Journal of Applied Poultry Research最新文献

{"title":"Effects of dietary Rhus coriaria L. powder on growth performance, antioxidant status, and immune competence of broiler chickens under high-density rearing conditions","authors":"Fayiz M. Reda ,&nbsp;Hemat K. Mahmoud ,&nbsp;Islam M. Youssef ,&nbsp;Mohammad M.H. Khan ,&nbsp;Elham Hamed Algahdali ,&nbsp;Hanan M. Alharbi ,&nbsp;Khairiah M. Alwutayd ,&nbsp;Mohamed E. Abd El-Hack ,&nbsp;Reda S. Mohamed ,&nbsp;Mohamed M.F. El-Mekkawy","doi":"10.1016/j.japr.2026.100674","DOIUrl":"10.1016/j.japr.2026.100674","url":null,"abstract":"<div><div>This study evaluated the potential of sumac seed powder (<em>Rhus coriaria</em> L.) as a natural feed additive to alleviate the detrimental impacts of high stocking density <strong>(HD)</strong> on broiler chickens. A total of 350 unsexed Arbor Acre chicks were randomly distributed into five groups. The control group was reared under normal density (<strong>ND</strong>; 10 birds/m²) and fed a standard diet, whereas the remaining groups were raised under HD conditions (15 birds/m²). Among the HD groups, one received the basal diet only, while the others were supplemented with 1, 2, or 3 g SSP per kg of feed. High rearing density markedly reduced growth rate, immune function, and antioxidant defense. However, SSP supplementation—especially at 2 and 3 g/kg—significantly improved live body weight, weight gain, and feed conversion ratio, with the 3 g/kg group showing performance values comparable to ND birds (<em>P</em> = 0.0021). Dressing percentage increased, while abdominal fat deposition declined. Birds receiving 3 g/kg SSP showed elevated hemoglobin, RBCs, and WBCs, and reduced serum glucose (<em>P</em> = 0.0039). Liver and kidney function indicators, as well as lipid profiles, were favorably affected, with reductions in total cholesterol and LDL levels (<em>P</em> &lt; 0.05). Supplementation enhanced antioxidant capacity by increasing SOD, CAT, GSH, and TAC activities, while decreasing malondialdehyde and corticosterone concentrations. Immune competence improved, as shown by higher IgM, IgA, and IgY titers, greater relative weights of immune organs, and elevated lysozyme activity. Moreover, serum mineral concentrations (Ca, P, K, Cu, Fe) and tibia bone characteristics were enhanced. SSP inclusion also boosted digestive enzyme activities and positively modulated the cecal microbiota by increasing lactic acid bacteria and reducing pathogenic bacterial counts (<em>P</em> &lt; 0.001). In conclusion, dietary supplementation with SSP, particularly at 3 g/kg, effectively mitigates the physiological, oxidative, and microbial stress associated with overcrowding, representing a promising natural strategy to enhance broiler health and productivity.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100674"},"PeriodicalIF":2.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applied research note: Validating energy systems for the formulation of laying hen diets","authors":"Frederik J. Kleyn ,&nbsp;Mariana Ciacciariello","doi":"10.1016/j.japr.2026.100676","DOIUrl":"10.1016/j.japr.2026.100676","url":null,"abstract":"<div><div>Practical diets used to feed laying hens can differ significantly, depending mainly on the energy systems (<strong>ES</strong>) and the relative cost of the feed ingredients used when formulating. The more accurate an ES is, the better it will predict performance. In earlier work, a predictive model was developed to evaluate the veracity of different ES for the formulation of layer diets. It was found that there was no advantage to using any particular ES. The work reported herein covers a trial conducted to validate the theoretical findings of the earlier model. Diets were formulated using Apparent Metabolizable Energy corrected for nitrogen retention (<strong>AME_n</strong>) or Net Energy (<strong>NE</strong>), using different oil pricing structures. This effectively meant that the diets either contained oil or did not. Individually housed Hy-Line Brown Layers (aged 45 weeks) were used in a completely randomized factorial design (2 × 2 and 12 replicates per treatment) for eight weeks. No significant differences were found in feed intake, feed conversion ratio, body weight, or egg output. The calculated energy requirement per gram of egg output was significantly higher when NE was used in combination with oil, suggesting that the correction factor ascribed to lipid in NE determination may be generous. In conclusion, the AME and NE are equally effective at predicting egg production parameters and energy requirements, validating earlier theoretical work that AMEn is an adequate ES for diet formulation in laying hens.