What Are the Differences in Starter & Grower Phases in Chickens?

Young chicks eating chick feed

There are three primary growth phases that most backyard chickens are going to go through – the starter phase, the grower phase, and the layer phase. In this article, we are going to concentrate on the starter and grower phases. We will learn what physiological functions take place in the starter and grower phases, how to feed chicks during these two phases, and what management practices to implement during each phase.

The Starter Phase

The first weeks of a chick’s life are referred to as their Starter Phase. Depending on chicken breed, the starter phase is between hatch and 3-5 weeks of age. Lots of very important physiological processes are happening in the starter phase. That tiny little chick has to start developing their digestive tract and digesting food. They also have to start developing and establishing their immune function. And, most obvious to us, they have to start putting on their feathers which are crucial for temperature regulation. Very generically-speaking, I always describe the starter phase as “before feathers.”

The Grower Phase

Following the starter phase, a chick will go through their grower phase. Chicks intended to become laying hens will go through the grower phase from about 5 weeks of age until 4 months of age, which is when sexual maturity starts. Meatbirds will go through their grower phase from 3 weeks of age until harvest, which usually happens around 6-8 weeks of age. During the grower phase, a chick has to hone their digestive process. They will also work on establishing a stronger immune system and maintain all of the work they did in the starter phase. During the grower phase, they must also do an incredible amount of growing. Very generically-speaking, I always describe the grower phase as “after feathers.”

How Do I Choose the Right Feed for the Starter and Grower Phases?

In recent years, it has become quite common to find one feed that can be used in both the starter and the grower phases. This feeding strategy removes the need to manage inventory and switch feeds. A combination starter-grower feed also makes feeding a lot easier. If you are raising chicks that will become laying hens, getting your babies off to a strong start will help them become thriving and healthy adult birds. The vast majority of people that buy baby chicks for backyard production intend for those chicks to become laying hens. Our 18% All Natural Start Right® Chick feed and Chickhouse Reserve® are perfect feeds for chicks in both the starter and grower phases of life. If you are raising meatbirds, you will want to look for a starter-grower feed that is high in crude protein and amino acids. Meatbirds grow at an incredible rate and they need a lot of energy, protein, and amino acids in order to build that muscle mass. Our 22% Start-to-Finish Meatbird is the best option for feeding large-bodied broiler chickens for harvest. If you would like information about choosing the right starter and grower feeds for ducks, geese, or turkeys, please check out our article Nutritional Needs of Mixed Flocks with Baby Birds.

Should I Choose a Medicated Chick Feed?

Medicated feed options are most popular in starter and grower feeds. When a chick hatches, it has a very immature immune system. Mammals get some innate immunity from their mothers during gestation and they also get antibodies from colostrum (the mother’s first milk). Baby chicks do not get these advantages. When that chick hatches, it has to start developing its immune system almost from scratch. Since these chicks are at their most vulnerable during the first few weeks, it’s quite common to see medicated starter and grower feeds. The vast majority of medicated starter feeds are going to be medicated with Amprolium. Amprolium is a coccidiostat that is used either for the prevention or for the treatment of coccidiosis. Coccidiosis is intestinal protozoa – microscopic parasites – that can develop in the digestive tract of the chicks. Because their immune system is not well established yet, younger chicks are more susceptible to the negative effects of coccidiosis. Sick chicks will look lethargic, unthrifty, and will not gain weight well. If the infection is severe, the chicks could die. Amprolium in feed is almost always used at the preventative levels.

Management Strategies for Chicks in the Starter and Grower Phases

Keeping poultry is so fun and fulfilling. However, just like any other baby animal, there is more work to be done in the starter phase. This is because chicks in the starter phase are “before feathers” and cannot properly regulate their body temperatures. We need to mimic the temperatures that would be found under momma bird’s wing, which is where that baby chick would normally stay warm. The temperature for your chicks needs to be 95oF at hatch and you can decrease the temperature by 5oF each week until the chicks are fully feathered, or you reach ambient temperature. Once chicks reach the grower phase, they are typically fully feathered and no longer need an extra heat source, unless you are raising them in very cold climates. At this point, the chicks become really fun. Chicks intended to become laying hens will be jumping, roosting, and interacting with their coop mates. The grower phase is also when you can start letting your chicks go outside, if you choose. Pay close attention to the chicks and make sure your run is very secure because the small size of chicks in the grower phase can make them very vulnerable to predators. Keeping poultry is such a wonderful experience and the rewards are many! At Kalmbach Feeds, we are always here to help. If you have any questions about the nutrient needs of your birds, feed options, or general poultry keeping, please let us know. We are so excited to continue writing about all of the topics that are important to you and can’t wait to continue learning about your flocks. Stay tuned and thank you for choosing Kalmbach Feeds!

Nancy Jefferson, Ph.D.

Dr. Nancy Jefferson has been a member of the Nutrition and Technical Services team at Kalmbach Feeds since 2013. She received her Ph.D. from West Virginia University in 2008 and has worked in the feed industry for over 15 years. She lives on a farm in Crown City, OH with her husband, John, and their children. Dr. Jefferson is a passionate poultry enthusiast and loves her chickens! Together, she and her family raise beef cattle and she keeps an ever-growing flock of backyard chickens.