EC Nutrition

The productive and reproductive performances of growing and laying chickens are affected by the genetic background of the birds, the environment where they are exposed, and the interaction effects of genotype by the environment. Among many environmental factors, the study concentrates on the effect of day length, light intensity, color, and source of light on growth, egg production, reproductive performance, and quality of eggs. Light levels (intensity or illuminance), colors, the duration of light (photoperiod), and the source of light are essential factors in poultry production. Intensity influences cannibalism, and aggression, along with feed and water intake, while the photoperiod influences reproductive and egg production cycles, total feed intake, and growth rate. Even though these kinds of information are very important in the poultry business, the availability in Ethiopia is very limited. Hence the objectives of this review study are to provide evidence-based information related to these parameters to poultry value chain actors and increase their profitability and resilience to external shocks. The result of this review study revealed that photoperiod does have its own effects on the growth, reproductive performance of pullets, and egg-laying percentage. During the growth phase of the chicks, light hours start at 24 hrs during the first week and decrease to nine hours per day at the age of six weeks and remain flat till the age of 17 weeks. However, exposing birds to higher photoperiods beyond 17 hours per day after 17 weeks will result in prolapse of the reproductive tract, smaller egg size, diminished lifetime egg output, encourage birds for cannibalism, and increased overall costs of production by extra lighting. During the laying phase, increasing the photoperiod (artificial lighting by 2 - 4 hrs) beyond the natural day length on laying hens indicated that, it can increase egg production by 20 - 30%. If the producer wants early egg production, a high total egg number, and moderate egg weight, he should use the quick step-down/step-up light arrangements. Light hours can be reduced by 15 - 30 minutes per week during the growth phase till they reach a constant day length. In a step-up lighting program, similarly, the day length of birds should be increased by 15 - 30 minutes per week till they reach 16 hours per day. Similarly, light color does have it’s own effect on the performance of birds. Birds exposed to red and white color lights do produce more eggs as compared to their counterparts exposed to blue and green lights. On the other hand, broilers exposed to blue light colors gained better body weight as compared to green light. Broilers exposed to red light had increased immunity titer levels as compared to broilers exposed to white, blue, and green light. The response of birds to light intensity indicated that the light intensity should be 30 lux (3 foot-candles) during the first week of age, after which it can be reduced to 5 to 10 lux (0.5 to 1.0 foot-candles) in cages or to 15 lux (1.5 foot-candles) when grown on the floor. The higher light intensity for floor-grown birds will allow the birds enough light to navigate their environment. In cages, there should be 10 lux (1.0-foot candles) at the feeder height, and 5 lux (0.5-foot candles) inside the cage. When the effect of the light source is evaluated, LED lamps are superior in terms of their technical performance, and economics compared to incandescent, and fluorescent lamps even though the initial cost of LED lamps is on the higher side. Light-Emitting Diodes Light bulbs (LEDs) are currently the most efficient source of light since they use 90 percent less energy than standard lighting and last up to 25 times longer. LEDs light up quickly, and they don’t contain any toxic materials that can operate in cold temperatures without flickering. LED lamps did not have any negative impact on the production, and egg quality of the laying hens. Therefore, poultry farmers should consider the photoperiod, light color, light intensity, and source of light during growing as well as the laying phase of their chickens for the betterment of their businesses.

 Keywords: Artificial Lighting; Light Color; Light Intensity; Photoperiod; Sources of Light

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