ISSUE FOCUS FEED & ADDITIVE MAGAZINE June 2022 25 What are some signs that indicate birds are experiencing heat stress? The list is extensive. Clinical symptoms can include panting, lethargy, lower feed intake, poor average daily gain, higher feed conversion ratios and a drop in production or performance. In layers, high temperatures can correspond to a noticeable decline in daily egg production and the situation may adversely influence elements like egg mass and shell quality. How can high heat conditions affect a bird internally? The negative effects of heat stress, such as generation of free radicals, antioxidant imbalance, intestinal hypoxia, and gut barrier integrity disruption happen prior to the occurrence of clinical symptoms (e.g. panting, drooling, reduced feed intake) (Varasteh et al., 2017). Therefore, it is of crucial importance to have preventive strategies in place before heat stress is expected to occur. Traditional strategies to manage harmful effects of heat stress have focused on reducing oxidative stress alone. Birds can develop “leaky gut” or internal damage to the intestinal track allowing for easier movement of pathogens and hampering immune system function. They also can generate larger amounts of cellular-damage-causing free radicals and may see increased blood pH, which can lead to electrolyte imbalances. However, with the more recently uncovered mechanisms suggesting a direct effect on the GIT in mind, new heat stress strategies have a twofold approach: reducing oxidative stress and supporting gut health. Gut health can be supported through Betaine, high level copper and organic acid products especially during heat stress conditions. What management practices can help prevent or mitigate heat stress? Producers should take a holistic approach of feed, farm and health management to defend against heat stress. The general management practices include reducing bird density, feeding during cooler parts of the day, reducing dietary protein levels, and adjusting nutritional density, or covering water tanks and flushing warm water out of a system to provide colder drinking water. But not all of these options may make sense based on the cost or infrastructure investment. For example, refrigerated water can be challenging to supply to birds in some regions. Also, some production environments traditionally have open houses, which
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