The vast majority of chickens raised for meat come from intensive farming systems where they never see outdoors, have the space of around the size of an A4 piece of paper each and live in huge flock sizes (there could be 20,000 birds in a shed).
They are also genetically selected to grow very fast (up to 60g a day) which can have significant negative effects on their health, including heart problems and leg defects.
Yet we've found supermarket packaging that could make you think you've bought a chicken that has spent time outdoors when it hasn't, or had a higher welfare life than the reality.
We examined chicken breast fillets from all the major supermarkets to see what welfare labels they use and what else they are saying on their packaging.
Many supermarkets use phrasing like 'Trusted farms' or 'Trusted farmers' on their chicken packaging.
Aldi, Asda, Co-op, M&S, Sainsbury's and Tesco all use a version of 'trusted farms' or 'farmers we trust'.
Lidl and Waitrose talk about the animals being 'reared with care'.
These phrases don't have any legal definition when applied to animal welfare. This doesn't mean that a supermarket won't have good standards, but you need to look instead for logos or participation in schemes that have recognised welfare benefits.
This is another phrase with no legal definition. In our analysis of chicken labelling we found Asda stating that its chickens are reared to 'high welfare standards' and Aldi using the phrase 'higher welfare'.
Lidl uses a self-designed 'higher welfare' logo.
While not technically inaccurate, as the chicken from these supermarkets is Red Tractor certified and reared using natural light, which is above EU and British standards, these supermarkets are not noticeably exceeding the standards offered by any of the other supermarkets with the exception of Iceland.
All of the other supermarkets we investigated either used the Red Tractor logo or state in their welfare policies that they meet Red Tractor standards as a minimum. They also all offer natural light.
Waitrose and Marks and Spencer offer additional space for their chickens (a maximum 30kg/sq metre as opposed to Red Tractor's 38kg/sq metre).
Iceland was the only supermarket we looked at that had fresh chicken breasts that came from the EU (from Poland). As they are not British, they cannot be Red Tractor certified. EU standards do not require natural light or enrichment.
Several supermarkets use picturesque-sounding farm names on their packaging.
Aldi uses Ashfield Farm; Lidl, Birchwood Farm; Marks and Spencer's, Oakham; and Tesco, Willow Farms.
However, these are brand names and do not relate to any of the actual farms that are involved in their supply chains.
In fact, the vast majority of the chicken we buy in the supermarkets comes from three suppliers who own farms all over the UK: 2 Sisters, Moy Park and Avara Foods.
Watch out for images that have the potential to mislead about animal welfare.
We spotted imagery on one of Tesco's ranges that could suggest the chicken lived and roamed outside, when in fact the bird is likely to have had the space equivalent to an A4 piece of paper by the time it was fully grown, after a life spent indoors.
Asda uses Butcher's Selection for one of its fresh chicken ranges, Iceland has Butcher's Market, and Tesco uses Butcher's Choice for some frozen chicken produce. But these are merely brand names, they don't tell you anything about welfare.
If you want to ensure certain welfare standards, labels to look for include Red Tractor, RSPCA Assured or anything labelled free-range or organic.
These labels guarantee that the farms rearing (and the slaughterhouses killing) the chickens have to adhere to certain standards. These vary considerably between schemes.
Here's how the various schemes compare against some key indicators for welfare: