#heatawarenessday is today Friday 31st of May. The Heat Awareness Day is observed on the last Friday in May every year to remind us of rising temperatures due to climate change. The day was created in order to spread awareness to overcome high-temperature related issues.
The U.S. livestock production industry incurs an estimated total annual economic loss of $1.69 to $2.36 billion due to heat stress.
Heat stress in broilers and laying hens
Heat stress is one of the most important environmental factors impacting on performance of chicken. One of the main effects is reduced feed intake, with subsequent drops in growth rate, egg quality and egg production. Broilers subjected to chronic heat stress had a significant reduction of feed intake of −16.4%. Many studies have shown impaired growth performance in broilers subjected to heat stress. In laying hens, a 12-day heat stress period caused a daily feed intake reduction of 28.58 g/bird, resulting in a 28.8% decrease in egg production.
In general, birds react similarly to heat stress, but express individual variation of intensity and duration of responses, which may also be affected by intensity and duration of the heat stress event. increasing evidence indicates that much of the variation in response to heat stress is apparently genetically based.
Under high temperatures as the bird’s body attempts to maintain its thermal homeostasis, increased levels of reactive oxygen species (ROS) occur. Consequently, the body enters a stage of oxidative stress, and starts producing and releasing heat shock proteins (HSP) to try and protect itself from the deleterious cellular effects of ROS.
Oxidative stress is the starting point of the intestinal permeability dysfunctional process. Under heat stress conditions, increased concentrations of ROS occur leading to increased intestinal permeability, which in turn facilitates the translocation of bacteria from the intestinal tract and inflammation.
The detrimental impact of heat stress on bird performance, urges producers to implement suitable managemental strategies to minimize the production losses incurred through heat stress in the poultry industry.
Heat resilience in chickens
As breeding goals increased production efficiency, the susceptibility towards heat stress also increased in domestic chicken. So, in the current changing climate scenario, researchers are looking for a permanent solution to heat stress to sustain poultry production longer term. Differences between genotypes of chicken in heat resilience provide evidence for the possibility of genetic intervention, when it comes to heat stress in chicken. Several superior thermo-tolerant genes have already been identified by researchers such as the naked neck gene, frizzle gene or the dwarf gene, which made the bird resistant to heat stress through slow and reduced feathering, curling the feather so as to improve the heat dissipation and reduction in body size to minimize metabolic heat production. Further genes were identified that increase the thermo-tolerance of birds without compromising the production potential.
Feeding for resilience to heat stress
New nutritional concepts, such as gut agility activators, are designed to support the adaptive capacity and hence resilience of the bird by nutritional means. They help the bird to adapt to nutritional challenges by minimizing stress reactions including oxidative stress and reduced feed intake, that would otherwise impact performance, health and wellbeing of the bird. The gut agility activator Anco FIT Poultry has shown to maintain high feed intakes and reduce oxidative stress in birds under heat stress compared to control animals and thus maintain higher growth performance.
Felver-Ghant, J.N. et al. (2012). Genetic variations alter physiological responses following heat stress in 2 strains of laying hens, Poultry Science
Lara, L.J. and Rostagno, M.H. (2013). Impact of Heat Stress on Poultry Production, Animals MDPI
Vandana, G.D. and Sejian, V. (2018). Towards identifying climate resilient poultry birds. Journal of Dairy, Veterinary & Animal Research