Understanding Outdoor Brooders: A Complete Guide

Outdoor brooder setup with proper ventilation

Intro

Outdoor brooders are vital for raising poultry and small animals. Understanding how they work and what they need is key for successful animal husbandry. This guide will explore various aspects of outdoor brooders, from setting them up effectively to maintaining them in a safe and sanitary manner. Each element plays a crucial role in ensuring the health and welfare of your animals.

Selecting the Right Brooder

Choosing the right brooder involves considering factors like size, material, and design. An adequate brooder provides basic necessities such as warmth, shelter, and space to grow. Brooders can be constructed from wood, plastic, or metal. Each material has its merits and limitations.

Wood is durable and offers great insulation but can be difficult to clean.
Plastic is lightweight and easy to clean but may not provide sufficient insulation, especially in colder climates.
Metal is very durable but can become overly hot in the sun.

It's essential to choose a structure with appropriate ventilation to ensure fresh air circulation. Overflowing humidity can have detrimental effects on the animals’ health.

Creating an Optimal Environment

The environment within the outdoor brooder must cater to the specific needs of the animals. Temperature control is vital, especially for young chicks and other small animals. They require a stable heat source and the temperature needs to be monitored frequently. Ideally, ensure:

A heating lamp is installed securely to prevent any fire hazards.
Heat sources should maintain a temperature of 95°F (35°C) for the first week and gradually decrease by 5°F each subsequent week.

Bedding must also be suitable; straw, pine shavings, and recycled paper products are concise choices.

Maintenance Tips

Proper maintenance extends the lifespan and functionality of the outdoor brooder. Regular cleaning schedules should be established. Here are key actions to consider:

Daily cleanings: Remove droppings and uneaten food to minimize health risks.
Weekly deep cleaning: Wash all surfaces with a safe cleaning solution.
Inspection: Regularly check for any damages in the structure.

Regular maintenance ensures a healthy living environment, preventing diseases and promoting the overall well-being of the animals.

Feeding Practices

Proper feeding practices are critical for the growth and health of poultry and small animals. Each species has unique dietary needs. For instance, chickens need a balanced diet of grains, greens, and proteins. Pay attention to feeding schedules that align with their natural behaviors.

Feed quality should always be high, free from mold and contaminants.
Fresh water must be available at all times to ensure hydration.

Educating yourself about the specific feeding habits of your animals will lead to better outcomes.

Biosecurity Significance

Biosecurity cannot be overlooked when raising poultry or small animals. Implementing strict biosecurity measures minimizes the risk of disease transmission. Simple practices can have a substantial impact:

Limit visitor access to the brooder area.
Establish separate clothing and footwear for handling the animals.
Manage waste properly to avoid attracting pests or further health issues.

Understanding and applying these elements will create a more resilient environment for your outdoor brooder.

Prelims to Outdoor Brooders

The realm of outdoor brooders is crucial for anyone engaged in poultry care or small animal husbandry. An outdoor brooder serves not only as a shelter but also as a controlled environment for young birds and animals to thrive. Understanding the structure and purpose of these brooders can significantly enhance the quality of care provided to the animals.

Outdoor brooders are designed to maintain optimal conditions necessary for the health and growth of chicks and other small animals. They offer a secure space, protecting the young from predators and environmental stresses. The importance of selecting the right brooder goes beyond mere aesthetics; it directly influences the wellbeing of the animals raised within.

Benefits of Outdoor Brooders:

They provide a safe environment against predation.
Temperature control helps in the healthy development of young poultry.
Brooders can be designed to fit specific space and environmental requirements.

Understanding the differences between various types of outdoor brooders is essential. This knowledge will guide you in making informed decisions regarding their selection and maintenance, ensuring that your poultry or small animals receive the best possible care.

What is an Outdoor Brooder?

An outdoor brooder is a sheltered area designed specifically for the raising of young poultry. This structure can range from simple enclosures to more complex setups that integrate heating systems, feeders, and water stations. The primary functions of an outdoor brooder are to provide warmth, protection, and an adequate space for chicks to socialize and grow.

Outdoor brooders must cater to the specific needs of young animals, including proper temperature management and safety from external threats. An ideal brooder will balance ventilation, insulation, and space to promote the health of the chicks. Factors such as design, material, and construction also play a critical role in ensuring well-being and comfort for the occupants.

