When it comes to chicken breeds, there is a lot of variation in size and weight. Some chickens are small and delicate, while others are large and muscular. However, the differences in size are not just due to genetics. The diet and living conditions of chickens can also have a big impact on their size and weight. For example, some chicken breeds are bred for meat production and typically have a higher calorie diet than other chickens. As a result, these chickens tend to be much heavier than other breeds. The following is a list of some of the heaviest chicken breeds: Jersey Giant: These chickens can weigh up to 13 pounds (5.9 kg). Originally bred in New Jersey in the 19th century, they were created by crossing several different large breeds, including the Brahma and Cochin. Orloff: These chickens typically weigh between 9 and 11 pounds (4-5 kg). They were originally bred in Russia in the late 18th century and are named after Alexander Orloff, the man who created them. Brahma: Brahmas are one of the largest chicken breeds, with roosters weighing up to 18 pounds (8 kg) and hens weighing up to 15