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Heat Stress in Poultry

March 5, 2015

OLYMPUS DIGITAL CAMERAAs an outdoor operation, there is little we can do to control the weather. Our birds have shelters to go into, a place that is dry but in cold weather and heat they are not in a climate controlled barn. Some would say they should be, but when farms DO have climate controlled barns then it’s “horrible” because they’re confined.

As yesterday’s post showed, when that climate controlled barn goes wrong or is tampered with, the results are deadly for birds. Like people, livestock gets used to steady temperatures. While newly hatched chicks need warmth, by the time birds are feathered out the cooler temperatures are fine. When there is a sudden increase, heat stress can take a toll. While 115 might be sauna warm to us, it’s also a point that it’s not recommended to be in a sauna for very long. Pets in overheated cars die with temperature increases.

Visual 2 (Living or Dying with a Hostile Heat Environment)600x72pxWhat about chickens? At mid 80s with high humidity, birds can be in dire circumstances quickly. Birds deal with heat by panting open mouthed, and often spread their wings to disperse the heat. In normal weather on a summer day, plenty of water, shade, and care make a difference. Birds in a barn, with the temperature altered to 115*, don’t have that option. It’s just HOT and there’s no escape.

The ph level of the blood rises and that of cells drops. Gene function is altered. Bicarbonate is lost, and stress hormones appear in the blood. Heat shock proteins are activated to shut down metabolic reactions and to protect heat-sensitive tissues.Added to this, broiler breeds don’t handle weather increases well – that’s not something they are bred for. These things may not be visible but are affecting the birds facing heat stress. Their core body temperature increases.

Up to 80% of heat is dispersed with panting – up to 250 breaths per minute – mediating evaporative cooling from the surface of the lungs. Increased urine, wet droppings, loss of electrolytes happen if there’s no relief. They’ll spread their wings, laying flat on the ground trying to disperse heat. In hot weather fans help circulate air, increasing bird comfort. In a closed barn, this isn’t an option. Electrolyte balance and mineral absorption is altered.  Stupor, convulsions and death follows.

20140901_184622More on heat issues in poultry can be found here. Electrolytes are needed to help the bird function or restore function. Just water isn’t always enough, and without relief from the heat birds suffer.

All types of systems have advantages and disadvantages, from barns to pens to pasture. Heat is something that is important to control as much as possible, but for those using climate controlled barns, it’s not expected sabotage of the system will be done to inflict suffering on birds. While an automatic alarm at any 10 degree or more difference would help, if someone shuts the alarm off, there is nothing that can be done for the birds.

Unfortunately, it’s no longer just the weather farmers must be concerned about – theft and deliberate destruction of birds and other livestock is a real threat. That makes a difference in the willingness to open operations up to visitors, which are difficult at best for the welfare of the birds. The risks are real. Heat stress is real and no longer a summer time only threat.

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