Effect of Pigeon Coop Lighting in Meat Pigeon Production
Directory:
1. The Role of Light in Poultry
2. Effect of Light on Meat Pigeons
3. The Role of Light in Meat Pigeon Production
Pigeon meat is characterized by its low fat and high protein content, with a notable polyunsaturated fatty acid (PUFA) level of 23.54%, which is significantly higher than that found in other types of livestock and poultry, making it an excellent nutritional choice. However, the breeding practices and feeding methods for meat pigeons are relatively outdated compared to chickens. The inconsistent genetic traits of breeding pigeons and the presence of mixed breeding varieties hinder the growth of the meat pigeon sector. Additionally, the inherent breeding traits of pigeons, such as their monogamous nature, natural mating habits, and reliance on parent pigeons for feeding, contribute to their low breeding performance, posing a significant challenge for the industry's advancement.
Light exposure is a crucial environmental factor influencing poultry production, as birds are highly responsive to light, which impacts their growth, health, and reproductive capabilities. Unfortunately, research on lighting systems specifically for meat pigeons is lacking. In practice, breeders often rely on the experiences gained from raising other poultry, like chickens, rather than implementing effective artificial pigeon coop lighting strategies tailored for pigeons. This gap in knowledge limits the potential for efficient and intensive pigeon breeding. This article aims to explore the impact of light on production and reproductive performance in pigeon farming, providing a theoretical framework for the effective application of artificial pigeon coop lighting systems to enhance breeding efficiency and support the growth of the pigeon farming industry.
1. The Role of Light in Poultry
Poultry production typically relies on natural light, but when natural light is insufficient, artificial lighting is often necessary. To assess light quality, three key factors are considered: photoperiod, intensity (brightness), and spectrum (wavelength). In poultry farming, a complete light cycle spans 24 hours, with the light period (L) representing the time when light is present, and the dark period (D) indicating the absence of light. Various combinations of light and dark periods create different light cycles. Light intensity, or illuminance, refers to the amount of visible light received per unit area, measured in lux (lx). It is widely accepted that light of different wavelengths produces distinct color perceptions, with light of a single wavelength being termed monochromatic light. Visible light includes red, blue, and yellow, while invisible light encompasses ultraviolet and infrared.
Birds have a unique mechanism for processing light information, making them more responsive to changes in their light environment compared to mammals. For most birds, light perception occurs primarily through two components: retinal photoreceptors in the eyes and deep brain receptors (extraretinal photoreceptors, ERPRs). Deep brain receptors are located outside the retina, including in the pineal gland, olfactory bulb, and hypothalamus. Research has identified deep brain photoreceptors in the hypothalamus that are linked to seasonal reproduction in birds. The avian retina contains three main types of photoreceptors: single cones, double cones, and rods, which are distributed randomly, enabling birds to detect a wide range of light wavelengths.
Light influences the pineal gland via the optic nerve, leading to a decrease in melatonin secretion, which in turn affects the hypothalamus-pituitary-gonad axis. Gonadotropin-releasing hormone (GnRH) and growth hormone-releasing hormone (GRH) produced by the hypothalamus travel to the anterior pituitary through the hypothalamus-pituitary portal circulation, prompting the release of gonadotropins into the bloodstream. Additionally, light exposure reduces the production of gonadotropin-inhibiting hormone (GnIH). These hormones subsequently act on various glands to stimulate the production of downstream hormones, which directly impact the growth, development, and reproductive capabilities of birds.
Numerous studies have demonstrated that various poultry lighting systems can enhance the reproductive performance of poultry. By adding supplemental lighting, the peak egg production in geese occurs earlier, leading to an increase in overall egg output. Additionally, manipulating light exposure has enabled off-season production in geese through artificial light regulation. Extending the light cycle can boost testosterone production in the interstitial cells of rooster testes. Research on laying ducks indicates that their egg-laying performance, ovarian development, and reproductive hormone secretion are optimal with light durations between 16.56 and 16.93 hours. Furthermore, red light has been shown to stimulate the reproductive axis more effectively than white or green light, extending the peak egg-laying period in chickens and increasing egg counts. Thus, implementing a well-planned poultry lighting strategy is crucial for maintaining healthy poultry farming.
