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.

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.

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.

An Updated Review on Chicken Eggs: Production, Consumption, Management Aspects and Nutritional Benefits to Human Health

Ancestors of the modern chicken were domesticated from members of the Gallus genus probably 7 to 8 thousand years ago in southeastern Asia. Subsequently, they spread globally for meat and egg production. In the chicken egg, there is a balance of numerous, high-quality nutrients, many of which are highly bioavailable. The egg confers a multitude of health benefits to consumers emphasizing its classification as a functional food. Current global per capita egg consumption estimates approach 9 kg annually but vary greatly on a regional basis. This review deals with global production, consumption, and management aspects such as hygiene, feeding, and housing. Management aspects play key roles in the composition, quality, food safety, and visual (consumer) appeal of the egg. Also the manipulation of egg nutrients and value for human health is discussed.

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.

Effects of Fermentation Product Containing Phytase on Productive Performance,Egg Quality,and Phosphorous Apparent Metabolism of Laying Hens Fed Different Levels of Phosphorus

This study investigated the effects of fermentation product containing phytase （FPP） that was fermented using waste vinegar residue （WVR） as substrate from Aspergillusficuum NTG-23 on productive performance, egg quality, and phosphorus apparent metabolism of laying hens. First, 375 22-wk-old Jinghong hens were allocated into 5 treatments （5 replicates of 15 hens each） in an 8-wk experiment for evaluating the parameters of productive performance, egg quality, serum, and tibia. Experimental diets contained 4% FPP and 96% corn-soybean diet. The levels of dicalciurn phosphate （DCP） were 1.34, 1.01, 0.67, 0.34 and 0%. Next, thirty 31-wk-old Jinghong hens were fed 5 types of diets for evaluating phosphorous apparent metabolism rate. Egg productive rate, egg weight, feed conversion ratio, Haugh unit, egg albumen height, serum calcium, tibia ash, tibia ash calcium and tibia breaking strength were not different significantly among 5 treatments. The significant difference of average daily feed intake was not appeared when the DCP content of corn-soybean-FPP diet was reduced to 0.67%; the eggshell hardness, eggshell thickness and serum phosphorus were not reduced significantly until the DCP content of corn-soybean-FPP diet was reduced to 0.34%. The yolk color was improved when the laying hens fed deficient DCP corn-soybean-FPP diet. A 22.14% reduction in excreta phosphorus was observed when the laying hens fed low phosphorus （0.67% DCP） corn-soybean-FPP diet. A 30% elevation of phosphorus apparent metabolism rate was obtained when the DCP content of corn-soybean-FPP diet was decreased from 1.34 to 1.01%. The reducing cost of layer diet was totalized about 120 CNY 1000 kg1 diet when the content of DCP was 0.67% in corn-soybean-FPP diet. These results indicated that FPP could be applied in laying hen as a potential, cost-effective and rational application of WVR.

Effect of Dietary Mulberry Leaves on Productive Performance,Egg Quality and Blood Biochemistry in Laying Hens

[Objective] The aim was to provide more information about the possible use of mulberry leaves in hen diets.[Method] Two hundred ninety two Hyline Gray laying hens, 48 wk old, were randomly allotted into four groups with 73 chickens per group. Each group was fed for 6 wk with diets that contained dried mulberry leaves at 0, 5, 10, or 15%. [ Result] The rate of egg production, egg weight, egg mass, feed intake, body weight, blood glucose level, total blood cholesterol, and triglyeride, and cholesterol of egg yolk in the dietary mulberry leaf groups were lower than the 0% mulberry leaves group. Compared with the 0% group, the feed required to produce 1 kg of eggs was 12.8% more in the 15% dietary mul- berry leaf group. Body weight and cholesterol of egg yolk decreased significantly in this group （P 〈0.05）. Blood glucose and triglyerides in the 15% dietary mulberry leaf group were significantly lower than in the 0 and 5% dietary mulberry leaf groups （P 〈0.05）. Yolk color in all treatments was higher than in the 0% group （P 〈0.05）, and Roche pigmentation score increased by 2 -2.9. One -deoxynojirimycin was detected from egg white in all treatments, and its content varied significantly between groups （ P 〈0.05）. E Conclusion] This study reflected the hypoglycemic and lipid -low- ering effects of mulberry leaves on productive performance and egg quality in laying hens. The suggested proportion of dietary mulberry leaves was 5% -10%.