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100676"},"PeriodicalIF":2.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic knockout of pagP in avian pathogenic Escherichia coli using CRISPR-Cas9/λ-Red system and growth characterization","authors":"Linan Jia ,&nbsp;Hailey Fugate ,&nbsp;Xin Ye ,&nbsp;Mark A. Arick II ,&nbsp;Chuan-Yu Hsu ,&nbsp;Jeffrey D. Evans ,&nbsp;Kelsy Robinson ,&nbsp;Pratima Adhikari ,&nbsp;Li Zhang","doi":"10.1016/j.japr.2026.100679","DOIUrl":"10.1016/j.japr.2026.100679","url":null,"abstract":"<div><div>Avian pathogenic <em>Escherichia coli</em> (<strong>APEC</strong>) causes costly colibacillosis across poultry systems, underscoring the need for safe, targeted vaccine antigens. The outer-membrane enzyme pagP, which palmitoylates lipid A and aids innate-immune evasion, is a promising subunit vaccine candidate if it proves non-essential for baseline fitness. We developed and documented a reproducible CRISPR-Cas9/λ-Red workflow to delete <em>pagP</em> in field-derived APEC strain MS1657, constructed donor DNA with short homologous arms, and verified editing by PCR/Sanger sequencing. Editing was efficient (4/5 colonies positive), and whole-genome sequencing of wild type strain and isogenic MS1657Δ<em>pagP</em> line confirmed a precise locus deletion with no additional coding changes or structural alterations, establishing genome-wide specificity. Following a multi-step counter-selection process, editing plasmid-free Δ<em>pagP</em> clones were obtained. To assess fitness, we compared growth kinetics in LB at 37°C using nine biological replicates per strain with OD₆₀₀ readings every 5 min for 24 h. Doubling times did not differ (MS1657: 59.4 ± 5.4 min; MS1657Δ<em>pagP</em>: 60.8 ± 9.9 min; two-tailed t-test, <em>P</em> = 0.697), indicating that <em>pagP</em> is dispensable under nutrient-rich conditions. These data, together with the protein’s surface exposure and functional relevance, support pagP as a safe, non-essential, and tractable antigen for subunit vaccine development. This study provides a stepwise, genome validated knockout pipeline for APEC that can be applied to additional loci and related poultry pathogens. Future embryo and chick challenge studies will define the contributions of <em>pagP</em> to virulence, host recognition, and protection, advancing rational antigen selection for colibacillosis control.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100679"},"PeriodicalIF":2.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of phytase superdoses on peaking Hy-Line W-36 laying hen egg production and egg quality","authors":"S.R. Bianchi ,&nbsp;D.R. Boontarue ,&nbsp;B.C. Bodle ,&nbsp;J.W. Boney","doi":"10.1016/j.japr.2026.100677","DOIUrl":"10.1016/j.japr.2026.100677","url":null,"abstract":"<div><div>This study evaluated the impact of superdosing a new generation phytase, HiPhorius™ (HP), on egg production (EP), egg quality, and bone mineralization in laying hens from 22 to 34 weeks-of-age. Four dietary treatments were studied: a Positive Control (PC), a Negative Control (NC) with 0.16% non-phytate phosphorus (nPP), NC + 1,100 FYT/kg HP, and NC + 1,500 FYT/kg HP. Weekly performance was analyzed using the GLM procedure in SAS, while four-week period data (Pd1: 23-26 wk, Pd2: 27-30 wk, Pd3: 31-34 wk) were analyzed using repeated measures ANOVA. Preplanned contrasts compared PC vs. NC, NC vs. phytase-supplemented diets, and PC vs. phytase-supplemented diets. Superdosed HP improved EP and FCR compared to the NC, with performance comparable to the PC, particularly in Pd1 and Pd3. Egg quality responses to HP were inconsistent, with some improvements in albumen height (AH) and Haugh unit (HU) in specific wks, but no sustained differences across the laying cycle. Bone mineralization was largely unaffected, although contrast analysis indicated that phytase supplementation to NC diets increased tibia ash weight (mg/kg BW) compared with NC alone. These findings suggest that superdosing HiPhorius™ can maintain production efficiency in reduced nPP diets, but its effects on egg quality and bone mineralization may be variable.