Experience Sharing on Lighting Management in Open-Sided Poultry Houses
1. Brooding Period
The lighting during the brooding period mainly stimulates the chickens' feed intake, and the effects of lighting on chicks are mainly manifested in two aspects: light duration and light intensity. At this time, problems with light duration are prone to occur.
Some farmers, without considering weight gain, provide 8 hours of light during the first 2-3 weeks of brooding. Chicks themselves have poor stress resistance and low feed intake, and combined with the frequent immunization and medication during the brooding period, the stress is relatively high, so the flock often fails to reach the standard body weight. If the light duration is too short at this time, the flock's feeding time is correspondingly shortened, body weight will be seriously insufficient, and consequently the number of weak and small chickens increases and the mortality and culling rate rises.
Some other farmers provide more than 20 hours of light throughout the brooding period, and even provide 14-16 hours of light after 60 days. Although the flock then has a longer feeding time and increased feed intake, the flock remains in a state of fatigue for a long time and cannot get sufficient rest, which will also affect the growth and development of the chicks, and further cause feather pecking, vent pecking, weakened constitution, and an increased mortality and culling rate.
The author advocates using 23 hours of light during the first 3 days of the brooding period, and afterwards, according to the chicks' body weight and physical condition, flexibly controlling the speed of gradually reducing the light duration. Under normal circumstances, reduce by 3 hours per week until natural light or the fixed light duration of the rearing period is reached. When the flock's body weight is relatively low and the constitution is relatively weak, the speed of reducing light can be slowed down. The light intensity is generally: use 40-watt bulbs in the first week (spacing 3 m, 2 m above the ground), and 60-100 watt bulbs can also be used in the first 3 days. After the second week, 25-watt bulbs can be used, with light intensity generally 3 watts per sq m, uniform lighting, and a single bulb not exceeding 60 watts, to avoid causing pecking vice.
2. Rearing Period
Because open-sided poultry houses differ by region and season, there is no and cannot be a fixed light duration during the rearing period; therefore, the confusion in farmers' light duration is mainly manifested in the rearing period.
First, continuously using natural light throughout the entire rearing period will inevitably cause the following adverse consequences: if natural light gradually lengthens at this time, it will cause the flock's sexual maturity to arrive early, while body weight has not yet reached the standard for the start of laying, so laying begins prematurely before the expected laying date, egg weight is light, the period of laying small eggs is long, and thus profit decreases. If natural light gradually shortens at this time, it will cause the flock's physical maturity to arrive early while the ovaries have not yet fully developed, thereby causing delayed start of laying, feed waste, and rising costs, likewise reducing profit.
Second, some farmers, fearing that the flock will not reach the body weight for caging, use a light duration 2-3 hours longer than the standard during the rearing period, or even 16 hours, which inevitably shortens the room for light stimulation before and after the start of laying. Facts have proven that short-term light stimulation is inferior to long-term light stimulation in laying performance, and may even delay the start of laying, shorten the duration of the peak period, and reduce total egg production.
The light duration during the rearing period must be scientific and fixed, and must not be arbitrarily lengthened or shortened. For rearing from late winter to early spring, when natural light duration gradually lengthens, the fixed light duration for the rearing period should be based on the natural light duration at 18 weeks of age. For rearing from late summer to autumn and winter, when natural light gradually shortens, the rearing-period light should use the natural light duration at the seventh week as the fixed light duration.
The light intensity throughout the rearing period should also be controlled. In summer, the external light intensity is too strong, so windows should be shaded to avoid direct sunlight on the chickens' bodies, which can cause pecking vice and affect growth and development. In winter, excessively weak light intensity should be prevented, and ensuring 1-3 watts of illuminance per sq m is relatively ideal. When supplementing light, 25-watt bulbs are generally used, with bulb spacing of 3 m and 2 m above the ground.
3. Laying Period
The laying period requires a fixed and unchanging light duration, and light intensity must not be weakened. Problems easily arise mainly during light stimulation before the start of laying.
Some add 2-3 hours of light at one time before laying, and can add light to 16 hours in 2-3 sessions. Because laying hens are relatively sensitive to light stimulation, except for the first light increase, each light increase should not exceed 1 hour. If stimulation is excessive, it will cause abnormal follicle development in chickens that mature sexually earlier, too many double-yolk eggs, and an increase in chickens with prolapse and difficult labor; another group of chickens that develop later will have reduced opportunities for light stimulation, follicle development will be inhibited, the start of laying will be delayed, and they may even never lay.
Under normal circumstances, the flock begins light stimulation before laying at 18 weeks. If light can continuously stimulate until the laying peak, the effect is best. At this time, 1 hour of light should be added, or the light should be increased to at least 13 hours, increasing by 15 minutes or 30 minutes every week or every two weeks until the light duration reaches 16 hours or 17 hours, after which the light duration should remain fixed and unchanged. The light intensity is preferably 5 watts per sq m.