ARTICLE FEED & ADDITIVE MAGAZINE September 2022 49 As heat stress reduces a sow’s feed intake, it can subsequently depress milk production, leading to reduced piglet body weight gain. In finisher pigs, a drop in feed intake will lower their growth rate. Every degree of increase in environmental temperature above 23 °C potentially reduces feed intake by 89 to 106 g (Huynh et al., 2005) in growing pigs, depending on the level of humidity. Feed efficiency is less influenced by hot conditions. Generally, a pig’s body tries to minimize the effects of heat stress by deploying two strategies: heat dissemination and reducing internal heat production. For heat dissemination, swine rely heavily on convective and conductive heat loss by increasing the body’s contact with the cool floor of the barn system, and by panting. A decrease in metabolic heat production is achieved mainly through reduction of feed intake. Under conditions of severe heat stress, animals can become more susceptible to immune challenges because of damage to the intestinal wall structure. When heat stressed pigs divert their blood flow to the skin to increase heat dissipation, the gastrointestinal blood vessels vasoconstrict to maintain blood pressure. This situation leads to fewer nutrients being absorbed to supply GI tract cells, which in turn leads to an observed reduction in growth or milk production. Adverse effects on cell wall integrity resulting from heat stress can lead to leaky gut and an increased risk for infections. If the animal’s respiratory rate continues to increase, it may lead to respiratory alkalosis that can be fatal. INFLUENCE OF TRACE MINERALS ON MITIGATING HEAT STRESS IN SWINE In addition to the internal mechanism’s pigs rely on to combat heat stress, nutritional interventions can support the animal in managing heat stress. Nutrition can provide a practical and cost-effective way to support the animal’s productivity and the producer’s business. The goal of heat stress feeding strategies is to formulate rations that reduce internal metabolic heat generation by increasing dietary fat and reducing the amount of crude protein or crude fiber. Dietary fat generates less heat compared to other nutrients. Dietary elements to consider feeding include essential nutrients like selenium, vitamin E, vitamin C, and zinc. These nutrients provide antioxidant properties that have immunomodulatory effects and could potentially reduce production losses during heat stress. Trace minerals play a crucial role in the development and maintenance of bones and maintenance of acid base balances. Trace minerals are also essential components for carbohydrate, lipid, protein, vitamins, metabolism, hormone production, immunity and intestinal function. But simply adding minerals isn’t sufficient. Precision matters when it comes to the type and level of trace mineral supplementation. During ration formulation, assuring that the minerals are provided at the right levels and that they are available to the animal is key to achieving pigs’ optimal health, welfare, and growth. Achieving the proper inclusion levels also minimizes the excretion of minerals into the environment, supporting environmental sustainability efforts. A diet excluding trace minerals or containing an insufficient supply will lead to deficiency symptoms and reduced performance. Excess amounts of trace minerals, on the other hand, may also lead to a reduction in performance and toxicity may occur. The amount of trace mineral content in raw materials is generally low and unpredictable, making the mineral premix of vital importance for proper trace mineral feeding. There are several sources available to deliver the ion metal. The proper source is a function of a mineral’s content, solubility, relative
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