A significant quantitative trait locus on chromosome Z and its impact on egg production traits in seven maternal lines of meat-type chicken

Background:Egg production is economically important in the meat-type chicken industry.To better understand the molecular genetic mechanism of egg production in meat-type chicken,genetic parameter estimation,genome-wide association analyses combined with meta-analyses,Bayesian analyses,and selective sweep analyses were performed to screen single nucleotide polymorphisms(SNPs)and other genetic loci that were significantly associated with egg number traits in 11,279 chickens from seven material lines.Results:Yellow-feathered meat-type chickens laid 115 eggs at 43 weeks of age and white-feathered chickens laid 143 eggs at 60 weeks of age,with heritability ranging from 0.034–0.258.Based on meta-analyses and selective sweep analyses,one region(10.81–13.05 Mb)on chromosome Z was associated with egg number in all lines.Further analyses using the W2 line was also associated with the same region,and 29 SNPs were identified that significantly affected estimation of breeding value of egg numbers.The 29 SNPs were identified as having a significant effect on the egg number EBV in 3194 birds in line W2.There are 36 genes in the region,with glial cell derived neurotrophic factor,DAB adaptor protein 2,protein kinase AMP-activated catalytic subunit alpha 1,NAD kinase 2,mitochondrial,WD repeat domain 70,leukemia inhibitory factor receptor alpha,complement C6,and complement C7 identified as being potentially affecting to egg number.In addition,three SNPs(rs318154184,rs13769886,and rs313325646)associated with egg number were located on or near the prolactin receptor gene.Conclusion:Our study used genomic information from different chicken lines and populations to identify a genomic region(spanning 2.24 Mb)associated with egg number.Nine genes and 29 SNPs were identified as the most likely candidate genes and variations for egg production.These results contribute to the identification of candidate genes and variants for egg traits in poultry.

Integrative analysis of hypothalamic transcriptome and genetic association study reveals key genes involved in the regulation of egg production in indigenous chickens

Indigenous chicken products are increasingly favored by consumers due to their unique meat and egg quality.However,the relatively poor egg-laying performance largely impacts the economic benefits and hinders sustainable development of the local chicken industry.Thus,excavating key genes and effective molecular markers associated with egg-laying performance is necessary to improve egg production via genetic selection in indigenous breeds.In the present study,comparative hypothalamic transcriptome between pre-laying(15 weeks old)and peak-laying(30 weeks old)Lushi blueshelled-egg(LBS)chicken was performed.A total of 518 differentially expressed genes(DEGs)were identified.Among the DEGs,64 genes were enriched in 10 Gene Ontology(GO)terms associated with reproductive regulation via GO analysis and considered as potential candidate genes regulating egg-laying performance.Of the 64 genes,16 showed high connectivity(degree≥12)by protein–protein interaction(PPI)network analysis and were considered as potential core candidate genes(PCCGs).To further look for key candidate genes from the PCCGs,firstly,the expression patterns of the 16 genes were examined in the hypothalamus of two indigenous breeds(LBS and Gushi(GS)chickens)between the pre-laying and peak-laying stages using quantitative real-time PCR(qRT-PCR).Eleven out of the 16 genes showed significantly differential expression(P<0.05)with the same changing trends in the two breeds.Then,correlations between the expression levels of the above 11 genes and egg numbers and reproductive hormone concentrations in serum were investigated in high-yielding and low-yielding GS chickens.Of the 11 genes,eight showed significant correlations(P<0.05)between their expression levels and egg numbers,and between expression levels and reproductive hormone concentration in serum.Furthermore,an association study on single nucleotide polymorphisms(SNPs)identified in these eight genes and egg production traits was carried out in 640 GS hens,and a significant association(P<0.05)between the SNPs and egg numbers was confirmed.In conclusion,the eight genes,including CNR1,AP2M1,NRXN1,ANXA5,PENK,SLC1A2,SNAP25 and TRH,were demonstrated as key genes regulating egg production in indigenous chickens,and the SNPs sites within the genes might be served as markers to provide a guide for indigenous chicken breeding.These findings provide a novel insight for further understanding the regulatory mechanisms of egglaying performance and developing molecular markers to improve egg production of indigenous breeds.

