A poultry house holds thousands of birds of the same age, sharing air, water and feed.
When a disease gets in, it can spread through the flock in days.
And cold weather adds its own risks: chilled chicks, stale air, wet litter, and viruses that survive longer in the cold. Newcastle disease virus survives for weeks in cool droppings and litter,
and avian influenza virus survives a long time in cold water and faeces.
In this video: why management comes first, brooding in the cold, air and ammonia, litter and coccidiosis, the respiratory diseases, Newcastle disease, avian influenza, reading your mortality records, biosecurity and vaccination, and safety. The advice is general and global.
Your veterinarian and national rules always come first.
Laisha's poultry manual puts it plainly.
Most disease in commercial flocks is a management failure before it is a microbiological one: chilled chicks, wet litter, poor ventilation, broken biosecurity, or a vaccine given wrongly.
Many calls that look like disease turn out to be chilling, a water failure or a feed error.
So before you handle a single bird, walk the house. Check the temperature, the ventilation, the litter, the lighting and the equipment.
Then look at the birds.
Brooding is the care of chicks from placement until they can control their own body temperature, usually two to four weeks.
A chilled chick eats less, uses its yolk poorly,
and grows a smaller gut and immune system.
Early mistakes show up later as poor uniformity, deaths and poor feed conversion.
Preheat the house long enough that the floor and the litter are warm, not only the air. A cold concrete floor under warm air still chills chicks.
Strain guides typically start at the low to mid thirties, in degrees Celsius, at chick level under spot brooders, and fall by about two to three degrees each week. Keep humidity moderate, around sixty to seventy per cent, in the first days.
But the chicks are the real thermometer.
Comfortable chicks are spread evenly, eating, drinking and resting.
Chicks that are too cold huddle under the heat and cry loudly.
Chicks that are too hot pant, droop their wings and move away.
Chicks crowded to one side are usually avoiding a draught. And a few hours after placement, feel the crops:
most should be full and soft.
In cold weather, it is tempting to close everything up. But ventilation removes moisture, heat and ammonia,
and a house still needs minimum ventilation in the cold.
Closed, fan-ventilated houses are built to give exactly that.
Open-sided houses use curtains or shutters that are adjusted by hand or automatically.
Ammonia above about twenty to twenty-five parts per million is widely cited as harmful to the birds' airways and eyes.
Damaged airways let bacteria in.
Cold, poorly ventilated houses also raise the risk of ascites in fast-growing broilers, a heart and lung failure that fills the abdomen with fluid. It is controlled by growth rate, lighting, ventilation, diet and genetics, not by drugs.
Deep litter is commonly five to ten centimetres of wood shavings, rice husk or chopped straw, kept dry and crumbly by ventilation,
good drinker management and stirring.
Wet or caked litter raises ammonia, causes foot-pad dermatitis, breast blisters and hock burns, and favours coccidiosis. Spilt water is the commonest cause of wet litter, so set drinkers at the right height.
Coccidiosis is caused by Eimeria parasites that damage the intestine.
Their eggs, called oocysts, become infective in warm, moist litter within one to two days, resist common disinfectants, and survive for months.
Disease is commonest in broilers of three to six weeks and pullets on litter, with bloody droppings, poor growth and deaths.
Control combines anticoccidial feed programmes or live vaccines,
chosen with your veterinarian, with dry litter and sound drinkers.
Coughing, sneezing and gasping birds are a classic sign of trouble in a closed-up house. Four causes stand out.
Infectious bronchitis is a highly contagious coronavirus.
Chicks gasp, cough, have a nasal discharge and huddle.
Nearly every bird can be affected, but few die unless bacteria such as E coli follow. In layers, egg numbers drop, and shells become thin, soft or misshapen.
Mycoplasma gallisepticum causes chronic respiratory disease.
It passes through the egg and by contact, infected birds stay carriers, and stress triggers disease.
Combined with respiratory viruses and E coli,
losses rise slowly over weeks. The best defence is to buy chicks from breeder flocks certified free of it.
