Cats breed very fast. Female cats may got pregnant even in age of 7-8 months. They are able to give birth 3 times with approximately 4 to 6 kittens each. Natural growth is large what may be proved by below calculations.
Imagine we are starting a breeding. We then have a male cat and a female cat. Lets assume the female cat, all her daughters, granddaughters and great-granddaughters give two births every year with 4 kittens each. Lets also assume that in every birth we have a half of males and a half of females.
1st year of breeding:
We are starting with two cats – male and female. Considering above assumptions our female gives 2 births with 4 kittens each:
2 x 4 = 8 kittens
Together we have 10 cats: 8 kittens and 2 adults.
2nd year of breeding:
We are starting with 10 cats, according the assumptions half of them are females.
We have 5 females, each gives two births with 4 kittens:
5 x 2 x 4 = 40 kittens
together with adults we have 50 cats where 25 are females.
3rd year of breeding:
25 females – 2 births – 4 kittens each:
25 x 2 x 4 = 200 kittens
Together with adults we already have 250 cats including 125 females.
4th year of breeding:
125 females x 2 births x 4 kittens each = 1 000 kittens
Together with adults we have 1250 cats including 625 females.
5th year of breeding:
625 females x 2 births x 4 kittens = 5000 kittens.
Including adults we have now 6250 cats including 3125 females.
6th year of breeding:
3125 females x 2 births x 4 kittens + 6250 adults =31250 cats.
7th year of breeding:
15 625 females x 2 births x 4 kittens + 31250 adults= 156250 cats
8th year of breeding:
78125 females x 2 births x 4 kittens + 156250 adults =781250 cats
9th year of breeding:
390625 females x 2 births x 4 kittens + 781 250 adults = 3906250 cats
10th year of breeding:
10th year we start with 3 906 250 cats (in words: 3 million nine hundred and six thousands two hundred fifty cats), including 1 952 125 females.
Each female gives two births with 4 kittens each: 1 952 125 x 2 x 4 = 15 625 000 kittens. Together with adult cats we have 19 531 250 cats(nineteen millions five hundred thirty one thousands two hundred fifty cats!)
This number is unbelievable. It is of course approximate and based on assumptions taken for the need of calculations. Reality is different – not every female is able to born 4 kittens every time. Sometimes there are more or less. Different is also number of births in a year and number of females and males may be different.