@農자료창고

신선하고 영양가 많은 달걀과 집에서 구운 닭고기는 닭을 키우기에 충분한 이유가 된다. 텃밭에서 닭을 키우고자 한다면, 최고의 퇴비에 들어갈 재료를 넣는 데에 닭을 활용할 수도 있다. 게다가 닭을 풀어놓을 수 있다면 특별 혜택을 볼 수 있으니, 그것은 해충을 잡아 먹는 것이다.  

닭을 키우는 비용

오하이오 주립대학에 따르면, 다 자란 암탉의 경우 1년에 약 38kg의 사료를 먹는다. 방목할 경우 풀이나 음식찌꺼기를 먹어 사료비가 덜 든다. 동물사료 소매점의 포장 사료는 현재 약 450g에 35센트이기에, 1년에 암탉 1마리에 약 30달러 정도 들 것이다. 이 액수는 유기농 사료를 먹이면 더 많이 들고, 도매점에서 사면 더 적게 들 것이다. 닭 1마리당 낳는 알의 갯수는 품종과 연령, 관리법에 따라 달라진다. 그러나 1년에 보통 200~250개를 낳을 것이다. 그래서 달걀 12개당 1.4~1.9달러를 쓰는 셈이다. 나중에 논의할 다른 혜택들을 감안하지 않고, 슈퍼마켓의 달걀에 비하여 12개당 2.5~5달러 들 것이다. (닭으로 키우는 병아리 사육비는 초기 투자가 필요한데, 이 비용은 알을 낳다가 폐기한 뒤 닭고기로 활용하는 가치에 의해 상쇄된다.) 사육비에 대한 상세한 논의는 닭고기를 위한 양계를 보아라. 

닭의 혜택: 텃밭에서

지금, 달걀과 닭고기 말고 닭을 키우는 혜택에는 무엇이 있는가? 어떤 사람들은 텃밭에서 진드기를 방제할 목적으로만 닭을 키운다. 닭을 방목하는 것이 유기적 해충방제의 수단으로 아주 좋다고 이야기한 적 있는데, 이에 대해서는 텃밭 양계: 유기적 해충방제를 보길 바란다. 

라임병에 걸리는 위험을 낮추는 일을 가치로 매기기는 매우 어렵다. 하지만 닭 1마리에서 얻는 닭똥거름의 가치를 추산하는 건 할 수 있다. 닭은 곡물사료 에너지의 일부만 활용할 수 있다. 그들은 나머지를 똥으로 싼다. 닭들의 똥은 나무 부스러기나 짚, 낙엽 등 탄소질이 많은 물질과 제대로 잘 버무려지면 토양에 영양분을 추가하고 유기물 함량을 증가시킨다. 

오하이오 주립대학과 하와이 협동조합 교육서비스의 보고에 따르면, 닭 1마리가 한 달에 3.6~5kg 정도의 똥을 싼다. 갓 싼 닭똥에는 다른 기본적인 많은 영양분과 함께 1.5%의 질소가 포함되어 있다. 질소는 가장 공급이 부족한 영양분이기에, 닭똥거름의 가치를 추산하는 데 사용할 것이다. 

 

Nigel Joice poultry farm tour. Photo: Emily West Photography

For the first time since the business invested in renewable energy strategy three years ago, it produced more power than it consumed.

Mr Joice, and his son, Patrick, welcomed young poultry producers to Uphouse Farm, South Raynham, near Fakenham. They told the 30 members of the joint National Farmers’ Union and ABN poultry industry programme that the primary goal was to produce quality chickens and minimise energy consumption.

Since 2010, they have invested in an energy centre, to warm the growing chickens, and installed solar panels.

The three arrays of photo-voltaic panels, rated to produce 450kW and mounted on roofs and on the ground, made the farm energy-positive for two days earlier this year.

Mr Joice, who started as a chicken producer in 1997, runs his flocks of birds on two self-contained farms with a team of three staff on each. To maintain strict bio-security, the staff only work on their “home” farm, he said. In a year, the 115-hectare arable farm finishes about six million table birds, roughly 12 million kg of chicken. It consumes about 20,000 tonnes of poultry feed.

The chickens produce about 8,500 tonnes of litter each year, which was a further challenge in the drive for energy production, he added.

When they started the first phase of the renewable energy strategy in 2010, two 500kW furnaces were installed to heat water for the poultry houses. For the first year, they burned woodchip but since the middle of last year, the fuel was chicken litter.

“This is under a special licence from the Environment Agency because we’ve been testing emissions,” said Mr Joice. “It has all been extremely successful and emissions have been extremely low. We’re amazed at the performance.”

There has also been another major benefit, said his son, Patrick, in terms of better poultry welfare because of the drier heat in the chicken sheds. “We didn’t think we’d get such a similar level in the improvement of the birds and their welfare. It has come as a bonus. We’ve got a better environment in the chicken sheds and they’ve rewarded us with better performance.”

He compared nine chicken crops, in a typical 50-day flock cycle, heated by LPG (liquid petroleum gas) and using the dry heat from the energy centre.

“We’ve seen a six point improvement in the food conversion rate,” said Mr Joice, who had spent £120,000 a year on LPG.

The farm, which was last year’s champion Norfolk Farm Business, was also the 2011 Farmers Weekly Poultry Farm of the Year.

As the farm produces about 8,500 tonnes of chicken litter a year, the aim was to burn the surplus to generate electricity. Mr Joice said about 2,500 tonnes was needed for heating but the rest could be generate electricity. In January his electricity bill was about £13,500.

The furnaces, installed by Irish specialists, bhsl, heat water to 85C for circulation to the chickens..

Patrick Dight, who is bhsl’s applications director, said that a new technique to burn litter on a smaller scale had been developed more than 11 years ago. Their design of fluidised bed combustion of poultry litter, used in big power stations, has operated consistently for months. It burns at more than 600C, he added.

“Chicken manure is not an easy product to manage. It was very difficult to handle because it is like shavings, honey and glue mixed together. It has high levels of ash and silica, variable moisture content and a low calorific value,” he added.

The manure is stored in a bio-secure area, under negative pressure to contain odour, before it is burnt – and the operation is monitored at bhsl’s headquarters in county Limerick.

“Our priority is the birds’ welfare. We have to maintain a set temperature of water to the birds at all times,” Although there is a back-up boiler, it has never been needed,” he said.