History and Evolution of Brooding Practices

Brooding practices have changed significantly over time, adapting to advancements in animal husbandry and changes in agricultural techniques. Historically, brooders were often basic structures providing shelter without much attention to environmental control. Early methods relied on natural elements, like the warmth of the sun or the body heat of the mother hen.

As the need for more efficient poultry raising became apparent, brooding technology evolved. The introductions of artificial heating sources revolutionized brooding, allowing for more controlled conditions. The 20th century saw the rise of commercial poultry operations, which contributed to the development of specialized brooders designed for mass production.

Today, outdoor brooders benefit from these advances, offering better environmental controls, automated feeders, and improved ventilation systems. Understanding this evolution helps current poultry owners appreciate the complexities of modern brooding and the wealth of options available today for raising healthy and productive livestock.

Types of Outdoor Brooders

Understanding the types of outdoor brooders is crucial for anyone aiming to raise poultry or small animals effectively. Each type serves a distinct purpose and offers unique benefits that can greatly enhance the overall brooding experience. By recognizing the differences between these options, pet owners can make informed decisions that align with their specific needs and circumstances.

Portable vs.

Stationary Brooders

When choosing a brooder, one of the first decisions is whether to opt for a portable or stationary model. Portable brooders bring several advantages. As their name suggests, they can be moved easily from one location to another. This flexibility allows for more effective management of space and resources, especially during different seasons. For instance, in warmer months, you might place your brooder in a sunny spot, while in cooler months, you may want to move it to a more sheltered area that still offers adequate ventilation.

On the other hand, stationary brooders tend to be larger and more robust. They are ideal for pet owners who have a permanent space dedicated to poultry. Stationary models often feature enhanced insulation and better environmental controls, which can be beneficial for maintaining the right temperature. However, they lack the versatility of portable options. Thus, understanding the pros and cons of both types is essential before making a selection.

Choosing the right brooder type can affect the health and growth of your poultry significantly.

Materials and Construction Options

The materials and construction of an outdoor brooder play an important role in its effectiveness and durability. Different materials can provide varying levels of insulation, ease of cleaning, and overall safety for the animals housed within. Common materials include wood, plastic, and metal.

Wooden brooders are favored for their natural insulation properties. They can retain heat well, which is beneficial in colder climates. However, wood requires regular maintenance to prevent rot and pest infestations. In contrast, plastic brooders are often easier to clean and resistant to weather conditions, making them a good option for regions with high humidity.

Metal construction provides sturdiness and can deter predators. However, it may not offer the same insulation as wood. When selecting materials, consider factors like your local climate, pest presence, and the frequency of required cleaning.

In summary, the choice in materials and construction will ultimately depend on the specific needs of the poultry you are raising, as well as your personal preferences.

Selecting the Right Outdoor Brooder

Choosing the right outdoor brooder is a crucial step in ensuring the health and well-being of your poultry or small animals. A well-suited brooder can significantly impact the growth rate, development, and overall quality of your birds. Therefore, understanding the specific needs and requirements of your flock is essential. The right brooder can provide a stable microenvironment that safeguards your young birds from external threats, such as predators and harsh weather conditions.

Assessing Your Space and Environment

Before selecting a brooder, evaluate your available space and surrounding environment. This assessment is vital as it determines the type and size of the brooder you can implement. The following considerations should guide you:

Size of Your Flock: Estimate the number of chicks or poultry you plan to raise. Larger flocks require bigger brooders to allow adequate space for movement, feeding, and warmth.
Type of Ground Surface: Consider the surface where the brooder will sit. Flat, secure ground is ideal, as uneven or soft ground may cause instability. If it’s placed on grass or dirt, ensure easy cleaning to maintain hygiene.
Proximity to Resources: The brooder should be positioned near water and feed supplies. Quick access is needed for meeting their feeding and hydration needs. Keeping the brooder close reduces stress for both the caretaker and the animals.

Assessing your space is not just about the physical area but also about the ambiance. A suitable environment can enhance the effectiveness of your brooding experience.

Considerations for Climate and Weather

The climate in your region plays a significant role in the type of outdoor brooder you select. Various aspects of climate can directly impact the birds' health and comfort.

