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As part of a systemic assessment toward social sustainability of egg production, we have reviewed current knowledge about the environmental impacts of egg production systems and identified topics requiring further research. Currently, we know that 1) high-rise cage houses generally have poorer air quality and emit more ammonia than manure belt (MB) cage houses; 2) manure removal frequency in MB houses greatly affects ammonia emissions; 3) emissions from manure storage are largely affected by storage conditions, including ventilation rate, manure moisture content, air temperature, and stacking profile; 4) more baseline data on air emissions from high-rise and MB houses are being collected in the United States to complement earlier measurements; 5) noncage houses generally have poorer air quality (ammonia and dust levels) than cage houses; .6) noncage houses tend to be colder during cold weather due to a lower stocking density than caged houses, leading to greater feed and fuel energy use; 7) hens in noncage houses are less efficient in resource (feed, energy, and land) utilization, leading to a greater carbon footprint; 8) excessive application of hen manure to cropland can lead to nutrient runoff to water bodies; 9) hen manure on open (free) range may be subject to runoff during rainfall, although quantitative data are lacking; 10) mitigation technologies exist to reduce generation and emission of noxious gases and dust; however, work is needed to evaluate their economic feasibility and optimize design; and 11) dietary `modification shows promise for mitigating emissions. Further research is needed on 1) indoor air quality, barn emissions, thermal conditions, and energy use in alternative hen housing systems (1-story floor, aviary, and enriched cage systems), along with conventional housing systems under different production conditions; 2) environmental footprint for different US egg production systems through life cycle assessment; 3) practical means to mitigate air emissions from different production systems; 4) process-based models for predicting air emissions and their fate; and 5) the interactions between air quality, housing system, worker health, and animal health and welfare. [ABSTRACT FROM AUTHOR]

An abstract of the article "Dietary corn distillers dried, grains with solubles does not affect generic E. coli numbers in the laying hen ceca," by S. Roberts and colleagues is presented.

Duck adenovirus type-3 (DAdV-3) is a poorly characterized duck virus. A comprehensive analysis of the DAdV-3 pathogenicity and host immune response could be a valuable addition. Herein, DAdV-3 was isolated from Muscovy duck and virus-specific genes were confirmed by polymerase chain reaction (PCR). The obtained gene fragments were sequenced and compared with the reference sequence. Results confirmed that the clinically isolated virus was DAdV-3, named as HF-AN-2020. To evaluate DAdV-3 host immune response, the expression levels of MDA5, STING, IRF7, MAVS, and NF-κB, and inflammatory cytokines (IFN-β, IFN-γ, and IL-1β) were determined by quantitative reverse transcriptase PCR (qRT-PCR). The expression levels of IFN-β and IFN-γ were 32.6- and 28.6-fold, respectively, higher (P < 0.01) than the control group. It was found that the upregulation of STING and NF-κB pathways was directly involved in the regulation of inflammatory cytokines (IFN-β, IFN-γ, and IL-1β). Furthermore, the gene regulation pathways consecutively upregulated the expression levels of MDA5, STING, IRF7, MAVS, and NF-κB up to 31.6, 10.5, 31.4, 2.2, and 2.6-fold, respectively, higher (P < 0.01) than the control group. The TCID 50 of DAdV-3 for Muscovy duck and chicken was 10 -3.24 /0.1 mL with 0% mortality, indicating low pathogenicity in both Muscovy ducks and chickens, but DAdV-3 can induce higher expression of interferons. Genome analysis showed mutations in 4 amino acids located in ORF19B (Ser to Thr), ORF66 (Leu to Phe, Ile to Leu), and ORF67 (Gly to stop codon). This study provides essential and basic information for further research on the mechanism of the cellular immune responses against adenoviruses., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Keel fracture has adverse effects on welfare, behavior, health, production performance, and egg quality of laying hens. To investigate this, 90 healthy Lohmann white laying hens with normal keel bones at 17 wk of age (WOA) were used in this study and housed individually in furnished cages. All hens were marked with fractured keel (FK) or normal keel (NK) based on the keel bone status through palpation at 5 time-points (22, 27, 32, 37, and 42 WOA). After the palpation, the behavior was observed for 2 consecutive days at each time-point, and the total number of eggs produced, dirty eggs, broken eggs, and feed intake of FK and NK laying hens were recorded at 27-32, 32-37, and 37-42 WOA, respectively. After each behavioral observation, 10 fresh FK hens and 10 NK hens were randomly selected to determinate the welfare and egg quality. The results showed that the incidences of keel fracture increased with the age of laying hens. Compared with NK hens, the sitting and standing behaviors significantly increased (P < 0.05) while feeding, walking, perching, and jumping behaviors significantly decreased (P < 0.05) in FK hens. There were no significant changes in drinking, preening, comforting, cage pecking, and nesting behaviors between NK and FK hens (P > 0.05). During the experiment period, the egg production rate, body weight, daily feed intake, and eggshell strength, thickness, and weight decreased (P < 0.05) and duration of tonic immobility increased (P < 0.05) in FK hens compared with those in NK hens. At 27-32 WOA, FK hens had significantly elevated broken egg rate (P < 0.05). There were no significant differences in the dirty egg rate, egg shape index, protein height, Haugh unit, feather cover score, and toe and foot pad health score (P > 0.05). Therefore, keel fracture in laying hens caused changes in behavior and reduced the welfare, production performance, feed intake, and eggshell quality., (Copyright © 2020. Published by Elsevier Inc.)