Analysis of the Production and Operation Status of Silkworm Eggs Producing Farms in China——Based on Questionnaire Survey to 136 Silkworm Eggs Producing Farms Nationwide

Through statistical analysis on questionnaire survey data from 136 silkworm eggs producing farms in China,it was concluded that most silkworm eggs producing farms had such problems as follows: old production facilities and poor production condition,heavy staff burden,weak scientific and technological support,small operation scale and heavy surplus production capacity; narrow silkworm eggs sale channels and stubborn regional segmentation,insufficient innovation and lack of technological support for diversified expansion. All these problems led to low labor productivity,low asset utilization rate and poor economic benefit in silkworm eggs producing farms in China. Except the provinces( regions) of Guangxi,Guangdong and Yunnan,the silkworm eggs producing farms in other provinces were generally at deficit condition. In the light of ownership,although silkworm eggs producing farms of different ownership systems were in the red,those of the private sector had the minimum deficit. Based on these findings,it is proposed to deepen system reformation of silkworm eggs producing farms,loosen control to price and circulation of silkworm eggs,implement large-scaled production and operation,speed up scientific and technological innovation,expand diversified development channels,and reinforce government support so as to increase production and operation benefits of silkworm eggs producing farms in China.

Effects of Lactobacillus Microecologics on Production Performance, Immune Function and Intestinal Microflora of Egg Chicks

[Objective]The paper was to study the effects of lactobacillus microecologics on production performance,immune function and intestinal microflora of egg chicks.[Method]Totally 18001-day-old chicks of Hyline brown were randomly divided into three groups,four repeats each group and 150 chicks each repeat.The chicks in control group were supplied with basic diet,and those in experimental groups I and II were supplied with the basic diet added with 100 and 150 g/t microecologics,respectively.[Result]Compared with the control group,the daily gain of egg chicks in experimental group II after 7 weeks was increased by 3.67%(P<0.05),and the feed conversion ratio was significantly reduced by 0.05(P<0.05);the thymus indexes in experimental groups I and II were significantly improved by 4.95%and 5.94%(P<0.05),and the spleen indexes were significantly improved by 3.32% and 4.36% compared with the control group(P<0.05).The index of bursa of fabricius in experimental group II was extremely improved by 9.66%compared with the control group(P<0.01).Meantime,experimental group II extremely improved the number of living lactobacillus in caecum of egg chicks(P<0.01),and extremely reduced the number of Escherichia coli in caecum(P<0.01).[Conclusion]Lactobacillus microecologics are beneficial to the improvement of production performance,immune function and intestinal flora of egg chicks.The optimal addition amount in the feed of chicks is 150 g/t.

Effects of Green Forage on Production Performance and Egg Quality of Suyou No.1 Laying Duck

[ Objective ] The paper was to study the effects of green forage on production performance and egg quality of laying ducks. [ Method] According to one- factor randomized complete experimental design, 200 healthy Suyou No. 1 laying ducks aged 200 days were randomly divided into five groups, four repeats each group, and each repeat contained 10 laying ducks. Parts of formulated feed in groups I - IV were replaced with different types and quantities of green forage, and group V was set as control. The trim lasted for 42 d. [ Result] Replacing parts of formulated feed with green forage could improve the production performance of laying ducks （P 〉 0.05 ）, and the economic benefits also increased. For egg quality, Haugh unit was improved （ P 〉 0.05 ） ; yolk color increased significantly ; compared to control group, yolk color was significantly increased in groups with 100 g chicory and 70 g clover （P 〈0.05 ）, and was extremely increased in the group with 100 g clover （P 〈0.01 ）. [ Conclusion] The group with 100 g chicory had the best effect on production performance of laying ducks, and the group with 100 g clover had the best coloring effect on yolk.

