If you'd like a more detailed look into the life of a broiler chicken, check out the below 

"Chicken Care" series. See how chickens are typically raised, the thought and research that 

goes into their housing, food, breeding, and medical care, and how farmers, veterinarians, 

and nutritionists are always working to do better.

Chicken Feed Tailored to each stage of life

By their fourth week of life, the chickens are really growing up! Their feathers are in and

they're getting big! There's a number of factors that go into getting chickens to a healthy

size at this age – nutrition tailored to each stage of the chicken's life, coordination between

farmers and veterinarians, and optimized living conditions – from temperature, to lighting,

to litter – all contribute to healthy growth of the chickens.

Also Read: chicken Feed Formula for Broilers of different ages

What isn't making the birds bigger are added hormones or steroids. And there are no 

genetically modified chickens period. Over the years, we've selected chickens with the

healthiest growth and size for breeding, and we couple that with feeding, housing, and 

raising them well to raise larger, healthier birds. Additionally, all chicken is free of added 

or artificial hormones and steroids. In fact, regulations prohibit the use of added hormones

and steroids in all poultry.