WINTER BONUS MAGAZINE 2026

Temperature gradually decreases from 34°C on day 0 to approximately 22°C by day 42. Carbon dioxide levels reduce as ventilation improves, while humidity declines gradually to maintain optimal air quality and prevent moisture- related issues. 1.1 The first 21 days of a broiler’s life The first 21 days of a broiler chicken’s life are critical for growth and development. During this period, broilers rely heavily on external heat sources to maintain body temperature and support metabolic processes. Proper brooding conditions promote optimal feed intake, uniform growth, strong immune development, and reduced early mortality. Although birds begin developing feathers and improved thermoregulation after 21 days, they still require supplemental heating, particularly during cold weather conditions or at night when temperatures drop. 1.2. What happens after 21 days? Beyond 21 days, broilers produce more body heat and become more tolerant of environmental changes. However, this does not eliminate the need for supplemental heating. Maintaining thermal comfort remains essential for consistent growth, proper ventilation, litter quality management, and disease prevention. Sudden withdrawal of heat can cause temperature fluctuations that negatively affect bird welfare and productivity. 2. Heat withdrawal as a cost-cutting strategy While reducing operational costs is essential for farm profitability, cutting heating costs prematurely can lead to several negative outcomes, including poor housing conditions, reduced growth performance, increased mortality, poor feed conversion ratio (FCR), and increased disease susceptibility. These outcomes ultimately result in higher long-term costs despite the short-term savings achieved through reduced heating. 2.1. Wet litter and air quality issues Inadequate heating can increase moisture buildup within the broiler house, leading to wet litter conditions. Wet litter contributes to ammonia buildup, poor air quality, respiratory problems, and increased disease challenges. Birds become less active and lie down, which prevents evaporation of moisture in the litter, burnt feet and breasts, as well as getting dirtier further (figure 1). Birds that are affected by wet litter are difficult to sell at a market, and they do not satisfy the needs of the market. Figure 1: Wet litter due to early withdrawal of the heating system Cold stress combined with poor air quality creates a cycle that reduces bird welfare, increases disease susceptibility, and raises mortality rates, ultimately affecting overall farm performance. Often, farmers who encounter this problem rely heavily on antibiotics to treat health issues that usually arise from wet litter in the house, which means more money is spent on raising each bird. 2.2. Suboptimal growth and performance Reduced heating results in cold stress, which affects broiler performance in several ways. Cold temperatures reduce feed intake, lower weight gain, and negatively affect meat quality. Additionally, energy that should be used for growth is diverted toward maintaining body temperature. This leads to slower growth rates and delayed market readiness, ultimately reducing farm profitability and efficiency. 2.3. Increasedmortality rates Cold stress weakens the immune system, making broilers more susceptible to respiratory infections and other diseases. Birds may also huddle together in response to cold temperatures, which increases the risk of disease transmission. Increased mortality rates result in financial losses, particularly because older birds represent a higher investment in feed, labour, and management. 2.4. Negative impact on feed conversion ratio (FCR) Suboptimal heating disrupts metabolism and reduces feed efficiency. Poor FCR results in increased feed costs and reduced profitability. Under ideal conditions, body weight increases with relatively efficient feed conversion during early growth, with efficiency gradually decreasing as birds age (figure 2). Also, bird losses such as late mortalities contribute to increased FCR because the total feed usage is allocated to the total mass of surviving chickens and that increases the conversion dramatically. Winter 2026 BONUS www.agribonus.co.za 64