As we know, a new year is always a good time to take stock of what we are doing and why we are doing it.
The latter part of last year saw discussions about the feasibility of increasing stocking rates for free range laying hens on range, closer to the EU maximum rate of 2500 hens per hectare of range. This was being considered to assist producers in responding to the increased demand for free range eggs from existing premises.
It gave many of us the opportunity to assess the possible effects this might have on ranging activity and bird welfare.
As veterinarians we always try to look to the science and practical implications of any such changes. Unfortunately, when you search through the scientific literature, there is a distinct lack of detailed research into the implications of range stocking density. The publications that are available tend, understandably, to relate to more general assessments of welfare outcomes of different systems where range use may be just one of the factors that has been considered. The few studies that do look more specifically at range use tend to involve small flock sizes, eg less than 500 birds and even then a large number of other variables such as range cover, breed of bird, layout of premises, feed provision and programme which tend to complicate the issue.
The pros and cons
This leaves us with looking at practical experience and "gut feeling" about what we think would be in the best interests of the bird.
Clearly the ethos of effective free range production is to give laying hens the fullest opportunity of access to their range area. Some of the perceived advantages include:
• An ability to forage and express
investigative behaviour.
• A potential for general
environmental enrichment.
• A reduction in stocking density in
poultry houses during daylight hours.
As all of you with practical experience know, such advantages need to be balanced against some of the potential problems access to range may present. On different sites these might include:
• Increased exposure to internal
parasites.
• Exposure to bacterial and viral
challenges, including exotics like
avian influenza but, more commonly,
day to day problems such as
Brachyspira and E.coli.
• Contact with pests and wild birds.
• Possible predation or theft.
• Sudden stresses, eg hot air balloons,
low flying aircraft etc.
• Exposure to extremes of climate or
inclement weather.
• Your birds are "on show" even if
they are poorly feathered.
Clearly, to fully benefit from some of these advantages, a large proportion of birds must range well to utilise the space and enrichment offered and hence reduce the impact of some of the suggested disadvantages.
What is "good" ranging?
One then has to consider what a definition of "good" ranging behaviour might include. This must involve a consideration of the time spent on range, the distance travelled away from the house and what proportion of the flock is actually taking advantage of the opportunity to range.
As we know, ranging behaviour is influenced by a large number of factors. These can include climatic factors (eg temperature, wind, rain, season) as well as the provision of cover (trees, vegetation or artificial), pophole design, size and number, site location, feed provision and pattern, flock size, breed and probably many other factors.
From the available literature, estimates of the proportion of birds ranging at any one time vary greatly, typically less than 10% but sometimes in excess of 50%. Even when many birds are outside, most generally stay close to available housing unless there is extensive external cover or feeding provided. It is not clear whether this relates to a fear response or gregarious (flocking) behaviour.
So what about flock size?
Some research has shown that the size of an individual flock can influence the percentage of birds actually ranging, with larger flocks ranging less well. Conversely, birds in small flocks don’t necessarily range further any from the house. Again in such research the effect is compounded by many other factors such as feeding regime, quality of pasture, range cover etc.
One of the biggest health headaches for free range production is heavy faecal contamination of poached pasture and puddles close to the house by birds not ranging far from the popholes. Birds exposed to such an environment, encouraging them to drink from dirty puddles on range, can suffer significant negative impacts on their health and welfare. As previously discussed in the Ranger, these problems can include worms, Brachyspira and Blackhead, all of which can have a detrimental effect on gut health, production and body weights.
So what can we conclude from all this?
From the literature and producer’s experience, there is no clear cut evidence that increasing the numbers of birds per hectare of range would necessarily compromise health and welfare in its own right. On the other hand, what is crystal clear is that the quality of range including good drainage, pasture cover and lack of puddles and poached or bare areas of soil has a major impact on bird health and welfare. The specific EU regulation on free range production (557/2007) requires that "open air runs to which hens have access must be mainly covered by vegetation". If we are all honest with ourselves, even at low stocking rates it can be a real challenge to comply with this requirement to provide pasture that is "mainly covered with vegetation" at all times of the year. What this means in practice is that to really safeguard bird health and welfare it is best to concentrate on the welfare "outcomes" (how many birds actually range, how far they range and how good the quality is of the pasture they are ranging on), rather than getting hung up on welfare "inputs" (such as flock size and meticulous calculation of theoretical numbers of birds per hectare of range provided). It is a clear case of quality not quantity!
Our advice for a practical New Year’s resolution for producers is to take a fresh look at pasture management on your farm:
• Concentrate on effective us of
popholes in different weather
conditions.
• Ensure pasture is adequately drained.
• Consider fencing off any wet, poached or puddle areas of range during wet weather.
• Work on an effective pasture rotation
to ensure paddocks are rested
sufficiently to ensure that all
available range remains "mainly
covered with vegetation".
• Experiment with cover on range to
encourage birds to range effectively
over the area you have provided
them.
Attention to detail here will help you manage your birds and their range to an optimum for best bird welfare and best egg production.
When considering range provision and management remember – quality not quantity.
Stephen Lister, Claire Knott & Philip Hammond
Crowshall Veterinary Services
www.crowshall.co.uk
