Light color and the commercial broiler: effect on behavior, fear, and stress

Effect of different LED light colors on welfare, performance, some behavioral patterns, and blood parameters of Muscovy ducks

BACKGROUND

The current study was conducted to assess the impact of different LED light colors on welfare indicators in Muscovy ducks. These welfare parameters encompassed growth performance, specific behaviors, tonic immobility (TI), feather score, haematological, and serum biochemical parameters. Eighty-four healthy unsexed Muscovy ducklings aged two weeks were randomly assigned to four groups (3replicates/group; each replicate contains 7 birds) based on different LED light colors. The first group was raised under white light, the second under red light, the third under blue light, and the fourth under yellow light. To assess the impact of various LED light colors on welfare, growth performance indicators (body weight, body weight gain, feed intake, and feed conversion ratio) were measured. Behavioral patterns including feeding, drinking, standing, walking, sitting, feather pecking, and other activities were recorded. Tonic immobility test (TI) and feather condition scoring were conducted at 3, 6, and 10 weeks of age. At the end of the study blood samples were collected for hematological and serum biochemical analyses.

RESULTS

The results revealed that using blue, yellow, and red colors had no adverse effect on the final body weight of the ducks (P > 0.05). Unlike to red light, blue light significantly reduced feather pecking, TI time and cortisol concentrations and improved the feather condition score (P ≤ 0.05).

CONCLUSIONS

The current findings suggest that the application of blue light effectively improves welfare indices and has no detrimental impact on the growth performance of Muscovy ducks thereby positively contributing to their welfare.

The inflammatory immunity and gut microbiota are associated with fear response differences in laying hens

The fear response is a crucial adaptive mechanism for coping with environmental changes, and the individuals have different levels of fearfulness. The purpose of this study was to determine the status of the immune response and gut health in hens with different fear responses. A total of 80 healthy 75-wk-old native Lindian chickens were individually housed in conventional cages and categorized into high (TH) and low (TL) levels of fearfulness using the tonic immobility (TI) test. The immunological status and intestinal health of the laying hens were assessed, and the intestinal microbial community was sequenced using 16S rRNA testing. The results showed that the immune-related genes of interleukin (IL)-1β, IL-4, IL-6, and IgG were significantly upregulated in the spleen of TH hens compared with hens in the TL group (P < 0.01). The inflammatory immune-related genes Toll-like receptor (TLR)2, TLR4, nuclear factor (NF)-κB, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, IL-10, and IgG were significantly increased in the intestinal tract, whereas IL-4, IgA, and the intestinal barrier gene claudin-4 were significantly decreased in TH hens (P < 0.05). In addition, serum concentrations of IL-1β, IL-6, IL-10, interferon (IFN)-α and IgG were significantly higher in TH hens (P < 0.01). A high fear response also led to changes in gut microbial diversity, with a higher Simpson's index and lower β-diversity similarity than hens with a low-fear response (P < 0.05). The TH group showed an increase in 8 genera, including Bacillaceae and Coprococcus, whereas the genus Anaerorhabdus decreased (P < 0.05). The gut microbiota has also been associated with gut barrier genes, and inflammatory cytokines. Bartonella stimulates IL-1β and IgG secretion, whereas Lactobacillus inhibits IL-6 secretion, and Coprococcus and Subdoligranulum are associated with the maintenance of intestinal barrier function. The results of this study suggest that laying hens with high fear response levels have a more sensitive immune response and a more enriched gut microbiota, which may have positive effects on adapting to a complex environment.

Green Light Mitigates Cyclic Chronic Heat-Stress-Induced Liver Oxidative Stress and Inflammation via NF-κB Pathway Inhibition in Geese

Heat stress (HS) induces various physiological disorders in poultry, negatively impacting feed intake, feed efficiency, and growth performance. Considering the documented anti-stress and growth-promoting benefits of monochromatic green light in poultry, we aimed to investigate its effects on cyclic chronic HS-induced oxidative stress (OS) and inflammation in geese. We established three treatment groups-geese exposed to white light (W), white light with HS treatment (WH), and green light with HS treatment (GH)-treated over a six-week period with daily HS sessions. The results revealed that cyclic chronic HS induced liver OS and inflammation, leading to hepatocellular injury and reduced growth performance and feed intake. In comparison, the growth performance of geese under green light significantly improved. Additionally, liver index, serum, liver malondialdehyde (MDA), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumour necrosis factor-α (TNF-α) levels were reduced. Serum total antioxidant capacity (T-AOC), liver catalase (CAT), and superoxide dismutase (SOD) activity were enhanced, reducing hepatic OS and inflammation. Liver transcriptomic analysis indicated that green light alleviates cyclic chronic HS-induced liver injury and promotes geese growth performance by suppressing NF-κB pathway activation.

