Influence of Monochromatic Light during Incubation on the Production and Metabolism of Low-Temperature Broiler Chicks

The use of artificial lighting during the incubation phase is a tool that has been studied with the aim of increasing the production rates and hatchability. Using this, this study aims to investigate the effects of the luminous incidence of white and red monochromatic light on the production and metabolism of broiler chicks subjected to low temperatures. A total of 315 eggs of Ross 708 heavy breeders were used. The eggs were distributed randomly, with 35 eggs per tray, totaling 105 eggs per incubator. The treatments were the following: incubation without the use of light; the use of white monochromatic light; and the use of red monochromatic light. The lamps used were of the LED type. The samples were distributed in the factorial completely randomized experimental design with position effect on the tray. Candling, egg weighing, calculating the probability of survival and egg weight loss were performed. Temperatures were recorded using a thermographic camera. At birth, three chicks per tray were euthanized for evaluation: weight with and without yolk residue, gastrointestinal tract biometry, and blood and liver biochemistry. Analyses were performed using the R computational program. It was observed that there was a significant effect of the treatments on the levels of calcium, phosphorus, cholesterol, amylase, glucose, urea and glutamate pyruvate transaminase on the biochemical profile of the blood and on the thermographic temperatures of the eggs; the experiment was kept at low temperatures resulting in thermal stress, with an average temperature of 34.5 °C. Therefore, the use of red and white monochromatic light in the artificial incubation process for brown-colored eggs is not recommended, because in the post-hatching phase, it promoted the metabolism dysregulation on the blood biochemical profile to control the differentiation in the wavelength of traditional incubation.

Evaluation of Light Color Manipulation on Behavior and Welfare of Broiler Chickens

This experiment evaluated the effect of light manipulation on the behavior and welfare of broilers using 280-day-old Arbor-Acre chicks, which were weighed and assigned to 7 treatments having 4 replicates and 10 birds per replicate. The light treatments were as follows: white light (WH), blue light (BL), green (GR), blue light switched to green light at 14 days (2BG), green light switched to blue at 14 days (2GB), blue light switched to green light at 28 days (4BG), and green light switched to blue light at 28 days (4GB). Feeding, drinking, resting, standing, walking, foraging and preening behaviors were observed using the scan sampling method. Behavior and welfare parameters such as footpad dermatitis and hock burn were evaluated and analyzed in a Completely Randomized Design. The results showed that feeding behavior of birds of BL, 2BG, and 2GB treatment groups was significantly higher (P < 0.05) than those of WH and GR at the starter phase. At the finisher phase, resting behavior of birds of 4GB was similar to those of 2GB but higher than those of the other treatments. It was concluded that switching of light from green to blue (4GB) at four weeks of age fostered ideal behavior and stimulated growth in broilers but had no effect on welfare parameters.

Effect of various monochromatic light-emitting diode colours on the behaviour and welfare of broiler chickens

This study was conducted to evaluate the effect of different monochromatic light-emitting diode colours on the behaviour and welfare of broiler chicks. A total of 750 one-day-old chicks were used and lighting was set up as follows: pure blue (PB, 440–450 nm), bright blue (460–470 nm), sky blue (480–490 nm), greenish blue (500–510 nm), and green (530–540), while fluorescent white (400–700 nm) was used as a control. Birds were placed into 30 independent light proof pens and each light treatment was replicated five times with 25 birds in each pen. Video was recorded and behaviour was evaluated twice per day and observed five consecutive days in a week. Broiler welfare was evaluated using the characteristics of gait score, tibia dyschondroplasia, tonic immobility duration, and heterophil:lymphocyte ratio. In results, sitting, walking, and ground pecking behaviour were influenced by the light colour from 0 to 7 d. Extending the rearing period from 8 to 21 d resulted in increased sitting behaviour and decreased walking and pecking behaviour in chicks in the PB treatment (P < 0.05). When the growth period was extended further (22–42 d), sitting behaviour increased when chicks were exposed to PB light (P < 0.05). The effect of light colour did not significantly influence welfare of broiler chicks. Thus, the present results suggest that PB light colour decreased broiler chickens movement and thus increased duration of sitting behaviour. These results would be helpful to choose light colour for broiler producers.

