A Swedish study in 2003 suggested that organic beef, raised on grass rather than concentrated feed, emits 40  per cent less greenhouse gases and consumes 85 per cent less energy.
New Scientist - by Daniele Fanelli
You also have to source your meat carefully – an animal which has been cooped up and fed antibiotics is obviously going to be less good for you than one which is free-range. An animal that has had lots of exercise is less fatty and therefore better for you."
The Telegraph - by By Jessica Fellowes
"Think about the meat that you eat. Is it good enough?"  Hugh Fearnley Whittingstall
'Global Warning - The impact of meat production and consumption on climate change'.

Current global animal production is responsible for 18 per cent of all human-induced green house gas emissions, with more than 60 billion farm animals reared each year. That figure is set to double by 2050. The need to change our diet is increasingly urgent.
An average household would reduce the impact of their greenhouse gas emissions by more, if they halved their meat consumption, than if they halved their car usage.
Dr Pachauri, one of the world’s leading experts on climate change, says that although people are now beginning to recognise the importance of cutting car and air journeys, insulating their homes and recycling, people don’t fully realise the impact of livestock production on climate change, let alone its future impact.
“Meat production represents 18 per cent of global human-induced GHG emissions, including 37 per cent of global methane emissions, which has 23 times the Global Warming Potential of CO2 and 65 per cent of nitrous oxide, which has 296 times the warming potential of CO2,” says Dr Pachauri.
From a lecture by Dr Rajendra Pachauri, the Chair of the Intergovernmental Panel on Climate Change [IPCC], London 8th September 2008.  Press Release CIWF.
The number of birds killed for meat each year in the UK is 850 million chickens, 23 million turkeys and 20 million ducks;
DEFRA UK Government 28 Aug 2009