Classification of LIGHTING FOR LAYING HENS
According to photoperiod, the classification of lighting for laying hens programs for the optimum layer production all year round is classified into two major classes-
- Hemeral
- Ahemeral
1.) Hemeral lighting programs
The Hemeral lighting programs consist of 24-h periods divided into light phases (photoperiod or photophase) and dark phases (scotoperiod or scotophase). Hemeral programs are used in open-sided houses, which take advantage of natural light (Campos, 2000).
Classification of Hemeral lighting programs
It is classified another two categories,
- continuous Hemeral lighting
- intermittent Hemeral lighting
Continuous Hemeral lighting
In continuous programs, artificial lighting complements natural lighting to establish a long and continuous photoperiod.
intermittent Hemeral lighting
Intermittent programs defined as alternate light (photophases) with dark periods (scotophases). It is two types-
Types of intermittent Hemeral lighting
There are two types of intermittent Hemeral lighting
a).Symmetrical
When the number of hours of photophases and scotophases is similar, intermittent programs are called symmetrical.
b). Asymmetrical
when different photophases and scotophases are applied. Asymmetrical hemeral programs have been used in egg production for energy-saving purposes (Rowland, 1985). Such programs allow workers to perform their activities inside the house during working hours (during the day).
2. Ahemeral Lighting Programs
When the total photoperiod or light period is not equal to 24 hours, then it is called Ahemeral Lighting Programs. they are various types of ahemeral lighting cycling worldwide. It is mainly in two forms- a Longer day (14 hr light + 14 hr dark) and a shorter day (11 hr light + 11 hr dark).
Advantages of Ahemeral Lighting Programs
Ahemeral programs apply photophases and scotophases that are shorter or longer, but not equal to 24h, and may continuous or intermittent (Etches,1996).
- improve eggshell quality and egg size, without affecting egg production.
- A longer day period increases eggshell quality whereas, a shorter day cycle increases the egg production by 2%.
- increase labor costs because daily tasks need to be performed outside regulated working hours, which, however, could be compensated by the production of larger eggs.
READ ALSO- DISADVANTAGES OF LIGTHING OFF AT NIGHT ON PULLET HENS
Others Lighting Classification For Chicken
There are other intermittent lighting programs for laying hen also available developed by the scientist. the practicing of this lighting pattern has a different style or designation according to the developer. This is a two classes-
- a) the Cornell program
- b) biomittent program
Cornell program
In the Cornell program, 2 hours of light (2L), 4 hours of dark (4D), 8 hours of light (8L), and 10 hours of dark (10D) are supplied (2L:4D:8L:10D). It was developed by Tienhoven and Ostrander (1976) at Cornell University. The bird interprets this program as 14L:10D, ignoring the period of four hours of dark and considering a night period of 10 hours. The program was created to allow farmers to perform their eight hours of activities during the natural photoperiod.
Biomittent lighting program
The biomittent lighting program consists of fractioning the time of alternate light and dark cycles (25%L:75%D). According to Morris & Butler (1995), the objectives of the programs are to increase egg size and to improve eggshell quality. In the biomittent program, only 15 min of light is supplied per hour during the stimulation period, which may be interesting as it reduces lighting by 75% and improves feed efficiency by 5-7%. However, studies have shown that egg size is reduced by 0.5-1% when this program is applied (Rowland, 1985).
Comparison on Cornell and Biomittent lighting program
Morris et al. (1988) demonstrated that the Cornell program reduces electric energy consumption and feed intake and promotes higher egg production.
On the other hand, despite reducing feed intake, egg size and weight are also reduced when the biomittent program is applied before hens are 22 weeks old (Morris et al.,1990).
Sources- Brazilian Journal of Poultry Science
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