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100677"},"PeriodicalIF":2.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel phytase improves the growth performance, tibia mineralization and phosphorus digestibility of male meat ducks under long- and short-term supplementation conditions","authors":"Yanhong Luo ,&nbsp;Kostas Stamatpoulos ,&nbsp;Aaron Cowieson ,&nbsp;Stephane Duval ,&nbsp;Jingcheng Zhang ,&nbsp;Shikui Wang ,&nbsp;Zhenzhen Wang ,&nbsp;Jinlong Wu ,&nbsp;Qian Zhang","doi":"10.1016/j.japr.2026.100673","DOIUrl":"10.1016/j.japr.2026.100673","url":null,"abstract":"<div><div>Exogenous phytase enzymes have been developed and widely used in poultry industry to enhance the phosphorous (<strong>P</strong>) utilization. However, duck production only accounts for 4.91% of the global poultry meat production, resulting in limited researchers on phytase application in this species. Consequently, duck producers often rely on broiler data as a reference, despite notable anatomical and physiological differences in the digestive tracts of ducks and broilers that could result in differences in nutrient utilization. Nevertheless, according to FAOSTAT data, the ducks contributed approximately 7.06 million tons of meat to global consumption in 2023, underscoring the importance of evaluating the utilization of phosphorus by phytase in the meat duck industry to support a more sustainable industry and precise nutrition management. Therefore, the current study aimed to evaluate the efficacy of a novel phytase (characterized by superior thermostability and pH tolerance) in meat ducks under long- and short-term supplementation conditions. Results shown that the novel phytase significantly improved the growth performance and bone mineralization of ducks by effectively hydrolyzing the phytate P and releasing both P and inositol across both long- and short-term conditions. Based on the duck bone ash weight and percent, the novel phytase addition of 500, 1,000, 2,000, 3,000 and 4,000 phytase FYT/kg were estimated to be equivalent to approximately 0.085, 0.164, 0.237, 0.261 and 0.270% non-phytate phosphorus (nPP), respectively. These findings demonstrate the potential of the novel phytase as a valuable tool for advancing precision nutrition and reducing environmental P output in commercial duck production.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100673"},"PeriodicalIF":2.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Ixeris polycephala meal on growth performance, antioxidant function, and immune function in broilers","authors":"X.J. Dai,&nbsp;J.A. Li,&nbsp;Z.J. Jia,&nbsp;X.T. Ye,&nbsp;D.Y. Ou,&nbsp;H.Y. Yao","doi":"10.1016/j.japr.2026.100672","DOIUrl":"10.1016/j.japr.2026.100672","url":null,"abstract":"<div><div>This study evaluated the effects of dietary <em>Ixeris polycephala</em> meal (IPM) on 192 male Partridge Shank broilers (30 days old). Birds were assigned to a control diet or diets supplemented with 1%, 2%, or 3% IPM. Growth performance, intestinal morphology, serum biomarkers, and splenic gene expression were assessed. Results indicated that 3% IPM maximized final body weight and average daily gain. However, a distinct immunological trade-off was observed. From 70 to 100 days, all IPM doses significantly reduced serum inflammatory cytokines (IL-1, IL-6, TNF-α). Notably, while the 1% group achieved the lowest cytokine levels, this coincided with a return to baseline TLR expression (\"Resolution\"). In contrast, the 2% group maintained significantly upregulated splenic TLR2 and TLR4 mRNA expression alongside cytokine suppression, suggesting a state of 'Active Tolerance'—preserving high pathogen surveillance without systemic inflammation. The 3% group exhibited attenuated TLR2 expression relative to the 2% group. Additionally, IPM supplementation enhanced antioxidant capacity (increased GSH-Px/SOD), although malondialdehyde levels were not reduced. In conclusion, while 3% IPM optimizes growth parameters, 2% IPM establishes the optimal physiological equilibrium between pathogen defense and inflammatory resolution. Therefore, 2% IPM is recommended as the precision dietary strategy for supporting immune homeostasis in the late growth phase.