Effect of Lighting Methods on the Production, Behavior and Meat Quality Parameters of Broiler Chickens

Many farms have been replacing traditional lighting sources with light-emitting diode (LED) bulbs because of technological modernization. We aimed to investigate the effects of incandescent lighting (IL) and LED lighting on Cobb 500 broiler chickens for six weeks. Production parameters (body weight, feed consumption, feed conversion ratio), calculated slaughter values (yield%, relative breast%, thigh%) and breast meat quality parameters (pH at 45 min and 24 h postmortem, color, drip loss, kitchen equipment losses, shear force, meat composition) were recorded. Non-stop recordings were used to analyze the behavior of the birds during several periods of rearing. The LED group was significantly better in the body weight parameter between week 1 and 5 and the feed conversion ratio between week 2 and 3. The most significant difference in behavior was observed in the middle of the rearing period. The chickens in the LED group spent more time eating, drinking and interacting, and rested less. There was no difference in the meat quality parameters; only shear force was significantly lower in the LED group (1781.9 g/s vs. 2098.8 g/s). According to our results, LED lighting can bring about positive changes in animal production efficiency, behavior and other important characteristics for meat consumers.

The Effects of Bacillus amyloliquefaciens SC06 on Behavior and Brain Function in Broilers Infected by Clostridium perfringens

Poultry studies conducted on Clostridium perfringens (CP) mainly focus on the effects of intestinal health and productive performance. Notably, the probiotic Bacillus amyloliquefaciens SC06 (BaSC06) is known to play a role in preventing bacterial infection. However, whether CP could induce the changes in brain function and behaviors and whether BaSC06 could play roles in these parameters is yet to be reported. The aim of this study was to evaluate the effects of BaSC06 on stress-related behaviors and gene expression, as well as the brain morphology and mRNA sequence of the hypothalamus in broiler chickens. A total of 288 one-day-old chicks were randomly divided into four groups: (1) a control group with no treatment administered or infection; (2) birds treated with the BaSC06 group; (3) a CP group; and (4) a BaSC06 plus CP (Ba_CP) group. The results showed that stress and fear-related behaviors were significantly induced by a CP infection and decreased due to the treatment of BaSC06. CP infection caused pathological damage to the pia and cortex of the brain, while BaSC06 showed a protective effect. CP significantly inhibited hypothalamic GABA and promoted HTR1A gene expression, while BaSC06 promoted GABA and decreased HTR1A gene expression. The different genes were nearly found between the comparisons of control vs. Ba group and Ba vs. CP group, while there were a great number of different genes between the comparisons of control vs. Ba_CP as well as CP vs. Ba_CP. Several different gene expression pathways were found that were related to disease, energy metabolism, and nervous system development. Our results will help to promote poultry welfare and health, as well as provide insights into probiotics to replace antibiotics and reduce resistance in the chicken industry.

A Comparison of LED with Fluorescent Lighting on the Stress, Behavior, and Reproductive Success of Laboratory Zebra Finches (Taeniopygia guttata)

There are limited evidence-based husbandry recommendations for laboratory zebra finches (Taeniopygia guttata), including appropriate light sources. Light-emitting diode (LED) technology has been shown to improve circadian regulation and reduce stress in some laboratory animal species, such as mice and rats, when compared with cool-white fluorescent (CWF) lighting, but the effects of LED lighting on zebra finches have not been published. We compared the effects of broad-spectrum, blue-enriched (6,500 Kelvin) CWF and flicker-free LED lighting on the behavior, stress, and reproductive outcomes of indoor-housed zebra finches. Using breeding pairs housed in cubicles illuminated with either CWF or LED lighting, we compared the reproductive output as determined by clutch size, hatching rate, and hatchling survival rate. We also compared the behavior of group-housed adult males, first housed under CWF followed by LED lighting, using video recordings and an ethogram. Fecal samples were collected from these males at the end of each recording period, and basal fecal corticosterone metabolite (FCM) levels were compared. A FCM assay for adult male zebra finches was validated for efficacy and accuracy using a capture-restraint acute stress response and parallelism analysis, respectively. The breeding pairs had no significant difference in the clutch size or percent hatching rate, but percent hatchling survival improved under LED with an increased proportion achieving 100% survival. There was no significant difference in FCM between the lighting treatments. However, the activity budgets of the birds were altered, with a reduction in flighted movement and an increase in enrichment manipulation under LED. Overall, these results support the use of blue-enriched, broad-spectrum flicker-free LED as a safe alternative to CWF lighting for breeding and nonbreeding indoor-housed zebra finches.