Correlation between Egg Production Traits and Broodiness Traits in Shiqiza,Langya and Luqin B2 Chickens

[ Objective] To investigate the relationship between the egg production traits and broodiness of Shiqiza, Langya and Luqin B2 chickens. E Method] Three chicken breeds, Shiqiza chickens （a breed preserved by Shandong Academy of Agricultural Sciences）, Langya chickens （a local breed in Shandong Province） and Luqin B2 chickens （a cultivated breed） were selected. Then their broodiness traits were observed and the egg productions were analyzed. Finally, the relationships between the egg production traits and broodiness were analyzed by SAS software. [ Result] The Shiqiza, Langya and Luqin B2. chickens were broody and their broodiness rate was 15.80%, 2.24% and 6.95%, respectively. Compared with the non-broody chickens, the egg productions of Shiqiza, Langya and Luqin B2 chickens were respectively decreased by 17.16%, 1.53% and 10.8% at the age of 43 weeks. The three breeds had significant differences in repeats of broody cycles （ P 〈 0.05）, and extremely significant differences in the broodiness duration, the the first day of broodiness, the age at the first egg, total amount of abnormal eggs and amount of double- yolked eggs （P 〈 0.01 ）. [Conclusion] The broodiness is a main factor affecting egg production traits. The degree of effects of broodiness on egg production traits is decreased successively in Shiqiza chicken, Luqin B2 chicken and Langya chicken.

Correlation between DRD2 Gene Polymorphism and Early Egg Production Performance of Libo Yaoshan Chicken

To improve egg production performance of local chicken breed in Guizhou Province, Libo Yaoshan chicken, with dopamine receptor 2 （ DRD2 ） as one of the candidate genes, we detected its genetic variation in 196 Libe Yaoshan hens using PCR-SSCP （single-strand conformation polymorphism） and sequencing method, and analyzed the correlation between genetic variation and egg production traits. The results showed that TT and TG genotypes in mRNA SNlX）62 （C→T） loci of the DRD2 gene had extremely significant difference in egg production at 38 weeks age （P 〈0.01 ）, and significant difference in egg weight at 300 days age （P 〈0.05 ）. The single nucleotide polymorphisms （SNPs） mutation induced synonymous mutation of the 312th amino acids （leucine） in DRD2 protein, from L （CTG） to L （TI＇G）. The mRNA SNP962 （C→T） loci had a larger genetic effect on egg production at 38 weeks age, and could be used as a molecular marker in early breeding of Libo Yaoshan chicken.

Microbiome and ileum transcriptome revealed the boosting effects of selenium yeast on egg production in aged laying hens

The declines in laying performance during the late productionperiod have adverse effects on the length of theproduction cycle. Improving the nutrition of laying hens is a crucialmeasure to reverse this declination. Thisstudy investigatedthe effect of seleniumyeast (SY)on egg production, ileal gene expressionandmicrobiota, aswell as elucidating their associations in aged laying hens. A total of 375 Jinghong laying hens at 76weeks oldwere randomly assigned into 5 dietary treatments, which included a selenium-deficient basal diet based oncorn-soybean meal, and dietary supplementation of SY at 0.15, 0.30 and 0.45 mg/kg, and sodium selenite at0.45mg/kg.The results showed that SYamelioratedthe depressionin aged layingperformance inthe 0.30mg/kg group (P < 0.01). Selenium yeast significantly increased ileum selenium concentration (P < 0.05), and SYgroups had higher seleniumdeposition efficiency than the sodiumselenite group. Functional enrichment andShort Time-series Expression Miner (STEM) analysis indicated that SY activated metabolic progress (e.g.,glycerolipidmetabolism, glycerophospholipidmetabolism, andfattyacidmetabolism),immune responseandoxidative stress response. Four hub genes including thioredoxin reductase 1 (TXNRD1), dihydrolipoamidedehydrogenase (DLD), integrin linked kinase (ILK) and leucine zipper tumor suppressor 2 (LZTS2) wereinvolved in intestinal metabolismwhich was closely associated with selenium deposition/status. Moreover,the relative abundance of Veillonella, Turicibacter and Lactobacillus was significantly increased, but the relativeabundance of Stenotrophomonas was significantly decreased by SY supplementation. Multi-omics dataintegration and Canonical correspondence analysis (CCA) showed that both the ileumselenium content andthe laying rate were highly correlated with pathways and bacteria enriched in metabolism and immuneresponse. Meanwhile, the “switched on” gene prostate stem cell antigen (PSCA) had a positive relationshipwith Veillonella and a negative relationship with the opportunistic pathogens Stenotrophomonas. Overall, ourstudy offered insight for the further exploration of the role of SY on boosting egg production and balancingileum intestinal flora in aged laying hens.