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100672"},"PeriodicalIF":2.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Commingled or sex-separate rearing on body composition, testicular development, and reproductive performance of broiler breeder cockerels","authors":"J. Hunter Mason ,&nbsp;Luis P. Avila ,&nbsp;Venkata Sesha Reddy Choppa ,&nbsp;Woo K. Kim ,&nbsp;Susan M. Williams ,&nbsp;Jeanna L. Wilson","doi":"10.1016/j.japr.2026.100667","DOIUrl":"10.1016/j.japr.2026.100667","url":null,"abstract":"<div><div>Over the years, achieving the reproductive potential of broiler breeders has become a challenge as they share the same growth potential of their offspring. As males with increased body and breast weight are less likely to efficiently mate, it is suggested to raise cockerels separate from pullets <strong>(SS)</strong> instead of commingled <strong>(CO)</strong> as it better facilitates the control of BW gain and the overall growth potential. However, due to the lack of knowledge surrounding the impact SS and CO rearing have upon broiler breeder performance, more research is required. The objectives of this study were to compare the BW, BW uniformity, testicular development, growth performance, and reproductive performance of broiler breeder males when reared SS or CO. Our results indicate that indirect feeding of CO males led to poor BW uniformity and decreased fertility towards the end of lay as well as increased the mortality rate of roosters during the laying period. However, direct feeding of sex-separate males was found to improve BW uniformity. The enhanced ability to control the sex-separate male’s growth along with more productive semen production as indicated by the wider seminiferous tubules and more Sertoli cells could explain the improvements observed in fertility towards the end of lay.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100667"},"PeriodicalIF":2.0,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ban of day-old chick culling: Ethical concerns and challenges for policy, industry, and research","authors":"Josefine Stuff ,&nbsp;Vivian C. Goerlich ,&nbsp;Senta Becker ,&nbsp;Sonja Hillemacher ,&nbsp;Longfei Cheng ,&nbsp;Qin Pu ,&nbsp;Stefanie Kuerten ,&nbsp;Ruijin Huang ,&nbsp;Inga Tiemann","doi":"10.1016/j.japr.2026.100668","DOIUrl":"10.1016/j.japr.2026.100668","url":null,"abstract":"<div><div>Worldwide, billions of day-old male chicks are culled each year in the egg industry due to the low market value of layer-type males. As a result of public pressure on this ethical issue, some countries banned the practice, leading to changes in animal welfare legislation. In addition to the use of dual-purpose chicken for egg and meat production, technologies for <em>in-ovo</em> sex determination, aiming to cull male embryos during early development and prior to the onset of pain perception, are feasible alternatives. However, the temporal onset of pain perception in chick embryos is still unknown, and its determination is challenging. Here we embed a review of the existing literature of <em>in-ovo</em> pain research under the country-specific umbrella of societal discussions and culling alternatives. Recently, a study on nociception measured first signs of responses by the embryo at day 13 of incubation. Still, neither the depiction of nociceptive pathways nor an EEG, which includes signals of general muscle contraction, provide definitive proof of the perception of pain. We urge that more knowledge about the development of pain perception in chick embryos is key to the ethical framework that should underpin policy decisions.