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The

Report

No. 42: Correct beak trimming resolves poultry welfare issue

THE FULL REPORTS

This is a summary of the unpublished RIRDC full report titled “Preventing chronic pain developing in layers subject to beak trimming and re-trimming” by Dr Philip C Glatz (phone 08 8303 7786, fax 08 8303 7797), Dr Christine Lunam, Dr John Barnett and Dr Ellen Jongman. A copy of this full report ($10) is available from Dr Irene Gorman on phone 02 9570 9222, email irene@aeia.org or view on the RIRDC website: www.rirdc.gov.au

Commercial laying hens beak trimmed to Australian Practice standards do not suffer severe chronic pain, as previously thought, according to research funded by the Rural Industry Research and Development Corporation (RIRDC).

For many years beak trimming has been controversial, with welfare groups closely scrutinising the practice. Some welfare groups believe the practice should be banned or at least not carried out routinely. The egg industry has responded that it is an essential practice in Australia to control injury and death from aggressive pecking in hens housed intensively. Beak trimming is estimated to reduce bird deaths from aggressive pecking by 25 per cent. The egg industry says that if beak trimming is banned in Australia, all hens will have to be either housed in individual cages or in light-proof sheds.

The major objection to trimming has been the perception that it may induce chronic pain through the formation of traumatic neuromas (bundles of tangled nerve fibres) in the beak stump. However, recent research indicates that neuromas formed when hens are moderately beak trimmed at hatch disappear over time and that hens return to normal feeding and pecking behaviours after beak trimming.

The research – the most comprehensive evaluation of beak trimming yet undertaken – was conducted by Dr Phil Glatz of the South Australian Research and Development Institute, Dr Christine Lunam of Flinders University’s Department of Anatomy and Histology, and Drs John Barnett and Ellen Jongman from the Victorian Institute of Animal Science.
Supporting the findings by the Australian researchers, highly renowned UK poultry researcher, Dr Mike Gentle of the Roslin Institute, who previously held that beak trimming was likely to cause chronic pain similar to that experienced by some human amputees, reports in a new literature study (see box) that he now agrees beak trimming is unlikely to cause long-term pain if done correctly. But he says the procedure does cause some sensory loss, although it is not yet clear if this has any impact on the welfare of the hen.

The Study

The objectives of the Australian research were to:

prevent chronic pain in laying hens subject to beak trimming and re-trimming;
examine current welfare concerns attributed to beak trimming by providing sound scientific data for the assessment of chronic pain; and
recommend best practice for beak trimming of poultry.

In the evaluation, 40 one-day old commercial (White Leghorn x Australorp) chicks were beak trimmed soon after hatching. Half of them were designated to be re-trimmed at 14 weeks of age. Another 20 control chicks were not beak trimmed. The trimming – using methods described in the Australian Model Code of Practice for the Welfare of Domestic Poultry (1995) – involved using a heated blade on a commercial electric beak trimming machine to cut and cauterise for two seconds half the upper beak and one-third of the lower beak.

Chicks were housed in a brooding cage to four weeks of age and then in rearing cages until 18 weeks. They were then transferred to a climate room and housed individually in layer cages until the end of the experiment.
The birds were fed a chick starter mash for their first four weeks, a pullet grower mash to 18 weeks and layer mash after that.

During their first five days, the chicks were given an hour a day to peck at a red plastic block held by the handler and moved around the brooder. This encouraged the chicks to follow and peck at the moving block. Throughout the experiment, the block was placed in the feed hopper for an hour each week to provide the birds an opportunity to peck at the block.

This enabled the researchers to measure pecking with the results shown below in figures 1, 2, and 3.

Figure 1. Effect of beak trimming on number of cage pecks (error bar is l.s.d.) Figure 2. Effect of beak trimming on number of toe pecks (error bar is l.s.d.). Figure 3. Effect of beak trimming and retrimming on number of cage pecks (error bar is l.s.d.).

At age 14 weeks, 20 birds were re-trimmed using a heated blade that removed 2mm of upper and lower beak. The end of the beak was again cauterised with the heated blade for two seconds.

In previous studies, neuromas were present in all upper beaks at 10 weeks, but neuromas were not found at 70 weeks after moderate trimming at hatch. This indicates the neuromas develop and persist for at least 10 weeks before disappearing (resolving).

