Chickens don't chew their food in their teeth, and so, nature has given them a sack (crop) in their lower throat(alimentary tract) in which the food passes. The grit being heavy rest in that sack, they move the sack around and the stone grit helps break down the food they eat. I hear they don't need grit until they start eating in the wild. In other words if given soft grains and chick starter, then they don't need grit. Grit from
Mannapro is just ground up granite rock.
In humans we chew (masticate) our food, then swallow it, it passes down the esophagus and enters our stomachs. Acids(aprox. up to 25% Hydrochloric acid) are pumped into our stomachs. You mom may have said "chew your food well", and that's because you need to break down the large food into small digestible pieces for your microvilli to absorb it. The acid breaks it down further as your food stays in your stomach from 30 min to two hours before moving on into your small intestine. The small intestine is made up of three pieces which do different jobs. The now acidic food enters the duodenum part of your small intestine, your pancreas and other sacs pump base solutions into the canal to lower the acidity to between 7-9 ph (slightly alkaline). It leaves the duodenum and enter the jujenum. The jujenum is lined with Villi and on the villi are microvilli. The nutrients and minerals are absorbed by the microvilli and passed into your blood stream for use by your body. I'll speed up here, the next part is the Ilium. The food then goes into the cecum (to which your appendix is attached), it's now out of the small intestine and into the large intestine. The food then goes up your ascending colon, the across on the transverse colon, the down the descending colon, then over on the sigmoid colon, then down your rectum and out your anus. Water is absorbed primarily via the large intestine(side note: which is why in an emergency case, a slow administration of water via an enema can rehydrate a human).
so, to come round circle, the chicks need to be able to break down their food (just like we need to) so that our bodies can absorb the nutrients that the food has available. If the molecule are too large, the microvilli or the chickens equivalent) can't absorb and use the nutrients.
So, I called vet and all she could say was mashed green beans, and she didn't sound very certain about that. I really want something to get them to be a little more comfy around me, seems like the forums say do it with food. So, are mealworms on the menu yet? Or are they too young for that? Whats ok at 2 weeks? Thank you guys! 
