Impact of daytime and supplemental feeder light spectrum on female broiler breeder growth and reproductive performance

Body weight (BW) management of broiler breeders is essential to optimize subsequent reproductive performance. A precision feeding system was developed to allocate feed to birds on an individual basis using real-time BW. However, sequential feeding systems require 24-hour access with continuous supplemental lighting to be economically viable, which may impact growth and reproductive performance. Therefore, we studied the impact of various constant supplemental light strategies on growth and reproduction. This experiment used a 2 × 3 × 2 factorial arrangement of treatments, with 2 rearing daytime LED lights (60 % Red; dtRED or 60 % Green; dtGREEN), 3 continuous monochromatic supplemental feeder lights (red: sRED; green: sGREEN; dark: sCON), and 2 adult daytime light treatments (dtRED or dtGREEN). Ross 708 chicks (n = 520) were placed under dtRED or dtGREEN light. Starting at 2 weeks of age (woa), chicks were exposed to the continuous supplemental feeder light treatments. All birds were provided with the same feed allocation following the management guidelines, and the rearing photoperiod was 8L:16D. At 21 woa, the adult daytime light treatment began. All pens retained their original supplemental feeder lighting treatment. At 22 woa, pullets were photostimulated with 14L:10D. Continuous exposure to sRED delayed the onset of lay by 4 weeks, decreasing cumulative egg production compared to sGREEN and sCON (125.0 ± 3.4, 149.0 ± 5.0, and 160.9 ± 2.3 eggs, respectively). Elevated BW under sRED beginning at 29 woa indicated that delayed sexual maturation resulted in energy diverted to growth. Additionally, the increase in estradiol associated with maturation was delayed to 30 woa under sRED compared to 25 (sGREEN) and 26 woa (sCON). Overall, circadian rhythm was maintained in birds under all supplemental light treatments; furthermore, sGREEN showed higher nocturnal melatonin levels compared to sCON. No disruption in circadian rhythm using 24-h supplemental light suggests that sRED acts independently of the retina and pineal gland and is likely mediated through deep brain photoreceptors. Commercial use of continuous red supplemental light is strongly discouraged; supplemental green light appears to be an acceptable light source for a precision feeding system.