Searching for broody hen physiology info

[NorthwoodsChick]

Can anyone give me leads on, or provide a link to peer reviewed article/text book reference on the physiologic changes that occur in broodiness? The more detailed the better. I’m looking to understand the intrinsic (and extrinsic) influencers, hormonal changes and neurochemical responses that trigger, progress and end broodiness in poultry. ( Basically the cellular physiological processes). Google limits to journals requiring payment to read an article.
I know this is geeky as H.
TIA

 

[saysfaa]

This is an interesting topic. I can't do a thorough search at this time but these are what I gathered in the time I have this morning - starting points at best; possible not worth much. Please share when you find interesting pieces.

This is not behind a pay wall
https://ejfood.org/index.php/ejfood/article/view/456
"...Despite the indigenous chicken's many natural advantages, broodiness continues to be a substantial barrier to minimizing egg production and economic losses. Prolactin is the primary regulator of broodiness. ..."

This is partially avialible (more than abstract)
I like it because the associated studies are more helpful than most. Eh, these are also mostly behind pay walls but I think they give a rich field to mine more search terms. I would sort through them to make a list of the most promising to read at a college library. Although it has been several years since I did that as a non-student. Even then, some colleges were beginning to have more restrictions on that (either limiting numbers or time or visits), I don't know how much that has spread.
https://www.sciencedirect.com/science/article/abs/pii/S0016648009001373
"...In this review we emphasize the potential ability of prolactin to mediate parental investment in birds (i.e., the trade-off between survival and parental effort). We review (1) the neurobehavioral interactions that link avian parental behavior and prolactin secretion, (2) the effects of stressors (acute and chronic) and energetic constraints on prolactin levels during the parental phase and (3) the modulation of circulating prolactin levels by acute stressors. ...Finally, we emphasize the importance of considering possible interactions between corticosterone and prolactin in the regulation of parental investment in birds..."

This one is behind a pay wall, it is here for terms to search for
https://onlinelibrary.wiley.com/doi/abs/10.1002/jcp.26844
The postovulatory follicle (POF) in birds is an enigmatic structure, the function of which remains largely unknown. Previous studies on chickens have shown that removal of POFs leads to the postponement of oviposition and the disturbance of broody behavior.

I didn't find much on POF and broodiness but found this about pausing for molt interesting.. it is from https://www.mdpi.com/1422-0067/22/15/8056
"An important phenomenon in the reproductive cycle of female birds is the regression of reproductive organs and the subsequent pause in laying and molting at the end of the reproductive season or after about a year of egg laying. This event leads to rejuvenation of reproductive tissues by the removal of old cells and proliferation and differentiation of new cells. During this period, yellow hierarchical follicles in the ovary undergo atresia. "

 

[NorthwoodsChick]

This is an interesting topic. I can't do a thorough search at this time but these are what I gathered in the time I have this morning - starting points at best; possible not worth much. Please share when you find interesting pieces.

This is not behind a pay wall
https://ejfood.org/index.php/ejfood/article/view/456
"...Despite the indigenous chicken's many natural advantages, broodiness continues to be a substantial barrier to minimizing egg production and economic losses. Prolactin is the primary regulator of broodiness. ..."

This is partially avialible (more than abstract)
I like it because the associated studies are more helpful than most. Eh, these are also mostly behind pay walls but I think they give a rich field to mine more search terms. I would sort through them to make a list of the most promising to read at a college library. Although it has been several years since I did that as a non-student. Even then, some colleges were beginning to have more restrictions on that (either limiting numbers or time or visits), I don't know how much that has spread.
https://www.sciencedirect.com/science/article/abs/pii/S0016648009001373
"...In this review we emphasize the potential ability of prolactin to mediate parental investment in birds (i.e., the trade-off between survival and parental effort). We review (1) the neurobehavioral interactions that link avian parental behavior and prolactin secretion, (2) the effects of stressors (acute and chronic) and energetic constraints on prolactin levels during the parental phase and (3) the modulation of circulating prolactin levels by acute stressors. ...Finally, we emphasize the importance of considering possible interactions between corticosterone and prolactin in the regulation of parental investment in birds..."

This one is behind a pay wall, it is here for terms to search for
https://onlinelibrary.wiley.com/doi/abs/10.1002/jcp.26844
The postovulatory follicle (POF) in birds is an enigmatic structure, the function of which remains largely unknown. Previous studies on chickens have shown that removal of POFs leads to the postponement of oviposition and the disturbance of broody behavior.

I didn't find much on POF and broodiness but found this about pausing for molt interesting.. it is from https://www.mdpi.com/1422-0067/22/15/8056
"An important phenomenon in the reproductive cycle of female birds is the regression of reproductive organs and the subsequent pause in laying and molting at the end of the reproductive season or after about a year of egg laying. This event leads to rejuvenation of reproductive tissues by the removal of old cells and proliferation and differentiation of new cells. During this period, yellow hierarchical follicles in the ovary undergo atresia. "

Thank you so much! I will def check these out.

 

[saysfaa]

Hu, S. (2017). Prolactin and its receptor in the follicular hierarchy of chickens.

The entire thesis is available without a pay wall. The focus is not exactly what you are looking for but the overlap is enough to give part of what you are looking for.

Ovary, A. (2000). Reproduction in the Female.

The entirety of chapter 22 is available as a pdf. It is also not exactly what you are looking for but I think it is worth stashing here just for the detailed overview of the anatomy and physiology of the reproductive system, including many the cellular processes involved.

I. C. DUNN (1998) Genetic mapping of the chicken prolactin receptor gene: A candidate gene for the control of broodiness, British Poultry Science, 39:sup001, 23-24, DOI: 10.1080/00071669888160

This one is partially behind a pay wall (the first page is not)
I find it particularly interesting because of the similarity to the let down neuroendocrine cascade in dairy which also has tactile and visual triggers.
(https://familycow.proboards.com/thread/85549/science-milk-out)

From the Dunn article: "...The prolactin receptor (PRLR) was selected as a candidate gene for broodiness because it plays a critical part in the neuroendocrine cascade which is triggered at the onset of broodiness. Information, both tactile and visual, from the presence of nest and eggs is interpreted by the laying hen as a signal to initiate broodiness is mediated by the secretion of vasoactive intestinal polypeptide (VIP) from the median eminence of the hypothalamus and in turn stimulates the release of prolactin (PRL) from the pituitary. Prolactin maintains the broody behavior by acting through the prolactin receptor...."

Although, several sources indicated day length is likely a primary triggering input for broodiness.

 

[NorthwoodsChick]

This was interesting. This is an older research study, but not new knowledge from today’s perspective, on the impact the stress hormone corticosterone has on laying hens in various crowded conditions. Conclusions: serum corticosterone levels rise in response to overcrowding (stressor) resulting in a linear decreased egg production.
(Mashaly et al., 1987)
https://doi.org/10.3382/ps.0632271