EGG PRODUCTION IN CHINA:CURRENT STATUS AND OUTLOOK

Eggs are one of the most nutritious and affordable animal products worldwide.From 1985,egg production in China has retained the leading place in the world.A total of 33 Mt of eggs were produced in 2019 representing˃40%of the world total production.Egg production in China is characterized by diversity in several aspects,including layer breeds,products and production systems.New breeds and synthetic lines are developed to improve the genetic potentials of egg production and feed efficiency of layers.In the past,layer farms were run mostly by small households with 100 to 1000 layers per farm.Over the past decades,egg production in China has developed toward standardization and expansion of production systems,and many of these modern intensive farms raise millions of layers.Although the Chinese egg products maintain strong competitiveness over other animal products and imported egg products,the egg industry will grow at a slower pace compared to the past.Chinese consumers are more concerned about the quality and safety of eggs and egg products,as well as the environmental issues related to animal production,which presents challenges for the Chinese egg industry.

Effects of Desmodium uncinatum Leaf Meal in the Diet on Lohmann Brown Hens’ Laying Performance and Eggs Quality

A cheap, safe and available alternative protein source to soybean is a huge priority for the developing world. This study is aimed at evaluating the effects of Desmodium uncinatum leaf meal incorporation levels in the diet on Lohmann Brown hens’ laying performances. For this purpose, 60 Lohmann Brown hens aged 33 weeks with an average weight of 1.78 kg were randomly assigned to 3 treatment groups of 20 birds each with 4 replicates. The experimental treatments consisted of DULM 0, DULM5, and DULM10 containing 0, 5 and 10 kg of D. uncinatum leaf meal (DULM) per 100 kg of feed respectively. The results reveal that except for the weights of hens, laying performances were significantly affected (p < 0.05) by DULM in the diet. Daily feed intake was lower with 10% incorporation of DULM in the diet as compared to a diet with 5% DULM which recorded the highest value for this parameter. Moreover, the highest value for the egg weight, egg mass, yolk index, albumen index and egg production were recorded with diet DULM5. On the other hand, the diet with 10% of DULM (DULM10) recorded the highest relative shell weight, feed conversion ratio and egg price. Nevertheless, the mortality rate found in this study was 0% for all treatments confirming the good quality of DULM as protein feedstuff for layer. It was concluded that incorporation levels of D. uncinatum leaves at 5% in the diet improved the laying performances of Lohmann Brown hens.

Effects of Cottonseed Meal on Production Performance and Egg Quality of Hisex Laying Hens

[Objective]In order to research on effect of different content of cottonseed meals on production performance and egg quality of Hisex laying hens. [Methods]120 Hisex laying hens of 37 weeks old are chosen,randomly divided into four groups and three repetitions are set in each group,there are 10 hens in each repetition. Group I is the control group,II,III and IV are experimental groups. Cottonseed meal contents are respectively 5%,10% and 15%,with test cycle of 10 weeks,effects of different cottonseed meal dosages on Hisex laying hens production performance and egg quality are observed. [Results]When the diet is added with 5% to 15% of cottonseed meal,the average laying rate,average egg weight and feed-gain ratio all show downward trends when compared with that of the control group,but with no significant difference（ P 〉 0. 05）; eggshell strength,eggshell thickness,Haugh unit,egg shape index all show no significant difference（ P 〉0. 05）,with the increasement of cottonseed meal,the color of egg yolk got brighter,egg yolk color of 15% added group increased by 12%,show a significant difference with that of control group（ P 〈0. 05）. [Conclusion]When the feed was added with 15% cottonseed meals,it has an unconspicuous effect on laying performance and egg quality of Hisex laying hens,but whether it had an effect on animal health and food safety or not,a further systematic research is needed.

Transcriptome profile analysis of the accompanying migratory parasitic wasp Aenasius bambawalei(=Aenasius arizonensis girault)(Hymenoptera:Encyrtidae):Genes related to fertilization involved at different stage of ovary development

