In order to make the hens lay more eggs, the hens can be forced to go bald.

Have you ever wondered why eggs are so cheap compared to other proteins?

Humans have developed super-egg-laying chickens, of course, but strange farming techniques have also allowed chickens to lay as many eggs as possible in a limited number of chickens. Today we're going to tell you a story about laying eggs that you don't know.

These laying hens are very capable of laying eggs. According to a 2007 report by the Food and Agriculture Organization of the United Nations (FAO), laying capacity of laying hens has leapt since the beginning of the 20th century: from 170a year in 1925 to 325in 2006.

However, even such a high-yielding breed can not maintain a stable output throughout the chicken. Commercial laying hens usually start laying eggs when they are 16 to 20 weeks old, but their egg production begins to decline around 25 weeks. By the time the hen is 72 weeks (18 months old), there will be no commercial value.

Therefore, the chicken farm is faced with a difficult problem: whether to let the old hens continue to lay eggs, or to change a batch of young chickens, although they have a strong ability to lay eggs, they need to spend money to renew them.

On balance, humans have come up with a middle way: to rejuvenate the fecundity of old hens by making them bald. This is the strategy widely used in the layer industry: artificial forced molting (induced molting).

To put it simply, artificial molting is a process that forces poultry to shed their hair ahead of time by artificially simulating autumn.

You might want to say that changing hair has something to do with laying eggs.

Feathers are very important to birds, so all birds change their feathers at least once a year. Because molting is a very energy-consuming physiological response, which conflicts with reproduction and migration, birds generally change their hair after breeding, but not during migration.

For hens, at the end of each natural laying cycle, that is, at the turn of summer and autumn, the hens will molt naturally, and the number and quality of eggs will decline before molting. When the hen is moulting, the reproductive system "shuts down and restarts". Generally speaking, high-yielding hens look miserable in autumn because they are very bald.

Gregg J. Cutler, former president of the American Society of Bird Pathology (American Association of Avian Pathologists), said that the physiology of birds and mammals is very different. During the laying period, the liver of birds accumulates fat and a piece of fat pad grows on their bellies; during molting, the fat in the liver and meat pad is consumed, while the ovaries are absorbed and reused; after molting, the reproductive system of the chicken is replaced by the old, and the reproductive ability is iterated. In other words, molting can be understood as the external manifestation of the hen's "sitting on the moon".

This natural phenomenon used to be an important factor affecting the periodicity of the egg industry. Because hens lose their hair and do not lay eggs in autumn, before the advent of modern farming, the supply of eggs on the market will decrease in autumn, and the price of eggs will rise accordingly.

But then humans found that they could reverse this natural law: forced depilation could allow hens to enter the next laying cycle as soon as possible, so they could make more money in the fall.

Morley A. Jull, a zoologist at the University of Maryland, documented the method of forced molting as early as 1938. Nowadays, in order to save costs, many chicken farms also use the method of forced molting to get the old hens to come again.

However, the specific measures of forced molting have been criticized because it seems very cruel.

In order to create an artificial autumn, it is not enough to reduce the light. Breeders have found that hens must lose about 30% of their weight in order for the hen's reproductive system to restart. As a result, the chicken farm will starve the hens for 1-2 weeks, forcing them to shed their hair. After that, the hens are re-fed by the chicken farm, and the hens can also enter a new egg-laying cycle. In addition to laying hens, broilers, turkeys and ducks also use this strategy.

Although the method of forced molting can extend the commercial life of hens, it cannot be used indefinitely, because with each loss of hair, the laying cycle of hens can be restarted, but the number of eggs will also be discounted, usually at a discount of 7-20% of the previous cycle. So more than 2 years can be regarded as an old hen with no economic value (although 2 years old is far from their natural lifespan-5-10 years).

Old hens that no longer have the value of laying eggs are called spent hens in the industry, and they are usually slaughtered to make low-grade chicken products.

For many consumers, forced molting is so cruel that big restaurant chains such as McDonald's, Burger King and Wendy Burger say they do not use artificially molted eggs. Forced molting was banned in Britain in 1987 and the European Union banned the breeding law in 1988. Of course, laying hens in these countries are directly "humanely" destroyed or "recycled" after the peak laying period.

At the same time, researchers and the layer industry are also developing new methods of artificial forced molting. Now another common method of forced molting is called chemical method, which does not give hens a deliberate diet, but causes them to lose their hair with a high zinc diet.

However, some laying hens in the United States are still using artificial forced molting. According to a survey conducted by the United States Department of Agriculture in 1999, 74 percent of farms in the United States forced hens to molt.

In 2008, the United Egg Farmers Association (United Egg Producers) no longer allowed its egg farmers to starve laying hens to force molting. More than 80% of eggs in the United States are produced under the regulations of the American Egg Farmers Association, and farmers who do not join the United Egg Farmers Association can still molt their hens by depriving them of food.

Some scholars believe that forced molting is no more cruel to birds than nature itself, because many birds experience a natural cycle of feeding and fasting in nature. For example, in the natural environment, geese can fast for two and a half months, while king penguins (Aptenodytes patagonicus) can fast for 4-6 months.

The question of whether to "work" for more than one year to be exploited of surplus value, or to be eliminated early after the peak, seems to be unsolved for the time being.

Bald chickens are useful for feathering.