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Do Chicks Benefit From 24 Hours of Light?

Published: April 25, 2022
By: Michael Czarick, Garret Ashabranner, Brian Fairchild / Department of Poultry Science - University of Georgia.
Do Chicks Benefit From 24 Hours of Light? - Image 1
Why do we, for the most part, give our chicks 24 hours of light during brooding? Do chicks actually benefit from being able to eat and drink at 2 am? Though it is widely believed that 24 hours of light is essential to maximizing chick performance and health, preliminary trails have found no significant benefit in doing so.
Numerous studies have shown that chicks, like all creatures, are essentially born with a 24-hour, circadian clock. This circadian clock can be seen at work when observing feeding/drinking activity during the first days of a chick’s life. Even when provided 24 hours of light, chicks will tend to drink and eat more during the day than at night. This pattern was clearly illustrated in a study of chick water usage during brooding. Hourly chick water usage was measured using high accuracy water meters installed in 18 houses across seven different farms. It was found that the chicks on all the farms exhibited a nearly identical circadian rhythm to their drinking during the first few days of their lives (Figure 1). Since drinking is tied closely to feeding, it can be safely assumed that there was a similar circadian rhythm to their eating as well (verified by camera data). Interestingly, the circadian pattern of the chick’s drinking appeared to decrease over time (Figure 2).
It has yet to determined if the cyclic pattern actually disappears or the circadian cycles of individual chicks become un-synced over time because there is no “nighttime” to keep all the chicks’ “clocks” in sync.
From the cyclic nature of the chicks drinking it appears that the chicks are in a sense “looking” for a period of low activity each day - a dark period. This shouldn’t be surprising because sleeping is a natural, necessary activity for all animals, especially when they are young. Though it is true chicks spend a lot of time “napping,” it is important to realize that biologically, napping is not the same as sleeping. Studies have suggested that poultry need to have at least four hours of contiguous darkness for them to truly benefit from having a dark period. If this is in fact true, why not give chicks a dark period during brooding?
Do Chicks Benefit From 24 Hours of Light? - Image 2
A preliminary study examining the effects of providing chicks with a four-hour-dark period was conducted at the University of Georgia Poultry Research Center. Ninety-two chicks in each of three rooms were started off with 24 hours of light then given four hours of darkness on the night of Day 7, while chicks in three adjacent rooms were provided with four hours of darkness from day of placement. Chick weights and feed consumption were measured on Days 0, 3, 7, 10 and 14. Mortality was monitored and recorded on a daily basis. The study was repeated three times.
Do Chicks Benefit From 24 Hours of Light? - Image 3
Table 1 summarizes chick performance for the three trials. The bolded values indicate a significant difference between treatments for the variable listed. If neither value is bolded then it indicates that the values are essentially the same. Chicks given 24 hours of light were found to have slightly higher weights on Days 3 and 7 than those with a dark period. Three days after the control birds were given four hours darkness, it was found that the treatment chicks tended to weigh significantly more than the control chicks. By Day 14 there was no significant difference in weight between the treatment and control birds. Feed conversion and mortality were not found to be affected by the introduction of a dark period during brooding. One benefit that had been noted in all three trials is that uniformity has been improved for the treatment group.
The study has been expanded to include the implementation of six-hour dark period during brooding. In addition to examining traditional bird performance indicators, the study will examine how a brooding dark period might affect chick health and welfare. To accomplish this goal, chick blood samples will be analyzed for melatonin, corticosterone, and superoxide dismutase (SOD) levels.
Melatonin: Levels increase during darkness and induces sleep. Has been shown to improve immune system function. Melatonin levels have also been linked to bird behavior, as well as cardiopulmonary, digestive, and thermoregulatory systems function.
Corticosterone: The stress hormone which helps regulates some behaviors like the drives to eat and forage. Normally as melatonin increases, corticosterone levels decreases.
SOD: An enzymatic antioxidant highly correlated with melatonin. Protects the body from free radicals oxidizing cells in the body.
In addition, chicks will be grown out to 42 days of age to see what long-term effects dark periods during brooding may have on overall weight and feed conversions as well as gait scores and bone strength.
To date, the study results have been very promising. Providing a dark period during brooding has not been shown to produce any negative results in any of the trials conducted. Though there is still long way to go, this study illustrates the need to always question our management practices, even if they have been used for decades. Though they may have once been appropriate, it is important to keep in mind that the bird we are growing today is very different than the ones grown decades ago.
This research is being funded through a grant provided by USPOULTRY.
      