Age-related declines in fertilization success have been reported for a wide range of species.The fertilization of parasitic wasps is closely related to egg production and sperm storage.Aenasius bambawalei(Hymenoptera:Encyridae)is a key parasitic wasp of the important invasive mealybug Phenacoccus solenopsis(Hemiptera:Pseudococcidae).The female offspring ratio of this parasitic wasp was declined with parental age in mass rearing under laboratory conditions.To investigate the molecular mechanisms involved in the reproduction of A.bambawalei,an extensive analysis of the impact of age on transcriptome profile of mated ovaries of this wasp was performed by comparing the gene expression profiles of various maternal ages:the early stage(ES),the intermediate stage(IS),and the advanced stage(AS).In total,358 differentially expressed genes were identified,with 17.60%(63 genes)of the changes associated with greater expression in fertilization.Moreover,the expression of serine protease 47 precursor,serine protease inhibitor 3/4,glucose dehydrogenase,fatty acyl-CoA reductase 1-like,major royal jelly,and acyl-CoA delta(11)desaturase-like was detected by real-time fluorescence quantitative(RT-qPCR).The results showed that fertilization related genes exhibited a stage-specific pattern.Egg production and sperm storage genes in A.bambawalei were significantly modified in the transcriptome,providing a starting point for the genetic dissection of fertilization.

Increased Oocyte Production after Acupuncture Treatment during Superovulation Process in Mice

Objective To investigate whether acupuncture treatment during superovulation process improves ovarian response and increases egg production. Methods ICR female mice aged 12 -5 weeks were divided into control group, anaesthesia group and acupuncture group. Female mice were injected intraperitoneally with pregnant mare＇s serum gonadotropin （PMSG）, followed by human chorionic gonadotropin （hCG） injection 56 h later. Anaesthesia group and acupuncture group were anaesthetized three times by injecting 10% nembutal solution according to 7.5-10.0μl/g weight. Acupuncture group was treated three times with puncture Sanyinjiao Points（SP6） under anaesthesia. After 17 h of hCG injection, eggs were recovered and ovaries were isolated. Matured eggs were counted, ovarian histology and expression of follicle stimulating hormone receptor（FSH-R） in ovary were analyzed. Results Acupuncture treatment statistically increased the number of ovulated eggs. Histological section showed that some matured follicles left in the ovaries of control and anaesthesia groups after ovulation. On the contrary, all matured follicles ruptured and converted into corpus lutea in Acupuncture group. Expression of FSH-R in ovary was decreased in acupuncture group compared with those of the two others. Conclusion Acupuncture treatment during superovulation process improves ovarian response so as to increase egg production. The positive effect of acupuncture may be associated with regulated FSH-R expression.

Efficacy of dietary phytase supplementation on laying performance and expression of osteopontin and calbindin genes in eggshell gland

This study was conducted to evaluate the effects of different levels of dietary phytase supplementation in the layer feed on egg production performance,egg shell quality and expression of osteopontin(OPN) and calbindin(CALB1) genes.Seventy-five White Leghorn layers at 23 weeks of age were randomly divided into 5 groups consisting of a control diet with 0.33% non-phytate phosphorus(NPP) and 4 low phosphorus(P) diets: 2 diets(T1 and T2) with 0.24% NPP t 250 FTU/kg laboratory produced phytase or commercial phytase and another 2 diets(T3 and T4) with 0.16% NPP t 500 FTU/kg laboratory produced phytase or commercial phytase with complete replacement of inorganic P.The results indicated that there were no significant differences(P > 0.05) in egg production performance and quality of egg during the first 2 months of trial.However,in next 2 months,a significant drop in egg production and feed intake was observed in birds fed diets with low P and 500 FTU/kg supplementation of laboratory produced phytase.Osteopontin gene was up-regulated whereas the CALB1 gene was down regulated in all phytase treatment groups irrespective of the source of phytase.The current data demonstrated that250 FTU/kg supplementation of laboratory produced phytase with 50% less NPP supplementation and500 FTU/kg supplementation of commercial phytase even without NPP in diet can maintain the egg production.The up-regulation of OPN and down regulation of CALB1 in egg shell gland in the entire phytase treated group birds irrespective of the source of enzymes is indicative of the changes in P bioavailability at this site.

Influence of host age and host deprivation on longevity, egg load dynamics and oviposition rate in Microplitis rufiventris