2. Effect of Light on Meat Pigeons
2.1 Effect of Light Duration on Meat Pigeons
Pigeons, being long-day animals, often struggle to fulfill their light requirements during production. Variations in light duration can affect the maturation age of breeding pigeons. Prolonged exposure to light can lead to early maturation in meat pigeons, while insufficient light duration can postpone their laying age. A long photoperiod of 15 hours of light and 9 hours of darkness (15L:9D) can significantly enhance the egg-laying performance of breeding pigeons, aligning with findings from Ding Jiatong, which suggest that increasing the photoperiod appropriately can boost pigeon egg production. A comparison of three different photoperiods—16L:8D, 12L:12D, and 8L:16D—revealed that the 16L:8D group exhibited the highest egg production and elevated levels of LH, FSH, and E2 in the serum of female pigeons. This further confirms that moderately extending the photoperiod (16L:8D) can enhance reproductive hormone secretion, promoting follicle development and indirectly improving ovarian function in poultry.
In 1994. Berger et al. examined the circadian rhythm changes in meat pigeons under continuous light and darkness, discovering that the light cycle significantly influenced the body weight of meat pigeons. Similar to other mammals, meat pigeons possess a circadian rhythm system under a 12L:12D light cycle, which is regulated by the synchronization of the light cycle with the body's food signal clock.
Melatonin is thought to be crucial for regulating the circadian rhythm in birds. During the light-dark cycle, melatonin secretion from pineal cells rises in the dark and falls in the light. While meat pigeons exhibit daily patterns in their activity, feeding, and melatonin levels in response to the light-dark cycle, these rhythms can be disrupted by prolonged exposure to bright light. Research indicates that light influences the expression of the retinal clock gene CRY2 in pigeons, suggesting that CRY2a/b may function in the retina through clock proteins. Furthermore, the light-induced circadian rhythm may impact energy balance in pigeons, with the photoperiod effect potentially linked to their higher energy expenditure. Analysis of body temperature patterns indicates that pigeons' circadian systems can adapt to various photoperiod changes, suggesting that increased energy balance during shorter photoperiods may result from inadequate feedback from nutritional and metabolic signals.
For poultry, particularly breeding birds, the development of sexual organs during the rearing phase is crucial for future reproductive success. However, there is a lack of research on the pigeon coop lighting systems used during the rearing of meat pigeons, which presents an opportunity for further investigation.
2.2 Effect of Light Color on Meat Pigeons
Research indicates that long-wavelength light inhibits the growth of poultry, whereas short-wavelength light promotes it. Different light wavelengths vary in their effectiveness at reaching the hypothalamus, with long-wavelength light penetrating 100 to 1.000 times more efficiently than short-wavelength light in meat pigeons. A study examining the influence of monochromatic light on the early weight gain of squabs revealed that pigeons exposed to red light showed significant weight increases at 14 and 21 days old, but this effect diminished after 28 days. In comparison to white light, green light also enhanced the weight of 21-day-old pigeons, but its impact on weight gain was not significant after 25 days. Blue light positively affected the weight gain of pigeons at 2 days, 4 days, and 1 week old, but had no significant effect on those aged 2 and 3 weeks. These findings demonstrate that various monochromatic lights have distinct effects on the growth of meat pigeons.
Additionally, research on the effects of monochromatic light as supplementary lighting for breeding pigeons found that red light significantly boosted egg production rates and fertilization rates while reducing egg breakage. In contrast, the effects of green, blue, and white light treatments were not significant. Ovaries from meat pigeons raised under different monochromatic lights were collected for deep sequencing, revealing multiple miRNAs that play crucial roles in regulating reproductive performance and shortening the egg-laying interval. The underlying mechanism may involve long-wavelength light (red light) penetrating the skull, stimulating ERPRs, and activating the gonadal axis, which increases egg production, advances the age of egg-laying, and enhances sperm quality and plasma testosterone levels in male poultry. Conversely, shorter-wavelength light (green-yellow light) may activate the retina and stimulate the secretion of GnIH, leading to reproductive inhibition while potentially accelerating poultry growth. Utilizing different light wavelengths to target specific photoreceptor sites can serve as an effective environmental strategy to enhance poultry reproduction.