With the majority of conventional cage (CC) laying facilities transitioning into cage-free (CF) systems in the near future, it is important to characterize biological markers of health in layers housed in commercial housings for sustainable production. The objectives of this study were to compare i) blood markers, that is heterophil:lymphocyte (H:L) ratios and susceptibility to avian pathogenic Escherichia coli (APEC) and ii) lung and ceca microbiome between hens at different maturity stages in commercial CC and CF farms. Laying hens at 3 maturity stages were randomly sampled (N = 20 per maturity and per farm). Blood was tested for H:L ratios and APEC killing ability using microscopy and in vitro assay, respectively. Microbiomes were assessed using 16S rRNA sequencing and QIIME2 analysis. Data show H:L ratios did not differ between maturities in both farms. Avian pathogenic Escherichia coli killing was only different in CC hens, where χ7122 level was higher (P < 0.05) in peak compared with early lay. In both farms, microbiome diversity was consistently different (P < 0.05) in both ceca and lung of early lay compared with peak and late lay. In the ceca and lung, relative abundances of the 3 predominant phyla (Bacteroidetes, Firmicutes, and Proteobacteria) did not significantly change with maturity in both farms. Potential pathogens Campylobacter and Staphylococcus reached greater (P < 0.05) abundances in CC lungs in early lay and in CF lungs in late lay, respectively. Overall, this study showed no differences in the stress marker H:L but identified some differences in resistance to APEC and microbiome composition across maturity stages in CC and CF. The lung and gut microbiomes were highly similar, with both serving as potential reservoirs for Campylobacter and Staphylococcus. Future studies on controllable environments for CF and CC are needed to develop adequate strategies for each housing and maturity stage to reduce pathogens and optimize disease-resistance., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

The effects of long-term cold stimulation on the immune function of ileum and adaptability to cold stress in broilers were examined. A total of 360 Arbor Acres broilers was divided into 3 groups and four replicates per group. C (control) was reared in normal thermal environment. C-3 and C-12 (treatments) were kept in cold condition of 3 or 12°C lower than the temperature of C from days 8 to 42. At day 42, all the groups were exposed to an acute cold stress challenge, designated as S, S-3, and S-12. The mRNA levels of immune molecules and heat shock proteins as well as oxidative stress-related indicators in ileum tissues, and immunoglobulins contents in serum were examined at 14, 42, and 43 d of age. The C-3 regimen had no adverse effect on production performance, whereas the C-12 regimen reduced the production performance relative to C (P < 0.05). At day 42, C-3 had higher levels of immune indexes (P < 0.05), whereas C-12 had lower levels than C (P < 0.05). No differences in levels of oxidative stress-related indicators were found between C and C-3 at day 42 (P > 0.05). S-3 had higher levels of immune indexes and lower levels of oxidative stress-related indicators (P < 0.05), as compared to S and S-12. The results suggest that 34 d of cold stimulation at 3°C lower than the normal temperature had no adverse impacts on production performance but enhanced the immunity of ileum and adaptability to acute cold challenge in broilers., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

