BASIC RULES FOR LIGHTING PROGRAMS FOR COMMERCIAL LAYERS
Post no 1361 Dt 15 th August 2019
Compiled & shared by- DR RAJESH KUMAR SINGH, JAMSHEDPUR,9431309542,rajeshsinghvet@gmail.com
The lighting program (day length and light intensity) to which a flock of laying hens is subjected during the growing and production phase is a key factor in determining the onset of sexual maturity and egg production
Role of light on egg production
The egg production is associated with the length and intensity of the light received by the bird daily. Light stimulates the anterior lobe of the pituitary gland through optic nerve for the release of FSH and LH. Light energy also penetrates through the skull, skin and feathers. FSH increases the growth of the ovarian follicles. Upon reaching maturity, the ovum is released by the action of LH.
Important points regarding light
• Wavelength between 400 and 700 millimicrons (nanometer) ® Visible to eye
• The longer wavelengths (Red) of visible light are more capable of reaching the brain than shorter wavelengths.
• The intensity of sun’s light rays varied due to
Position of the sun
Cloudiness
Dust and moisture in the air
• Length of day light varies ® due to the relative position of the earth to the sun
• In Northern Hemisphere,
June 21st ® Longest day of the year
December 21st ® Shortest day of the year
(In southern hemisphere it is reversed)
• Day light occurs from 15 to 30 minutes before sunrise and darkness occurs 15 to 30 minutes after sunset is due to the curvature of earth’s surface and thus the length of light day is somewhat longer than the hours between sunrise and sunset. But the time between sunrise and sunset is usually considered as the “light day”
Light management
The manner in which lights are installed in the poultry house has a role on their efficiency. Some of the important points regarding fixing bulbs in poultry houses are,
• The distance between bulbs should be 1½ times the distance from the bulb to the bird level.
• The distance from the bulbs to the outer edges of the house should be only ½ the distance between bulbs.
• In cage system, the bulbs should be placed in such a way that their rays fall on the feed and on the birds.
• Clean reflectors increase the light intensity at bird level by 50%, compared with no reflector.
• Avoid cone shape reflectors since they confine the light rays to limited area. Better to use flat type reflector with rounded edge.
• In case of deep litter system, the bulb is to be placed at 7-8’ height whereas in cage house, keep in aisle.
• Avoid hanging bulbs by a cord in open houses
• Very dirty bulbs emit about 1/3 less light than clean bulbs.
• Light bulbs should be cleaned once in two weeks.
Light effects during growing period
Decreasing the length of light day during growing period will lead to
• Increase the age at sexual maturity
• Increase the number of eggs laid during the first half of the egg production (but not in total number of eggs laid)
• Increase the size of the first eggs produced.
Light restriction alone delays the sexual maturity at the maximum of 3 weeks. If feed restriction is combined with light restriction we can delay up to 4 weeks period.
Light effects during laying period
Birds reared under increased day-light produce more eggs due to the release of FSH and LH from the pituitary. Brightness of light also has influence on egg production. On practical conditions, 1 ft candle light intensity is needed in layer houses. In multi-duck cage system, minimum of 0.5 foot candle light intensity is needed at the lower deck. For maximum egg production, 16 hours light is needed during peak egg production period. Reducing photoperiod during laying period seriously affects egg production. The artificial light can be given either in the morning, evening or both morning and evening.
Combination growing-laying light programs
Two important points to be consider regarding lighting are,
• The length of the light day should never increase for growing pullets.
• The length of the light day should never decrease for laying pullets.
In-season flocks
Those birds grown during a period when the length of the natural light day is decreasing, at least during the last part of their growing cycle are called in-season flocks. As a general rule, chicks hatched between March 1st and August 31st in the Northern Hemisphere is called in-season flocks.
Out-season flocks
Chicks hatched between September 1st and February 28th are called out-season flocks since their growing period falls on increasing light-day.
