What percentage of African Serval is each generation of Savannah?
Savannahs are originally produced by crossbreeding an African Serval and a domestic cat, and each generation is marked with a filial number (F). The percentage listed for each generation is the lowest possible. Higher percentages are achieved by breeding a Serval to a Savannah in the F1 creation vs. breeding a Serval to another breed of cat to produce the F1 generation and then only breeding Savannah to Savannah without the use of an outcross breed in the early generations. Please note that these averages are determined by simple mathematic calculation and there could be a variance of about +/ 5% due to the fact that the mathematical percentages for the cats used for any specific breeding may vary.
F1: 5053% Serval, produced from Serval and a domestic cat (Savannah or other breed) parents.
F2: 2528% Serval, has a Serval grandparent and is the offspring of an F1 Savannah.
F3: 12.516% Serval, has a Serval great grandparent and is the offspring of an F2 Savannah (and so on through subsequent generations).
F4: 68% Serval. If there have been no other breed of cat used in the prior generations other than Savannahs (no outcross breeds), this is the first generation that can be TICA registered as an SBT (stud book traditional), eligible for championship status to be able to compete at the breed level at TICA cat shows. All Savannahs that are not at least 4th generation Savannah to Savannah breeding are registered as Foundation stock with TICA and are not eligible to compete at cat shows.
F5 and beyond: 47% Serval. At this point, as long as breeding only Savannah to Savannah takes place with no nonSavannah outcrossing, the mathematical percentage of Serval will remain constant from this point on.
It is important to bear in mind that the percentages listed are simply mathematical calculations of the percentage of Serval genetics a cat could theoretically carry, but it is not an accurate measurement or guarantee of the actual inheritance of Serval traits of any cat/kitten.
The fact is that genetics, particularly in hybrid animals, are quite complicated and largely unpredictable as traits do not inherit equally among all kittens some may inherit more of the father’s dominant traits and some may inherit more of the mother’s dominant traits.
Once you get past the F1 generation, mathematical calculations are essentially of no use since they are not at all indicative of actual trait inheritance passed from parent to offspring. Even with kittens from the same litter, one kitten may have inherited more dominant Serval traits and another kitten almost no Serval traits, but all the kittens would still have the same mathematical percentage of Serval in them. Please see the following diagram as an example of genetic variation possible in a litter of kittens:


All of these kittens would be mathematically considered 25% Serval, but as you can see, each offspring has the potential to inherit higher or lower concentrations of the dominant genetic material contributed by their parents.
There is no genetic test to determine how much of the Serval genetics have been inherited in each kitten, and not all traits are outwardly visible, so even going on appearance alone is no guarantee that the kittens that have the most Servallike appearance are actually the kittens that inherited the highest percentage of Serval traits genetically, or that they would pass on to the next generation.
The bottom line is that genetics do not obey math rules, which is why it’s always best to pick a cat by using the principle of ‘what you see is what you get’, and not count on mathematical formulas to guide your decision. You can’t go by percents when choosing a kitten, and breeders who advertise the mathematical percentage of Serval blood that their kittens have as a major selling point, particularly calling attention to higher than average percentages of Serval that is typical for a particular generation, is using this strictly as a sales gimmick. This is misleading to the average kitten buyer and a poor business practice to use something that is theoretical and portray it as if it is a fact or guarantee of some type.
The key to getting a good example of the breed is good breeding practices where cats with the desired traits are chosen to be bred together based on type and overall quality, not relying on mathematical percentages as an indication of quality. The fact is that there are often better looking, more Servallike appearing cats with a lower mathematical percentage of Serval blood than some cats with a higher mathematical percentage of Serval blood.