Tips on Selective breeding
Cross Back
If you like to try selective breeding using the cross back method this post is for you. There has been a lot on-going on my side but things will start settling down and i’ll be able to resume providing new blog post.
To recap what cross back is and does.
Cross back happens when the F1 female is use to cross back with the F0 Male. This way when the first shrimplet that comes out would be the Crossback 1 or CB1. Usually i will use the Female as the F1 cross with the F0 Male instead of the other way around. The reason for this so we have 1 fix variable to selectively breed.
As you continue to use CB1 female to cross back with F0 male again will result in CB2.
What it does with cross back in such a way is to increase the genetic similarity towards the male that was use to breed in this case F0.
This was the F0 male
After 2 back crosses this is the female that i have chosen to use for continuing the line. There is still a long way to go to improve the shell, the colors and such. The size is good at 2.5cm very big.
When we are in this stage, the F0 Male x BC1 Female will result in a higher % of trait similarity genetically to the F0 male.
| F1 | 50 | 50 |
| BC1 | 75 | 25 |
| BC2 | 87.5 | 12.5 |
| BC3 | 93.75 | 6.25 |
| BC4 | 96.875 | 3.125 |
To prevent deform shrimps and also to keep a good line of shrimp require diligence in ensuring the shrimp do not over in breed. When you do see any of the above effects, the shrimp had already reached a very late stage of inbreeding. You can use that as a gauge if not you can consider injecting new blood/genetics whenever you can and the method of doing so is call outcrossing.
Outcrossing: The idea for outcrossing on the other hand is to inject new genome to the current shrimp which has been line bred for some time. The reason this need to be done is because when line breeding get too excessive, deform start showing, shrimps stop breeding, growth stagnant, etc hence it is important for the health of the line to occasionally introduce new blood. There is no hard and fast rule when to introduce the new genetic into the pool because different people get the shrimp at different generation. If the shrimp i have gotten is already line bred for 5-6 generations it will reach the deform point faster if the shrimp has been already outcross before. A reputable breeder will be able to provide high quality new generation of shrimps when they have a large number of tanks to prevent too frequent inbreeding.
Not all selective breeding projects are successful sometimes after a couple of years (Yes it takes this long), so having a few project running at the same time is recommended. In other words, you’ll need to have a few more tanks to select and try to see if it works.
I hope this post provided you some insights into breeding high quality shrimp.
