Differences in fear response strategy and stress susceptibility amongst four different commercial layer strains reared cage free.

Different commercial lines of laying hens may show varying levels of fearfulness in response to stressful events or situations. It is important to understand the differences in fear response and stress susceptibility. In this study, four commercial laying hen lines reared from hatch to 32 weeks of age in a cage free system Strains consisted of a brown egg laying line (Hyline Brown; HB) and three white egg laying lines (W36, W80, and LSL). Sixty hens from each strain were used. Each hen was assessed for fearfulness using the following tests: isolation (ISO), emergence (EMG), inversion (INV), and tonic immobility (TI). Stress was assessed based on physical asymmetry (ASYM), corticosterone (CORT) concentrations, and heterophil:lymphocyte ratio (HL). At 3 weeks of age, the W80 birds exhibited more vocalizations during ISO and a shorter duration to emerge than other lines except the HB birds during EMG. Conversely the W36 birds had fewer vocalizations during ISO and emerged quicker than other birds except the LSL during EMG. At 16 weeks of age, the LSL and the W36 bird demonstrated greater fear in TI than the HB. At 30 weeks of age, the observed fear response strategies of each strain changed from previous age and differences were observed between lines (p < 0.05). At both 16 and 30 weeks of age the HB birds had the highest (p < 0.05) stress indicators (CORT, HL, and ASYM). Furthermore, they had a higher CORT after acute stressor (p < 0.05). Commercial lines of laying hens show clear variation in their stress response strategy and stress susceptibility. Brown egg laying hens tend to actively avoid perceived threats whereas white egg laying hens use passive avoidance. Brown egg laying hens also have higher levels in the measures of stress susceptibility than white egg laying hens. Understanding of individual strain response to fearful stimuli and other stressors is important knowledge to appropriately determine welfare differences between strains of layers as the baseline measures are often different.

Experimental monochromatic light-emitting diode fixture impacts Pekin duck stress and eye development.

Poultry color perception of artificial light-emitting diode (LED) lighting mediates bird physiology and behavior; however, very limited research has focused on how changes in LED light color affect these same parameters in Pekin ducks. Therefore, the objective of this investigation was to determine how four LED bulbs emitting various portions of the visible light spectrum - monochromatic blue (BLUE), monochromatic green (GREEN), monochromatic red (RED), and white (WHITE) - impact the stress, fear responses, eye development, and growth of 768 straight run Pekin ducks. Elevated plasma corticosterone concentration and heterophil to lymphocyte ratio was observed in BLUE and RED ducks compared to WHITE and GREEN ducks (P = 0.005 and P = 0.001, respectively), and asymmetry scores were highest in BLUE ducks (P < 0.001), indicating BLUE and RED lighting increase the stress susceptibility of Pekin ducks. Eye weight was lowest in BLUE and RED ducks compared to GREEN and WHITE ducks (P < 0.01). No differences were observed in d 35 body weight, FCR, gait score, or fear response parameters (P > 0.05). These results indicate BLUE and RED lighting may not be adequate for Pekin duck growout, and Pekin ducks may require artificial light sources containing a broad range of wavelengths, as seen with WHITE and GREEN lights, rather than lights containing more concentrated ranges such as in RED and BLUE lights, but further investigation is needed to understand how eye weight affects duck light perception and welfare. The current findings emphasize that although Pekin ducks and chickens are both sensitive to light color, species-specific nuances in light perception may cause distinct differences in Pekin duck versus broiler physiological responses and must be considered when selecting artificial light color in Pekin duck growout facilities.

Effects of Monochromatic Lighting During Incubation and Vaccination on the Splenic Transcriptome Profiles of Chicken.

