Translucent eggs of laying hens: a review.

Eggshell quality is a significant characteristic that influences consumer preferences. Eggshell translucency is a common defect in the appearance of eggshells, which are characterized by gray spots that are visible to the naked eye under natural light. The presence of various defects resulting from eggshell translucency has caused a decrease in consumer willingness to purchase eggs, leading to considerable economic losses in the egg industry. Although the impact of eggshell translucency on food safety, egg quality, and hatchability has been extensively investigated, the classification and causes of eggshell translucency remain unclear and lack a systematic summary. In recent studies, new interpretations of evaluation methods and causes of eggshell translucency have been proposed, along with numerous innovative solutions. Therefore, this paper aims to provide a comprehensive review of the evaluation methods, classification, causes, effects, and influencing factors of eggshell translucency and to summarize the treatments for translucent eggs. We believe that this review will serve as a valuable reference for researchers involved in the study of translucent eggs.

ELOVL5 and VLDLR synergistically affect n-3 PUFA deposition in eggs of different chicken breeds.

There was no significant difference in the composition and content of fatty acids in eggs among different breeds initially, but following the supplementation of flaxseed oil, Dwarf Layer were observed to deposit more n-3 polyunsaturated fatty acid (PUFA) in eggs. Currently, there is limited research on the mechanisms underlying the differences in egg composition among different breeds. Therefore, in this study, 150 twenty-four-wk-old hens of each breed, including the Dwarf Layer and White Leghorn, were fed either a basal diet or a diet supplemented with 2.5% flaxseed oil. After 28 d, eggs and liver samples were collected to determine fatty acid composition, and serum, liver, intestine, and follicles were collected for subsequent biochemical, intestinal morphology, and lipid metabolism-related genes expression analysis. Duodenal contents were collected for microbial analysis. The results showed that there was no significant difference in the content and deposition efficiency of total n-3 PUFA in the liver of the 2 breeds, but the content and deposition efficiency of total n-3 PUFA in the egg of Dwarf Layer were significantly higher than those of White Leghorn after feeding flaxseed oil. Flaxseed oil and breeds did not have significant effects on cholesterol (CHO), free fatty acids (NEFA), low-density lipoprotein (LDL), and estrogen (E2) levels. After feeding with flaxseed oil, the villus height and the villus-to-crypt ratio in both breeds were increased and duodenal crypt depth was decreased. The villus-to-crypt ratio (4.78 vs. 3.60) in the duodenum of Dwarf Layer was significantly higher than that in White Leghorn after feeding with flaxseed oil. Flaxseed oil can impact the gut microbiota in the duodenum and reduce the microbiota associated with fatty acid breakdown, such as Romboutsia, Subdolibranulum, Lachnochlostridium, and Clostridium. This may mean that less ALA can be decomposed and more ALA can be absorbed into the body. Additionally, after feeding flaxseed oil, the mRNA levels of elongation enzymes 5 (ELOVL5), fatty acid desaturase 1 (FADS1), and fatty acid transporter 1 (FATP1) in the liver of Dwarf Layer were significantly higher than those in White Leghorn, while the mRNA levels of peroxisome proliferator-activated receptor alpha (PPAR), carnitine palmitoyl transferase 1 (CPT1), Acyl CoA oxidase 1 (ACOX1), and Acyl-CoA synthetase (ACSL) were significantly lower than those in White Leghorn. The mRNA level of FABP1 in the duodenum of Dwarf Layer was significantly higher than that of White Leghorn, while the mRNA level of FATP1 was significantly lower than that of White Leghorn. The protein levels of ELOVL5 in the liver of Dwarf Layer and very low-density lipoprotein receptor (VLDLR) in the follicles were significantly higher than those of White Leghorn. In summary, after feeding flaxseed oil, the higher ratio of villus height to crypt depth in Dwarf Layer allows more α-linolenic acid (ALA) to be absorbed into the body. The higher mRNA expression of FADS1, ELOVL5, and FATP1, as well as the higher protein expression of ELOVL5 in the liver of Dwarf Layer enhance the conversion of ALA into DHA. The higher protein expression of VLDLR in follicles of Dwarf Layer allows more n-3 PUFA to deposit in the follicles. These combined factors contribute to the Dwarf Layer's ability to deposit higher levels of n-3 PUFA in eggs, as well as improving the deposition efficiency of n-3 PUFA.

The Effects of Different Doses of Canthaxanthin in the Diet of Laying Hens on Egg Quality, Physical Characteristics, Metabolic Mechanism, and Offspring Health.

