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Yes, chicken can also be depressed, here is why

By Dr Watson Messo

Gumboro disease is scientifically known as Infectious bursal disease (IBD). It was first described in a village called Gumboro in USA but has since spread to the rest of the world. It is a disease predominantly affecting young birds and associated with rapid onset, whitish diarrhoea, depression and high death rate. In dense poultry farming area, when it occurs, you will hear farmers complain of my birds are feeling cold, ‘wamevaa kabuti’ meaning they are wearing a coat.

What causes Gumboro?

It is caused by a tiny micro-organism called a virus belonging to a genus of Birnavirus. Once this virus enters the chicken house, it is consumed, and it migrates to the lymphoid tissue called Bursa and multiplies. It destroys the ability of the bird to fight diseases as it attacks the lymphatic tissues and renders birds vulnerable to any infection (immuno-suppressed).

How does it spread?

The Gumboro virus spend their lifetime in birds of the air, wild poultry, poultry manure from where they are transported by people, darkling beetle, rodents and pets into our poultry farms. These viruses are stable and will be spread by contact through inhalation, consumption of contaminated water or feed. It is not passed from mother- hen to chick.

How do you detect the disease?

This disease only affects young chickens and therefore will only occur in broilers between the age of day 21-28 while in slow growing birds like layers and improved Kienyeji, it will be seen at the age of week 3-8. It cannot affect birds in egg production since it only multiplies in the Bursa which disappears with age. Affected chickens go off-feed, appear depressed, ruffled feathers, will huddle together and will pass whitish watery diarrhoea.

If flocks were not vaccinated at all, mortality can reach up to 30 per cent. If you are a keen farmer who keeps records of all visitors getting into your poultry unit, this disease out-break normally coincides with a visit three to four days ago, from an infected farm. If you call your vet for a postmortem examination, the most outstanding feature is reddish discolouration of the thigh and breast muscles due to hemorrhages. The Bursa at the back of the tail will also be swollen and full of gelatinous fluid or completely be red in severe infection.

Is there any treatment to Gumboro disease?

Unfortunately, there is no known treatment once birds are affected. You can however put them on liver and kidney stimulants like Hepaturyl, Livergen or Bedgen 40 for three to five days. You should avoid any use of antibiotics during illness. The course of the disease is for 7-8 days after which the affected birds recover.

How do you control Gumboro disease?

Vaccination

The most common line of controlling this disease is still multiple immunisation. It is important that the breeding companies have a good vaccination programme for the mother hen with the use of two live and one killed strain of vaccine at week 18 before production of hatching eggs. This will confer enough immunity that will be passed down to the progeny, this is referred to as maternally derived antibodies (MDAs) which will play a major role in protecting the young chicks. Some breeding companies are also immunising all chicks at the hatchery against Gumboro using vectorized or antibody-antigen complex vaccines that give prolonged protection to the chicks’ way down after their MDAs have waned.

Biosecurity

The next important tool is good bio-security program. This always involves all measures needed to keep flocks free from disease causing organisms. It involves education of all personnel involved in your poultry production on the importance of keeping flocks safe and what is required of every member involved in the value chain. The immediate vicinity of the chicks is considered ‘clean area’ while anywhere outside the chick environment is considered ‘dirty area’.

 Anything moving from dirty to clean area must be subjected to thorough cleaning and disinfection to prevent any introduction of disease-causing organisms. At the end of the crop, the units must be cleaned and disinfected before a new lot is allowed in. Avoid keeping flocks of different ages in one site and finally, ensure there is a good pest control programme on the farm.

[The writer is the Head vet at Kenchic. Send queries to [email protected]]

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