Lighting is a crucial environmental variable in poultry operations, but illumination during incubation is relatively understudied. The ability to stimulate development or immune performance using in ovo lighting is a promising approach for improving poultry health and welfare. This study investigated how monochromatic green light during incubation and vaccination method and timing affected chicken splenic gene expression patterns. We performed this study with 1,728 Hy-Line white layer eggs incubated under two light treatments during incubation: continuous dark and continuous green monochromatic light, over the entire incubation period. Half the eggs in each light treatment received in ovo vaccination, applied on embryonic day 18 (ED18). The remaining half were vaccinated by spraying on hatch day. After hatching, the light treatments followed the industry-standard lighting regimens. The study had six treatment groups with light-dark pairs for non-vaccinated, in ovo vaccinated, and post-hatch vaccinated. We assessed splenic gene expression at ED18 and at 7 days post-hatch (PH) in all the treatments. We isolated and sequenced 24 mRNA libraries on the Illumina platform, followed by bioinformatics and differential gene expression analyses. RNAseq analysis showed between 62 and 6,755 differentially expressed genes (DEGs) between comparisons, with the most prominent differences observed between ED and PH samples, followed by comparisons between vaccination methods. In contrast, light vs. dark treatments at ED showed limited effects on transcriptomic profiles. However, we observed a synergistic effect of lighting during incubation on post-hatch vaccination responses, with differentially expressed genes (DEGs) unique to the light treatment showing stimulation of cell proliferation with significance for immune activity (inferred from gene ontology terms). Gene ontology and pathway analysis indicated biological processes like cellular component organization or biogenesis, rhythmic process, developmental process, response to stimulus, and immune system processes were explained by the DEGs. While lighting is an important source of circadian stimulation, other controlled studies are required to clarify whether in ovo circadian entrainment plays a role in modulating immune responses.

Comparison of an intermittent, short-dawn/dusk photoperiod with an increasing, long-dawn/dusk photoperiod on broiler growth, stress, and welfare.

Photoperiod has been shown to significantly affect broiler performance. However, the effects of the traditional 1-min dimming period on broiler growth and welfare are unclear. In this study, 4 consecutive trials were conducted to compare the effects of an intermittent, short-dawn/dusk photoperiod (ISD) to an increasing, long-dawn/dusk photoperiod (ILD) on broiler growth, stress, and welfare. Straight run day-of-hatch Ross 708 × Ross 708 broilers were placed in 1 of 4 commercial broiler barns (2 b of 26,200 birds each per treatment) and grown to 45 D of age. The photoperiod in the ISD treatment consisted of 24L:0D day 0 to 6, 16L:8D day 7 to 13, 12L:4D:2L:6D day 14 to 20, 12L:4D:3L:5D day 21 to 27, 12L:4D:4L:4D day 28 to 41, and 13L:3D:5L:3D day 42 to 45, with a 1-min transition between light and dark periods. The photoperiod in the ILD treatment consisted of 23L:1D day 0 to 7, 16L:8D day 8 to 21, 18L:6D day 22 to 32, and 20L:4D day 33 to 45, with a 1-min light/dark transition period day 0 to 7 and a 30-min transition period day 8 to 45. Treatments were rotated among the barns between trials. On day 45, blood samples were collected from 20 birds/barn (n = 40/treatment) to assess plasma corticosterone (CORT) and heterophil/lymphocyte (H/L) ratio. One hundred birds per barn (n = 200/treatment) were weighed individually and assigned scores for hock burn, foot pad dermatitis, and feather condition on day 45. Trial differences were observed for all measures (P ≤ 0.001). Birds in the ISD treatment were heavier on day 45 (P < 0.001) and had lower hock burn (P = 0.044) and foot pad dermatitis (P < 0.001) scores. Birds in the ILD treatment had lower plasma CORT (P < 0.001) and H/L ratio (P < 0.001). No treatment differences were observed for feather condition (P > 0.05). Overall, birds reared under the intermittent, short-dawn/dusk photoperiod had higher day 45 live body weights and lower hock burn and foot pad dermatitis scores, whereas those reared under the increasing, long-dawn/dusk photoperiod had reduced measures of short-term and long-term stress.

Effects of supplementing yeast fermentate in the feed or drinking water on stress susceptibility, plasma chemistry, cytokine levels, antioxidant status, and stress- and immune-related gene expression of broiler chickens.

