ISSUE FOCUS 32 FEED & ADDITIVE MAGAZINE June 2024 humidity can reduce the effectiveness of evaporation. Increased water consumption is crucial, but severe heat stress may cause cows to stop drinking, leading to dehydration and other health issues. Advice is to implement heat stress management programs about three weeks before cows are expected to experience heat stress. This proactive approach allows cows to adjust, minimizing the adverse effects on their health and productivity. Effective heat stress management involves both managerial and nutritional strategies: Managerial Strategies: • Provide Shade: Ensure all cows have access to shade to increase rumination and milk yield while decreasing body temperature. • Ensure Adequate Water Supply: Increase water points and ensure high-quality water is available. Chilled water can further help in reducing heat stress. • Enhance Ventilation: Improve barn ventilation to keep the temperature close to outside levels, enhance convectional heat loss, and remove humid air. • Use Evaporative Cooling: Utilize cooling pads or atomizing nozzles along with strong ventilation to reduce barn temperature without increasing humidity. • Sprinkling: Sprinkling cows with cold water can be effective but requires large amounts of water and might lead to avoidance behavior if not managed well. • Maintain Bedding and Flooring: High-quality bedding and flooring can reduce the risk of lameness and encourage cows to lie down. Nutritional Strategies: • Adjust Feeding Times: Feed cows earlier in the morning and later in the afternoon to align peak heat load with cooler parts of the day. • Increase Diet Energy Density: Substitute roughages with concentrates to increase energy density and compensate for reduced DMI, though this needs careful balancing to avoid rumen pH issues. • Prevent Feed Heating: Add substances to inhibit microbial growth in feed, ensuring it remains appealing and reduces reluctance to eat. • Provide Nutritional Supplements: Use buffers to stabilize rumen pH, increase DCAD, and add prebiotics and probiotics to support gut health and immune function. Prebiotics and probiotics such as Selko® LactiBute® to improve gut integrity, to Selko LactiBute Effect on Heat Stressed Cows Figure 2. Effect of providing Selko LactiBute (2021) on milk composition from heat stressed grazing cows. The blue bars show THI and the green and gray lines show the fat and protein levels for 2020 and 2021. Fat level decreased in 2020 whereas in 2021, when Selko LactiBute was fed, the fats stabilise and rise even over heat stress. Source: Selko, 2021
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