Disease patterns

Ducks, we are told, suffer fewer of the 'standard' diseases than either chickens or turkeys - Marek's disease, infectious bursal disease (Gumboro), infectious bronchitis, fatty liver and kidney syndrome and rhino-tracheitis. Between them, these and other conditions account for a mortality of six per cent in intensive chicken and turkey houses, even under optimum conditions.

The duck industry portrays ducks as being tough and healthy. Cherry Valley boasts a 'livability of 95 per cent at 47 days of age' (1). This, however, indicates an expected five per cent mortality - not far short of the average figure for other types of poultry.

Five per cent mortality equates to 500 duck deaths in a flock of 10,000 birds before the age of 47 days. If this figure is rolled out to the 18 million ducks slaughtered in the UK in 2004, this would indicate that, annually, just under one million birds die before reaching 47 days. Undoubtedly, Cherry Valley's figure assumes 'best practice'. Companies worldwide will fall far short of this. A spokesman for Cherry Valley recently claimed below three per cent mortality based on the company's own flocks where husbandry may be better than the norm.

Five per cent? Three per cent? Sometimes a lot higher? The question remains - if ducks are relatively disease-resistant, why are they dying in such numbers? The very term 'infectious disease' points to the vulnerability of birds forced to live together in their thousands, without the benefit of fresh air and space around them.

UK diseases

The following are the most common causes of death amongst UK ducks from infectious diseases.

Duck virus enteritis (duck plague). A highly infectious disease caused by the herpes virus, it can cause mortality of up to 90 per cent. Ducks of all ages can be affected and vaccination is often used to control existing outbreaks rather than as a preventative measure.

Duck virus hepatitis (DVH). An acute and highly infectious disease with death following within hours of its onset. A live vaccine is available but vaccines are not magic bullets. Antec International admits that although vaccination plays an important role in the control of some of these conditions, disease frequently still occurs (2).

E. coli septicaemia. Potentially fatal, treatment involves dosing with a broad-spectrum antibiotic. It commonly attacks young animals, especially those kept under intensive and therefore stressful conditions.

Streptococcal septicaemia. Infection of the blood caused by the streptococcus bacteria.

Pasteurellosis. A common secondary invader following respiratory viral infections in poultry, including ducks. It can also cause fowl cholera and septicaemia in ducks.

Salmonellosis. Disease caused by infection with bacteria of the Salmonella type. Often attributable to stress. Can be spread via feed and water contaminated by faeces.

Aspergillosis. Invasion or colonisation of body tissues by a fungus, especially affecting the respiratory tract. It is often caused by mouldy litter - a constant potential problem because of damp litter in duck units.

Egg peritonitis. The main cause of death in laying birds - female breeders. It is probably linked to the unnaturally high output of eggs, achieved through decades of genetic selection. Post-mortem examination may reveal yolk debris, yolk caseous material or milky fluid in the abdominal cavity, together with inflammation and distortion of the ovaries as well as an offensive smelling mass of caseous material. Alternatively the oviduct may be obstructed by a core of inflammatory debris which may sometimes result in rupture of the oviduct wall. A whole or partly formed egg may be impacted in the oviduct and almost invariably, E. coli can be isolated from it (3).

Plantar pododermatitis. An ulceration of dead skin tissue under the foot caused by contact with damp litter and resulting in pain and lameness.

Starvation and injury

If the above diseases are not rampant and account for only a small part of the three or five per cent mortality, as producers claim, death must be from starvation or injury, possibly as a result of aggression. Also, breeding heavy birds causes suffering and sometimes starvation through difficulty in walking. The Council of Europe, in its Recommendations Concerning Domestic Ducks, states that 'Mallards fly, swim and walk efficiently but the heavier domestic birds, in particular those selected for meat production, may be unable to fly, have difficulty in walking and be subject to leg disorders' (4). Incredibly, in a letter to Viva!, Ben Bradshaw put forward Defra's official position that there were "... no problems observed with leg weakness in ducks." (8) This shows an alarming ignorance on Defra's part - be it willful or otherwise.

Also, in crowded conditions, ducks get knocked over by other birds and are often unable to right themselves. Even when put back on their feet it takes some time for them to reorientate themselves and they need to be watched for a while to make sure the same thing doesn't happen again. In the packed conditions of a shed containing up to 10,000 birds, it is likely that stranded ducks go unnoticed. They may be trodden underfoot by other ducks and die from injury or starvation. Cannibalism may follow, either before or after death. Cannibalism is caused by stress.

Antibiotics

There are currently four antibiotics currently authorised for use in ducks in the UK. These are Amoxinsol 100, Amoxinsol 50, Amoxinsol Proportioner and Aurofac 100 Granular (7).

Amoxinsol (containing amoxicillin) for the treatment of Streptococcus bovis, Pasteurella anatipestifer and E. coli.

Aurofac100 (containing Aureomycin chlortetracycline hydrochloride) for the treatment of respiratory and systemic infections.

