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.

Effects of salinity on egg and fecal pellet production, development and survival, adult sex ratio and total life span in the calanoid copepod, A cartia tonsa:a laboratory study

The ef fects of salinity on the copepod, A cartia tonsa in terms of daily egg production rate(EPR), hatching success, fecal pellet production rate(FPR), naupliar development time and survival, sex ratio, and total life span were determined in laboratory conditions through three experiments. In experiment 1, EPR, hatching success, and FPR of individual females were monitored at salinities of 13, 20, 35 and 45 during short-periods(seven consecutive days). Results show EPR was aff ected by salinity with the highest outputs recorded at 20 and 35, respectively, which were considerably higher than those at 13 and 45. Mean FPR was also higher in 35 and 20. In experiment 2, the same parameters were evaluated over total life span of females(long-term study). The best EPR and FPR were observed in 35, which was statistically higher than at 13 and 20. In experiment 3, survival rates of early nauplii until adult stage were lowest at a salinity of 13. The development time increased with increasing of salinity. Female percentage clearly decreased with increasing salinity. Higher female percentages(56.7% and 52.2%, respectively) were signifi cantly observed at two salinities of 13 and 20 compared to that at 35(25%). Total longevity of females was not af fected by salinity increment. Based on our results, for mass culture we recommend that a salinity of 35 be adopted due to higher reproductive performances, better feeding, and faster development of A. tonsa.

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.

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.

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.

Evolution of sex ratio and egg production of gilthead seabream(Sparus aurata)over the course of five reproductive seasons

Spawning performance-relative fecundity and fertilization success-was studied in two hatchery-reared broodstocks of gilthead seabream(Sparus aurata)held under relatively constant well-water temperature(18-20◦C)and simulated natural photoperiod,for five consecutive spawning seasons,between 3 and 7 years of age.The spawning season lasted between 4 and 6 months each year,and the total number of eggs produced annually ranged between 1480000 and 3100000 eggs/kg female body weight,being the highest during the first and second spawning season.No difference was observed in monthly relative fecundity between years-although high variation existed within years,whereas fertilization success was the highest during the second and third reproductive season,and dropped significantly during the last year of the study.The male percentage of the broodstocks was 35%during the first spawning season of the females,and thereafter it decreased further and remained stable at around 15%-20%for the second and third spawning season.Substitution of older females with smaller males to readjust male percentage to 50%in the fourth spawning season,was followed by sex change of larger males to females and a drop of the male percentage to 18%in the following spawning season.The present study demonstrated the long spawning season of gilthead seabream-especially under constant water temperature,the high fecundity and fertilization success,and the stabilization of male percentage to~20%after the first spawning season or when a broodstock is modified to increase male percentage.These results are useful to the aquaculture industry,demonstrating that there is no need to add males to gilthead seabream broodstocks over the years,as the sex ratio is stabilized and egg production and fertilization success remain high with a relatively low male:female sex ratio.

Fermented soybean meal improved laying performance and egg quality of laying hens by modulating cecal microbiota,nutrient digestibility,intestinal health,antioxidant and immunological functions

Antinutritional factors in feedstuffs may limit their utilization in livestock production,but fermentation process can be used to improve feed quality;however,studies on fermented soybeans for laying hens remain limited.We investigated the effect of fermented soybean meal(FSBM)at various inclusion levels as a partial replacement for soybean meal(SBM)on egg production,egg quality,amino acid digestibility,gut morphology and microbiota,antioxidant capacity and immune response of young laying hens.A total of 360 Hy-line Brown laying hens aged 18 weeks were selected and divided into 5 groups of 6 replicates each and 12 birds per replicate.The control group received a basal diet while the trial group received the basal diet with FSBM included at 2.5%,5.0%,7.5%and 10.0%,respectively,for 12 weeks.Our findings revealed that the nutritional value of FSBM was higher compared to that of SBM in terms of reduced content of trypsin inhibitors and increased contents of crude protein,amino acids and minerals.FSBM enhanced egg production(P<0.05),feed-to-egg ratio(P<0.05),and albumen quality(albumen height and Haugh unit)(P<0.05).Furthermore,FSBM improved apparent fecal amino acid digestibility(P<0.05),gut morphology(increased villus height,villus width,villus height-to-crypt depth ratio and decreased crypt depth)(P<0.05),antioxidant capacity(reduced malondialdehyde and increased catalase,total superoxide dismutase,glutathione peroxidase and total antioxidant capacity)(P<0.05)and immune function(increased concentrations of IgG,IgA,and IgM;increased levels of transforming growth factor beta and Toll-like receptor 2;and reduced levels of interleukin 1βand tumor necrosis factor alpha)(P<0.05).Further analysis showed that FSBM altered the composition of the gut microbiota favoring beneficial microbes.These findings suggest that probiotic fermentation improved the nutritional value of SBM.The inclusion of FSBM in the diets of laying hens at 2.5%or 5.0%improved amino acid digestibility,gut health,immune function,egg production and egg quality.

