
Also if you are looking at profit it would be fair to reckon in the cost of keeping the bitch to breeding age, as this would equate investment into Plant and Machinery so to speak, lol.
Another way to look at it, is if anyone wants to look at your breeding from your bitch as a commercial enterprise then I would also think the amount it will cost you to keep her to 12 years of age will be a lot more than any profit on two or theree litters in her lifetime. Few people (except puppy farmers) would take more than four litters from any bitch.
My oldest bitch has had two litters, is now 11 years of age, and the profit on the two litters (just the costs of the litter not keeping Mum) £600, so she has cost a lot more than £50 a year to maintain.