With different cage-free (CF) housing styles and management schemes, retailers have developed their own CF criteria. One highly debated aspect is if hens may be kept inside the system for part of the day-during the first few hours after lights-on. Research is lacking regarding the impacts of such a practice on hen welfare, incidence of eggs laid on the litter floor, litter condition, and air quality. This 14-mo field study was conducted to help assess such impacts. Hens (Dekalb White) in an aviary house (50,000-hen nominal capacity) were allowed to have full litter access (FLA) vs. part-time litter access (PLA) from 10:50 am to 9:00 pm, coupled with the absence or presence of experienced hens (1.5% of the population), hence a 2 × 2 factorial arrangement. The measured variables included a) incidence of floor eggs, b) percentage of birds remaining on litter floor at night, c) mortality, d) body weight (BW) and BW uniformity, e) litter condition (depth, moisture content, texture, amount removed, and bacteria concentration), f) environmental conditions, and g) welfare conditions (10 variables). Compared to FLA, PLA had a significantly lower incidence of floor eggs (1.4 ± 0.1 vs. 12.6 ± 1.1 eggs per hen housed as of 76 weeks of age (WOA), i.e., approximately 89% reduction), less manure deposition on the floor (0.53 ± 0.02 vs. 1.05 ± 0.04 kg/100 hens/d, dry basis, i.e., approximately 50% reduction), and lower ammonia concentrations due to drier litter (averaging 22% lower). Inclusion of 1.5% experienced hens in the young flock did not show benefit of reducing the incidence of floor eggs (P = 0.48). The percentage of hens remaining on the floor at night was low (< 0.01%) in all cases from 24 WOA onward. No differences were detected between FLA and PLA in hen welfare conditions, mortality, BW, BW uniformity, bacteria concentration in the litter, air temperature, or relative humidity., (© The Author(s) 2018. Published by Oxford University Press on behalf of Poultry Science Association.)

Acclimation can alleviate the negative impacts of adverse environmental factors on an organism. To investigate the effects of prior cold stimulation on inflammatory and immune regulation in ileum of cold-stressed broilers, 360 1-d-old chicks (Arbor Acres) were divided into 3 groups (G1, G2, G3) and raised at normal (thermal comfort) temperatures during 1 to 7 d. From 8 d, G1 (control) continued to be raised at normal temperatures, whereas G2 and G3 (treatments) were cold-stimulated at 3°C and 12°C, respectively, below the temperature of G1, but not below 17°C (reached at 32 d in G2 and 14 d in G3). At 42 d, all the groups were subjected to a 24-h acute cold stress of 7°C, designated as S1, S2, and S3. Ileum tissues and serum of the birds were collected at 42 d and 43 d to detect the levels of pro-inflammatory and immune-related factors as well as morphology changes. At 42 d, ileum of G1 and G2 had intact morphological structure and clear outline, with no differences in levels of iNOS, NF-κB, COX-2, PTGEs, TNF-α, IFN-γ, or IL-4 (P > 0.05). G3 ileum suffered inflammatory injuries, with levels of iNOS, COX-2, PTGEs, TNF-α, and IL-4 being higher than those of G1 (P < 0.05). At 43 d, compared with G1, S1 had severely damaged ileum, increased levels of iNOS, NF-κB, COX-2, PTGEs, TNF-α, and IL-4 (P < 0.05), but decreased level of IFN-γ (P < 0.05). The morphological structure of S2 was intact, and there were no differences between G2 and S2 in levels of NF-κB, PTGEs, TNF-α, IFN-γ, or IL-4 (P > 0.05). Compared with S1, S2 had decreased levels of iNOS, NF-κB, COX-2, PTGEs, TNF-α, and IL-4 (P < 0.05), but increased level of IFN-γ (P < 0.05). There were no differences between G1 and S2 in levels of NF-κB, PTGEs, TNF-α, IFN-γ, or IL-4 (P > 0.05). The results demonstrate that a 3°C-lower-than-normal temperature stimulation of the broilers from 8 to 42 d led to cold acclimation. This prior cold acclimation effectively alleviated elevation of pro-inflammatory cytokines and Th1/Th2 imbalance of the birds induced by subsequent cold stress.

