting

Dawson, Alistair

doi:10.1016/b978-0-12-407160-5.00038-5

Cited by 15 publications

(23 citation statements)

References 105 publications

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“…However, we detected no effect of yolk THs on the timing or speed of moult. THs are important in moult and feather growth (reviewed in Dawson (2015) ). For example thyroidectomised birds fail to moult after being exposed to long photoperiods ( Dawson, 2015 ).…”

Section: Discussionmentioning

confidence: 99%

“…THs are important in moult and feather growth (reviewed in Dawson (2015) ). For example thyroidectomised birds fail to moult after being exposed to long photoperiods ( Dawson, 2015 ). In addition, thyroidectomised nestling starlings failed to grow normal adult plumage and grown feathers presented an abnormal structure ( Dawson et al, 1994 ).…”

Section: Discussionmentioning

confidence: 99%

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Testing the short-and long-term effects of elevated prenatal exposure to different forms of thyroid hormones

Sarraude

Hsu

Groothuis

et al. 2020

PeerJ

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Maternal thyroid hormones (THs) are known to be crucial in embryonic development in humans, but their influence on other, especially wild, animals remains poorly understood. So far, the studies that experimentally investigated the consequences of maternal THs focused on short-term effects, while early organisational effects with long-term consequences, as shown for other prenatal hormones, could also be expected. In this study, we aimed at investigating both the short- and long-term effects of prenatal THs in a bird species, the Japanese quail Coturnix japonica. We experimentally elevated yolk TH content (the prohormone T4, and its active metabolite T3, as well as a combination of both hormones). We analysed hatching success, embryonic development, offspring growth and oxidative stress as well as their potential organisational effects on reproduction, moult and oxidative stress in adulthood. We found that eggs injected with T4 had a higher hatching success compared with control eggs, suggesting conversion of T4 into T3 by the embryo. We detected no evidence for other short-term or long-term effects of yolk THs. These results suggest that yolk THs are important in the embryonic stage of precocial birds, but other short- and long-term consequences remain unclear. Research on maternal THs will greatly benefit from studies investigating how embryos use and respond to this maternal signalling. Long-term studies on prenatal THs in other taxa in the wild are needed for a better understanding of this hormone-mediated maternal pathway.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Testing the short-and long-term effects of elevated prenatal exposure to different forms of thyroid hormones

Sarraude

Hsu

Groothuis

et al. 2020

PeerJ

View full text Add to dashboard Cite

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“…Different regimens of food deprivation/limitation together with altered photoperiod induce molting in layers, as well as in other birds ( Berry, 2003 , Webster, 2003 , Dawson, 2015 ). Induced molting is used in the layer industry to rejuvenate the laying capacity in hens following its gradual decline with age ( Webster, 2003 ).…”

Section: Discussionmentioning

confidence: 99%

“…Molting is a major physiological event in the annual life cycle of many avian species, and its initiation may be because of various endogenic and environmental stimuli ( Dawson, 2015 ). In the poultry layer industry, induced molting ( IM ) is used to increase or rejuvenate egg production and is achieved by reducing the photoperiod and by either feed removal or by feeding a nutritionally deficient diet ( Berry, 2003 , Webster, 2003 , Koelkebeck and Anderson, 2007 ).…”

Section: Introductionmentioning

confidence: 99%

Increased serum levels of advanced glycation end products due to induced molting in hen layers trigger a proinflammatory response by peripheral blood leukocytes

2020

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Induced molting ( IM ), a severe detriment to animal welfare, is still used in the poultry industry in some countries to increase or rejuvenate egg production and is responsible for several physiological perturbations, possibly including reactive oxidative stress, a form of metabolic stress. Because metabolic stress has been shown to induce a proinflammatory response involved in attempts to restore homeostasis, we hypothesized that similar responses followed IM. To confirm this hypothesis, we initially confirmed the establishment of oxidative stress during IM in 75-wk-old layers by demonstrating increased production of advanced glycation end products ( AGE ). Concomitant with increased oxidative metabolites, cellular stress was demonstrated in peripheral blood leukocytes ( PBL ) by increased levels of stress gene products (the glucocorticoid receptor, sirtuin-1, and heat shock protein 70 mRNA). Increased expression of stress proteins in PBL was followed by a proinflammatory response as demonstrated by increased levels of proinflammatory gene products (IL-6 and IL-1β mRNA); increased expression of these gene products was also demonstrated in direct response to AGE in vitro, thus establishing a direct link between oxidative and cellular stress. To establish a possible pathway for inducing a proinflammatory response by PBL, we showed that AGE increased a time dependent expression of galactin-3, Toll-like receptor-4, and nuclear factor - κB, all involved in the proinflammatory activation pathway. In vivo, AGE formed complexes with increased levels of circulating acute phase proteins (lysozyme and transferrin), products of a proinflammatory immune response, thereby demonstrating an effector response to cope with the consequences of oxidative stress. Thus, the harmful consequences of IM for animal welfare are extended here by demonstrating the activation of a resource-demanding proinflammatory response.

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“…Feathers are critical derivatives of the avian integument, which are made primarily of keratin with a central shaft (rachis) and rows of parallel branches (barbs) rooted in a follicle ( Dawson, 2015 ). Some feather types provide insulation, waterproofing, or are a means for communication, whereas others, the flight feathers of the wing, provide aerodynamic lift for flight ( Lucas and Stettenheim, 1972 ; Saino et al, 2013 ; Dawson, 2015 ). Feathers are a vital and defining part of a birds’ biology, but they naturally become damaged or worn during the life of a bird ( Saino et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers

Leishman

Staaveren

McIntyre³

et al. 2020

Journal of Animal Science

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The use of feathers as non-invasive physiological measurements of biomarkers in poultry research is expanding. Feather molting pattern and growth rates, however, are not well described in domestic poultry. These parameters could influence the measurement of these biomarkers. Therefore, the objective of this study was to describe the juvenile primary feather molting pattern and feather growth rates for domestic turkeys. The ten primary wing feathers of 48 female turkeys were measured weekly from week 1 (0 days of age) to week 20. Feathers were manually measured, and the presence or absence of each primary feather recorded weekly. Generalized linear mixed models were used to investigate if feather growth differed between the primary feathers. The molting of the juvenile primary feathers followed a typical descending pattern starting with P1 (5 weeks of age) while P9 and P10 had not molted by the end of the study (20 weeks of age). Average feather growth rate was 2.4 cm/week, although there was a significant difference between the ten primary feathers (P<0.0001, 2.1 – 2.8 cm/week). Over time, feather growth followed a pattern where growth rate reaches a peak and then declines until the feather is molted. The results of this study provide a critical update of patterns of molting and feather growth in primary wing feathers of modern turkeys. This can have implications for the interpretation of physiological biomarkers, such as the longitudinal deposition of corticosterone, in the feathers of domestic turkeys.

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Avian Molting

Cited by 15 publications

References 105 publications

Testing the short-and long-term effects of elevated prenatal exposure to different forms of thyroid hormones

Testing the short-and long-term effects of elevated prenatal exposure to different forms of thyroid hormones

Increased serum levels of advanced glycation end products due to induced molting in hen layers trigger a proinflammatory response by peripheral blood leukocytes

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers

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