不同生产方式对鸽产蛋间隔的影响

为探究不同生产方式(捡蛋、孵化、孵化+哺乳)对产蛋间隔的影响,试验以正常繁殖、公母配对、同一天产蛋的白卡奴鸽110对,随机分成3组:Ⅰ组30对,不承担孵化哺育任务,只捡蛋,共统计三次产蛋间隔;Ⅱ组40对,只承担孵化任务,统计两次产蛋间隔,第二个孵化期20对孵化2个模型蛋,20对孵化3个模型蛋。Ⅲ组40对既承担孵化任务还要哺育乳鸽至28日龄,统计两次产蛋间隔,第二个孵化哺育期,20对孵化3个模型蛋,20对孵化2个模型蛋,哺育3只雏鸽。同时统计亲鸽体重变化、Ⅲ组后代28日龄体重等指标。结果显示:采用不同生产方式鸽产蛋间隔差异极显著(P<0.01),Ⅰ组平均产蛋间隔11.29 d,Ⅱ组产蛋间隔26.78 d,Ⅲ组产蛋间隔40.52 d,相同生产方式下产蛋间隔变异系数都在10%以内;试验结束时,Ⅰ组公鸽体重增加29 g,Ⅱ组公鸽体重增加40 g,Ⅲ组公鸽体重减少14 g,Ⅲ组和Ⅰ组、Ⅱ组间差异极显著(P<0.01);Ⅱ组、Ⅲ组第二个产蛋期中孵化2个模型蛋和孵化3个模型蛋产蛋间隔没有显著差异(P>0.05);Ⅱ组亲鸽第一个产蛋期和第二个产蛋期产蛋间隔差异不显著(P>0.05),Ⅲ组第一个产蛋期和第二个产蛋期产蛋间隔极显著差异(P<0.01),乳鸽28日龄体重差异显著(P<0.05)。研究提示,白卡奴鸽产蛋间隔整齐度高,采用不同生产方式鸽产蛋间隔差异较大,公鸽在哺育后代过程中消耗更大,孵化模型蛋数对亲鸽产蛋间隔和后代哺育效果没有影响。

不同品种(系)鸡66周龄蛋品质比较研究

为研究不同品种(系)产蛋后期鸡蛋品质差异,试验以海兰褐、京红1号、文昌鸡和苏禽青壳蛋鸡共4个品种为素材,测定并比较66周龄鸡蛋常规品质、营养品质和矿物元素含量。结果显示:京红1号蛋鸡蛋重、蛋黄重以及蛋壳强度相对较大,均显著高于文昌鸡(P<0.05);文昌鸡和苏禽青壳蛋鸡蛋黄色泽显著高于海兰褐蛋鸡和京红1号蛋鸡(P<0.05);文昌鸡蛋壳厚度和蛋壳强度均最低,显著低于海兰褐蛋鸡和京红1号蛋鸡(P<0.05);苏禽青壳蛋鸡蛋黄比率最大,显著高于海兰褐(P<0.05)。海兰褐蛋鸡鸡蛋脂肪含量、胆固醇含量均最低,显著低于其他品种(P<0.05);苏禽青壳蛋鸡鸡蛋水分含量最低,显著低于海兰褐蛋鸡(P<0.05);文昌鸡和苏禽青壳蛋鸡鸡蛋卵磷脂含量显著高于京红1号蛋鸡和海兰褐蛋鸡(P<0.05)。苏禽青壳蛋鸡鸡蛋中锌含量显著高于京红1号蛋鸡(P<0.05),文昌鸡鸡蛋中钙含量显著高于海兰褐蛋鸡(P<0.05),苏禽青壳蛋鸡和文昌鸡鸡蛋中磷含量显著高于海兰褐蛋鸡和京红1号蛋鸡(P<0.05)。研究表明,66周龄时,京红1号蛋鸡蛋壳质量较优,苏禽青壳蛋鸡的蛋黄品质特征明显,而文昌鸡鸡蛋的矿物质元素含量和卵磷脂等营养品质特征明显。

