) using Zoology 3 in one of her upcoming guides, and voiced some concern over the previous books. I guess the reason I'm even looking at them is that I have two boys who LOVE animals, and I thought they might be a fun biblically-sound resource.
This means you do not have to feel that you need to tweak it here or there to make it a complete program, because it already is! However, what is also great is that you can add something extra, and it still will not take ALL DAY to complete school. So, I think if you want to add the extra Science you could, and it would be fine. I don't know how they would be as readers for your dc to read, I guess that depends on their reading ability. I have a dd who LOVES all things animal too, so I completely understand your 'dilemma'. I would say adding this one day a week might be a good addition to your schooling; that way it's not adding time to your day every day, but you can still make your dc's studies a bit more personal to them. You could even work on a lapbook or notebook to go with each lesson you do. Just my thoughts. I'm sure others will be along to offer their opinions and suggestions as well. InHisTiming and I are thinking exactly alike here, so ditto to what she already said so well. 
I looked at Apologia pretty extensively this past summer, and I think the one Carrie is looking at is more living than the other ones. The other ones I looked at can read a bit encyclopedia-like with many facts in a row, which results in them sounding not very living sometimes. It seems like the more recent ones are more living with better photographs (not so small). But, that is just my opinion. They are definitely Christian, which is such an asset. I'm not sure how old your dc are, but that would probably make a difference in how they'd respond to it. It also would make a difference what you do with it. It would be a neat reference book for information, and it probably would lend itself well to notebooking or nature journaling. If you are looking for a great read-aloud book about animals though that is really going to be fun, I think there are other books you might enjoy more. Masterbooks has some neat books about animals that are Christian, depending on the ages of your dc. However, you should do whatever you think you and your dc would be best because only you know what purpose best fits your Fridays with your dc! HTH! If your dc are into something - they're INTO it, and they'd probably love the extra learning! 