Instructions for growing and laying light programs in open-sided houses
a) In-season flock
No artificial light is needed up to 20 weeks (in case of meat-type breeders 22 weeks). At 20 weeks of age increase the light to 13 hours. Then add 1 hr per week until it attains 16 hours light.
b) Out-season flock
Two methods can be adopted
i) Constant light-day program
Determine the length of the longest natural light day before the pullets reach 20 weeks of age. Maintain this period of daily light hours from the 3rd day until 20 weeks by supplementing artificial light with natural light. Then increase 1 hour of light at this stage and increase 1 hour every week until it reaches 16 hours total light period.
ii) Decreasing day-light program
Determine the total natural day-light hours when the pullets reach 20 weeks of age. Then add 7 hours. This represents the length of the light day from the 3rd day. Thereafter reduce the length of light day by 20 minutes per week. At 20 weeks of age increase the length of the light day by 1 hour. Then increase 1 hour per week until it attains 16 hours light per day.
Photo-refractoriness
Photo-refractoriness is a condition in which the bird is not capable of responding to long day lengths. Greater the stimulatory day length, the sooner and more pronounced the reduction in egg production due to photo-refractoriness.
Ahemeral lighting programs——–
When the total period of light and dark not equals 24 hours we can call it as ahemeral lighting cycle. There are two types: Longer day (14 hr light + 14 hr dark) and shorter day (11 hr light + 11 hr dark). Longer day cycle increases egg shell quality where as, shorter day cycle increases the egg production by 2%. However, these cycles are not compatible with normal working schedule and needs light proof houses.
Guidelines for growing period———
Start pullets with 20 to 22 hours of continuous and bright (30 to 50 lux, 3 to 5 foot-candles) light during the first week of age. Alternatively, an intermittent lighting program (4 hours of light followed by 2 hours of darkness) can be used during the first week of age. The dark period (or periods) serves as ‘resting time’ and helps strong chicks show the weak chicks how to find feed and water.
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 and 5 lux (0.5 foot-candles) inside the cage.
Reduce the day length weekly to reach 9 to 10 hours at 10 weeks of age or, if longer, the day length dictated by greatest natural day length in open or brown-out houses. In Hy-Line Brown and CV-22 varieties, a constant day length of 9 hours may be used to control excessive body weight after 10 weeks of age.
The light intensity in the grow and lay houses should be similar because pullets can be stimulated to start egg production by an increase in light intensity, even if the day length is unchanged. Therefore, the light intensity in the grow house should be gradually increased in increments of 5 lux (0.5 foot-candles) per week to the intensity used in the lay house, starting 2 to 3 weeks before the pullets are moved.
Guidelines for laying period———
Onset of sexual maturity (egg production) generally depends on 4 requirements:
• a minimum chronological age which is genetically determined (17 weeks)
• a minimum body weight (see tables of 18-week target body weight for individual Hy-Line varieties)
• a nutrient and energy consumption to support production
• a constant or increasing day length of at least 12 hours
Light stimulation should not be provided until flocks reach the optimum body weight (see tables of 18-week target body weight for individual Hy-Line varieties). Flocks which are light-stimulated into production at lower body weights will likely produce below normal egg weight and suffer from reduced peak production and post-peak dips in production.
Timing of light stimulation can be used as a tool to help attain desired egg size. In general, earlier light stimulation will result in a few more eggs per hen, but at a tradeoff for slightly reduced egg weight. Later light stimulation will result in a few less total eggs, but a slightly larger egg weight earlier in production. In this way, lighting programs can be customized to best meet the egg size demand of a particular market.
Provide light stimulation when the target body weight is reached, usually around 17 to 19 weeks of age. The appropriate target body weight depends in part on the variety of hen and in part the desired egg size. Stimulation at a relatively early age or low body weight will result in production of a greater number of eggs with a lower average egg size, which will negatively impact chick quality. Stimulation at an older age or a heavier body weight will produce a few less eggs, but of greater average egg size.
The initial light increase should be no less than 1 hour (especially in open or brown-out houses). Increase the day length by 15 to 30 minutes per week or once every 2 weeks until 16 hours of light is reached. Preferably, the period of increasing day length stimulation should last until peak production (i.e., until about 30 weeks of age). The light intensity at housing should be 15 to 30 lux (1.5 to 3.0 foot-candles) in light-controlled houses and 30 to 40 lux (3 to 4 foot-candles) in open-sided houses.
