Effects of B-Wave Ultraviolet Supplementation Using Light-Emitting Diodes on Caged Laying Hens during the Later Phase of the Laying Cycle

Abstract

Caged laying hens are prone to calcium deficiencies, resulting in osteoporosis and egg quality deterioration during the later phase of the laying cycle. Fluorescent light and light-emitting diodes (LEDs), which are widely used in poultry houses now, are both deficient in ultraviolet (UV) light, the lack of which is detrimental to chickens' welfare and health. This study was conducted to investigate the effects of UVB light supplementation using LEDs on the bone traits, blood parameters, laying performance, and egg quality for caged laying hens at 68-75 weeks. In total, 120 Jingfen laying hens were randomly assigned to four different groups, with three replicates in each group (10 hens in each cage as a replicate). UVB-LED lamps installed under the feed troughs were used to provide UVB light (296-316 nm) for the birds in the three treatment groups (1 h, 2 h, and 3 h UVB supplementation per day, respectively), while the control group was not exposed to UVB-LED light. Bone traits, egg quality, and amounts of calcium (Ca), phosphorus (P), 25-hydroxyvitamin D₃ (25(OH)D₃), 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), and 7-dehydrocholesterol (7-DHC) in both the serum and egg yolks were tested during the experiment. The results demonstrated that UVB-LED exposure significantly increased the bone mineral density (BMD), egg production, and yolk 1,25(OH)₂D₃ concentrations (p < 0.05), and reduced the content of serum 7-DHC (p < 0.05), especially in the 2 h/day group; however, it did not improve egg quality, vitamin D metabolites, or photoproducts in the serum and yolk 25(OH)₂D₃ concentrations (p > 0.05). This study concluded that UVB supplementation using LEDs had a positive effect on caged laying hens during the later phase of the laying cycle.

Keywords: bone quality; egg quality; light supplementation; poultry; ultraviolet light-emitting diode.

Figure 1

Main view of experiment cage. During the 8 weeks experiment, 1 h, 2 h, and 3 h of B-wave ultraviolet (UVB) light supplementation per day was provided for the birds in the three treatment groups (UVB1, UVB2, and UVB3, respectively), while the control group was not exposed to UVB-light-emitting diode (LED) light (UVB0).

Figure 2

Spectrogram of ultraviolet light-emitting diode light. UVB: B-wave ultraviolet.

Figure 3

Effect of different UVB-LED light exposure durations on egg production. During the 8 weeks experiment, UVB-LED light supplementation was provided for the birds in the three treatment groups (1 h, 2 h, and 3 h per day), while the control group was not exposed to UVB-LED light. Data are presented as the means ± standard error (SE). A, B—Within a same week, different capital letters indicate significant differences (p < 0.05).

Figure 4

Effect of different UVB-LED light exposure durations on yolk 1,25(OH)₂D₃ and 25(OH)D₃. During the 8 weeks experiment, UVB-LED light supplementation was provided for the birds in the three treatment groups (1 h, 2 h, and 3 h per day), while the control group was not exposed to UVB-LED light. The change rate of 0–4 week: the ratio of the average concentration at the 4 weeks to the average concentration at the 0 weeks; the change rate of 4–8 week: the ratio of the average concentration at the 8 weeks to the average concentration at the 4 weeks. Data are presented as the means ± standard error (SE). ^{A, B, C}: Different capital letters indicate significant differences in the same duration (p < 0.05). (a) effect of different UVB-LED light exposure durations on change rate of yolk 1,25(OH)₂D₃ concentration; (b) effect of different UVB-LED light exposure durations on change rate of yolk 25(OH)D₃ concentration

Figure 5

Correlation between serum 1,25(OH)₂D₃ concentration and yolk 25(OH)D₃ concentration. Data are presented as the means ± standard error (SE), and r is the correlation coefficient.