Infectious laryngotracheitis causes gasping with the neck stretched out, and coughing up blood-stained mucus. Recovered birds can carry the virus and shed it again under stress.
And colibacillosis, infection with harmful E coli,
often follows viral damage or poor air quality.
Biosecurity and good ventilation limit the losses from all of them.
Newcastle disease is usually the main killer in village and backyard flocks,
and it is notifiable almost everywhere.
Virulent strains cause breathing distress, greenish diarrhoea, twisted necks and paralysis, a sharp fall in eggs,
and deaths that can approach one hundred per cent in unvaccinated flocks.
In vaccinated flocks, there may be only an egg drop and a few nervous birds, so it is easily missed.
The virus survives for weeks in cool droppings and litter.
Vaccination with live and inactivated vaccines, plus biosecurity, is the control. For village flocks, heat-tolerant vaccines given by eye drop by trained community vaccinators, every three to four months, have greatly reduced losses in many African and Asian countries.
Wild waterfowl and shorebirds are the natural reservoir of avian influenza viruses.
Highly pathogenic strains, the H five and H seven types, cause sudden death of many birds, with deaths approaching one hundred per cent within days, swollen heads, blue combs and wattles, and bleeding on the shanks. Since twenty-twenty, one H five N one lineage has caused a panzootic in wild birds and poultry on several continents.
Prevention means keeping wild birds and their droppings away:
closed houses, covered feed and water, and controlled access.
Some countries issue housing orders in high-risk seasons.
Free-range flocks carry a higher risk of contact with wild birds. If you suspect avian influenza, report it at once to your veterinary authority.
Daily deaths are your early warning.
Here is the worked example from Laisha's guide.
A broiler house is stocked with ten thousand chicks.
Weekly deaths are eighty, forty, thirty, then suddenly three hundred and fifty in week four. That is three point six per cent in one week, far above the usual weekly zero point one to zero point two per cent at that age.
Sudden losses at three to four weeks, with ruffled feathers,
watery droppings and swollen or bloody bursas at post-mortem, suggest infectious bursal disease, or Gumboro. It also leaves survivors immunosuppressed, so they respond poorly to other vaccines.
The farmer should confirm with a laboratory,
review the vaccination timing, and tighten cleaning and disinfection before the next flock.
Biosecurity is the foundation.
Use all-in, all-out placement, with cleaning, disinfection and a rest period between flocks.
Keep one age per site where possible.
Control the entry of people, vehicles and equipment, with footbaths and a change of clothing. Keep out rodents and wild birds.
And buy chicks from tested, disease-free breeder flocks.
Vaccines fail for avoidable reasons: a broken cold chain, the wrong timing against maternal antibodies,
chlorinated water, Gumboro immunosuppression, or a strain the vaccine does not cover. Most vaccines must be kept at two to eight degrees Celsius.
For water vaccination, use chlorine-free water,
slightly thirsty birds, and enough drinker space for every bird to drink within about one to two hours.
Schedules vary by country and product, so follow the label and your veterinarian.
Now, safety, for you and for your customers.
Some avian influenza strains and some Salmonella can infect people. Wear protective equipment when handling sick or dead birds, wash your hands, and dispose of dead birds safely.
Report any suspicion of avian influenza or Newcastle disease.
Antibiotics treat only bacterial disease.
None helps a viral disease.
Use them only under veterinary guidance, at the label dose,
and respect the withdrawal period before selling meat or eggs.
Several antimicrobials are banned in food birds in some countries.
And never mix live vaccines with disinfectants.
To recap.
Walk the house before you handle birds. Brood on a warm floor, and let the chicks be your thermometer.
Ventilate even in the cold, and keep ammonia low and litter dry.
Know the respiratory diseases, Newcastle disease and avian influenza. Watch daily deaths.
And make biosecurity and correctly given vaccines your routine.
For more on poultry, livestock and every crop, visit laisha.ai. Thank you for watching.