2.3 Effect of Light Intensity on Meat Pigeons
It is widely accepted that suitable light intensity supports the normal production activities of poultry. Insufficient light intensity can lead to rapid fat accumulation and decreased feed consumption in poultry, while excessive light intensity can cause irritability and restlessness, exacerbating issues like feather pecking and neurosis. During the feeding and management of squabs, it was observed that a light intensity of 10 lx is ideal for young pigeons, and 5-10 lx is optimal for laying pigeons to promote squab growth. However, some studies indicate that there is no significant difference in the initial weight of squabs under three light intensity ranges: 1-10 lx, 10-20 lx, and above 20 lx. Nonetheless, the growth patterns of squabs during weight gain differ significantly across various light conditions. The low light system notably impacts the weight gain of squabs at 14 and 21 days old, with the most pronounced effect observed under 1-10 lx blue light.
Providing appropriate supplemental lighting during autumn and winter can enhance the egg-laying performance and antioxidant capacity of American king pigeons, with the most effective results achieved with 4 hours of light at 20.5 lx. For laying pigeons, the right light intensity can stimulate sexual maturity and boost egg production, while excessively low or high light levels can negatively affect reproductive performance. Therefore, further research is needed to determine the optimal light intensity for meat pigeons during their egg-laying phase.
2.4 Effect of Light on the Artificial Incubation of Pigeon Eggs
In commercial production, large farms often opt for artificial incubation over natural methods for some parent pigeons to reduce the interval between egg-laying and boost egg output. However, the success rate of artificially incubating pigeon eggs remains low, and optimal incubation results have yet to be achieved. Factors such as the quality of the breeding eggs, incubation temperature, and humidity influence hatching rates, but light may also play a significant role in the incubation environment. Our research team previously discovered that applying green light during the early stages of goose egg incubation can enhance embryo development, reduce incubation time, and improve hatching success. While there is existing data on incubation temperature, humidity, and ventilation for artificial pigeon egg incubation, there is no conclusive information on which pigeon coop lighting system can enhance hatching rates. One of our current research projects involves testing various light colors during the artificial incubation of pigeon eggs to evaluate their effects on hatching rates and the birth weight of squabs. Initial findings suggest that white light is more effective in increasing the hatching rate and promoting early hatching of pigeon eggs (results not yet published). This contrasts with previous findings where green light was beneficial for hatching and embryo development in other poultry species. The likely explanation for this difference is that the color and thickness of pigeon eggs vary significantly from those of other poultry, leading to substantial differences in light penetration.
3. The Role of Light in Meat Pigeon Production
An overview of the use of light in meat pigeon breeding reveals that the implementation of artificial lighting throughout the breeding process is still lacking, and a comprehensive set of pigeon coop lighting program standards has yet to be established. Generally, providing 16 hours of light and maintaining a light intensity of 15-25 lx can enhance egg-laying performance during the laying period, with the addition of red light also contributing to increased egg production. However, due to the late-maturing nature of pigeons, young pigeons require parental care after hatching, making it challenging to manage the lighting for both parent and young pigeons separately. This complicates the staged application of light. During the period when parent pigeons are feeding their young, it is crucial to determine the optimal monochromatic light, intensity, and duration that can promote the weight gain of young pigeons while also fulfilling the lighting needs of breeding pigeons for egg production, which warrants further investigation. Additionally, there is a lack of research on the application of light during both the breeding phase of parent pigeons and the incubation phase of pigeon eggs.
Developing a systematic and rational pigeon coop lighting scheme, integrating various lighting strategies over different stages, and optimizing the breeding rates of both parent pigeons and young pigeons through simultaneous artificial lighting is essential for practical production. In conclusion, a thorough analysis of how light duration, wavelength, and intensity affect the production and reproductive performance of meat pigeons at various stages is necessary. This exploration aims to create a suitable lighting system for meat pigeons and establish standardized lighting protocols, which can provide theoretical guidelines for efficient and intensive meat pigeon breeding in our country, ultimately enhancing the economic viability of pigeon farming.