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Monday, February 14, 2011

Can You Successfully Re-breed Females To A Different Male?

Can You Successfully Re-breed Females To A Different Male?

© Alan S. Bias
Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.

In my world many breeders are just too hung up on the use of "Virgin Females" to propagate successive generations.  Even though I work with breeding trios much of the time, I also rely on breeding groups just as often.  With the latter you are trying to incorporate, if not maintain existing phenotype or diversity of genotype in your strains.  From this perspective it is not as important who actually sires offspring as is what is the result.  When working with compatible genetics I commonly use related females on multiple phenotypes.

We don't have the luxury of gene banking semen and embryos for later use in the guppy world, but you can take a similar approach by recycling visible & proven older genetics.  On occasion I will use the same female in multiple matings in a line or even multiple strains.  My reasoning is very simple, if an older female has left positive results on a strain, then why not use her again within the same strain or even another?  Don't get hung up on progressing by F1, F2, F3 and so on.  Sometimes working within a generation with multiple breedings, or back breeding, over an extended time can produce very positive results.

I adhere to an old principle handed down to me by several guppies breeders of old.  That being, "If you put a new male in with a female who has just given birth a certain percentage of offspring will be his".  I've always heard a 10% reduction in his offspring for each passing hour.  Is this true?  Possibly, although it just might sound good as a sales pitch.  Are the percentages affected by different strains?  Possibly.  Are the results also affected by different strains?  I would suspect so.  Can the time frame be increased?  Again possibly, with varying strains.

Why such vague response on my part?  I have never put this theory to test using methodical scientific standards and valid evaluation of results.  None the less, results do stand with tests in my fishroom.  If you have a basic understanding of genetics and know the makeup of your fish it can be a simple process.  The easiest test would be the use of pure grey (no gold recessive) males on gold females already bred gold.  Results are visible in the F1.  With the use of double or even triple recessives it may take another generation or two disseminate.

In example, such a opportunity presented itself last summer when  Gabriel Niculescu of VA sent me several trios of Grey & Gold (Blond) Vienna Lowers and Schimmelpennig Platinums from my old lines.  While he was critical of his efforts over the last two years and the specimens received, I was not.  The females particularly stood out.  I selected one gold (blond) who was very large, deep bodied, thick in the peduncle and beautifully shaped.  Typical of my lines she showed very little age being well over a year old, and her litters were bound to be large for a swordtail.  Just what I needed to jump start my newly established fish room.   Though I did not photograph the initial P female, here is a picture of a 3 month old daughter, who is also a sibling of the males below.

1st Breeding
F1 Gold Vienna Emerald Lower * Gold Vienna Lower
So I set out to see what I could accomplish with this grand old dam.  The first litter was the result of Gold Vienna Emerald Lower * Gold Vienna Lower breeding. She dropped on 9.3.10.  All offspring were gold and lowers.  The sire was an Emerald with a base color of green.  You will notice in the photo that the F1 offspring are also emeralds in both green and purple base body color.  They grew fast and large.  (Note of Interest:  I have since taken sibling sisters from this litter and used them in at least 5-6 other breedings with different strains and lines.  At this time 40% or more of my fishroom descend from the P generation female)

2nd Breeding
F1 Grey Schimmlepennig Platinum * Gold Vienna Lower
For the next breeding I took things a little different.    It would be a Grey Schimmlepennig Platinum * Gold Vienna Lower mating.  As soon as the female finished dropping her litter on 9.3.10 a new was put in with her.  The second sire was from my old lines, though grey, had a gold gene.  His offspring dropped on 9.29.10 and where all grey & gold (blond) Schimmelpennig Double swords.  Being from a line often breed to Vienna,  the resulting platinum is a very diluted version in multiple shoulder colors.  The males are able to turn color off and on at will.

Again, as soon as she dropped I bred the girl to a 3rd different male.  This breeding would also be Grey Schimmlepennig Platinum * Gold Vienna Lower.  Except this time I selected a mature male from a Darryl Tsutsui line.  The particular line he sent me were all grey body and have to date only produced grey bodied offspring.  The resulting F1 offspring were also all grey body and of the same phenotype as the sire.  This particular Schim. phenotype is very distinct, limited to dark yellow color in the metal shoulders.  A second litter from this mating dropped on 11.22.10 is identical.
3rd Breeding
F1 Grey Schimmlepennig Platinum * Gold Vienna Lower

So, is it possible to successfully use non virgin females in a controlled manner within your breeding program on the same strain or another?

I think so...


1 comment:

  1. Alan,
    I always use non-virgin females. The rule I follow is to let her drop the old male's fry twice before taking a drop from the new male. This seems to work. I'll get three or four fry from the old male in the third drop occasionally. For hobbyists who are not running labs with strict protocols this method is just as accurate, and probably more accurate! I once used the virgin female approach and found that the margin of error (males impregnating females before you separate them, the presence of fry in the drop tank from another strain, fry inadvertently getting moved into the drop tank during cleaning etc.) is greater than people think. I ruined my results! At least when I use non-virgin females I know there is possible contamination of my results! I like your idea of making the use of virgin females context sensitive. This is the approach I use. Scientists think that the old sperm is less competitive than new (fresh) sperm. The female secrets a hormone during or after giving birth. You can see males going crazy following a female after she has given birth. I think the rule of thumb is that she will accept a new male within 48 hours of giving birth. That is the window of opportunity.