Temperature Regulation: Outdoor brooders must provide adequate warmth to chicks, especially during colder months. Consider brooders with insulation and heating elements to maintain a stable temperature. The ideal temperature for chicks can vary from 90°F to 95°F during the first week, gradually decreasing as they grow.
Ventilation Needs: Good airflow is necessary to eliminate excess moisture and harmful gases that accumulate from waste. However, ensure ventilation does not compromise warmth. Using adjustable air vents can achieve this balance effectively.
Exposure to Elements: Factors such as rain, wind, or strong sunlight need to be mitigated. A brooder should be protected from direct elements while still allowing sufficient natural light during daytime.

Proper assessment of your environment leads to informed choices that enhance the success of your outdoor brooding setup.

Setting Up Your Outdoor Brooder

Setting up your outdoor brooder is vital for the health and well-being of your poultry and small animals. A well-designed brooder creates a safe environment, promotes proper growth, and ensures that the animals adapt well to their surroundings. Inadequate setup can lead to stress and health issues, which can affect the overall productivity of your flock.

Essential Equipment Required

To create an optimal brooder setup, specific equipment is essential. Here’s a list of the key items:

Heat Source: A brooder lamp or heat plate is crucial to maintain a warm environment. For short-term use, heat lamps work fine. However, heat plates are safer and more energy-efficient for long term.
Brooder Box: The box should be spacious enough to accommodate the number of chicks or poultry. It can be constructed from wood, plastic, or even cardboard.
Feeding and Watering Equipment: Use proper feeders and waterers designed for poultry. These ensure that the food and water remain clean and accessible.
Thermometer: A thermometer is necessary to monitor the temperature, which should be around 95°F (35°C) for day-old chicks. Adjust gradually as they grow.

Attending to these elements will streamline the transition for the young birds and foster a healthy growth phase.

Proper Bedding and Flooring Choices

Choosing the right bedding and flooring is another key aspect of setting up the brooder. It contributes to comfort and health. Here are some considerations:

Bedding Materials: Opt for a bedding material that is absorbent and easy to clean, such as pine shavings, straw, or hemp. Avoid cedar shavings due to their harmful oils.
Depth of Bedding: Having at least 2-3 inches of bedding will help absorb moisture and provide insulation. This allows your chicks to nest comfortably and stay warm.
Flooring Options: If you use a brooder box with a solid floor, make sure to provide ample bedding on top. For portable or wire-bottom brooders, ensure that they have soft bedding to prevent foot injuries.

Appropriate bedding and flooring not only enhances comfort but also reduces the likelihood of disease, thereby ensuring a healthier flock.

Temperature Control and Heating Options

Temperature control is paramount in the brooding process. Young chicks depend on external heat until they can regulate their own body temperature, usually around five weeks old. Here are the primary methods to achieve suitable heating:

Feeding station for small animals in an outdoor environment

Brooder Lamps: These are common heating sources, but caution is needed because they carry a fire risk. Ensure they are securely placed and monitored.
Heat Plates: A safer alternative to lamps; they mimic the warmth provided by a mother hen. They are typically more energy-efficient and reduce the risk of overheating.
Adjustable Height: Whichever method is chosen, it should be adjustable. The distance between the heat source and the chicks should be modified as they grow. Initially, the heat should be quite intense, but gradually decreasing it will help the chicks acclimatize.

Effective temperature control encourages healthy growth and development, keeping your birds comfortable and thriving.

Remember, consistent monitoring of the environment is key. Regularly check temperature and adjust as needed.

For additional information and guidelines, visit Wikipedia or Britannica.

Feeding and Care in the Outdoor Brooder

Feeding and care play a crucial role in the successful management of an outdoor brooder. Proper nutrition and hydration ensure that the poultry grows strong and healthy. In an outdoor brooder, environmental conditions must also be considered for optimal premium care. This section delves into the nutritional needs, hydration requirements, and overall health monitoring essential for chicks and poultry in an outdoor setting.

Nutritional Requirements for Chicks and Poultry

Chicks and adult poultry have specific nutritional needs that vary by age and breed. They need a balanced diet to develop correctly. Here are key elements to consider:

Starter Feed: For chicks, a high-protein starter feed between 18-24% protein is ideal during the first few weeks. This feed helps in muscle and feather development.
Grower Feed: After the initial period, typically around six weeks, a grower feed with 16-18% protein is beneficial for continued growth.
Layer Feed: For hens that begin laying eggs, a layer feed with 16-18% protein and added calcium supports egg production.