Effects of light-sources and photoperiod on hemato-physiological indices of broilers grown to heavy weights

We evaluated the influence of light sources and photoperiod on blood physiological variables in four trials. In each trial, 720 1-d-old Ross × Ross 708 chicks were randomly distributed into 12 environmentally controlled rooms (30 males/30 females/room). The experimental design was a 4 × 3 factorial treatments consisting of four light sources [incandescent (ICD, standard), compact fluorescent, neutral light emitting diode, and cool poultry-specific-filtered LED] and three photoperiods [long/continuous (23L:1D), regular/intermittent (2L:2D), and short/non-intermittent (8L:16D)] from d8-d56 at 50% relative humidity. Birds were fed the same diet, while feed and water were provided ad libitum. Blood samples were collected from the brachial wing vein on d 14, 28, 42, and 56 of age and analyzed immediately. Light sources had significant (P ≤ 0.05) effects on body weight (BW), and some of the selected blood physiological indices except Hb, Hct, Ca2+ angap, glucose, and corticosterone. Also, the photoperiods had significant (P ≤ 0.05) effects on BW and most of the selected blood physiological indices except HCO3-, angap, glucose, corticosterone, and T4. However, all these changes were still within the normal acid-base homeostasis and physiological ranges of this species. Acid-base regulation during the short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone and glucose concentrations were not affected by treatments, suggesting an absence of physiological stress. It was concluded that the three LED light bulbs evaluated could be suitable for replacement of ICD along with the regular/intermittent photoperiod. Commercial poultry facilities can thereby reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights (>3 kg).

Color temperature of light-emitting diode lighting matters for optimum growth and welfare of broiler chickens

Light-emitting diode (LED) light bulbs are becoming more prevalent in broiler production as they are dimmable and more energy efficient than compact fluorescent lamps. Although there is some research on how spectrum of light can affect production, little has been conducted on how it may affect stress, and behavior. To determine how different spectrum of light produced by LED lights could affect production, stress and behavior we raised broilers under either 2700 K (WARM) or 5000 K (COOL) color temperature LED bulbs. To determine stress susceptibility bilateral asymmetry (ASYM, n=128), plasma corticosterone concentrations (CORT, n=40) and heterophil/lymphocyte ratios (HL, n=80) were measured. Fear was measured using tonic immobility (TI, n=128), inversion (INV, n=128) and isolation (ISO, n=128). Weight gain and feed conversion ratio (FCR) were also determined. The COOL birds had lower ASYM (1.65±0.08 mm, P=0.001), CORT (5.8±1.2 ng/dl, P=0.01) and HL (0.16±0.01, P=0.03) than the WARM birds (2.38±0.14 mm, 13.4±2.7 ng/dl and 0.21±0.02, respectively). The COOL birds righted faster during TI (136.2±11.1 s, P=0.001), flapped less intensely during INV (4.1±0.1 flaps/s, P<0.001) and vocalized less during ISO (45.3±2.8 vocalizations, P=0.005) when compared with WARM birds (207.2±15.8 s, 4.9±0.1 flaps/s and 56.5±2.9 vocalizations). The COOL birds (2.89±0.03 kg, P=0.02) grew to a heavier weight at the end of 42 day then WARM birds (2.79±0.03 kg). The COOL birds (1.54±0.03) had better FCR (P=0.02) than WARM birds (1.61±0.01). These results demonstrate that raising broilers under 5000 K LED lights can reduce their stress, fear and increase weight gain when compared with 2700 K. These results indicate that the spectrum of light used for rearing of broilers is not only important for production, but also for welfare of the birds.