Currently, there is a dearth of in-depth analysis and research on the impact of canthaxanthin on the production performance, egg quality, physical characteristics, and offspring health of laying hens. Furthermore, the metabolic mechanism of cantharidin in the body remains unclear. Therefore, to solve the above issues in detail, our study was conducted with a control group (C group), a low-dose canthaxanthin group (L group), and a high-dose canthaxanthin group (H group), each fed for a period of 40 days. Production performance was monitored during the experiment, in which L and H groups showed a significant increase in ADFI. Eggs were collected for quality analysis, revealing no significant differences in qualities except for yolk color (YC). The YC of the C group almost did not change, ranging from 6.08 to 6.20; however, the trend in YC change in other groups showed an initial intense increase, followed by a decrease, and eventually reached dynamic equilibrium. By detecting the content of canthaxanthin in the yolk, the YC change trend was found to be correlated with canthaxanthin levels in the yolk. The content of unsaturated fatty acid increased slightly in L and H groups. Following the incubation period, the physical characteristics and blood biochemical indices of chicks were evaluated. It was observed that the shank color of chicks in the L and H groups was significantly higher than that in the C group at birth. However, by the 35th day, there were no significant differences in shank color among the three groups. Further investigation into the metabolic mechanism involving canthaxanthin revealed that the substance underwent incomplete metabolism upon entering the body, resulting in its accumulation as well as metabolic by-product accumulation in the yolk. In summary, this study highlighted the importance of understanding canthaxanthin's role in production performance, egg quality, and offspring health, providing valuable insights for breeders to optimize feeding strategies.

Mechanisms of hepatic steatosis in chickens: integrated analysis of the host genome, molecular phenomics and gut microbiome.

Hepatic steatosis is the initial manifestation of abnormal liver functions and often leads to liver diseases such as nonalcoholic fatty liver disease in humans and fatty liver syndrome in animals. In this study, we conducted a comprehensive analysis of a large chicken population consisting of 705 adult hens by combining host genome resequencing; liver transcriptome, proteome, and metabolome analysis; and microbial 16S ribosomal RNA gene sequencing of each gut segment. The results showed the heritability (h2 = 0.25) and duodenal microbiability (m2 = 0.26) of hepatic steatosis were relatively high, indicating a large effect of host genetics and duodenal microbiota on chicken hepatic steatosis. Individuals with hepatic steatosis had low microbiota diversity and a decreased genetic potential to process triglyceride output from hepatocytes, fatty acid ß-oxidation activity, and resistance to fatty acid peroxidation. Furthermore, we revealed a molecular network linking host genomic variants (GGA6: 5.59-5.69 Mb), hepatic gene/protein expression (PEMT, phosphatidyl-ethanolamine N-methyltransferase), metabolite abundances (folate, S-adenosylmethionine, homocysteine, phosphatidyl-ethanolamine, and phosphatidylcholine), and duodenal microbes (genus Lactobacillus) to hepatic steatosis, which could provide new insights into the regulatory mechanism of fatty liver development.

Single-nucleus transcriptional and chromatin accessible profiles reveal critical cell types and molecular architecture underlying chicken sex determination.

INTRODUCTION: Understanding the sex determination mechanisms in birds has great significance for the biological sciences and production in the poultry industry. Sex determination in chickens is a complex process that involves fate decisions of supporting cells such as granulosa or Sertoli cells. However, a systematic understanding of the genetic regulation and cell commitment process underlying sex determination in chickens is still lacking. OBJECTIVES: We aimed to dissect the molecular characteristics associated with sex determination in the gonads of chicken embryos. METHODS: Single-nucleus RNA-seq (snRNA-seq) and ATAC-seq (snATAC-seq) analysis were conducted on the gonads of female and male chickens at embryonic day 3.5 (E3.5), E4.5, and E5.5. RESULTS: Here, we provided a time-course transcriptional and chromatin accessible profiling of gonads during chicken sex determination at single-cell resolution. We uncovered differences in cell composition and developmental trajectories between female and male gonads and found that the divergence of transcription and accessibility in gonadal cells first emerged at E5.5. Furthermore, we revealed key cell-type-specific transcription factors (TFs) and regulatory networks that drive lineage commitment. Sex determination signaling pathways, dominated by BMP signaling, are preferentially activated in males during gonadal development. Further pseudotime analysis of the supporting cells indicated that granulosa cells were regulated mainly by the TEAD gene family and that Sertoli cells were driven by the DMRT1 regulons. Cross-species analysis suggested high conservation of both cell types and cell-lineage-specific TFs across the six vertebrates. CONCLUSIONS: Overall, our study will contribute to accelerating the development of sex manipulation technology in the poultry industry and the application of chickens as a unique model for studying cell fate decisions.

Exercise Therapy Research in Ankylosing Spondylitis-Induced Back Pain: A Bibliometric Study (2004-2023).