Regularly providing fresh and clean feed ensures optimal health. Avoid overpacking the feeder to prevent wastage. Additionally, watch for signs of improper feeding, such as decreased activity or poor feathering.

Hydration Needs and Water Stations

Water is also a vital component of an outdoor brooder. Poultry requires a consistent water supply for hydration and overall well-being. Here are essential aspects to consider:

Clean Water Supply: Ensure that the water is refreshed daily, as dirty water can lead to health issues.
Water Stations: Use shallow water containers to prevent drowning in younger chicks and provide easy access.
Temperature Considerations: In extreme temperatures, add ice cubes or place water containers in shaded zones to prevent overheating. Watch for signs of dehydration, such as lethargy or droopy wings.

Proper hydration supports digestion, nutrient absorption, and general health. Invest in a reliable water system to ensure it is always available.

Health Monitoring and Signs to Watch For

Monitoring the health of chicks and poultry is essential to catch any issues early. Here are signs to keep an eye on:

Behavior Changes: Pay attention to changes in activity levels. Lethargy may indicate illness.
Feeding and Drinking Habits: Sudden changes in their feeding patterns can be a warning sign that something is wrong.
Physical Symptoms: Look for any unusual physical signs, such as respiratory distress, pasty vent, or feather loss.

Regular health checks should be part of your routine. This can include looking for pests or any injuries. You can also ensure flock health by keeping the brooder clean and observing behavior closely.

Proper feeding, hydration, and health monitoring are fundamental to a thriving outdoor brooder environment.

Maintenance and Hygiene

Maintenance and hygiene are fundamental to the success of any outdoor brooder. Proper upkeep not only enhances the well-being of the animals but also ensures a healthier environment. This section outlines essential routines and cleaning protocols that contribute to overall hygiene and maintenance.

Daily Maintenance Routines

Daily maintenance routines are crucial for the smooth operation of your outdoor brooder. Here are some key tasks that every owner should follow:

Check water supply: Ensure that clean and fresh water is available at all times. Stale or dirty water can lead to serious health issues.
Inspect feed: Regularly check the feed levels and quality. Remove any spoiled or moldy feed to prevent illness among the chicks or other poultry.
Observe behavior: Keep an eye on the animals. Healthy animals are usually active and alert. Look for any signs of distress, lethargy, or unusual behaviors.
Temperature check: Use a thermometer to monitor the brooder's temperature regularly. Maintain optimal conditions to ensure comfort and growth.
Spot clean: Remove waste and debris from bedding and flooring. This simple step can prevent the buildup of harmful bacteria.

Following these daily routines not only promotes animal health but also sets a good precedent for overall management practices.

Cleaning Protocols for Optimal Hygiene

Cleaning protocols establish a level of hygiene that prevents disease and promotes growth. It is essential to follow systematic procedures:

Establish a cleaning schedule: Regularly scheduled cleanings should be noted. Consider deep cleaning weekly or biweekly, depending on the size of your brooder and the number of animals.
Remove bedding: Start the cleaning process by removing the old bedding. This can contain waste products, which harbor bacteria and attract pests.
Scrub surfaces: Use a mild disinfectant suitable for poultry. Scrub all surfaces including walls, feeders, and drinkers. Make sure all residues are removed before allowing any contact with the animals once again.
Rinse thoroughly: After cleaning, rinse all surfaces to ensure no cleaning product residues remain. This step is crucial to avoid any toxicity to the animals.
Replace bedding: After thorough cleaning, add fresh bedding. Choose appropriate materials like straw or wood shavings that promote dry and clean conditions.

Following a strict cleaning protocol not only improves the quality of life for your birds but also reduces the risk of diseases.

Maintaining hygiene and integrating proper maintenance routines is not a one-time task. Instead, it’s an ongoing commitment that yields positive outcomes for both the animals and the owner.

Addressing Potential Challenges

Addressing the potential challenges that come with using outdoor brooders is crucial for anyone interested in poultry and small animal care. Many new pet owners might underestimate the risks, which can result in significant issues. By understanding these challenges, one can better prepare for and mitigate problems before they arise.

Predator Protection Strategies

Predators pose a significant risk to young chicks and other poultry. Animals like raccoons, snakes, and birds of prey often look for an easy meal. Thus, implementing predator protection strategies is vital to ensure the safety of your birds.