基于机器学习的地方鸡产蛋曲线拟合探索

[目的]本研究探索以机器学习方法对2个地方鸡品系周产蛋率建模,并将其与非线性回归方法比较,旨在提高养鸡生产中产蛋曲线的拟合精度。[方法]产蛋数据采集自地方鸡杂交组合试验群,自22周龄开始统计产蛋数,至50周龄截止。试验鸡于全封闭鸡舍单笼饲养,产蛋期人工补光16 h。试验鸡分为两组,每组150只鸡。第Ⅰ组是黄羽肉鸡合成系,第Ⅱ组是兼用型地方鸡种。以IBM SPSS Statistics 21.0软件中的非线性回归方法拟合产蛋曲线,所用模型包括Logistic模型、McNally模型、杨宁模型以及Grossman模型。以MATLAB R2014a构建机器学习模型,神经网络选用多层感知器,用300次迭代的拟牛顿法训练数据。以贝叶斯最小二乘支持向量机构建产蛋模型,针对正则项系数和核函数参数进行优化。[结果]依据MSE、R 2、AIC评判标准,Grossman模型在4种非线性回归模型中拟合度最好,McNally模型表现最差。McNally模型预测的高峰产蛋率偏离真实值;Logistic模型、杨宁模型以及Grossman模型高峰产蛋率统计值与真实值基本相符。两组试验鸡的模型参数不同,Ⅱ组持续产蛋能力优于Ⅰ组。基于MSE、R 2以及图形评估结果,神经网络优于传统的非线性方程拟合,而支持向量机略好于神经网络。优化后神经网络参数为2个隐藏层,每个隐藏层包含5个神经元。第Ⅰ组支持向量机的正则项系数为30.97,核参数为0.0701;第Ⅱ组支持向量机的正则项系数为566.53,核参数为0.1754.[结论]机器学习方法可用于产蛋模型构建,相比于传统单变量回归方法,机器学习方法可加入更多变量,提供更准确的预测。

广西麻鸡卵巢组织中差异lncRNA筛选及ceRNA网络构建

【目的】筛选广西麻鸡卵巢中差异表达的长链非编码RNA(long non-coding RNA,lncRNA)、信使RNA(messenger RNA,mRNA)以及微RNA(microRNAs,miRNA),并进一步筛选出与鸡产蛋性状相关的lncRNA,为后期研究lncRNA对鸡产蛋性状的调控提供理论支持。【方法】根据广西麻鸡从开产到41周龄的产蛋情况筛选出高产和低产的广西麻鸡各3只,并以其卵巢组织为材料,进行转录组测序,使用edgeR和DEseq2软件从测序得到的数据中筛选出差异表达的lncRNA、mRNA以及miRNA,利用miRanda软件和lncRNA的顺式作用分别预测miRNA和lncRNA的靶基因,对差异lncRNA的靶基因进行GO功能和KEGG通路富集分析后,利用Cytoscape(v 3.8.2)软件构建竞争性内源RNA(ceRNA)网络图。利用实时荧光定量PCR验证转录组测序结果。【结果】本研究共获得广西麻鸡卵巢组织中438个差异表达的lncRNAs、18个差异表达的miRNAs以及301个差异表达的mRNAs。对上述差异表达的lncRNA的靶基因进行GO功能和KEGG通路富集分析后发现,其显著富集于激素分泌调节、中胚层形成、中胚层发育以及中胚层形态发生等与产蛋有关的生物过程,以及MARK、甘露糖O-聚糖的生物合成、卵母细胞减数分裂、孕激素介导的卵母细胞成熟以及促性腺激素释放激素等信号通路。通过GO功能和KEGG通路富集分析获得6个与产蛋性状相关的lncRNAs,分别是TCONS_00091814、TCONS_00051866、XR_006939520.1、XR_005839807.1、TCONS_00088588、TCONS_00037324。根据测序结果成功构建出包含9个miRNAs、60个lncRNAs和3个mRNAs的ceRNA网络图,且网络中所有的基因均在低、高产组中差异表达。所选差异表达基因实时荧光定量PCR结果与转录组测序的基因表达水平一致,说明转录组测序结果可靠。【结论】通过RNA测序技术从广西麻鸡卵巢中筛选到了一系列差异表达的lncRNA,并筛选出了6个可能与产蛋性状相关联的lncRNAs,为进一步提高鸡的产蛋性能提供了理论支持。