A preliminary evaluation of novel artificial light conditions during incubation and growout on broiler
chicken performance and welfare
House, Gabrielle M., Ph.D., Curtis A. Leyk, D.V.M., Jack Tieberg, B.S., Aaron Stephan, Ph.D.
ONCE/Signify, Plymouth, MN
Lighting is a critical environmental factor in incubation and growout conditions that can influence performance and well-being of broiler chickens post-hatch. The objectives of this study were to evaluate the performance and welfare of broilers incubated under 12 h of white light and 12 h of blue light (12L:12Lb) or continuous light (24L:0D) and subjected to either one or two photophases per 24 h period during growout. A total of 844 Ross 308 eggs were set in two incubators where Incubator 1 utilized a 24L:0D photoperiod, and Incubator 2 utilized a 12L:12Lb photoperiod. Upon hatch, chicks were allocated to one of 10 rooms (50 chicks/room) at the ONCE Research Facility – 5 rooms utilized a 16L:8D photoperiod (1P), and 5 rooms utilized a 8L:4D:8L:4D photoperiod (2P). All rooms were equipped with NatureDynamics Dome lights using a mixture of red, green, and blue wavelengths during brood, grow, and finish phases. Weights and FCR were monitored throughout the 42 d trial. Behavior and stress measures were conducted during the final week of growout to evaluate bird welfare. Behavior measures included inversion, emergence (EMERG), isolation, and tonic immobility tests. Stress measures included heterophil-to-lymphocyte ratios (H:L) and serum lactate concentration (LAC). Data was analyzed using GLMs by incubation condition, growout condition, and incubation x growout condition. Significant differences were considered at p < 0.05, and Fishers LSD test was used for post hoc mean separation. The 12L:12Lb birds were heavier than the 24L:0D birds on all weigh days (p < 0.05). The 12L:12Lb/1P birds weighed more than 24L:0D/1P, 12L:12Lb/2P, and 24L:0D/2P birds at d7 (0.200 kg vs. 0.183, 0.183, 0.183 kg; p = 0.003), d15 (0.610 kg vs. 0.585, 0.586, 0.545kg; p = 0.001), and d25 (1.534 kg vs. 1.448, 1.415, 1.395 kg; p = 0.049). The 12L:12Lb birds had higher H:L compared to 24L:0D birds (1.199 vs. 0.741, p < 0.001). Birds reared under 2P had elevated LAC compared to 1P birds (5.727 vs. 4.893 mmol/L, p = 0.001). The 24L:0D/2P birds had a longer EMERG time compared to 12L:12Lb/2P (171.756 vs. 68.7 s; p = 0.001) while 12L:12Lb/1P and 24L:0D/1P were intermediates. The results indicate 12L:12Lb during incubation and 1P during growout may improve growth during the first 25 d of growout. The 12L:12Lb treatment can be beneficial for post-hatch bird growth. The stress measure results indicate elevated stress in both 12L:12Lb birds and in birds reared under 2P; however, no interactions between incubation and growout lighting conditions were observed. These results may indicate the physiological consequences of incubation and growout lighting conditions do not present in the same manner; however, future investigation is required.