Effects of LED Lights with Defined Spectral Proportion on Growth and Reproduction of Indigenous Beijing-You Chickens

Light presents an important exogenous factor for poultry. This study examined effects of LED lights with different defined spectrums on growth and reproduction of indigenous Beijing-You chickens. A total of 576 one-day old female chicks were divided into 16 rooms, and each were exposed to four different lights: LED A (21% green light, 30% blue light, 24% yellow light, and 25% red light), B (35%, 35%, 18%, and 12%), C (27%, 30%, 22%, and 21%), or compact fluorescent lamps (CFL, 15%, 28%, 41%, and 16%). Results showed that feed intake and feed conversion ratio were comparable among treatments throughout the 17 week rearing period (p > 0.05). LED C showed similar body weight gain with CFL, but higher than LED A and B. The CFL birds start to lay on 132.25 d, while LED B did not lay until 148.25 d. The age at 50% egg production did not vary among groups (p = 0.12). Total egg number until 43 week of LED B was higher than others (p < 0.05). Therefore, LED lights with defined spectral proportion have different effects on chickens' growth and reproduction. The LED C promotes the prepubertal growth, and the LED B provides proper sexual maturation age and better egg-laying persistence.

Continuous exposure to red light induces photorefractoriness in broiler breeder pullets

The management of body weight (BW) in broiler breeder pullets is critical to offset the negative correlation between their growth potential and reproductive success. Therefore, a precision feeding system was developed to allocate feed individually based on real-time BW in more frequent, smaller portions. However, this system requires access beyond the 8 h daylength of the rearing period. Since green and red spectra have been shown to stimulate growth and sexual maturation, respectively, this study aimed to evaluate the impact of continuous supplemental illumination of feeders with monochromatic wavelengths on sexual maturation. Furthermore, the best combination of supplemental and daytime lighting for optimizing the pullet-to-hen transition period was investigated. This study contained a 2 × 4 × 2 factorial arrangement, with 2 daytime lights (dtRED and dtGREEN; n = 2 rooms), 4 supplemental lights (sBLUE, sGREEN, sRED, and sCON; n = 12 pens), and 2 supplemental intensities (High and Low). At 3 wk of age (woa), 480 female Ross 708 chicks were randomly distributed across treatments (n = 10/pen). All birds were feed restricted per management guidelines and maintained under 8 h of dtRED or dtGREEN. Birds were photostimulated at 20 woa with 14L:10D. All birds were weighed weekly, with age at first egg (AFE) and production rate calculated weekly per pen. Birds under sRED were heavier than all other treatments from 27 woa to the end of the study (P < 0.001; 30 woa), resulting in hens that were over 400-g heavier. This resulted from a delayed AFE and lower production rate under sRED, with higher intensity further hindering reproductive performance (P < 0.001). Interestingly, despite the inhibitory effect of continuous red lighting (sRED) on reproduction, dtRED resulted in a 3.15% higher rate of lay than dtGREEN. Therefore, this study suggests that while red light remains superior at stimulating reproduction, continuous red supplemental lighting results in photorefractoriness. Thus, we recommend green light in PF systems.

Effects of blue-green LED lights with two perceived illuminance (human and poultry) on immune performance and skeletal development of layer chickens

Light is one of the essential environmental factors in the production process of laying hens, which can directly affect their behavior, growth and development, and production performance. The spectral sensitivity of humans is different from that of poultry, and the perceived illuminance units of human and poultry are lux and clux, respectively. If the light management of laying hen production is carried out according to human perceived illuminance, the growth and development of laying hens during pullet rearing may be adversely affected due to the discomfort of the perceived illuminance. Preliminary research has found that blue-green LED light can improve the immune function of laying hens during the brooding and rearing periods. However, the differences of the effects caused by blue-green light on the immune performance and bone development of laying hens during pullet rearing are still unclear for the 2 spectral sensitivities. A total of 120 Jinghong layer chickens were raised from 1 d to 13 wk of age in one of three groups with a white LED light (light intensity unit lux, WL) group, a blue-green LED light (light intensity unit lux, HBGL) group, and blue-green LED light (light intensity unit clux, PBGL) group, and unlimited feed and water were provided during the whole experiment. At 7 and 13 wk of age, the immune performance, bone parameters, and related gene expression were investigated. The results showed that compared with the WL groups, HBGL and PBGL increased the immunoglobulin A (IgA) content at 13 wk of age and the IgM content at 7 wk of age (P < 0.05). The bone mineral density (BMD) at 7 and 13 wk of age and tibial strength (TS) at 13 wk of age of the pullets in the WL group were significantly higher than those in the HBGL and PBGL group (P < 0.05). Osteoclastogenesis inhibitory factor gene (OPG mRNA) expression was increased in the layer chickens at the age of 7 and 13 wk for the WL group (P < 0.05). Compared with the WL group and PBGL group, the melanopsin gene (OPN4 mRNA) transcription level of hypothalamus and pineal gland of the chickens under HBGL significantly increased at 7 and 13 wk of age (P < 0.05). In conclusion, blue-green LED light with two perceived illuminance (human and poultry) can increase the Ig content and the immune performance of layer chickens, and blue-green LED light (light intensity unit lux) can promote the expression of OPN4 gene in the hypothalamus and pineal gland. In addition, white LED light can enhance bone quality by increasing tibia OPG gene expression.