More energy-efficient, durable, affordable, and dimmable light-emitting diode (LED) lights are finding applications in poultry production. However, data are lacking on controlled comparative studies concerning the impact of such lights during the pullet rearing and subsequent laying phase. This study evaluated two types of poultry-specific LED light (PS-LED) vs. fluorescent light (FL) with regards to their effects on hen laying performance. A total of 432 Hy-Line W-36 laying hens were tested in two batches using four environmental chambers (nine cages per chamber and 6 birds per cage) from 17 to 41 weeks of age (WOA). Dim-to-red PS-LED and warm-white FL were used in the laying phase. The hens had been reared under a dim-to-blue PS-LED or a warm-white FL from 1 to 16 WOA. The measured performance variables included 1) timing of sexual maturity, 2) egg production performance, 3) egg quality, and 4) egg yolk cholesterol. Results showed that the two types of light used during the laying phase had comparable performance responses for all response parameters (P > 0.05) with a few exceptions. Specifically, eggs laid from hens in the PS-LED treatment had lower shell thickness (P = 0.01) and strength (P = 0.03) than those in the FL treatment at 41 WOA. The two types of light used during the rearing phase did not influence the 17 to 41 WOA laying performance, except that hens reared under the PS-LED laid eggs with lower shell thickness (P = 0.02) at 32 WOA as compared to hens reared under the FL. This study demonstrates that the emerging poultry-specific LED lights yield comparable production performance and egg quality of W-36 laying hens to the traditional fluorescent lights.

The impact of supplementing laying-hen feed with annatto tocotrienols (T3s) and alpha-tocopherol on the distribution of various forms of vitamin E and cholesterol throughout the hen's body was evaluated. A total of 18 organs or tissues (skin, fat pad, liver and gall bladder, heart, oviduct, forming yolk, laid yolk, lungs, spleen, kidney, pancreas, gizzard, digestive tract, brain, thigh, breast, manure, and blood) were collected after 7 wk of feeding on diets enriched with various levels of alpha-tocopherol and annatto extract that contained gamma-T3 and delta-T3. Tissue weights, contents of lipid, alpha-tocopherol, gamma-T3, delta-T3, cholesterol, and fatty acid composition of extracted lipids from the collected organs and tissues were determined. Tissue weight and lipid content did not change significantly with feed supplementation treatments, except that the liver became heavier with increased levels of supplementation. Overall, the main organs that accumulated the supplemented vitamin E were fat pad, liver and gall bladder, oviduct, forming yolks, laid yolks, kidney, brain, thigh, and breast. Much of annatto gamma-T3 and delta-T3 (> 90%) was found in the manure, indicating poor uptake. In some tissues (brain and oviduct,) a significant increase in polyunsaturated fatty acids was seen with increased supplementation. Alpha-tocopherol impacted the transfer of gamma-T3 to forming and laid yolks, but did not impact delta-T3 transfer. No significant differences were found in most of the tissues in cholesterol, except a reduction in heart, based on tissue as-is. Blood samples showed large variations in individual hens with no significant differences in total and HDL cholesterol, or total triacylglycerols. Supplementing feed with annatto T3s and alpha-tocopherol showed that the vitamin E profile and distribution of the laying-hen body can be altered, but to different extents depending on tissue. The result of this research has significance in enhancing meat nutrient content., (© 2015 Poultry Science Association Inc.)

The US egg industry has evolved considerably over recent decades by incorporating new technologies and production practices. To date, there has been no comprehensive assessment of the resource demand and environmental effects of these changes. This study quantifies the environmental footprint of egg production supply chains in the United States for 2010 compared with 1960 using life cycle assessment. The analysis considers changes in both foreground (e.g., hen production performance) and background (e.g., efficiencies of energy provision, fertilizer production, production of feed inputs, and transport modes) system variables. The results revealed that feed efficiency, feed composition, and manure management are the 3 primary factors that determine the environmental impacts of US egg production. Further research and improvements in these areas will aid in continual reduction of the environmental footprint of the US egg industry over time. Per kilogram of eggs produced, the environmental footprint for 2010 is 65% lower in acidifying emissions, 71% lower in eutrophying emissions, 71% lower in greenhouse gas emissions, and 31% lower in cumulative energy demand compared with 1960. Table egg production was 30% higher in 2010; however, the total environmental footprint was 54% lower in acidifying emissions, 63% lower in eutrophying emissions, 63% lower in greenhouse gas emissions, and 13% lower in cumulative energy demand compared with 1960. Reductions in the environmental footprint over the 50-yr interval considered can be attributed to the following: 27 to 30% due to improved efficiencies of background systems, which outweighed the declining energy return on energy invested for primary energy sources; 30 to 44% due to changes in feed composition; and 28 to 43% due to improved bird performance.