Periodic and Local LED Light Switching Induces Broiler Locomotion

Wooden breast myopathy and leg weakness are serious problems in the broiler chicken industry. The color and intensity of light in the chicken habitat affect behavior, including walking of chicks. The present study was conducted to determine whether periodic and local light switching induces locomotion and affects wooden breast myopathy and leg weakness in broiler chicks. Thirty five-day-old broiler chicks were assigned to two pens (4.72 m × 0.73 m each). In the control pen, chicks were reared under three white-light emitting diode (LED) lights until they were 42 days old. In the other pen, chicks were reared under a white LED light located in the center, supplemented with blue or red LED lights on either side of the pen. The color of the LED lights changed every 3 h, from blue and red to red and blue. From 21 d of age, all LED lights were changed and only one of the side lights was turned on every 3 h. From 35 d of age, all three white lights were turned on until 42 d of age. Periodic and local color switching and on-off switching significantly induced locomotion in broiler chicks. Wooden breast scores tended to improve with light-switching treatment. The tibia length, diameter, and breaking strength were not significantly affected. This is the first report showing that locomotion may be induced in broiler chicks by periodic and local lighting switching, and may be useful for improving the health status of broiler chicks.

New approaches to selecting a scan-sampling method for chicken behavioral observations and their practical implications

The use of the scan-sampling method, especially when a large amount of data is collected, has become widespread in behavioral studies. However, there are no specific guidelines regarding the choice of the sampling interval in different conditions. Thus, establishing a standard approach for video analysis represents an important step forward within the scientific community. In the present work, we hypothesized that the length of the sampling interval could influence the results of chicken behavioral study, for which we evaluated the reliability, accuracy, and validity of three different sampling intervals (10, 15 and 30 min). The Bland-Altman test was proposed as an innovative approach to compare sampling intervals and support researcher choices. Moreover, these sampling intervals were applied to compare the behavior of 4 chicken genotypes kept under free-range conditions. The Bland-Altman plots suggested that sampling intervals greater than 10 min lead to biases in the estimation of rare behaviors, such as "Attacking". In contrast, the 30-min sampling interval was able to detect differences among genotypes in high-occurrence behaviors, such as those associated with locomotory activity. Thus, from a practical viewpoint, when a broad characterization of chicken genotypes is required, the 30-min scan-sampling interval might be suggested as a good compromise between resources and results.

LED Light Applied to the Feeder: Impact on Growth Performances of Chickens under Productive Conditions

This study assessed the use of feeders equipped with light-emitting diodes and their effects on the productivity of broiler chickens under productive conditions. A total of 87,200 ROSS 308 chickens, 1-day old, were housed in two poultry houses (CONTROL, F-LED). In CONTROL, 20,000 females (mean body weight 41.12 ± 3 g) and 25,000 males (mean body weight 41.56 ± 3 g) were housed, while 19,200 females and 23,000 males of the same genetic make-up and mean body weight were housed in F-LED under the same environmental conditions. In F-LED, to encourage chickens to feed and to redistribute more feed down the feeding line, a feeder equipped with a LED light has been installed at the end of each line. In CONTROL, no light was located on the feeders. At the end of the cycle, the average body weight never showed significant differences both for females (1345 g in CONTROL; 1359 g in F-LED) and for males (2771 g in CONTROL; 2793 g in F-LED). Uniformity improved in F-LED, at 75.2% in females and 54.1% in males, compared to CONTROL, at 65.7% and 48.5%, respectively, for females and males. The feed conversion ratio followed the same trend, being more favorable in chickens reared in F-LED (1.567) compared to those raised in CONTROL (1.608). The application of a single F-LED at the end of each feeding line demonstrated its utility in improving size uniformity and feed conversion.

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.

Light wavelength and its impact on broiler health

Light is a powerful management tool in poultry production systems, affecting productivity, physiology, and behavior. The objective of this study was to understand the impacts of three light colors (blue, green, or white) on broiler health. Broilers (N = 14,256) were raised in floor pens with fresh litter from 0 to 35 d in 9 rooms (2 blocked trials). Additionally, 2 genotypes (Ross YPMx708 and EPMx708) and sex were studied (6 room replications per lighting treatment and 18 pen replicates per sex × genotype × lighting program). Blood samples and tissue samples from the retina and the pineal gland were collected from birds (16-18 d of age) 9 times in one 24-hr period per trial, then analyzed to determine melatonin levels (pg/mL). Mobility was assessed via gait scoring, using a 0 to 5 scale at 31 to 32 d of age. Footpad dermatitis was assessed using a 0 to 4 scale, and litter quality by a subjective scoring system (scores ranging from 0-4). Mortality and morbidity causes were identified through necropsies performed by pathologists. Data were analyzed as a 3 × 2 × 2 factorial design, with trial as a random variable block and lighting treatment nested within rooms (MIXED procedure, SAS). Birds raised under blue light had lower serum melatonin levels during one time-point during the scotophase, but no other differences were noted. No effect of light color was observed for melatonin produced in the tissues, nor mobility and footpad dermatitis. An interaction was noted for litter quality where a higher percentage of pens housing YPM-708 broilers had litter categorized into dry, but not easily moved with the foot (category 1). Males had higher incidence of infectious and metabolic deaths than females. Interactions were observed between light and sex, where males raised under white light had a higher incidence of skeletal causes of mortality. Overall, the results showed that light color had minor impacts only on melatonin levels, mobility, footpad dermatitis, litter quality, and cause of mortality.