This study aimed to elucidate the mechanism by which adding Saccharomyces cerevisiae-derived yeast fermentate to the feed (XPC) or drinking water reduces stress in poultry. Day-old male Cobb 500 broiler chicks were assigned to 1 of 3 treatments: stressed control (CS), stressed + XPC (1.25 kg/metric ton feed, day 0-43; XPC), or stressed + AviCare (160 mL/100 L drinking water, day 0-43; AVI). All birds were spray-vaccinated for coccidiosis (day 0), raised on reused litter, spray-vaccinated for Newcastle/Bronchitis (day 18), and exposed to heat stress (32°C-34°C) and feed/water withdrawal for 12 h (day 18). Blood samples were collected to assess plasma corticosterone (CORT) and heterophil/lymphocyte (H/L) ratio (60 birds/treatment; day 40); plasma biochemistry and growth hormone (12 birds/treatment; day 38); and serum serotonin and plasma prolactin, thyroid hormones, antioxidant capacity, and selected cytokines (12 birds/treatment; day 39). Composite asymmetry scores were obtained from 60 birds/treatment on day 41. Organs were collected from 20 birds/treatment on day 43 to measure gene expression of CYP1A2 and melanocortin 2 receptor (MC2R) in the adrenal glands and IL10 and AvBD1 in the spleen. Serotonin was lower in CS than XPC (P = 0.049), whereas AVI was intermediate. Plasma interleukin (IL)-1ß was higher in AVI than CS (P = 0.009) and XPC (P = 0.009). The CS treatment had higher CORT than AVI (P = 0.013) and XPC (P = 0.037) and higher H/L ratios than AVI (P = 0.026) and XPC (P = 0.034). Expression of CYP1A2, MC2R, and IL10 was lower (P < 0.05) in XPC and AVI compared with CS. Furthermore, IL10 expression was lower in XPC than AVI (P < 0.05). Adding yeast fermentate to the feed or drinking water reduced measures of stress and MC2R gene expression in birds exposed to acute and rearing stressors. However, differences in IL10 gene expression and circulating serotonin and IL-1ß suggest that supplementing yeast fermentate in the feed is slightly more effective than supplementation via the drinking water in mitigating the physiological effects associated with the stress response in broilers.

Light emitting diode (LED) color and broiler growth: effect of supplementing blue/green LED to white LED light on broiler growth, stress, and welfare.

Light emitting diode (LED) lighting provides an affordable lighting option for use in commercial poultry production. However, more information is needed to understand the effects of LED color on broiler welfare and growth. Five consecutive flocks (1 in summer, 1 in fall, 2 in winter, and 1 in spring) of straight run Ross 708 × Ross 708 broilers were reared in commercial type barns for 45 D. For white only (WO) treatment, birds were reared under white LED only (Agrishift MLB). For white supplemented (WS) treatment, birds were reared under white LED (Agrishift MLB) in the center aisle, with supplemental blue/green LED lighting (Agrishift MLBg) above the feed and water lines on either side of the barn. Each barn housed 26,200 chicks, and there were 2 barns in each treatment (n = 52,400/treatment). Treatments were rotated among barns between each flock. On day 45, blood samples were collected from 20 birds/barn (n = 40/treatment) to assess the plasma corticosterone (CORT) level and heterophil/lymphocyte ratio. On day 45, 100 birds/barn (n = 200/treatment) were weighed individually and assigned scores for hock burn and foot pad dermatitis. All measures were affected by trial (P < 0.001). Plasma CORT and body weight were affected by the treatment × trial interaction (P ≤ 0.001). Overall, birds in the WS treatment had higher day 45 live body weight (P < 0.001) and lower hock burn scores (P = 0.032) than birds in the WO treatment. Birds in the WS treatment had higher day 45 body weight overall (P < 0.001) and in trials 1, 3, and 5, although the overall body weight was lower in trials 1, 3, and 5 than in trials 2 and 4. Supplemental blue/green LED improved hock burn scores and increased overall day 45 body weight. However, trial differences suggest that more data are needed to determine whether supplementing blue/green LED to white LED improves body weight gain in mixed sex broiler chickens.

