BONUS SPRING SUMMER 2025

Age (days) Temperature (min–max) Relative humidity (%) 1–3 30°C–33°C 60%–70% 4–6 28°C–30°C 60%–70% 7–9 26°C–28°C 60%–70% 10–12 24°C–26°C 60%–70% 13–15 24°C–25°C 60%–70% 16–18 23°C–25°C 50%–60% 19–21 22°C–24°C 50%–60% 22–24 21°C–24°C 50%–60% 25–slaughter 20°C–24°C 50%–60% Table 2: Temperature and relative humidity (RH) guidelines for broilers. Regular checks help identify issues early, allowing for timely interventions. Behavioural monitoring also aids in detecting any signs of illness or discomfort related to environmental conditions. Maximum ventilation is used to achieve a high rate of air exchange, generally during warm weather or when older birds generate more heat. This system is designed to expel large volumes of warm, humid air and bring in cooler, fresh air to maintain optimal temperature and remove high levels of gases like ammonia and carbon dioxide. Maximum ventilation uses more fans or larger inlets, providing increased airflow. Figures 1 and 2: Open-sided broiler house curtains set for minimum ventilation (left) and maximum ventilation (right). Effective winter management requires understanding these conditions: 1. Hypothermia: Prolonged exposure to low temperatures reduces body temperature, weakening immunity, slowing growth, and increasing mortality. Signs include shivering, lethargy, and reduced feed and water intake. 2. Pneumonia: Cold stress can impair respiratory health, increasing pneumonia risk, especially with poor ventilation and high humidity. Symptoms include coughing, nasal discharge, and laboured breathing. wellbeing. Healthy broilers are active, feed regularly, and exhibit normal social interactions. In contrast, lethargy, poor feed intake, and huddling are signs that the birds may be uncomfortable or stressed. Controlling air quality: minimum versusmaximumventilation Minimum ventilation involves a low level of continuous or interval pulsed airflow to ensure air exchange without significant heat loss, typically used in cold weather or when birds are young. This is done to provide small amounts of fresh air into the house to remove excess moisture, carbon dioxide, and ammonia, helping maintain air quality without compromising warmth. Minimum ventilation is typically achieved through intermittent fan operation and small inlets, ensuring a steady, but minimal air movement. Spring/Summer 2025 BONUS www.agribonus.co.za 4