Do slow growing meat chickens have better welfare than fast growing meat chickens?

In Australia, the two predominant commercial breeds of meat chicken are conventional fast-growing breeds. These breeds have been selectively bred over time to rapidly gain muscle mass and reach slaughter weight at 4-5 weeks of age to meet production and consumer demands. Genetically selecting for fast growth has led to an increased risk of meat chickens having significant welfare concerns such as skeletal abnormalities, lameness, and metabolic diseases. The development of slow-growing meat chicken breeds aims to address these welfare concerns and these meat chickens gain muscle mass more slowly and reach slaughter weight at a later age.

What is the difference between fast and slow-growing meat chickens?

Meat chickens can be differentiated based on whether they are conventional fast-growing or slower growing breeds. A conventional fast-growing meat chicken gains on average >60 grams per day, whereas a slow growing meat chicken gains on average <50 grams per day ​[1]​.

Compared to conventional fast-growing breeds, slow-growing breeds have shown improved welfare outcomes for walking ability, foot and leg health, feather cover and dirtiness, mortality rate, and behaviours associated with positive welfare [​1–3]​. Therefore, using slower growing meat chicken breeds has been suggested as one possible solution to address some of the animal welfare concerns associated with fast growth rate in conventional meat chickens.

Do slow-growing meat chickens have different welfare considerations?

A number of behavioural and physical differences between fast and slow-growing meat chicken breeds have been identified. These differences should be considered to ensure housing and management systems are suited to the particular breed of meat chicken and good animal welfare outcomes can be achieved.

Behaviour

The behaviour of meat chickens, regardless of their breed, differs between males and females, and changes with age. Meat chickens become more inactive as they age mainly because they are getting bigger and gaining weight. However, slow-growing breeds are generally more active than fast-growing breeds. Slow-growing meat chickens have been observed to spend more time walking around, foraging (i.e., scratching at the ground and in litter), and perching, while fast-growing meat chickens spend more time sitting, eating, and drinking​ [4–9​].

The better physical ability and slight differences in behaviour of slow-growing meat chickens means they may need more perches, ramps, and environmental enrichment than fast-growing meat chicken to fully satisfy their behavioural needs. Slow-growing meat chickens are also kept for several weeks longer before they are slaughtered and therefore have more time to benefit from being provided perches, ramps, and environmental enrichment in their housing systems.

To read more about why environmental enrichment is important for meat chicken welfare, click here.

Space allowance

All meat chickens need enough space to exercise, explore, peck, dust bathe, forage, and rest. Housing fast and slow-growing meat chickens at higher stocking densities can increase the risk of negative welfare outcomes.

Slow-growing meat chickens housed at stocking densities of 30kg/m² and lower have been shown to have improved foot and leg health. At these stocking densities, slow-growing meat chickens have also been shown to be more likely to perform comfort (e.g., preening and dustbathing), exploratory (e.g., foraging and pecking), and active (e.g., socially interacting, running, jumping) behaviours which have been associated with improved health and welfare outcomes​ [2,8,10–13]​.

To read more about how much space meat chickens need, click here.

Housing systems

The two most common housing systems for meat chickens in Australia are indoor and free-range systems. In indoor housing systems, meat chickens are kept in large sheds with litter covering the floor, while in free-range housing systems meat chickens are kept in similar sheds but provided outdoor access during the day once they are fully feathered and able to regulate their body temperature, which is usually around 21 days of age. This means fast-growing meat chickens slaughtered at 4-5 weeks of age have outdoor access for 1-2 weeks, compared to slow-growing meat chickens who will have outdoor access for longer depending on the breed.

In addition to having more time to use the outdoor range area, slow-growing meat chickens appear to adapt better to free-range housing systems. In free-range housing systems, slow-growing meat chickens have been observed to better use and interact with the outdoor range because they are more active and they therefore tend to forage, explore and interact with enrichment more than fast-growing meat chickens​ [7,14,15​]. Slow-growing meat chickens have also been shown to be more resilient in hotter climates than fast-growing meat chickens [​13,16,17].

Are slow-growing meat chickens available in Australia?

Slow-growing meat chicken breeds have been developed and are available in some countries, including in Europe. In Australia the availability of slow-growing meat chicken has been limited mainly because importing and establishing new genetics takes several years and slow-growing breeds are generally cost more to farm and therefore result in a higher- priced chicken meat product. However, as of 2023, slow-growing meat chicken products are now available in major supermarkets in Australia.

Slow-growing meat chickens could become more widely available in Australia if more slow-growing breed genetics were imported and breeding programs developed. Consumer demand and consumer willingness to pay for the increased cost of production would be an important trigger for this to occur. While meat from slow-growing meat chickens will likely cost consumers more than conventional chicken meat, increasing the availability of slow-growing genetics in Australia would have significant positive animal welfare impacts and provide Australian consumers with additional choice when purchasing higher-welfare chicken meat products.

What is the RSPCA’s view on slow-growing meat chickens?

The genetic selection for fast growth in meat chickens has led to a number of significant animal welfare concerns including an increased risk of skeletal abnormalities, lameness, metabolic diseases, and higher rates of mortality. The RSPCA encourages the meat chicken industry to implement breeding programs that optimise welfare and increase the proportion of slower growing genetics in the Australian meat chicken flock. However, until slow-growing meat chicken breeds are more widely available in Australia, the RSPCA remains committed to ensuring and improving animal welfare for all meat chickens.

The RSPCA has produced Meat Chickens: Challenges and priorities for good animal welfare which highlights key areas where welfare can be improved, how this might be achieved and a clear indication of our expectations for the future of meat chicken farming for the industry and retailers.

The RSPCA also works closely with farmers through the RSPCA Approved Farming Scheme. Today over 80% of meat chickens in Australia are raised under the RSPCA Standard for meat chickens and as a result are provided increased space to move freely, adequate lighting intensity and duration, good quality litter, as well as perches and environmental enrichment.