Effects of Ultraviolet Light Supplementation on Pekin Duck Production, Behavior, and Welfare.

Ducks, like other domestic poultry species, can visualize the ultraviolet (UV) portion of the light spectrum; however, the importance of UV light radiation in artificially lit duck growout facilities remains unknown. The objective of this study was to determine the effects of UV light supplementation on Pekin duck production parameters, eye development, stress, and fear. Pekin ducks were reared with light-emitting diode (LED) lights supplemented with UV light or just LED lights (control). There were no differences in body weight (p = 0.32), feed conversion ratio (p = 0.38), or gait score (p = 0.89). Differences in eye morphology were observed, with ducks reared under UV light having narrower (12.3 ± 0.06632 mm; p = 0.010) and lighter (1.46 ± 0.01826 g; p = 0.025) eyes than the control (12.5 ± 0.05583 mm; 1.53 ± 0.02386 g). Ducks reared in UV environments had lower acute and chronic stress susceptibility with lower plasma corticosterone (6317 ± 593.79 pg/mL; p = 0.024), heterophil to lymphocyte ratios (0.43 ± 0.02889; p = 0.035), and composite asymmetry (0.58 ± 0.0298; p = 0.002) than control ducks (9242 ± 1120.7 pg/mL; 0.54 ± 0.04212; 0.76 ± 0.03726 mm, respectively). Ultraviolet ducks had a faster latency for the first head movement during tonic immobility (61.28 ± 9.4863 s, p = 0.026) and required more attempts to induce tonic immobility (1.71 ± 0.07333, p = 0.018) than control ducks (100.7 ± 14.846 s and 1.48 ± 0.06478, respectively). There were no differences in inversion testing (p = 0.91). These results indicate that UV lighting can lower stress and fear responses in Pekin ducks and can therefore increase welfare. Additionally, this study emphasizes the importance of choosing correct artificial lighting for all poultry species.

Supplementation of a water-soluble zinc-AA complex to reduce stress in broilers, pullets, and layers1.

This study consisted of three 5-wk experiments to test the effects of administering Zinpro-LQ (Zinpro-LQ, Zinpro Corporation, Eden Prairie, MN) for different time intervals in stressed broilers, pullets, and layers. Treatments included: nonstressed control (NC), stressed control (SC), stressed and supplemented Zinpro-LQ for 14 d prior to stressor (S1), 10 d prior (S2), 7 d prior to and 7 d during stressor (S3), and 5 d prior (S4). Birds included 1-d-old Cobb 500 male broilers (Experiment 1), 7-wk-old white Leghorn pullets (Experiment 2), and 50-wk-old white Leghorn layers (Experiment 3). All stressed birds were vaccinated against Newcastle Disease Virus (NDV) on day 28 and exposed to random feed and water withdrawal days 28 to 35 for 6 h/d. Pullets were beak trimmed on day 21, and layers were heat stressed days 28 to 35. Blood was sampled on day 35 to determine plasma chemistry, corticosterone (CORT), anti-NDV antibody titer, and heterophil/lymphocyte (H/L) ratio. Mortality, feed and water consumption, and BW were also recorded. In Experiment 1, CORT and H/L ratio were highest in SC (P < 0.05). In Experiment 2, CORT was higher in SC than S4 (P < 0.05) while all other treatments were statistically intermediate. NDV titer was lower in SC than S4 while all other treatments were statistically intermediate. Treatment differences were also observed for H/L ratio, and plasma uric acid and cholesterol in Experiment 2. In Experiment 3, treatment differences were observed for H/L ratio, plasma glucose, sodium, and chloride. H/L ratio was lower in NC, S1, and S4 compared with SC (P < 0.05); and NC and S1 were lower than S2 (P < 0.05). In conclusion, dietary inclusion of zinc AA complex for any length of time prior to a stressor helped reduce measures of stress in broilers. The S1 and S4 treatments helped reduce stress and improve humoral immune response in pullets and layers.