BACKGROUND Ankylosing spondylitis (AS), a chronic inflammatory disease predominantly causing back pain, affects up to 0.5% of the global population, more commonly in males. Frequently undiagnosed in early stages, AS is often associated with comorbid depression and anxiety, imposing significant healthcare burdens. Despite available pharmaceutical treatments, exercise therapy (ET) has emerged as an effective, side-effect-free alternative, particularly for managing AS-induced back pain. This study aims to explore the research trends in ET for treating AS back pain from 2004-2023. MATERIAL AND METHODS A comprehensive analysis of 437 articles, sourced from the Science Citation Index-Expanded within the Web of Science Core Collection, was conducted using CiteSpace 6.2.R5. This study spanned from 2004 to October 15, 2023, examining publications, authors, institutions, and keywords to assess keyword co-occurrences, temporal progressions, and citation bursts. RESULTS Research interest in ET for AS began escalating around 2008 and has since shown steady growth. The USA emerged as a significant contributor, with Van der Heijde, Desiree, and RUDWALEIT M being notable authors. Key institutions include Assistance Publique Hopitaux Paris and UDICE-French Research Universities, with ANN RHEUM DIS being the most influential journal. The field's evolution is marked by interdisciplinary integration and branching into various sub-disciplines. CONCLUSIONS Exercise therapy for AS-induced back pain is a growing research area, necessitating further exploration in clinical management and rehabilitation strategies. The relationship between ET and osteoimmunological mechanisms remains a focal point for future research, with a trend towards personalized and interdisciplinary treatment approaches.

Effects of Breeds on the Content of Functional Nutrition in Eggs.

The purpose of this study was to compare the differences in the content of functional nutrients in eggs, performance parameters, and egg quality parameters of different chicken breeds. In Trial 1, 150 41-week-old hens of each breed, including the Dwarf Layer, White Leghorn, Silky fowl, Beijing-you chicken, and Shouguang chicken, were randomly assigned to the control (CON) and 2.5% flaxseed oil (FSO) groups to compare the difference in n-3 polyunsaturated fatty acid (PUFA) content in eggs. The contents of α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total n-3 PUFA in eggs were increased (p < 0.05) in the FSO groups. The ALA (4.28%), DHA (2.03%), and total n-3 PUFA (6.46%) contents in eggs of Dwarf Layer were the highest among the five breeds (p < 0.05). To further verify if other functional nutrients also have such differences, 600 24-week-old White Leghorn and Dwarf Layer were allocated to four groups: CON, FSO, 0.02% selenium-enriched yeast (SEY), and 0.20% marigold flower extract (MFE), in Trial 2. The content of functional nutrients in eggs was significantly increased (p < 0.05) after feeding these additions. After feeding FSO, the eggs of the Dwarf Layer had a higher n-3 PUFA content than the White Leghorn (p < 0.05). However, no significant differences were found in selenium and lutein content in different breeds. Performance and egg quality were not negatively impacted by FSO, SEY, or MFE.

Research Note: Three-dimensional microstructural basis for chicken eggshell translucency.

Eggshell translucency, an externally observable feature, can influence consumer purchase intentions. The eggshell quality often deteriorates in aging laying hens, leading to increased eggshell translucency. Eggs exchange water vapor through the pores. It is commonly believed that the moisture remaining in the mastoid space contributes to translucent egg formation. However, the precise mechanisms underlying eggshell translucency require further structural investigations. This study aimed to explore the 3-dimensional microstructure of eggshells using micro-computed tomography (micro-CT) to provide insights into the microstructural basis of eggshell translucency. The results revealed that the ratio of pore volume to mastoid space volume was significantly higher in the high-translucency (TH) group than that in the low-translucency (TL) group (P < 0.01); however, the ratio of mastoid space to eggshell volume showed no significant difference. Additionally, measurements of the individual pore morphological features showed that the roundness of the pores in the TH group was significantly higher than that in the TL group, whereas the flatness of the pores in the TH group was significantly lower (P = 0.01). Eggshell porosity directly reflects the water vapor exchange capacity of eggshells, with the TL group exhibiting significantly higher eggshell porosity compared to the TH group (P = 0.02). In conclusion, based on observations of the 3-dimensional microstructure of eggshells, this study elucidated how the volume and morphological characteristics of pores influence the water vapor exchange capacity of eggshells, resulting in eggshell translucency.

Research on Chinese consumers' shell egg consumption preferences and the egg quality of functional eggs.

