Introduction
The Optient gradient lighting system developed by Once by Signify offers improved welfare and increased margin through lower feed conversion. Although maximizing return is an important objective, it is possible to indirectly attain higher weight gain or lower feed conversion efficiency through upgrading welfare. Financial return can be optimized by producing a more saleable product with enhanced quality.
House with two feeder lines showing the
relative light intensities from the Optient gradient lighting system |
VAL-CO Industries has been appointed as the distributor of the Optient lighting system for the U.S. and Canada. The system is fully compatible with the FUZE® V feeder, and the combination provides synergy in flock performance, welfare, sustainability with an optimal grow-out margin.
The Science Supporting Gradient Lighting
It is evident that broiler chickens favor a variation in intensity of illumination. With gradient lighting feeding and drinking are stimulated at higher light intensity (30 to 40lux) compared to darker areas of the house (5 to 10 lux). These lower levels of light allow for natural behaviors including non-aggressive interaction, dust-bathing and resting. Gradient (variable area) light intensity in a house contrasts with traditional uniform lighting at 20 lux from ceiling fixtures that spread light evenly across the entire floor. Studies from 2009 onwards have examined the response of flocks to gradient lighting. This has generated data on quantifiable physiological responses and performance data confirming benefits for integrators.
A comprehensive evaluation of gradient lighting was conducted by the Center of Excellence for Poultry Science at the University of Arkansas in 2023*. Lighting regimes that were compared included intensities of 5 lux, 20 lux, natural light and gradient light ranging from approximately 5 lux in the dark areas to 40 lux adjacent to feeder lines.
The effects among the four treatments were compared with respect to conventional production parameters including live weight, daily weight gain, adjusted feed conversion efficiency, livability, skeletal integrity, gait and footpad scores. The study also involved an assessment of natural behaviors including curiosity, physical activity and dust bathing. The performance and behavioral factors were correlated with brain function including gene expression for neurotransmitters contributing to either stress or homeostasis.
With respect to the four growing trials terminating at 56, 51, 49 and 55 days respectively, the gradient light treatment consistently resulted in a very highly significantly lower adjusted feed conversion, approximating two points, compared to a house operated at 20 lux. Daily weight gain and final weight were also numerically superior. There was no statistical difference in total mortality through 49 days. The category designated “leg problems” was statistically lower in the gradient light treatment at a level of approximately 1.5 percent among the 4,880 broilers in each treatment, compared to higher values in the other three treatments. Cumulative mortality was in region of 5.4 percent among all four light treatments. It was considered important that litter was significantly drier in the house with the gradient light installation. This has implications for intestinal health and suppression of coccidiosis Moisture content was assessed by the number of zones in the house that yielded levels over 35 percent. Gradient light resulted in a factor of 0.2 compared to the 20-lux treatment at an average of 2.1 zones. Daily physical activity as measured electronically was significantly higher in the house with gradient light at 155 joules per day compared to 80 joules per day in the treatment grown with a uniform light intensity of 20 lux. This confirms that gradient light stimulates movement that is correlated with improved skeletal integrity and locomotory function. The number of dust bathing holes in litter signifying natural activity was significantly higher with gradient lighting compared to the 20-lux treatment on days 9, 16 and 23 during the trial.
Light affects the serotonin (5-HT) system in the brain stem. This parameter together with measurements of tryptophan hydroxylase 2, tyrosine hydroxylase and glucocorticoid receptor denoted reduced stress in broilers reared under gradient light. Measures of brain function are correlated with observed behavior of flocks. There are also positive relationships between neurotransmitters and enhanced production parameters including feed conversion efficiency, gait score and the prevalence of leg abnormalities in a flock. These benefits were attributed to the gradient lighting system contributing to increased movement in the house, less stress and higher feed and water intake compared to flocks exposed to a constant light intensity of 20 lux.
*Kang, S.W. et al. Effects of a variable light intensity lighting program on the welfare and performance of commercial broiler chickens. Frontiers in Physiology. doi.org/10.3389/fphys.2023. 1059055.
Field Trials
A team of scientists conducted a series of field evaluations comparing light intensities of 20 lux with gradient lighting using the Optient system. The series of comparisons was conducted from June 2023 through August 2024. The scope of the field trial involved seven integrators in five U.S. states (AR, MS, NC, TX and CA) and Ontario. Twentyfour comparisons involved ten farms with replication of whole-house comparisons. Harvest ages ranged from 39 to 58 days and live weights from 4.5 to 9.5 pounds.
Feed conversion efficiency was the important difference between the constant 20 lux and the gradient light treatments using the Optient system. There was a difference of 3 points in adjusted feed conversion with a p-value of 0.0001 confirming a very highly significant difference in favor of gradient lighting over ceiling lighting at a uniform 20 lux. There were no statistically significant differences in harvest weight, average daily gain or livability among the treatments compared in the meta-analysis.
Parameter. Gradient Lighting. Ceiling Lighting. Difference. P Value
Weight (lbs.). 7.58. 7.52. +0.06. 0.11
Adj. FCR. 1.75 1.78. -0.03 0.0001
Mortality (%). 5.4. 5.4. 0. n/a
Summary of 24 field trials comparing Optient Lighting with conventional ceiling lighting
Financial Value of Improved Feed Conversion
The very highly significant 3-point difference in feed conversion over 24 field trials, represents 0.12 pounds of feed per bird saved applying the live weights and adjusted feed conversion ratios for the Optient system compared to ceiling light, as tabulated in the previous section. The difference amounted to 8.25 tons of feed saved each year. This assumes 25,000 birds per house at 0.8ft.2 stocking density; a cycle length of 66 days (48 days growing plus 18 inter-cycle) contributing to 5.5 cycles per year for a total of 137,500 birds per house.
The financial benefit was calculated for a five-year period with the base cost of feed at $230 per ton, increasing by three percent annually. Applying a five percent discount factor to the annual benefits derived from feed saving, the value of the improved feed conversion efficiency amounted to $8,599.
The Optient installation in the house with a 25,000 flock would cost $6,500 compared to a conventional ceiling LED system at $8,000. The $1,500 differential added to the discounted annual benefits over five years provides a net present value of $10,099 for an Optient light system in the 500 by 40 ft. house.
Conclusion
The Optient lighting system manufactured by Once, a subsidiary of Signify is justified by feed saving. The range of scientific evaluations provides a mechanism for improved performance and welfare using gradient lighting for broilers. Field trials conducted on the Optient system established a 3-point improvement in feed conversion efficiency projecting realistic prices for feed over a five-year period confirming the financial benefit for integrators specifying the Optient gradient Lighting system. The contractor would benefit from reduced power consumption since Optient lights are rated at 2 watts compared to conventional LED ceiling lights at 10 watts. In addition, growers using gradient lighting would benefit from enhanced settlement payment with contracts specifying incentives for improved feed conversion or harvested weight livability or their combination.