Are chickens fed hormones in order to grow big?

Professor and Dean at College of Agriculture, Fisheries and Forestry,
Fiji National University


If you are the type that do not like to read long articles, and simply want a quick answer to this question, then the answer is No. However, I would advise that you read this article to the end, so that you can be completely informed and be able to educate those who may not read the article. I have written few blogs for online sites, including LinkedIn but this is the first article that I will write for Fiji Sun, having only just arrived in the country in April this year. I am passionate about animal production and the totality of agriculture. Agriculture is what sustains the world and will be here with us to the end of times. However, times are evolving and agriculture faces the challenges of re-defining itself, as it must do this for people to eat and stay alive. If anyone has held the view that modern chickens are raised on hormones to grow quickly or lay more eggs, it is not a lone or an embarrassing view. This erroneous view is held even by scholars who are studying agriculture but are not into poultry production. The view has waxed stronger over the years, and it is a distraction to the poultry industry, particularly as poultry meat consumption is rapidly rising to displace pig meat as global number one. Currently global pig meat consumption is about 16 kg/person/year while poultry meat consumption is 15 kg/person/year. However, poultry meat is already number one in over 110 countries, including Fiji, out of 174 in the Food and Agriculture database. The main reason that pigmeat is still globally number one is because of its high consumption in China, vis-à-vis the large human population. Meat consumption per person is low in India, although poultry meat is number one there.  

It is unthinkable how rapidly poultry meat production has grown since the humble background of the industry about 70 years ago. Most of the growth happened post-1950. Prior to the 1950s, poultry meat was only a Christmas delicacy in many parts of the world since it took more than 6 months to grow chickens to market weight. Apart from this time loss, the birds ate a lot of feed to get to market weight. It was, overall not a very profitable industry. Between 1950 and 2000, the time required to get chickens to the market was reduced by one day per year. During the same period and after 2000, chickens gained more weight per unit feed. In 1980, chickens gained about one kg weight for every 2.3 kg of feed that they consumed. Currently, with good management chickens could gain one kg for every 1.5 kg of feed, which in a large flock of birds is a large saving on feed.  

So, how did the industry manage to get this far over such a short period of time? To the layman, the answer is in hormones, probably because the Internet and human body building magazines are full of adverts on how to build muscle. The poultry industry does not use hormones to grow chickens. The only time that the industry (and only in France) used hormones was pre-1950s. This was when chickens took a very long time to reach market weight. That then meant that the meat produced by male chickens was very tough and was not liked by the public. It is generally well known that when male animals are castrated, they grow like female animals, and produce tender meat. The French poultry industry experimented with male hormones to castrate the male chickens, in order to make their meat tender. One may wonder why hormone was used for castrating the chickens. This is because chickens have their testes deep in the body, hear the kidneys. It is laborious to open millions of chickens to remove the testes and many chickens will not recover from this operation. The quickest way out was to inject them with male hormones, which has a negative effect on the natural development of the testes. These castrated birds then grew like females and were called capons, hence the process was called caponization. Fast-forward to the present era or even 40 years ago, chickens were growing faster and reaching market weight more quickly. The meat stayed tender when birds are sold, so there is no longer a need to caponize the males. Not many countries copied the French experiment anyway, so in so many countries, including Fiji, the Asia-Pacific region down to Australia and New Zealand, the poultry industry has never used hormones. So, why have chickens grown so large?

We need to look at simple breeding techniques to answer this question. It is generally known that large animals produce large offspring, just as in the human population. The animal industries, but in particular poultry industry, made use of this knowledge and practice. They selected large male and large female chickens to produce eggs for the next generation every time. This created chickens that became larger and larger with each passing generation. It may seem to be too simple but that was what was done. This breeding approach produces quick response in poultry because the reproductive cycle is short and chickens produce a large number of eggs over a short period of time. For one, commercial meat chickens begin to lay eggs from four-and-half months of age. Once a fertile egg is incubated, it takes only 21 days for the chick to hatch. However, we know that large chickens do not lay many eggs, so breeders tend to use large males against relatively smaller female family lines, to ensure that enough eggs can be produced, otherwise the industry cannot produce many chicks. Commercial layers, which produce infertile eggs for the table can lay up to 330 eggs per year but chickens which are maintained for meat production can lay only about 250 eggs.  

With breeding effort and good housing, feeding and health management, meat chickens can now reach 2.5 kg or more at 35 days of age, after eating about 3.6 kg of feed. Poultry breeders are not continuously working at increasing this body weight. Once the breeders got the birds to such a large size, they paused and began to fine-tune the birds, to reduce fat content, improve lung and heart function and strengthen the legs, to carry the large weight. Along with the breeding development, there has been spectacular improvement in knowledge of the nutritional needs of chickens. We can feed them right down to how much nutrients they need to grow at the rate we want them to grow.  

Health care, in particular vaccine development and the overall rearing environment have also improved over the years. Basically, breeding is now being re-directed to the fine-tuning process, and in many countries in Europe, the industry is actually reversing, creating slower growing birds that take longer to reach the market (more than 50 days). The belief is that meat from such birds has better taste, but such meat is expensive due to the rearing costs. Most of the poultry industry is unlikely to reverse because it is one industry that has improved animal protein supply, particularly in poor countries. So, the jury is out on this case: the poultry industry does not use hormones. If any consumer is still worried about what is being presented, be rest assured that poultry producers trust their product and eat the same meat. In my upcoming articles, I will touch on what commercial chickens eat and how the birds are reared. Without promoting one meat over another meat, the consumer can be assured that poultry meat is a healthy protein choice. 

Article first published in the Fiji Sun of 13 July 2018. The Author, Prof Paul Iji is an animal scientist and Dean of the College of Agriculture, Fisheries and Forestry at the Fiji National University. 


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