Have you ever wondered why birds in the wild only lay eggs in the spring and early summer and then cease laying as winter approaches?
This is all due to day-length or hours of daylight, as well as changes in light intensity. Birds that hatch in the spring require a shortening day-length approaching winter and an increasing day-length after midwinter to trigger maturity and begin to lay eggs. In technical terms, this is known as photorefractoriness. The modern commercial layer has almost had this phenomenon bred out of it and given sufficient time and food, a flock of commercial layer hens will eventually reach sexual maturity and start to lay some eggs, even without light stimulation. However, production will be poor as will peak of lay. Conversely, layers having access to natural daylight (typically in free range situations) usually do very well from late spring to mid-summer and one often notices a significant drop in egg production as autumn and winter approach. This is due to birds within the population exhibiting photorefractory behaviour and going out of lay.
Fortunately, with the use of artificial light, we can “trick” these birds into believing summer is permanent and thereby reduce the drop-off in egg production. The choice of lighting is not that critical, so incandescent, fluorescent or even modern LED lighting can be used, although it is preferable to select warm white options when using fluorescents or LEDs.
In open housing typical of free range layers, the artificial light needs to complement the natural day length and this is true of both rearing and during lay with open housing. For hens in lay, knowing the maximum day length for your region is really important. Find out when sunrise will occur and sunset on the longest day and how this changes over time. Then set the timer for the lights to come on half an hour before sunrise and stay on until the sun is up. The lights must then be turned on prior to sunset and remain on half an hour after sunset on the longest day in your region. The lights need to be bright enough, without shadows in corners, so the hens still perceive that it is daylight. A single 75 watt bulb will cover 20 square metres of floor space depending on how high the ceiling is. Some trial and error may be required to arrive at the ideal amount of light the birds need for optimum production. If birds are flighty and nervous then reduce the light intensity with lower wattage bulbs. The Hy-Line website (www.hyline.com) has a customised lighting programme for any location and this will work for any breed of layer.
Tossing birds a handful of whole grains, birdseed or some chopped greens in the late afternoon can help calm birds and help keep litter friable.
Tip – the earlier lights come on in the morning, the more eggs will be laid before noon. This is more difficult to achieve as one goes further south in New Zealand, since the longest day reduces this flexibility.
For further information, contact your local Nutrition Specialist.
Article supplied by Natalie Chrystal, Nutritionist.