Traditional chick-grading standards do not always pick up damage due to overheating. Because overheated chicks hatch earlier than they should, they are often smaller, weaker and more prone to infections as well as a host of other health problems. To properly assess chicks and establish if they have overheated, check for the following characteristics: Color and Strength Chicks should be bright yellow. Overheated chicks have poorly absorbed yolk sacs and hence pigments are whiter than normal. Also, chicks should be active and be able to stand up right away. If placed on their backs, they should turn over within seconds. Yolk-free Body Mass (YFBM) Overheated chicks are smaller and have bigger, non-absorbed yolk sacs. The more serious cases of poorly absorbed yolk sacs translate in unhealed navels. Some yolk is left as chicks need that for nutrition during their very first hours. This is quickly absorbed and should be gone about the time chicks transition to feed/water. If there is too much yolk, however, live chick weight is lower and indicates a weaker chick. Chick/Shank Length Overheated chicks are smaller since they used available protein during incubation as an energy source, rather than fuel to grow muscle. This is apparent when the chicks’ shank length falls below the established target, as indicated in the chart below. Find more tips on measuring shank length in our Broiler Development Guide. Feathering Good feather development is synonymous with good chick development during incubation. Chicks should look dry and fluffy soon after hatching. However, excess development of the wing feathers does indicate early hatching – and most likely overheating – due to prolonged time in the hatcher baskets. Disease Control One consequence to overheating embryos is they are more susceptible to Colibacillosis, or E. Coli. Colibacillosis prevention includes good hygiene of hatching eggs and good hygiene in the hatchery. Contaminated hatch debris and chick fluff in the hatchery are major sources of bacterial infection. It is also important to follow good hygiene during waste disposal. Properly disinfecting the hatcher trays will kill bacteria and prevent E. Coli. For more in the Cobb Academy about Hatchery best practices and why incubation is the key to broiler development and long-term performance.