Allow no decrease in day length or light intensity in adult layers. Such decreases in day length will adversely affect egg production.
Guidelines for housing styles———–
It is necessary to first determine what style of houses are being used regarding light control for both growing and laying. For the purpose of designing a flock lighting program, each house has to be designated either dark-out or open.
Dark-out means there is essentially no outside light coming in the house that would physiologically affect the flock’s maturity. In that case, the outside natural day length can be ignored and the lighting program be planned using only artificial lights. That said, it is beneficial to consider and synchronize the time of lights-on and -off with the natural sunrise and sunset, respectively, under the constraints of the artificial day length.
Open house styles mean there are windows, curtains, or even just enough light leakage through fans and air vents that allow outside natural daylight to significantly illuminate the interior of the house. In many cases this cannot be avoided, but a lighting program with the desired light patterns can still be planned using artificial interior lighting added to the natural daylight changes occurring outside.
Sometimes it is not clear whether a house is sufficiently dark-out or not, and these houses are often called brown-out. It is mostly light-controlled, but not totally dark, as some light gets in through the ventilation, etc. The question is how to consider the house, open or dark-out?
• One method is to measure the light intensity with a light meter. Compare the maximum mid-day light intensity with the lights on to the intensity with the lights off (measuring just the light leakage from outside). If the light leakage is less than 10% of the maximum value, it is probably insignificant in stimulating the birds and can be ignored (i.e,. consider the house dark-out). However, if it is more than 10% of that maximum value, it probably needs to be considered open.
• Another method is just to observe the flock’s activity. With the lights off, will the flock awaken and become active when the sun rises, just from light leaking in from outside? If so, then consider the house as open for this purpose. Even with these guidelines, it is still a judgment call whether a significant portion of the flock is being affected by outside light.
Light-controlled growing to light-controlled laying———-
• Step-down day length from 20-22 hours of light the first week of age to 9-10 hours of light at 10 weeks of age and hold constant.
• Increase day length 1 hour at the 18-week body weight target. Add 15-30 minutes per week until 16 hours total light is reached and hold constant.
Light-controlled growing to open or brown-out laying
• Step-down day length from 20-22 hours of light the first week of age to either
o 9-10 hours of light at 10 weeks of age or
o 1 hour less than the natural day length the flock will be exposed to after moving to the layer house.
• Increase day length to
o natural day length or
o a minimum increase of 1 hour at the 18-week body weight target.
• Add 15-30 minutes per week (or every 2 weeks) until either
o 16 hours total light or
o at least the longest natural day length of the year.
Open or brown-out growing to light-controlled or brown-out laying—–
• Step-down day length from 20-22 hours of light the first week of age to either
o 9-10 hours of light at 10 weeks of age or, if longer,
o the longest natural day length the flock will be exposed to from 8-18 weeks of age.
• Increase day length 1 hour at the 18-week body weight target.
• Add 15-30 minutes per week (or every 2 weeks) until either
o 16 hours total light or
o at least the longest natural day length of the year for brown-out.
Midnight Feeding
An optional lighting technique that will promote greater feed consumption is the “midnight feeding.” The technique involves turning the lights on for 1-2 hours in the middle of the dark period and running the feeders during this time.
Midnight feeding will generally increase feed intake about 2 to 5 g/day per bird (0.4 to 1.1 lb/day per 100 birds). The technique is applicable for heat stress conditions, or any time a greater feed intake is desired in either growing or laying flocks.
For a typical layer lighting program with 16 hours of light and 8 hours dark, the night would consist of 3 hours of darkness, 1-2 hours of light, and 3 hours of darkness. The regular 16-hour light period should not be changed (because the 1-2 hour midnight-feeding period is not long enough to count as “daylight”). However, it is important that the dark periods surrounding the 1-2 hour midnight-feeding period are at least 3 hours long.
The 1-2 hours of light can be added all at once, but, when no longer necessary, should be removed gradually at the rate of 15 minutes per week.
Consistent Morning Lighting
Consistent morning lighting is a technique utilized to help birds go to the nest in free range and colony environments, and to stagger the time of egg laying for large farms with multiple houses. The lights are turned on at the same time in the morning every day, and the light step-up will be added in the evening.