When setting up your outdoor brooder, consider the following strategies:

Biosecurity measures in an outdoor brooder

Secure Fencing: Use strong, sturdy fencing around the brooder area. A fence should penetrate the ground to prevent digging and have a solid top to deter aerial attacks.
Covering: A mesh cover can be an effective deterrent against larger birds and animals. Using welded wire or hardware cloth keeps young animals inside while preventing larger ones from entering.
Motion-Activated Lights: These lights can startle predators and deter them from getting too close.
Regular Checks: Routinely inspect the brooder for any signs of compromise, like digging or claw marks. This proactive approach helps in maintaining safety.

Protecting your poultry from predators is not just a benefit; it's a necessity.

Dealing with Extreme Weather Conditions

Outdoor brooders must also withstand extreme weather. Both heat and cold can endanger the health of the birds. Understanding how to manage these conditions will lead to a healthier flock.

Hot Weather Considerations:

Shade and Ventilation: Ensure that your outdoor brooder has shaded areas where birds can escape direct sunlight. Proper ventilation is also essential to reduce heat build-up.
Water Availability: In hot weather, access to fresh water is crucial. Increasing the number of water stations can help ensure hydration.

Cold Weather Considerations:

Insulation: If temperatures drop too low, adding insulation around the brooder can help retain heat. This is especially important for very young or small breeds.
Heating Options: Utilizing heat lamps or heated pads can maintain a stable environment.

Regular monitoring of temperature extremes and implementing these strategies can help your flock thrive regardless of weather conditions. Being aware of the challenges related to predators and extreme weather helps in creating a safe, nurturing environment for your birds.

Understanding the Specific Needs of Different Breeds

Understanding the specific needs of different poultry breeds is essential for successful brooding. Each species has its own unique requirements in terms of temperature, diet, and space. Addressing these needs can lead to healthier, more productive animals. Failing to cater to breed-specific traits may result in poor growth, health issues, and, in some cases, increased mortality.

Best Practices for Chickens

Chickens are one of the most popular poultry raised in outdoor brooders. They thrive in a warm environment, ideally between 90°F and 95°F during their first week of life. Each subsequent week, the temperature can be reduced by about 5°F. Choosing the right bedding material is also critical; straw or pine shavings can provide comfort and insulation.
Feeding is another important element. Chickens require a balanced diet rich in protein, especially during the early stages. Starter feeds that contain 18-20% protein are advisable. As they grow, growers should be transitioned to feeds with lower protein content. Providing ample clean water at all times is fundamental for their health. Monitoring their behavior is also crucial; any signs of lethargy or unusual behavior should be addressed immediately.

Care for Ducks and Geese

Ducks and geese have different needs from chickens. They require more space due to their larger size and active behavior. Ducklings should be kept in a warm environment, similar to chicks, but they also enjoy access to water for dabbling. They need a shallow water source to promote natural foraging behavior. When it comes to diet, ducklings require a higher niacin intake than chickens. A duckling starter feed is strongly recommended.
Geese are social creatures that do better in pairs or small groups. They require less protein than ducks, making a grower feed with around 14-16% protein suitable. Keeping their environment clean is vital, as they can be messy eaters and drinkers. Regular monitoring for signs of illness or distress is essential for both ducks and geese.

Unique Requirements for Other Poultry Species

Different breeds of poultry, such as quails, turkeys, and pheasants, have unique requirements. Quail, for example, are less demanding in temperature but need good ventilation. They are prey animals and thrive in an environment that minimizes stress. A high-protein feed and adequate space for movement are crucial for their development.
Turkeys require more space than chickens due to their larger size. They prefer to roam and require a diet rich in protein during their early stages. Pheasants are also habitat specific and need a varied diet that mimics their natural forage. Proper light exposure is important for their growth.

Key Takeaway: Understanding breed-specific needs improves poultry health and productivity. Tailoring your outdoor brooder setup to these requirements is a foundational step in effective poultry keeping.
Meeting the individual needs of various poultry species requires an ongoing commitment to observation and adaptation. Providing suitable conditions fosters better growth and ensures the well-being of your birds.

