Hi, Shortysil, I haven’t personally used Karo syrup to soften their stools but I imagine the theory behind it is the same as adding a little vegetable oil (or mineral oil or hairball solution, which are also sometimes suggested), i.e. to lubricate kitty’s digestive tract to help things pass more smoothly through. So I imagine it would work in the same way.You could also try sieving the formula before you give it to them, though I’m not sure how much that actually helps (so if you find out, let us know!) To be honest, with such young kittens, I would try the most conservative and least invasive solutions first, and I would give them a little more time before I started to get really worried (i.e. on the third day without pooping is when I would start to worry).
These websites are also really great for general information:
http://www.messybeast.com/handrear.htm
http://www.kittenrescue.org/pages.php?pageid=15
http://www.fanciers.com/cat-faqs/orphans.shtml
http://www.feralcat.com/raising.html
The last one has a feeding chart. The amount they can take in at each feed depends on the size of their little stomachs so I’d tend to go by size rather than by age in days, as you don’t know what their mum’s nutrition was like during pregnancy. So at five ounces, I think I’d still be going for six feeds a day and take it down to four when they reach 7 oz. But if you know how much they are taking in at each feed, you can probably work out how many feeds they need a day, i.e. if they are taking in 14 ml/cc at each feed, you could cut it down to 4 feeds, so long as they each got 56 ml/cc per day in total. As the website says, a kitten needs approximately 8 cc’s of formula per ounce of body weight per day. The video chapter on feeding also has a food chart.
As a general rule, little and often is best. If they were feeding from their mum, they’d be basically feeding on demand.
It’s great that you’re fostering for an organisation. Don’t forget you can also ring them for advice, they should be supporting you as much as they can. They may also have a ‘tame vet’ you can call. Keep checking back for more advice from experienced foster mums and let us know how you get on!