Starvation of older zebrafish to increase egg production?

[Michael Lardelli]

Hello, I would like to know whether anyone has ever used starvation of older, laboratory-bred zebrafish (or other fish) to try to stimulate egg production.

 

In our fish system egg production by females more than 12 months old can become unreliable. This is possibly because they are too well fed since wild zebrafish remain fertile far longer.

 

Recently I became aware of the practise of “forced moulting” that can increase the egg-laying performance of older hens. See this entry on Wikipedia:

 

http://en.wikipedia.org/wiki/Forced_molting

 

Apparently, when hens are starved such that they lose 1/3^rd of their body weight then, after a normal diet is reinstated, they regenerate their reproductive tract and being laying at a rate similar to their first year of reproductive life. (The practise is banned in some nations but permitted in others.)

 

Since zebrafish have such a great ability to regenerate tissues I was wondering whether the same method might work with older laboratory bred fish. Does anyone do this or has anyone tried it?

 

Regards,

 

Michael

 

 

 

 

Michael Lardelli
Zebrafish Genetics Laboratory
School of Molecular and Biomedical Science The University of Adelaide, AUSTRALIA 5005
Ph    : +61 8 8303 3212
Fax   : +61 8 8303 4362
e-mail: michael....@adelaide.edu.au CRICOS Provider Number 00123M
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[David G. White]

First off, I don't care if it works or not it is obviously inhumane. Secondly, your not tackling the problem of why your fish are unreliable after 12 months. Your fish should be viable and reliable for ~18 months and next generation of breeders should be reaching maturity before that date. I would take a look your fed regime, water quality, spawning techniques before looking for short-cuts.

David G White
Research Coordinator
HSB Zebrafish Labs
University of Washington
Department of Biological Structure
HSB G520 Box 357420
1959 NE Pacific Street
Seattle, WA 98195-7420
Tel. 206-685-7512
FAX 206-543-1524

[Michael Lardelli]

I am not sure which is more inhumane – starving fish to lengthen their productive life or culling them after 18 months because they have become unreliable spawners. Culling could certainly be regarded as a “short cut”! In any case, I am still interested to hear from anyone who has knowledge or experience in this area.

[David G. White]

If your following proper animal laboratory protocols you would not have the problem in the first place. Your fish may already be under stress and you seek knowledge to possibly exacerbate your situation! Perhaps culling the fish after 12 months is better than 18, either way we do neither here, our fish are reliable breeders up to 2 years.

I must admit I was a bit shocked when I saw your subject and I apologize if you took offense to my comments. We are all looking for knowledge but I don't think your subject is proper for this forum.

David G White
Research Coordinator
HSB Zebrafish Labs
University of Washington
Department of Biological Structure
HSB G520 Box 357420
1959 NE Pacific Street
Seattle, WA 98195-7420
Tel. 206-685-7512
FAX 206-543-1524

[Michael Lardelli]

I think David has made a number of assumptions about how we manage our fish without knowing our current situation. We have many fish in our system that are 18-24 months old. However, it concerns me when people try to suppress discussion of animal welfare topics because they find them unpleasant or for some reason personally offensive. I think the topic of feeding regimes and fish reproductive health is directly relevant on this forum.

Regards,

Michael Lardelli

[Burdine, Rebecca D.]

David perhaps you could share with us the laboratory protocols and practices that you feel are helping your fish to remain productive for up to 2 years.

Michael - I find the time a fish stays fertile has a lot to do with stress, strain, and use.In our facility, we feed fish that are adult but not bred weekly a dry food diet once a day. These fish will often lay when set up, even without a rich diet. Fish we want to encourage to breed, we supplement with brine shrimp which usually increases their egg production within a week.

But we have some strains that just give out at 1 year no matter what we do, and others that still produce reasonably ok at 3. I am happy to share our feeding protocols with you if you like. They are essentially modified protocols that are used at ZIRC.

Becky
________________________________________
From: zbrafish...@oat.bio.indiana.edu [zbrafish...@oat.bio.indiana.edu] on behalf of David G. White [dgw...@u.washington.edu]
Sent: Thursday, May 17, 2012 8:15 PM

To: Michael Lardelli
Cc: bionet-organi...@moderators.isc.org
Subject: Re: [Zbrafish] RE: Starvation of older zebrafish to increase egg production?

If your following proper animal laboratory protocols you would not have the problem in the first place. Your fish may already be under stress and you seek knowledge to possibly exacerbate your situation! Perhaps culling the fish after 12 months is better than 18, either way we do neither here, our fish are reliable breeders up to 2 years.

I must admit I was a bit shocked when I saw your subject and I apologize if you took offense to my comments. We are all looking for knowledge but I don't think your subject is proper for this forum.

David G White
Research Coordinator
HSB Zebrafish Labs
University of Washington
Department of Biological Structure
HSB G520 Box 357420
1959 NE Pacific Street
Seattle, WA 98195-7420
Tel. 206-685-7512
FAX 206-543-1524

[Steven Waldron]

You might also try separating the males from females for at least a week, increase the frequency of water changes, and most importantly... feed a diet heavy in Artemia nauplii.

Breeding success can start to become less predictable once a fish reaches its first birthday.

I've never tried the starvation trick, never really had reason to...but I do wonder if it might mimic some seasonal variation in food supply availability and spawning frequency (e.g. dry season vs. monsoon)?

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