My chickens have all gotten skinny, they act normal except for eating less. Their keel bone is protruding. They have eaten about 1/2 of a 50lb bag of feed for a whole month. They are almost 4 months and the hens only weigh about 3lbs. The cockerel is almost pound heavier. I did change the brand of crumbles last month, but it shouldn't cause this right? The breed standard says they are suppose to be 7-8lb hens full grown. Since they are only half grown, i thought the weight was okay, but they are so bony! Any tests I can do at home to see if anythings wrong?