Broiler producers need to get light right. How many hours a day? What intensity? Natural or artificial? Red, white or blue? The debate around, and advances in, lighting technology continues apace, and demands from welfare groups, whether right or wrong, show no signs of losing intensity.
How can producers balance productivity and welfare benefits where lighting is concerned?
Multiple studies show behavioral and welfare improvements linked to light spectrum, intensity and distribution, noted Jason King, sales leader with smart lighting company Signify, who added that there is documented proof of improvements in bird stress and stress-related conditions based solely on light, especially how light can be utilized to improve growing conditions.
"We've seen marked improvements in performance and animal welfare. For example, red spectrum can be used to improve activity of chicks during the first week of life, helping the bird to find feed and water faster and leading to better early weight gains and less starve-outs. The blue spectrum provides a more calming and lower-stress environment for older broilers, leading to a better feed conversion ratio and less damage and stress during catch. The green spectrum aids in early muscular and skeletal development," he explained.
The three spectrums, and a blend of each, can be used from day one through to catch, to give birds an advantage over birds raised under common light-emitting diode (LED) lights or sunlight.
Is natural light necessary?
And sunlight, or natural light, is something that many welfare certification bodies demand — but should they?
According to Signify's innovation and research leader Aaron Stephan, Ph.D., whether lighting comes from nature or through a carefully defined and controlled artificial light is irrelevant.
"Because natural sunlight varies dramatically in terms of intensity, spectrum and photoperiod, depending on the latitude, time of year and surrounding environment, there is no simple lighting environment that can be considered 'natural,'" he said.
Many natural lighting conditions can be harmful to welfare, including excessively bright or overly hot conditions or an excessively long photoperiod. Conversely, other natural lighting conditions can be beneficial, including gradual dawn-to-dusk transitions, full spectral compositions and predictable photoperiods day to day. Many lighting systems are designed to maximize these benefits while mitigating the downsides that natural light may bring, he explained, adding that, in cases where natural lighting is required, it is still important to supplement with a lighting system that ensures baseline light characteristics necessary for bird health and well-being.
While it may be possible to optimize light spectrum within a barn, it is also important that light reaches all the birds.
Prior to an installation, it is helpful to create a lighting layout of the barn — a 3D CAD drawing of the barn structure with light fittings detailed. Software can calculate the lighting distribution and intensity from each fitting and create a model of the light environment across the barn, accounting for direct and reflected light from all barn surfaces. This helps to refine the lighting placement in the layout to adhere to intensity and uniformity requirements.
Signify is also working with Tyson Foods and McDonald's on a gradient light solution. It offers brighter activity zones near feed and water lines while maintaining dimmer comfort zones for resting. This gives birds the ability to choose the environment that best suits their needs throughout the day.
Shorter photoperiods
Longer dark periods are a requirement of many broiler welfare schemes, but it has long been believed that using longer daylengths maximizes broiler growth rates, meaning producers must weigh the benefits against the drawbacks.
A study conducted by Aviagen with the University of Saskatchewan, however, found that 23 hours of daylight negatively impacts broiler welfare, raises mortality and impacts growth rate, feed intake and processing performance. Their trials found that welfare and performance were optimized when birds were exposed to 17 and 20 hours of light.
The trials, comprising 16,000 birds — either Ross 308 or Ross 708 — were designed to determine the effect of daylength across various production parameters. Daylengths of 14, 17, 20 and 23 hours were examined, with darkness provided in a single period.
Birds raised under near-constant, i.e., 23-hour, photoperiods never grew the fastest. The failure of birds given 23 hours of light to grow as fast as birds given 20 hours at any age, or 17 hours at 48/49 days, was unexpected — the birds were able to see feeders and drinkers and had free access. There were no other obvious limiting factors in the 23-hour program, suggesting that reduced bodyweight may be indicative of reduced welfare.
As broilers age, they adapt to shorter daylengths. In older birds, 48-49 days, daylength can be reduced to 17 hours with no negative effects on growth rate, the study found.
Where mortality is concerned, increasing daylength resulted in higher rates, regardless of target weight or marketing age, indicating the negative impact of long days on bird welfare.
Mortality and culls due to leg weakness increased with increasing daylength. Broilers given 23 hours of light had the highest incidence of leg weakness compared with birds given shorter daylengths but with the same growth rate. Leg scoring data showed that the number of birds considered to be in pain rose with increasing daylength.
Looking at bird behavior, the study found that walking and running activity was highest in broilers given 17 hours of light. Increasing the daylength led to a significant decline in walking and running, with the two activities lowest in birds given 23 hours of light. The trial data suggested that the lack of movement was related more to a lack of motivation rather than an inability to move.
New dimensions
While traditionally lighting has supported productivity and behavior, it is now being explored in new ways, such as achieving continuous environmental control.
Jimmy Weng, director of sales and marketing with UV technology company Silanna, said: "Advances in semiconductor technology are making it possible to integrate UV LEDs into standard lighting, adding a background layer of pathogen reduction without interrupting operations."
For pathogen control, measures such as chemical disinfection will remain essential, but there is growing interest in solutions that can operate continuously in the production environment.
"Because far-UVC disrupts the genetic material of pathogens, its effect is not limited to a single organism. It has shown efficacy across a range of threats relevant to poultry production, including avian influenza, Salmonella and Escherichia coli," Weng added.
Do your homework
Danny Cross, president of Precision Lighting Systems, noted that whatever aims a producer might have when considering lighting, it is important that lighting systems are fully researched prior to purchase.
He noted the importance of purchasing LED fixtures that have been specifically engineered for use with broilers, as they produce a higher lumen output, better housing for the shed's harsh environment and better dimming options, resulting in more low-level control.
New LED specialty lights can produce a spread, specific color spectrum and other claims for production improvement, he continued, but he encouraged producers to ask questions and know the warranties offered, or lack thereof.