The Importance of Biosecurity in Brooding

Biosecurity is a critical aspect of raising poultry in outdoor brooders. It refers to the measures taken to protect birds from diseases and infections that can arise from various sources. Ensuring biosecurity not only safeguards the health of individual birds but also maintains the overall stability of the flock. In a setting where multiple species are raised, such as poultry, ducks, and pigeons, the risk of disease transmission can increase. This makes the understanding and implementation of biosecurity measures essential for any responsible pet owner.

Effective biosecurity can prevent outbreaks of illnesses that can have devastating consequences on your flock’s vitality. For instance, avian influenza, Newcastle disease, and other serious conditions can spread rapidly amongst birds. Such scenarios might lead to significant financial losses and emotional distress for pet owners. For these reasons, practicing good biosecurity is more than just beneficial; it is a necessity.

Biosecurity Measures for Outdoor Brooders

Implementing biosecurity measures is vital in minimizing risk. Various steps should be taken, including:

Restricting Access: Limit the number of people who can enter the brooder area. This helps reduce the introduction of pathogens into your birds' environment.
Footbaths: Set up footbaths at entrances to disinfect shoes before entering the brooder area.
Quarantine Procedures: New birds should undergo a quarantine period before mingling with the existing flock. This allows time to monitor for any signs of illness.
Regular Health Check-ups: Conduct regular health monitoring of all birds in the brooder. Look out for any unusual behavior, appearance, or signs of illness.
Cleanliness: Maintain cleanliness in the brooder by regularly cleaning and disinfecting feeding and watering equipment, bedding, and surfaces.

Taking these steps can create a safer environment for your birds, reducing the chances of disease outbreaks.

Health Protocols and Best Practices

Health protocols are necessary for maintaining a healthy flock. These practices should be integrated into the daily routine of the caretaker. Some recommended best practices include:

Vaccination: Keep up to date with vaccinations for chick and poultry. This provides an important line of defense against common diseases.
Proper Nutrition: Ensure birds have access to a well-balanced diet. Proper nutrition boosts the immune system, which is vital for preventing illness.
Hydration Levels: Make sure clean, fresh water is available at all times. Dehydration can severely impact health and well-being.
Observation: Pay close attention to the flock’s behavior. Sudden changes can be indicators of health issues that need prompt attention.

Regularly updating biosecurity measures and health protocols contributes significantly to the long-term well-being of your birds, ensuring they lead healthy, productive lives.

Finale

The conclusion serves as a vital component in this article, summarizing the overarching themes related to outdoor brooders. This section emphasizes not only the gathered information, but also its relevance for both novice and seasoned poultry enthusiasts. It outlines the importance of knowledge, care, and adaptability when managing brooding environments, ensuring the health and well-being of the animals involved.

Recap of Key Points

To encapsulate the information presented, several points stand out:

Definition and Purpose: Understanding what an outdoor brooder is, alongside its historical context, is foundational for effective use.
Types: Knowing the difference between portable and stationary brooders allows more informed choices based on specific needs.
Setup Requirements: Recognizing essential equipment, proper bedding, and temperature control are critical for creating a safe environment.
Feeding and Care: Meeting the nutritional and hydration needs of chicks ensures healthy growth.
Maintenance Routine: Daily practices and cleaning protocols maintain hygiene and prevent health issues.
Challenges: Developing strategies for predator protection and weather extremes can avert potential risks.
Breed-Specific Needs: Understanding diverse requirements for various breeds fosters a tailored care approach.
Biosecurity: Implementing biosecurity measures protects from diseases that could impact overall health.

These points are pivotal for committed poultry caregivers, shaping their approaches towards optimal management of outdoor brooders.

Final Thoughts on Outdoor Brooders

As the interest in sustainable and home-based poultry raising increases, understanding outdoor brooders becomes essential. They are not just enclosures but reflective of broader practices in animal husbandry. Considering best practices, potential challenges, and the specific needs of various breeds ultimately guides successful outcomes.

In summary, committing to informed decision-making regarding outdoor brooders enhances the experience of raising poultry. For pet owners and enthusiasts, becoming knowledgeable about the intricate dynamics of brooding will not only improve animal welfare but also foster a deeper connection with the animals they care for. Engaging in thoughtful practices will position individuals as effective stewards of their flocks, promoting both productivity and ethical responsibility.

More wonderful Articles:

A vibrant selection of chicken breeds known for egg production