ISSUE FOCUS FEED & ADDITIVE MAGAZINE July 2025 41 to estimated economical losses of about $1,5 billion per year in the United States alone. ENVIRONMENTAL AND NUTRITIONAL INTERVENTIONS Offering shade on pastures and optimizing ventilation in the barn are measures to be taken to alleviate the impact of heat stress. Unlimited access to clean water and the use of misters and sprinklers are additional steps to make animals more comfortable. On the nutritional side, it has to be considered that the lower dry matter intake inevitably leads to a lower number of nutrients which are available for absorption. In addition, absorption efficiency is negatively impacted. Ruminally undegraded protein should be optimized and the balance between nutrient density on one hand and adequate fiber content and energy density on the other hand should be maintained. The use of electrolytes is recommended to stabilize the blood acid-base chemistry. In addition, feed additives can be implemented to further support dairy cows during heat stress periods. Here, a standardized blend of isoquinoline alkaloids (IQs) has shown promising results already in broilers, swine, and ewes under heat stress conditions. IQs are known for their well-documented mode of action on inflammation and stress management. STUDY DESIGN AND OBSERVATIONS To assess the effects of IQs supplementation on dairy cows under summer conditions, a field study was conducted in Italy and overseen by the University of Milan. The study started in June and lasted 13 weeks. 116 multiparous HF cows were enrolled in the study and divided into two groups (Control and IQs; n = 58), balanced by parity, days in milk, and total milk production of the previous lactation. The Temperature Humidity Index was calculated daily and indicated moderate heat stress for the trial period, with values between 70 – 77. IQs were added to the TMR of the treatment group (12 g Sangrovit® Feed / head / day). A routine analysis of the TMR (same TMR used in both groups) revealed that the TMR was contaminated with DON, indicating mycotoxicosis. As heat stress has a negative impact on the gut integrity, higher amounts of mycotoxins can reach the bloodstream and cause additional health issues, such as lameness, mastitis, and fertility. OUTCOMES AND PRACTICAL IMPLICATIONS On average, IQs supplementation led to a significant (p ≤ 0.05) increase in milk yield by 2.8% (Figure 1). The effect became more pronounced after a trial period of eight weeks. No differencControl 1 2 3 4 5 6 7 8 9 10 11 12 13 Study Week Milk yield was increased by 2.83% (0.85 I/animal/day; P<0.05) * P < 0.05 ** 0.05 ≥ P ≤ 0.01 Control (n=58): 30.04 ± 3.9 I IQs (n=58): 30.89 ± 4.3 I Milk Yield (I) 35 33 31 29 27 25 IQs Figure 1. Effect of IQs on milk yield
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