Corid is usually not necessary in the first week of life, and with stressed chicks, I would tend to give the vitamins and electrolytes for a couple of more days. But that is strictly up to you. It is the thiamine or B1 that is not given when on Corid, because it works by mimicking thiamine. Many of us dig a piece of sod and place it in our brooders for chicks to peck on and gradually be exposed to coccidia in our environment. Chicks love to peck the grass and it can be replaced every couple of days. A little chick grit can be put in a container for free feeding, because of the grass.