The Jacksons ratio was worked out specificly for Hermans and Greeks. It is also intended to be a guide and not a specific regime.
The ratio is based on size and weight. Age does not factor in at all.
Developement is most directly dependent on temperature and nutritional input. The actual growth will depend on this.
Quote:
Originally Posted by Gem
It's worrying how people use the Jackson Ratio as a "well its the right size for the weight so that must be ok"  It just doesn't work like that(IMO). The whole idea of the jackson ratio is that it is used to work out wether a tortoise of a certain species is of the right weight and size for hibernation or not, although it can also help to identify torts that are of a low weight for their size through illness or other problems too 
A hatchling Hermann's when first hatched can weigh anything from 6-7 grams when born to a wopping 16-17 grams  (from my own experience) and has alot to do with size of the parents (mainly mum from personal experience). A hatchling (from many reliabl web sites) should put on no more then 1-2 grams a month for at least the first couple of year of its life to help aid smooth slow growth. So it would make sense to me that people actually worked out the correct weight of their young Hermann's by adding the 1-2 grams for every month of its life plus its hatch weight rather then going by the "Jackson Ratio Chart" as this would give a more detailed picture of wether or not they are growing too quickly or not.
Just My own opinion of course! 
But maybe its some thing that someone could look into making like the Jackson ratio so members could map out the correct weight gain for their very young torts. 
I have herd of several breeders now that actually give with their hatchlings when sold a chart showing the hatch weight of the tort with the expected weight gain on it so that the new owners has something to go on and try to adear too. Its a steep learning curve sometimes taking on such a young tortoise and even with the best researchand intentions in the world its still easy to run into problems........just like people do that have been keeping torts for oodles of years do occasionally too, this is because husbandry ideas are always on the change and so is feeding ideas too,some work, some don't, its all trial and error kind of  |