Adult size, longevity, egg load dynamics and oviposition ofMicroplitis rufiventris Kok. which began their development in the first, second, third （preferred hosts） or fourth （non-preferred hosts） instar larvae of Spodoptera littoralis （Boisd.） were studied. The parasitoid size was largely determined by the initial host size at parasitism. Non-ovipositing females derived from older hosts lived for longer periods than those derived from younger ones. However, the ovipositing females, irrespective of their size, lived for almost the same periods. At emergence, the oviducts of adult females contain a significant amount of mature eggs available for oviposition for a few hours on eclosion day. Egg load increases during the early phase of adult life. The amount of additional mature eggs and rate of egg maturation per hour was greater for wasps derived from preferred hosts compared with those in females derived from non-preferred hosts. The pattern of egg production in M. rufiventris females depended on the availability of hosts for parasitization. Host-deprived females depleted the egg complement with aging; the longer the host deprivation, the lower the oviduct egg load. Marked reduction in both realized or potential fecundity of host-deprived females was observed following host availability. Host privation for more than 3 days induced a marked deficit fecundity pattern through the female＇ s life. The realized fecundity was determined by the interaction among host availability, the number of eggs that are matured over the female＇ s life span, oviposition rate and host size from which the female was derived. These results suggest that： （i） M. rufiventris wasp is a weak synovigenic species; （ii） the maturation of additional eggs is inhibited once the maximum oviduct egg load is reached; （iii） the egg load of the newly emerged female is significantly less than the realized fecundity; and （iv） because M. rufiventris females oviposit fewer eggs when they begin depleting their egg supply at 3 days, augmentative releases will require release immediately following emergence to ensure the highest parasitization rate in the field.

Cloud-based data management system for automatic real-time data acquisition from large-scale laying-hen farms

Management of poultry farms in China mostly relies on manual labor.Since such a large amount of valuable data for the production process either are saved incomplete or saved only as paper documents,making it very difficult for data retrieve,processing and analysis.An integrated cloud-based data management system(CDMS)was proposed in this study,in which the asynchronous data transmission,distributed file system,and wireless network technology were used for information collection,management and sharing in large-scale egg production.The cloud-based platform can provide information technology infrastructures for different farms.The CDMS can also allocate the computing resources and storage space based on demand.A real-time data acquisition software was developed,which allowed farm management staff to submit reports through website or smartphone,enabled digitization of production data.The use of asynchronous transfer in the system can avoid potential data loss during the transmission between farms and the remote cloud data center.All the valid historical data of poultry farms can be stored to the remote cloud data center,and then eliminates the need for large server clusters on the farms.Users with proper identification can access the online data portal of the system through a browser or an APP from anywhere worldwide.

A simple daily dynamic feeding regimen for reducing phosphorus consumption and excretion in laying hens

Phosphorus metabolism in laying hens is a highly dynamic process over the course of the 24 h egg-laying cycle.Adjusting the phosphorus feeding regimen according to the daily egg-laying cycle may help to improve phosphorus utilization efficiency.Hy-Line Brown layers(n=120;70 wk old)were offered 4different phosphorus daily regimens:(1)RR,fed regular phosphorus at both 09:00 and 17:00;(2)RL,fed regular phosphorus at 09:00 and low phosphorus at 17:00;(3)LR,fed low phosphorus at 09:00 and regular phosphorus at 17:00;(4)LL,fed low phosphorus at both 09:00 and 17:00.The regular and low phosphorus diets contained 0.32% and 0.14% non-phytate phosphorus,respectively.The feeding trial lasted for 12 wk.As a result,layers on the RL regimen had decreased laying rate(P<0.05;5 to 8,9 to 12,and 1 to 12 wk)when compared to all other regimens.Layers on the LL regimen had decreased eggshell thickness and specific gravity(P<0.05;wk 8)when compared to all other regimens,and had decreased egg shell strength(P<0.05;wk 8)when compared to RL and LR regimens.When compared to the RR regimen(a common practice in the industry),layers on the LR regimen had:(1)identical laying performance and egg quality(P>0.05);(2)decreased phosphorus excretion(P<0.05)during the period of09:00 to 17:00;(3)increased jejunal calbindin D28k protein expression(P<0.05)2 h after feeding in the morning;(4)decreased serum fibroblast growth factor 23 and calcitriol levels(P<0.05),decreased jejunal type Ⅲ sodium-phosphate cotransporter 2 gene and protein expression(P<0.05),and decreased renal type Ⅲ sodium-phosphate cotransporter 1 protein expression(P<0.05),2 h after feeding in the afternoon.In summary,when dietary phosphorus was supplemented in accordance with daily serum phosphorus rhythms(i.e.,the LR regimen),laying performance and egg quality were well supported whilst significantly decreasing phosphorus consumption and excretion.Thus,serum phosphorus rhythms will need to be carefully maintained when developing dietary phosphorus-reduction strategies in laying hens.