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100668"},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isolation and molecular characterization of multidrug-resistant APEC isolates from Pakistan poultry, including high-risk ST410 subclones","authors":"Zulquernain Haider ,&nbsp;Zafar Hayat ,&nbsp;Shafiq ur Rehman","doi":"10.1016/j.japr.2026.100665","DOIUrl":"10.1016/j.japr.2026.100665","url":null,"abstract":"<div><div>Colibacillosis is a systemic disease of poultry caused by avian pathogenic <em>Escherichia coli</em> (APEC). The prevalence rate of colibacillosis in Pakistani poultry production ranges 12.5- 89.2% with 20- 40% mortality. Many studies have reported the high prevalence of serotype O78, O1, O2, and O18 while a significant number of isolates remain non-typeable. The current study was conducted to isolate and characterize non-typeable or less commonly reported APEC isolates from Pakistani poultry. A total of ten APEC isolates were isolated from heart, liver, and lungs of morbid birds showing typical symptoms of colibacillosis. The isolates were characterized by the Congo red binding assay, phylotyping, serotyping, virulence factor profiling, and antibiotic susceptibility testing. The genomic DNA of five isolates were sequenced and characterized for virulence associated genes (VAGs), antibiotic resistance associated genes (ARAs), multi-locus sequence typing and phylogenetic analysis. The predominant virulence factors included o<em>mpA, IbeB, mat, irp2, iucD, iroN, and iutA.</em> All isolates were multidrug resistant with highest resistance against ampicillin/β-lactams, quinolones/fluoroquinolones, and cephems. The virulence associated genes (VAGs) of the studied APEC isolates were compared to VAGs of previously reported APEC isolates. Three isolates of high-risk ST410 representing B2/B3-H24R subclones were identified. In conclusion, these APEC isolates from diseased broiler birds exhibited high pathogenic potential and one health risks due to zoonotic MDR <em>E. coli</em> strains. All strains showed multidrug resistance to β-lactams, quinolones, and cephems, while pangenome clustering highlights genomic plasticity and niche specialization driving convergent pathogenicity across diverse isolates and clades in Pakistani poultry.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100665"},"PeriodicalIF":2.0,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of aviary design on measures of production, egg quality, mortality, floor eggs, feed delivery, and body weight","authors":"Kathryn A. Baugh ,&nbsp;Janice M. Siegford ,&nbsp;Cara I. Robison ,&nbsp;Tina M. Widowski ,&nbsp;Ahmed A.B. Ali","doi":"10.1016/j.japr.2026.100663","DOIUrl":"10.1016/j.japr.2026.100663","url":null,"abstract":"<div><div>As the laying hen industry transitions to cage-free housing such as aviaries, balancing egg production and profitability with bird welfare will ensure long-term industry sustainability. Commercially available multi-tiered aviaries come in various configurations intended to meet hens’ needs and maximize efficiency for the producer. To evaluate whether aviary configuration impacted egg production, egg quality, mortality, mislaid eggs, feed delivery, and body weight, this study evaluated a flock housed in two aviary styles, NATURA60 (N60) and NATURA Step (STEP). Mortality, production, and feed delivery data were collected daily across the flock cycle (17 to 60 weeks of age), and egg quality and body weight data were collected at specific timepoints within this period. STEP hens tended to produce at a higher rate than N60 hens across time as well as laying a significantly lower number of eggs on the floor of the aviary. From 43-60 WOA, cumulative mortality was higher in the N60 than the STEP. Egg quality parameters followed expected age-related changes, with no effect of aviary type averaged over time. Feed delivery was higher in STEP than N60, but body weights were similar. Genetics, nutrition, and management were consistent between the two aviaries, suggesting that differences in production measures could be due to differing configuration and accessibility to resources like nest space for laying eggs; future research can help illuminate these underlying factors.</div></div>","PeriodicalId":15240,"journal":{"name":"Journal of Applied Poultry Research","volume":"35 2","pages":"Article 100663"},"PeriodicalIF":2.0,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}