A spokesperson for a leading drug company gave his opinion that ducks suffer from respiratory and other diseases but knew of no precise data on the percentage of antibiotics given to the duck sector of the poultry industry. Such figures are unlikely to be collated anywhere. In light of two major reports on antibiotic resistance in farm animals (Soil Association's The Use and Misuse of Antibiotics in UK Agriculture and the House of Lords Science and Technology reports), this is an unacceptable situation.

The Veterinary Medicines Directorate, an Executive Agency of Defra, holds no information separating ducks from other species in its figures for annual total usage of antibiotics (7).

Global diseases

Large numbers of intensively-reared ducks have been exported worldwide from the UK. World Poultry Misset (No. 7 Vol 13, 1997) provides a list of poultry diseases which can occur anywhere in the world. Those affecting ducks are in addition to those described above and include the following.

Adenovirus - associated with many diseases including respiratory disease and viral arthritis.

Amyloidosis - associated with infected lesions on the feet and amongst adults in heavier strains of commercial ducks.

Ascites - More often associated with chickens, it made its first appearance in birds kept at a high altitude. It is mostly caused by increased oxygen demand resulting from too-rapid growth in combination with restricted

blood flow through the small capillaries in lungs of birds selected for 'meatiness' (5). Avian influenza - Believed to be spread by close contact. Results in respiratory distress and depression. The

recent outbreak of the deadly H5N1 strain in Asia has been linked to ducks, which often do not show outwardsymptoms of infection. A notifiable disease. Avian malaria - Similar to the human form of the disease.Avian salmonellosisAvian staphylococcus - Associated with a wide variety of diseases including arthritis and tenosynovitis.Bacterial synovitis - An infection of the joints, tendons and surrounding tissues resulting in lameness. Fowl Pest (Newcastle disease) - Ducks show few signs of infection even with virulent strains of fowl cholera but

the disease can spread via ventilation apertures into the environment. Vaccines have little effect in overcrowded

conditions where management is poor and may even produce the disease. It is a notifiable disease. Keratoconjunctivitis (Ammonia blindness) - It is caused by ammonia in concentrations of 170ppm or more (6). Poorly managed, damp litter in badly ventilated housing can be instrumental in triggering this extremely painful disease, which can result in haemorrhages of the conjunctiva and corneal ulcers. Damp litter is a major problem in duck units and some countries tackle it by allowing only nipple drinkers or by keeping ducks on wire flooring.

Yolk sac infection (Omphalitis) - Often the result of poor conditions in hatcheries, it can cause 100 per centmortality in the worst outbreaks by infecting most organs.Perosis - Slipped tendon - a leg deformity in ducklings, causing lameness.

Tibial dyschondroplasia - A skeletal deformity associated with rapid growth and mineral imbalances.Cloacitis (Vent gleet) - An infection of the cloaca in breeding ducks and drakes - occurs particularly 'under dirtyconditions of husbandry' (6). Scarring can damage the vent, making egg laying and even defecating impossible.

Visceral gout - Caused by renal failure, it results in swelling and ulceration of the joints.Starve out - This results when young or injured birds fail to recognise or reach food and water points.Rickets - A nutritional disorder caused by lack of certain minerals, vitamins and trace elements.

Diseases of intensification

Birds have always suffered from a range of diseases and wild birds are implicated in the spread of some of the most serious threats such as Newcastle disease. However, many of the conditions listed above are the result of intensive farming methods.

The increasing popularity of duck meat both here and abroad will inevitably cause an escalation in the incidence of these diseases, guaranteeing large-scale suffering amongst the duck population. Recent, disastrous outbreaks of Avian Flu - both in Asia and Europe - have prompted fears of an inevitable pandemic. The World Health Organisation insists that free-range poultry are being infected by wild birds, who carry the virus but are not affected by it. The United Nations Food and Agriculture Organisation has placed the blame for the impending outbreak on livestock markets, poor biosecurity and the trade in live poultry and dismisses the charge that wild birds are responsible for its spread. The World Health Organisation, however, insists the answer is to put all poultry into factory farms - ignoring their past advice to end to all intensive farming. Which, if done, will also further accelerate the reckless over-use of antibiotics which is already a major human health problem.

Though killed while still, in effect, baby birds, modern ducklings will still have had time to endure much pain and discomfort before reaching the slaughterhouse. It is likely that their entire life, no matter how short, will be one of acute stress and perhaps disease and severe pain.

References (part seven)

1. Cherry Valley, Super M2 information booklet
2. Antec International, Poultry Disease Control Programme
3. Poultry Diseases, Ed. F.T.W. Jordan, Bailliere Tindall, 1990, p39
4. Council of Europe, Recommendation Concerning Domestic Ducks, 1999, Article 3(d)
5. As 3
6. Cook, JKA et al., Diseases of Ducks, Poultry Diseases, 1996
7. Email to Viva! from Dr Kay Goodyear, Defra’s Veterinary Medicines Directorate, 2005
8. Letter to Viva! from Ben Bradshaw MP, Minister forNature Conservation and Fisheries, 26 July 2004