Effect of Yeast Fermentate Supplementation on Intestinal Health and Plasma Biochemistry in Heat-Stressed Pekin Ducks.

One experiment was conducted to determine the effects of supplementing Saccharomyces cerevisiae-derived yeast fermentate (Diamond V Mills, Cedar Rapids, IA, USA) in the feed (XPC; 1.25 kg/metric ton feed, days 0-35) or drinking water (AviCare; 160 mL/100 L, days 0-35) on plasma biochemical and immune parameters, as well as ileal histomorphology of mixed-sex Pekin ducks grown to 35 d and exposed to cyclic heat stress (8 h/d) or thermoneutral environment (days 21-35). On the day of hatching, 144 straight run White Pekin ducks were randomly assigned to one of six treatments: stressed control (CS), stressed + XPC (XS), stressed + AviCare (AS), non-stressed control (CN), non-stressed + XPC (XN), and non-stressed + AviCare (AN). On day 33, blood samples were collected from 12 birds/treatment to assess plasma chemistry, packed cell volume, and plasma levels of interleukin (IL)-1α, IL-8, and α1-acid glycoprotein (α1-AGP). On day 34, ileum sections were collected from 12 birds/treatment to assess goblet cell density, villus length, crypt depth, and villus/crypt ratio from 6 villi per sample. Plasma phosphorus was influenced by diet (p < 0.001) and heat-diet interaction (p = 0.003), and was higher in XS than XN, and higher in AS than AN. Heat stress increased plasma glutamate dehydrogenase (GLDH) (p = 0.008). Uric acid was increased by adding yeast fermentate to the feed or drinking water (p = 0.002), but was not influenced by heat (p > 0.05). The heat-diet interaction affected plasma IL-1α (p = 0.021) and sodium (p = 0.046). Heat stress reduced villus length (p < 0.001), villus/crypt ratio (p < 0.001), and goblet cell density (p < 0.001), but did not affect crypt depth (p > 0.05). Both XPC and AviCare increased villus length (p < 0.001) and villus/crypt ratio (p < 0.001), and decreased crypt depth (p < 0.001), but did not affect goblet cell density (p > 0.05). Although adding yeast fermentate to the feed or drinking water does not appear to alleviate the effects of heat stress on goblet cell density, both routes of administration improved other measures of villus morphology and affected amino acid metabolism.

Reducing Stress Susceptibility of Broiler Chickens by Supplementing a Yeast Fermentation Product in the Feed or Drinking Water.

Reducing stress is an important goal in animal production. Previous research has demonstrated the ability of Original XPCTM to reduce the stress response of broilers during heat stress. Three trials were conducted to evaluate the effects of adding Original XPCTM to the feed or AviCareTM to the water on stress susceptibility of broiler chickens. Treatments included: control nonstressed (CNS), control stressed (CS), stressed with Original XPCTM (1.25 kg/metric ton feed, 0⁻42 days; XPC), and stressed with AviCareTM (160 mL/100 L drinking water, 0⁻42 days; AVI). All stressed treatments received the following stressors: live coccidiosis vaccination (day 1), reared on reused litter (days 0⁻42), and heat stress with feed/water withdrawal (12 h on day 18). Plasma corticosterone and heterophil/lymphocyte (H/L) ratio were determined from 60 birds/T on day 19, and 24 birds/T on day 41. Physical asymmetry was determined using bilateral bone measurements from 60 birds/T on day 41. Birds provided XPC or AVI had lower corticosterone and H/L ratios than CS (p < 0.05) on day 19 and lower corticosterone, H/L ratios, and asymmetry scores than both CNS and CS on day 41 (p < 0.05) in all three trials. Supplementing XPC or AVI improved broiler welfare measured by reduced stress indicators after acute heat stress or normal rearing stress in all trials.