Underweight Backyard Chicken and What to do

Chickens, like all other living things, have to be of a certain weight range so as to stay healthy. The recommended weight also helps in the maintenance of bodily functions such as egg-laying.

If a chicken is underweight, its bodily will not function well. If not dealt with this will lead to severe consequences. 

What Makes Chickens Lose Weight. 

There are several issues that lead to underweight backyard chickens.  These include stress, diseases, parasites, growth spurts, malnutrition, and hen sitting on eggs. 

  1. Stress

When we talk of stress in chickens, we mean that the chicken’s system is overwhelmed. Stress in chickens is caused by a multitude of factors. 

External factors that can cause stress in chickens include parasites and heat. Internal factors can be internal parasites or even growth spurts. 

Stress in chickens will make the bird not eat or drink as required. This leads to weight loss and can lead to the chicken being underweight.  

  1. Diseases and health conditions

The disease is another reason your backyard chicken is underweight. Sick chickens will not eat well or their bodies will not function well. 

Diseases in chickens can either be caused by viruses or bacteria. When chickens are sick, they do not eat. A vet once told me that most sick chickens lose their lives due to starvation, not necessarily illness. 

Some sicknesses and conditions such as sour crop and impacted crop affected the functions of the gastrointestinal system. 

This means the feed is not processed as required by the chicken’s digestive system. This leads to weight loss and if not immediately dealt with, the birds will be underweight. 

  1. Parasites

Parasites can lead to underweight chickens. 

External and internal parasites operate in one way – sucking blood and nutrients from the chicken’s body. This means that as the chickens feed and drink to replenish their bodies, the parasites also take their share.

 A few parasites might not cause much harm, but an infestation will overwhelm the affected chickens.

Most parasites such as worms, fleas, and mites multiply fast due to their short life cycles. An example is fleas that lay about 200 eggs in their short life cycle of 30 days. This means within 30 days, they will be 200 new fleas per adult flea. Multiply this by 1000 adult fleas! Your chickens will be overrun in no time. 

Other than getting blood and nutrients from chickens, parasites cause discomfort as they bite and nimble through the skin. You will notice your chickens scratching as they try to soothe their skins and get rid of the tiny creatures. 

This means that your chickens will spend more time trying to deal with the disturbance by the parasites than nourishing their bodies through drinking, feeding, and foraging. 

  1. Malnutrition

Chickens require a balanced diet of energy, minerals, protein, vitamins, and water in order to function normally. These foods need to be in the right quantities and form. 

If any of the required nutrients for grown, development, and production are missing or in the wrong quantities, the chicken will most likely be malnourished. 

Malnourished chickens can not only be underweight but are a target for diseases that can lead to drastic weight loss. 

Make sure that you feed your chickens with the recommended feed with the right formulations. Chickens being raised for meat are given broiler feeds while the ones being raised for eggs are given layer feed. 

  1. Molting

Molting is a process where chickens shed old feathers and grow new fresh ones. During this process, the bird’s nutritional resources are used in regrowing the feathers and maintenance of critical body functions as opposed to production. 

When my chickens are molting, they sit in a corner as if they are brooding. They do not feed and drink as normal. They seem to lose some weight but quickly regain it after molting. 

Extra feed, especially rich in protein should be provided during this crucial period in their life cycle. 

If chickens do not have access to enough protein-rich feed during molting, they will lose a lot of weight, eventually becoming underweight. This is especially true during winter molts, where chickens need extra energy to heat their bodies. During this season, the chickens will not have enough feathers on their bodies to keep their bodies warm. 

  1. Brooding

Brooding is the process where hens hatch eggs naturally. The chickens sit on the eggs, providing them the warmth needed in order to develop into new chicks. 

The process takes 21 days and during this time, the chicken has to spend most of the time sitting on the eggs. This means that the chicken will not feed normally and will most likely lose weight. 

It is important to provide highly nutritious feed to the chickens at this time as they only feed once every few days. The food and water should be kept near the brooding nest. This way the chicken does not have to leave the eggs for long to forage for feed. 

The good thing is that most of the time, weight lost during this brooding period is quickly gained after hatching. However, it is good to watch the new mother and see if she has issues regaining her weight. 

How to tell that a backyard chicken is underweight.

It is important to know how to identify an underweight chicken. The are several ways to be able to tell if your chicken is underweight including observation, using a weighing scale, and feeling the keel bone. 


If you have a small flock, chances are that you know each of your chickens and their individual temperaments. You probably know them by name and spend some time each day admiring how great your chickens are. 

Observing your chickens is one of the ways of being able to tell if your chicken is underweight. You will notice if one looks smaller than normal. While this helps in identification, it is not foolproof since chickens’ plumage changes with time and season. One time the chickens look fluffy (big) and other times it looks smaller. 

This leads us to the second method of identifying underweight chickens. 

Feeling the keel bone. 

The keel bone is a bone that runs lengthwise on the chicken’s cavity. It holds together all the flight muscles and protrudes at the front, under the crop. The keel bone weight test is done this way. 

  1. Gently identify the keel bone. Move your fingers down from the neck. You will come to the crop, which feels soft and full, like a ballon. 
  2. Move your fingers down and there in between the chicken breasts should be the keel bone. Fell the protruding end. 
  3. Try to gently pinch the keel bone. If it feels hard, without any meat, then the chicken is underweight. 
  4. If the only thing you can feel is cleavage, then the chicken is overweight(This is normal for broiler chickens like the cornish cross). 
  5. The keel bone of a chicken should feel like it has some meat on it. 


Weighing the chicken using a weighting scale is another sure way to tell if your chicken is underweight. However, this is only effective if you have been keeping track of the age of the chickens and have a growth chart. 

A growth chart for chickens shows how much a chicken should weigh at a certain age. 

What to do if a backyard chicken is underweight. 

The next thing after identifying if your chicken is underweight is to get it to a weight gain regimen. You first need to deal with the causes, isolate the chicken, and put it on a weight gain diet. 

  • Isolate the chicken

Putting the chicken under quarantine will help the chicken recover. If the weight loss is due to sickness or parasite, isolating the chicken enables you to be able to administer medication, away from other chickens. This also enables you to give the chicken a special diet for weight gain. The chicken will have its meals all by itself, enabling it to feed as much as it wants. 

  • Put the chicken on a weight gain diet

After isolating the chicken, it is time to put it on a weight gain diet. Weight gain feed for chicken should have high percentages of protein and carbohydrates. In this case, feed the chickens with grower feed and not layer feed. This is because grower feed contains more protein and fat. Supplement with a source of calcium such as oyster shells. 

Scratch and cracked corn are rich in carbohydrates. They do not contain all the needed nutrients but make a great addition to underweight chickens. 

One reason for isolating the chicken is so that it can have feed throughout. Make sure the chicken has feed and water though out so that it can feed as it wishes. 

With no time the chicken will regain its normal weight and will be able to join the flock. 

Have had the challenge of underweight chickens. What did you do? Let us know in the comment section below. 

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About James Polystead

I grew up on a small farm. My parents used to grow food and keep animals for our sustenance. They would sell the surplus to make an extra coin to supplement the income from their jobs. I am taking the same path. I have over 40 chickens for eggs and meat. I also grow vegetables in my backyard. follow me on Twitter

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