This article was originally published in Poultry Housing Tips, Volume 34, Number 7, 2022. University of Georgia, College of Agricultural and Environmental Sciences Cooperative Extension (https://www.poultryventilation.com/).
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Authors:
Mike Czarick
University of Georgia
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Dr. Brian D. Fairchild
University of Georgia
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Talaat Mostafa El-Sheikh
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Talaat Mostafa  El-Sheikh
9 de junio de 2022

While the light is very important the dark is very important too. Light is good for pituitary gland activation to secretion growth hormone. The same thing the dark period is important for bineal gland activity and melatonin hormone which is very important to immune response and stress tolerance.
A lighting program it is not only photoperiod but also light intensity weave length as well as a source of light

Dr Kotaiah Talapaneni
Indbro Research & Breeding Farms
23 de mayo de 2022
In India, we have bright days and day temperatures are seasonal. Our day length ranges from 12 to 14 hours. We work with open sided houses and it is not possible to reduce the day length to 8 hours as recommended for layers during growing. Our layers brooded in winter mature early by a week to10days due to increasing day length while growing. They do not respond to additional night light. We do use additional 2 to 4 hours ( to make it 16 hours) at peak. Not to stimulate maturity. Birds started in summer and approach maturity in winter respond for additional evening or morning light in terms of sexual maturity. This is true only with birds with proper body weight in layers and broiler breeders. Broilers growing in summer during summer months are extremely benefitted with 24 hours light because they do not eat enough during day time due to high temperature. The birds grown in winter eat well during day time and also night time. They face sudden death during the day if the day temperature goes up suddenly. Putting off the night lights and not allowing them in night helps in less sudden deaths and better flock Feed efficiency.
dan hofer
10 de mayo de 2022
It works good for us here I guess not each barn is the same
dan hofer
8 de mayo de 2022

Good information there Geoge I find that using same of time from day one to finish is good idea get them eating and drinking good amount before they rest but 4 hours max cause it takes 4hours to empty gut that leaves empty section in Gut which bad bacteria can grow in the empty section when longer dark hours they hit feed and water to hard sometimes causing overeating which causes necrotic enteritis and More cellulitis at least that’s what I’ve been seeing. We recently installed light stimulation for 20 minutes every four hours and that seems to get better feed and water intake and in results better feed conversion

George Entz
4 de mayo de 2022

Look for Dr.Karen Schwean-Lardner work on lighting. She found that birds regulate the feed passage according to number of darkness. Link below.

https://en.engormix.com/poultry-industry/articles/dirunal-lighting-programs-broilers-t49707.htm

Mike Czarick
University of Georgia
1 de mayo de 2022
I personally believe it is better to have a single dark period, the length of which would remain the same for essentially the entire length of the flock.
George Entz
1 de mayo de 2022
In the field, I have raised chicks on 4 hour darkness at hatch till day 4 and working up to 6 by day 8, and I have found the same. That the 7 day weight is slightly lower but the "burst" of growth after day 9 more then makes up for it. The concern was that in finishing when feeding mash diets that in higher density barns (3.5 kg/ sq ft) that the chicks wouldn't have enough time and feed intake would be depressed. But that has also not been the case as flocks with 6 hours of darkness versus 3 or 4 have the same feed intake and performance data. It's been amazing how "programmable" they have been towards lights. I have 54 birds to a feeder, maybe that changes if it goes higher and feeder management is important either ways. I was wondering if any broiler growers have used lighting programs similar to Layer/pullet growers. Where they use a number of shorter lights on/off cycles in a day, and what they have seen with that?
Ahmad Karimi
University of Kurdistan
25 de abril de 2022
Thanks for this nice article. though, there is no much difference between performance data, but 4 light saving is still a big achievement.
Wijaya Saputra
15 de mayo de 2022

thank you, it's an article that is very useful to me.

Ensapuh Veterinary Services limited
5 de mayo de 2022
This is very instructive. Thank you
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