Winter Broiler Management in Manual Poultry Houses
Winter presents significant challenges for small-scale broiler farmers in South Africa, as cold stress can harm broiler health and productivity, leading to slower growth, poorer feed efficiency, and higher mortality. As a result, many farmers halt production to avoid losses, impacting their annual income. Small-scale and subsistence farms face unique challenges due to reliance on manual management, while larger farms benefit from automation.
Effective winter management in open-sided houses requires careful control of environmental conditions to support optimal growth and health. This article outlines key considerations for successfully growing broilers in colder months, including maintaining the correct temperature, observing chicken behaviour, and controlling air quality.
Cold stress in broilers
Cold stress in broilers is closely linked to several health and management challenges, including coccidiosis, wet litter, water belly (ascites), and poor air quality, creating a cycle that can significantly impact flock health and productivity.
Cold-stressed broilers tend to huddle together to conserve body heat, leading to uneven distribution of body heat within the flock. This behaviour can cause some areas of the poultry house to become excessively damp, contributing to wet litter conditions. Wet litter is a breeding ground for pathogens, particularly the protozoa that cause coccidiosis, a common and debilitating intestinal disease in broilers.
The presence of coccidiosis exacerbates the wet litter problem, as infected broilers often produce loose, watery droppings, further increasing moisture levels in the litter. Wet litter not only promotes the spread of coccidiosis but also deteriorates air quality by increasing ammonia levels in the poultry house. High ammonia concentrations can irritate the respiratory system of broilers, leading to compromised lung function and making them more susceptible to respiratory diseases.
Air quality management
Poor air quality and cold stress can also contribute to the development of ascites, or water belly, a condition where fluid accumulates in the abdominal cavity. Ascites is often triggered by insufficient oxygen supply due to poor ventilation and the birds' increased metabolic demands in response to cold stress. The reduced oxygen availability, coupled with the effects of poor air quality, strains the cardiovascular system, leading to ascites.
Controlling litter moisture is essential to break this cycle and maintain broiler health during winter.
|
Gas |
Acceptable Level |
Hazardous Level |
Effects of Exposure |
|
AMMONIA (NH₃) |
≤ 10 ppm |
> 25 ppm |
Respiratory issues, eye irritation, reduced feed intake, and growth rate. |
|
CARBON DIOXIDE (COâ‚‚) |
≤ 3,000 ppm (0.3%) |
> 5,000 ppm (0.5%) |
Impaired respiration and productivity, poten- tial suffocation at high levels. |
|
CARBON MONOXIDE (CO) |
< 10 ppm |
> 50 ppm |
Headaches, dizziness, and potentially fatal at high concentrations. |
|
HYDROGEN SULFIDE (Hâ‚‚S) |
≤ 5 ppm |
> 20 ppm |
Irritation of the respiratory tract, potentially fatal in high concentrations. |
|
OXYGEN (Oâ‚‚) |
19.5% - 21% |
< 19.5% |
Reduced oxygen levels cause respiratory distress, potentially fatal for chickens. |
|
METHANE (CHâ‚„) |
< 1,000 ppm (0.1%) |
> 5,000 ppm (0.5%) |
Explosive hazard at high levels, respiratory issues for broilers. |
Table 1: Gasses produced in a broiler house, accepted levels and hazardous levels with potential consequences.
House Temperature Management
Providing a consistent and evenly distributed temperature at the chick level is important to keeping the chicks
thermally comfortable. The table below shows the dry bulb temperatures during the growth period.
|
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
Cold stress initiates a cascade of issues: it promotes wet litter, which increases the risk of coccidiosis; coccidiosis, in turn, worsens litter conditions and air quality, leading to respiratory issues and potentially triggering ascites. Effective management of environmental conditions, including maintaining appropriate temperatures, ensuring proper ventilation.
Monitoring Broiler Behaviour
Observing the behaviour of broilers is a practical approach to assessing their well-being. 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. 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.
Controlling Air Quality: Minimum vs. Maximum Ventilation
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.
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.
Effective winter management requires understanding these conditions:
- 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.
- 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.
- Coccidiosis: Cold-stressed broilers are more prone to coccidiosis due to weakened immunity. Signs include diarrhoea and poor growth.
- Salmonellosis: Stress from cold lowers immunity, making broilers susceptible to infections like salmonellosis. Symptoms include diarrhoea and lethargy.
- Leg Problems: Cold conditions can worsen leg issues such as bumblefoot and joint inflammation, affecting mobility and health.
Prevention and Management:
- Improve Housing: Ensure insulation and effective heating to maintain stable temperatures.
- Optimize Ventilation: Prevent moisture and ammonia buildup to reduce respiratory stress.
- Enhance Nutrition: Provide quality feed with nutrients suited for colder months.
- Monitor Health: Regular health checks for early disease detection.
- Enforce Biosecurity: Implement practices to prevent disease spread.
Conclusion
Successfully raising broilers in winter requires a comprehensive approach to managing internal house climate and environmental conditions. By maintaining appropriate temperatures, controlling bacterial survival, leveraging weather services, monitoring chicken behaviour, and adjusting ventilation strategies, poultry farmers can ensure the health and productivity of their broilers throughout the colder months. Effective climate control and proactive management practices are essential for achieving optimal growth and minimizing stress on the birds.
Get in touch with your local De Heus Specialist to learn more about Winter Broiler Management in Manual Poultry Houses - https://www.deheus.co.za/meet-our-team