Evaluation of nesting behavior of individual laying hens in an enriched colony housing by using RFID technology

The US egg industry is progressively adopting alternative housing systems for laying hens.Provision of nesting places accommodates natural behaviors and may improve the welfare of the laying hen.However,some fundamental questions remain about nesting behaviors of hens under different housing conditions,which would impact system design and management.For instance,how long does a hen use nest per day for egg laying or nest exploration?How many hens nest simultaneously?In such schemes,information on hens’behavioral and production responses of hens remains relatively sparse.The primary objective of this work was to demonstrate that RFID technology can be used to continuously quantify dynamic nesting behaviors of individual laying hens in a 60-hen enriched colony housing(ECH).Results show that hens spent on average 63.7±1.4 min(mean±SE)in the nest box and made 23.4±0.7 nest visits during a 16 h daily light period.Time spent in and visits to the nest box during the 6 h laying period accounted for 56% and 45% of the light-period value,respectively.Maximum nest occupancy was 29.0%±0.4%.Three distinct phases of egg production in nest boxes were observed:initial(1.5 h),peak(3.2 h,egg laying rate of 0.24±0.01 eggs/min),and late(1.3 h).The majority(95.1%±0.6%)of the daily eggs were laid in the nest box.Considerable variations in nesting behavior among individual hens and day-to-day variations for a given hen were observed.The RFID system will enable researchers to examine the impacts of resource allocations on nesting behaviors of laying hens in alternative hen housing.

Effect of mating status on the fecundity of a cricket, Teleogryllus emma

Fecundity in some insects is affected by mating status. The effect of mating status on the fecundity and total egg production of Teleogryllus emma （Ohmachi et Matsumura） （Orthoptera： Gryllidae） was examined in this study. The results showed that the pre-oviposition period was shorter for amphigonic females than that for virgin females. However, no significant difference in pre-oviposition was found between amphigonic females and those that had mated with a male with either the phallodeum or testes extirpated. There is no difference in adult longevity between the above four groups. The fecundity and total egg production were much higher in amphigonic females than in those controlled under the three non-amphigonic treatments. The females of T. emma that mated with the testes-extirpated males produced more eggs （up to two-fold more） than both the virgin females and those that mated with the phallodeum-extirpated males, but there was no difference between them. The fecundity-enhancing substances transferred from male to female can stimulate the female to produce more eggs, but this stimulation has to occur in collaboration with sperm.

Body weight and range usage affect net energy utilisation in commercial free-range laying hens when evaluated in net energy chambers

Within a given free-range flock,some hens prefer to spend the majority of their time in the shed(stayers),while others frequently access the range(rangers).Laying performance has been associated not only with the development of these sub-populations but also with different body weights(BW).The purpose of this study was to determine if range usage,BW or a combination of both is associated with energy metabolism and as such co ntribute to improved hen performance.Forty-eight Lohmann Brown hens at 74 wk of age were selected from a commercial free-range farm based on their BW and range usage over a 56-week period.Using a 2 × 2 factorial arrangement,hens were either classified as heavy(mean ± SEM;2.01±0.02 kg,n=24) or light(1.68±0,01 kg,n=24),and also classified as rangers(accessed the range for 84.1 % of available days,242±3.75 d;n=24) or stayers(accessed the range for 7.17% of available days;23,4±6.08 d,n=24).Stayers had significantly higher metabolizable energy(ME) intake per metabolic BW per d(0.852 vs.0.798 MJ/kg BW0.75 perd;P=0.025),higher heat production(0.637 vs.0.607 MJ/kg BW0.75 perd;P=0.005),higher heat increment(0.267 vs.0.237 MJ/kg BW0.75 per d;P=0.005) and retained more nitrogen(1.59 vs.1.46 g/hen perd;P=0.023) compared to the rangers.Light hens had significantly higher metabolic energy intake per metabolic BW(0.854 vs.0.796 MJ/kg BW0.75 per d;P=0.018),net energy(NE) intake(0.595 vs.0.551 MJ/kg BW0.75 per d;P=0.032),and retained energy(0.225 vs.0.181 MJ/kg BW0.75 per d;P=0.032),as well as lower heat production(0.936 vs.1.003 MJ/hen per d;P=0.002) compared to heavier hens.An interaction was observed across levels of analysis i.e.between light stayers and light rangers.The light rangers had significantly higher NE intake compared to the light stayers(9.77 vs.9.27 MJ/kg BW0.75 per d;P=0.024).In conclusion,light hens were more energy efficient compared to heavy hens.Moreover,light rangers had a more efficient feed utilisation compared to the light stayers.