Nutritional considerations during summer months (Poultry Specialist)
(Editor’s note: Jennifer Timmons is an assistant professor at the University of Maryland Eastern Shore.)
The summer months are upon us, and the focus to keep birds comfortable during hot weather is probably on the forefront of growers minds.
From a management standpoint, growers are always inspecting fans, cool pads, drinkers, bird distribution, generators — this list could go on; to ensure bird comfort.
However, understanding how birds maintain their body temperature when environmental temperatures rise will allow growers to be more effective managing their houses for better bird cooling.
Birds, like mammals are warm blooded and must maintain a fairly constant internal temperature around their core or internal organs.
When it comes to maintaining their body temperature, birds have an outer shell which includes their skin and feathers and the temperature of the shell can vary.
The shell functions to protect the core from large losses or gains of heat. In hot weather, vasodilation occurs (widening of blood vessels to increase blood flow) which increases blood flow to the outer shell.
This is to increase the transfer of heat from the core to the shell and then release the heat to the environment.
A bird rids itself of excess heat primarily in two ways: it loses heat to the air around it, and it loses heat through evaporation of water from its respiratory system.
The birds’ ability to release excess heat to the environment becomes less effective when the environmental temperature increases.
As the birds’ internal temperature rises, the birds will become heat stressed.
High temperatures can cause a metabolic chain reaction than can result in reduced feed consumption, decreased weight gain, in some cases damage to organs and death.
When birds consume a meal, heat is generated during digestion which increases the birds’ body temperature.
It has been reported that there are some feed ingredients such as fiber and protein that generate more heat during digestion than other ingredients.
Research has suggested that feeding individual amino acids in place of feed protein (bound amino acids) may allow birds to be able to digest protein easier which may have a positive impact on lowering body temperature.
When blood flow is redirected to the skin for cooling purposes, this could cause a decrease in organ function.
The ability of the intestinal tract to digest and absorb nutrients may be reduced and may also cause inflammation and organ damage in the long term.
A Feed Strategy article published in July 2020, suggested that supplemental vitamin C which is an antioxidant may reduce some of the negative effects of organ function caused by heat stress.
Heat stress can also lead to a condition called “leaky gut” when the intestinal tract lining is make up of a layer of epithelial cells.
These cells are bound together by complex protein structures called “tight junctions,” and they function to prevent pathogens and toxins from going through the intestinal lining into the blood.
Heat stress can weaken these “tight junctions.”
It has reported that zinc may have the potential to offset this damage by strengthening the bonds of the cells that line the gut and it may also help reduce the inflammation that has occurred in the gut as a result of any pathogen.
It is important to note that feed formulation alone will not eliminate the negative impacts of heat stress, but instead can be used as an additional tool or strategy to combat the effects of heat on broiler health and performance.
Maintaining cooling equipment such as fans and cool pads, providing easy access to water, managing bird migration are all management practices that help to maintain bird performance during the summer months.