Fong's music eggs are even more precious: distributed in speciality outlets such as organic food shops, they sell for HK$7 each, double the price of organic eggs in most supermarkets. He also sells them online.

He insists it is a reasonable premium: "Unlike ordinary mainland eggs, which have flaccid yolks and runny whites, the yolk of a music egg is firm and there are two distinct layers of white."

Hong Kong's poultry sector has shrunk dramatically since the first person died from H5N1 bird flu in 1997. Fears over the ability of the flu virus to jump species, from bird to human, led to mass culls and a government policy to discourage poultry farming. Spurred by a licensing buy-back scheme, just 28 farms survive compared to thousands that supplied residents during the 1960s.

Those poultry farmers who persevere try to get an edge by stressing quality over quantity. In fact, it has been the strategy of local farm operators to focus on producing high-quality chicken, says Fong, who is also promotion chief of the New Territories Chicken Breeders Association. He embraced the tuneful technique in 2005, two years after starting Harvest Musical Farm.

"When I first raised chickens, many died. They were scared by noise from firecrackers and nearby construction," he recalls. "I saw some documentaries that showed people using music when rearing cattle and ducks. So I tried playing music to my chicken to get them used to loud sounds."

After some trial and error, Fong has perfected his formula for chicken muzak: the birds are divided into three groups by age and played different music based on their stage of development.

Chicks up to 15 days old get classical works such as Mozart as they mostly eat and sleep at that age, he says. Those from 16 to 30 days old listen to romantic ballads and adult birds of more than 31 days are piped uptempo tunes such as Lady Gaga.

Fong's latest innovation is to set aside the uppermost tier of coops for what he calls the "roof garden" to give his chickens a semi-free-range experience.

"Usually, there are 60 chickens to a coop, but some have just 20. Selected chickens are put in the top rack, where there are only five, to give them more space to move around."

For decades, the government ran an experimental farm in Tuen Mun, where different chicken-rearing techniques were tested but it was closed in 2002. Now few officials remain who are knowledgeable about poultry farming, Fong says.

"The government now sees the whole sector from the perspective of containing epidemics and public health."

Edward Yiu Chung-yim, an associate professor in geography and resource management at Chinese University, argues there are better ways of regulating the sector. Poultry farming is a twilight industry in Hong Kong, but plays an important role in local agriculture, Yiu says. Hong Kong's self-sufficiency in food is generally very low (almost all our rice is imported, for example). But the rate for live chicken and eggs is high, with 80 per cent of eggs consumed here coming from local farms.

However, chicken from China will always be cheaper than locally reared chicken. Chinese farms may inject their flocks with hormones to boost growth. Coupled with lower wages and lower land costs, local farmers can't beat their Chinese competitors on price.

Instead, they should go high-end, providing pleasant environments to rear quality chicken that can sell for more and minimise environmental impact, Yiu says. Local chicken can be superior to imports, such as those from industrial farms in the US.

Yiu, who is conducting a study on how local poultry farming can improve local ecology, says the UK and Taiwan offer subsidies to poultry farms that benefit the environment and punish those that cause damage.

"Instead of seeing the poultry industry solely from the perspective of avian flu, the government should encourage local chicken farmers to learn from UK and Taiwan as the conservation of chicken farming can boost biodiversity," he says. By using chicken droppings in making compost, for example, poultry farming can supplement agriculture.

Farm boss Kwok Ming-cheung set the bar in the city when he collaborated with University of Hong Kong zoologists to develop the Kamei chicken in 1997. Aided by a HK$10 million government grant, they spent years examining the genetic make-up of different types of chicken and bred them together to create a tastier and healthier variety.

"Mainland breeds have less flesh and are mainly suitable for soup. Imported varieties are fleshier but have little flavour. So we bred mainland species with those from overseas to produce the unique local variety. Hongkongers also don't like chicken that is fatty; so by breeding for selected traits we eventually developed the Kamei chicken, which has lean meat, thin skin and a strong chicken flavour," says Kong.

A specialist in poultry nutrition who trained at the University of British Columbia, Kong has continually improved the facilities at his Hong Lik farm in Yuen Long. The 50,000 sq ft site has undergone many upgrades since it first opened; among them the installation of a solar heating system in 2010 to pipe heated water to the nursery to maintain a cosy environment for his chicks in cool weather.

"Baby chicks do not have fully developed feathers and need to be kept warm in winter," Kong explains.

In the pens for adult chickens, rows of whirring fans boost ventilation and mist sprinklers help cool the air. The power bill alone is HK$60,000 per month, but it's a necessary expense, Kong says. "If the chickens feel too hot, they won't grow well."

Kong's investment in quality birds gets a thumbs-up from chef and food writer Choi Kit-yee. Locally produced chicken sold at wet markets generally have good flavour but Kamei chicken stands out for its emphasis on health, she says.

"Many people don't eat fatty chicken skin, but the Kamei chicken is healthy as the jelly-like substance beneath the skin is mostly collagen. Simple cooking brings out its flavour."

Like Kwok, Lee Leung-kei, founder of Yuen Long's Wing Ming Farm, has developed his own breed of chicken, the Huizhou, a Chinese and French hybrid. Mixed breeds are more resistant to disease, he says.

Lee started his farm in 1984 but has suffered several crushing blows over the years because of bird flu. Faced with a mass cull following the first outbreak of H5N1 avian flu, he could not bear to see his Huizhou chickens disappear and kept dozens at a friend's home.

"I would rather break the law then let the unique species die out," he says. "I used those surviving chickens to revive my business afterwards."

Although his brother took up the government's buy-back offer for poultry farmers and gave up his licence in 2008, Lee wanted to keep going.

"I insist on doing it because I love birds," he says. "There should be some space for our industry. The government just wants to phase out live chickens to prevent outbreaks but customers should be given a choice besides chilled chicken."

Kwok agrees: "Over the years, there hasn't been one case of avian flu originating from local chickens. Avian flu spread from wild birds getting into farms which used to keep chickens in the open. After the outbreaks, I pioneered the use of netting to keep out wild birds.

"As long as local chickens are segregated from outside environment, they are 100 per cent safe. With science and the proper set-up, we can provide a comfortable environment for the birds so that Hongkongers can enjoy delicious and healthy locally produced chicken."