The new study examined whether chronic pain in the beak was evident in the hens at 10, 20 and 60 weeks after being trimmed at hatch. The second group of birds that were re-trimmed at 14 weeks were tested at 20 and 60 weeks of age.
Chronic pain was assessed by measuring pecking behaviour, pain responses and the presence of neuromas.

Code of Practice

The operator may remove not more than half of the upper beak and one-third of the lower beak. For day-old chickens this means removing not more than 3mm of the upper and 2.5mm of the lower beak. For 10 day old chickens this means removing not more than 4.5mm of the upper and 4mm of the lower beak. When required, re-trimming of hens should be performed at 12–14 weeks with 2mm of upper and lower beak removed.

The Results

If hens were suffering from chronic pain, the beak would feel sore, resulting in less pecking. However, it was found there was no difference in the total number of pecks made by beak-trimmed and the untrimmed control birds. In fact, beak-trimmed birds pecked more at the cage and had more toe pecks, indicating there was an absence of chronic pain.

The re-trimmed birds engaged in a greater number of pecks than both the control and once-only trimmed birds, also indicating an absence of chronic pain.

Beak sensitivity tests revealed that birds trimmed at hatch only, and birds re-trimmed at 14 weeks, showed more head shakes and head shakes per peck when drinking hot water and tended to use less force when pecking at a red disc than non-trimmed birds.

This provided some evidence that the beak of the trimmed birds might be more sensitive but there was no evidence that re-trimming resulted in a more sensitive beak than when hens were trimmed at hatch only.

Reduction in the severity of neuromas with age suggested that they develop after trimming and are in the process of being resorbed by 28 weeks of age. The presence of microneuromas in the upper beaks suggests trimming of one-half of the upper beak is the critical amount of tissue that can be removed without the development of persistent neuromas.

The absence of neuromas at 66 weeks in the lower beaks suggests that removal of one-third of the lower beak allows complete resorption of the neuromas prior to adulthood.

Sensory receptors were present in the upper beak and in the region of the bill tip organ of the lower beak after trimming. Re-trimming of 2mm had minimal effects on nerve and general tissue structure.

True or False?

Beak trimming is a severe mutilation of the beak - FALSE
Beak trimming is carried out by experienced operators according to a Code of Practice which states that not more than 3mm of upper and 2.5mm of the lower beak be trimmed in day-old chickens.

Beak-trimmed birds suffer severe pain from chronic neuromas for the rest of their lives - FALSE
When birds are beak trimmed according to the Code of Practice, neuromas resorb with time, nerves retarget receptors and birds do not suffer chronic pain.

Beak-trimmed birds have difficulty eating, drinking and using their beaks for other activities - FALSE
After beak trimming, birds regain full use of the beak and are able to engage in the full range of beak-related activities.

Beak-trimmed birds produce fewer eggs - FALSE
Beak-trimmed birds produce as many eggs as non-trimmed hens and are less susceptible to vicious attacks from other birds.

In the Australian egg industry, birds do not have to be beak trimmed - FALSE
Low light intensity reduces aggressive pecking in hens. However, the majority of hens in Australia are housed in open-sided sheds where light intensity cannot be controlled. Beak trimming can reduce the number of deaths due to cannibalism by up to 25%.

Summary

The research showed that beak trimmed and re-trimmed birds exhibit feeding and pecking behaviours in the long term that indicate they are not suffering chronic pain. There is evidence that beak trimmed birds use less force when pecking and this suggests their beaks might be more sensitive than those that have not been trimmed.

Implications for the Australian egg industry are significant, as the work establishes beak trimming as a practice that benefits bird welfare by reducing death and injury from aggressive pecking without causing chronic pain. In particular, the evidence that neuromas are frequently resorbed as birds age, disproves the long-held view that neuromas persist through the birds’ life.

Before this new research, it was considered that the beak trimming procedure was too traumatic for the bird and should be banned or not be routine. This project has shown that hens trimmed soon after hatch to the Australian Code of Practice standard give no indication that they suffer chronic pain.

Figure 1. Effect of beak trimming on number of cage pecks (error bar is l.s.d.)	Figure 2. Effect of beak trimming on number of toe pecks (error bar is l.s.d.).	Figure 3. Effect of beak trimming and retrimming on number of cage pecks (error bar is l.s.d.).