Association of VIPR-1 gene polymorphisms and haplotypes with egg production in laying quails

The laying quail is a worldwide breed which exhibits high economic value. In our current study, the vas- oactive intestinal peptide receptor-1 （VIPR-1） was selected as the candidate gene for identifying traits of egg produc- tion. A single nucleotide polymorphism （SNP） detection was performed in 443 individual quails, including 196 quails from the H line, 202 quails from the L line, and 45 wild quails. The SNPs were genotyped using a polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP）. Two mutations （G373T, A313G） were detected in all the tested quail populations. The associated analysis showed that the SNP genotypes of the VIPR-1 gene were sig- nificantly linked with the egg weight of G373T and A313G in 398 quails. The quails with the genotype GG always exhibited the largest egg weight for the two mutations in the H and L lines. Linkage disequilibrium （LD） analysis in- dicated that G373T and A313G loci showed the weakest LD. Seven main diplotypes from the four main reconstructed haplotypes were observed, indicating a significant association of diplotypes with egg weight. Quails with the hlh2 （GGGT） diplotype always exhibited the smallest egg weight and largest egg number at 20 weeks of age. The overall results suggest that the alterations in quails may be linked with potential major loci or genes affecting reproductive traits.

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.

A Multi-Generation Schmakeria poplesia Culturing System for Use in Ecotoxicological Study

Crustacean zooplankton form the keystone link between primary producers and fish stocks in marine and estuary, ecosystems. We have established a multi-generation cultivation system for zooplankton ruth which future experiments on the biological effects of pollutants in marine and estuary environments can be better performed. A population of calanoid copepod, Sehmakeria poplesia, was collected in December 2003 and maintained in a static system through all stages （eggs to adults）. The population ex- hinted an average developmental time of 13.6 d in conditions corresponding to the natural environment （water temperature 20~C salinity 15）. A series of experiments were performed to examine copepod egg production and hatching success as functions of food type and feeding concentration. Results in our study showed that Isoehrysis galbana was more favored for the reproduction of cope- pods than Phaeodactylum tricornutum, and 10xl0%ellsmL-1 was the most practical algae concentration. We have demonstrated that the Schmakeria poplesia population can be maintained in the laboratory through multiple generations. In addition, methods to control egg production through changes in food concentration have been established, making it feasible to control the start date of exposure experiments or the timing of the collection of oftspring to initiate a new generation.

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.

Study on Vaccination Efficacy against Avian Influenza in Rajshahi, Bangladesh

Vaccines are used in integrated control strategies to guard poultry against H5N1 high-pathogenicity avian influenza （AI）. This study was to evaluate the efficacy of AI vaccine against AI in poultry. About 400 serum samples were collected from the selected 130 farms located at Rajshahi region, Bangladesh. The study was carried out from January, 2013 to January, 2015. The AI vaccine titres were compared in different breed of layer, environmental temperature, feed and egg production. Result showed that the value of titres （mean ± SD） in Hyline brown, Hyline white, Bovans white and Novogen white were 6.71 ± 0.05, 6.67 ± 0.06, 6.79 ± 0.03 and 6.43 ± 0.04, respectively. The highest serum antibody titres were 6.61 ± 0.24 against AI antibody in 〉 26 ℃ environment temperature. The highest and lowest serum antibody value of AI against feed brand （nutrient） were 7.75 ± 0.08 and 5.58 ± 0.22 for Aftab and Quality brand feed, respectively.

Aqua Forestry and Duck Integration in Tamil Nadu, India

A study was taken up on integration of ducks in private and community fish ponds in Tami Nadu. A total of 50 ha of land under private holding and community water bodies each were selected to implement this model. Ducks were integrated based on the water spread area. Fodder, fruit, nuts, fuel, timber trees and vegetables were grown on pond bunds. Control units of fish ponds of farmers holding without integration of ducks also were taken up. A control unit also was established in the university farm land with and without integration of ducks. In private water bodies coconut trees and banana fetched additional revenue. During the first year the average fish production from the private land model was 1,552 kg and 1,731 kg for the first and second year respectively per Hectare. In community ponds the yields were 1,610 and 1,337 kg for the first and second year respectively. In field control units there was no increase in fish yield over the years. In private water bodies the beneficiaries got egg yield of 148 and 90 eggs and community water bodies 144 and 127 eggs per bird were obtained during first and second year resoectivelv.

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.

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.