The purpose of this study is to investigate the characteristics of egg consumption in China and the production of functional eggs, and finally enrich the types of shell egg products. Trial 1 explored the influence of egg quality on Chinese consumers' willingness to purchase eggs through a questionnaire, which investigated 1,317 consumers' preferences for egg appearance, factors influencing egg purchase, and purchase of functional eggs. The results showed that about 65% of respondents ate more than 4 eggs per wk, pink eggs were the most popular in China, about 65% of consumers preferred eggs with an egg weight of 48 to 58 grams. For functional eggs, 75.32% of consumers have never heard of them. Preferences for eggshell color and yolk color varied by geographic region, with darker colors preferred in Northeast China. Based on the survey results of functional eggs consumption in Trial 1, the dwarf layers of China Agricultural University were used in Trial 2 to produce functional eggs. The eggs are small and pink in color, which is in line with the preferences of Chinese consumers. Three hundred dwarf layers were divided into 4 groups, using the linseed oil added, marigold extract added, and yeast selenium added diets to produce normal, n-3 fatty acid-enriched, lutein-enriched and selenium-enriched eggs by feeding for 28 d, determined the eggs' nutrient content and egg quality. The results showed that the n-3 fatty acid, lutein and selenium contents of the eggs of dwarf layers were significantly increased by changing the diets and did not affect the egg weight, eggshell strength, Haugh units or the proportion of egg parts. The results of this study are helpful to understand the trend of egg consumption preferences in China, and on this basis to produce functional eggs that meet the consumers' expectations.

A Method to Reduce the Occurrence of Egg Translucency and Its Effect on Bacterial Invasion.

Translucent egg consumption is low due to consumer acceptance and quality concerns, which is a problem that egg producers need to address. This study was performed to evaluate the reasons for the high occurrence of egg translucency in summer, as well as whether the addition of mono-dicalcium phosphate (MDCP) to the diet can relieve eggshell translucency and whether eggshell translucency is associated with the risk of bacterial invasion. A total of 72 laying hens that were 36 weeks old were randomly divided into control (CON) and MDCP groups and fed in the same environment. Results showed that the number of translucent eggs increases in July and August as the temperature and humidity increase. Compared with the CON group, in July, August, and October, the translucent egg grade (TEG) of the MDCP group was lower than that of the CON group (p < 0.05). TEG was correlated with mastoid space height (MSH), width (MSW), and area (MSA) (correlation coefficients 0.63, 0.59, and 0.68, respectively, p ≤ 0.05). There was no significant difference in the invasion rate of E. coli between translucent and non-translucent egg groups (47.2% vs. 39.33%), and translucent area and non-translucent area (13.49% vs. 15.08%). In conclusion, our results show that dietary MDCP may alleviate eggshell translucency and that eggshell translucency would not increase the probability of E. coli cross-shell penetration rate.

Comparative N-Glycoproteomic Investigation of Eggshell Cuticle and Mineralized Layer Proteins.

The eggshell cuticle layer (ECL) and eggshell mineralized layer (EML) contain amounts of glycoproteins and proteoglycans. However, there were few comprehensive reports about the effect of post-translational modifications on protein structure and function which requires investigation. Therefore, we used comparative N-glycoproteomics to study glycoproteins in the ECL and EML. We identified a total of 272 glycoproteins in this experiment and found that glycoproteins located in EML were more than that in ECL. Moreover, they showed distinct functional difference between both layers. As N-glycosylation of ovocleidin-17 and ovocleidin-116 in the EML affected eggshell mineralization, some glycoproteins located in ECL, like ovotransferrin and ovostatin-like, possessed antibacterial activity. The several regulated glycoproteins in the EML may pertain to the regulation of mineralization, while glycosylated proteins in the ECL may contribute to molecular adhesion and defense against microbial invasion. This study provides new insights into the eggshell matrix protein contents of the ECL and EML.

Overview of Avian Sex Reversal.

Sex determination and differentiation are processes by which a bipotential gonad adopts either a testicular or ovarian cell fate, and secondary sexual characteristics adopt either male or female developmental patterns. In birds, although genetic factors control the sex determination program, sex differentiation is sensitive to hormones, which can induce sex reversal when disturbed. Although these sex-reversed birds can form phenotypes opposite to their genotypes, none can experience complete sex reversal or produce offspring under natural conditions. Promising evidence indicates that the incomplete sex reversal is associated with cell autonomous sex identity (CASI) of avian cells, which is controlled by genetic factors. However, studies cannot clearly describe the regulatory mechanism of avian CASI and sex development at present, and these factors require further exploration. In spite of this, the abundant findings of avian sex research have provided theoretical bases for the progress of gender control technologies, which are being improved through interdisciplinary co-operation and will ultimately be employed in poultry production. In this review, we provide an overview of avian sex determination and differentiation and comprehensively summarize the research progress on sex reversal in birds, especially chickens. Importantly, we describe key issues faced by applying gender control systems in poultry production and chronologically summarize the development of avian sex control methods. In conclusion, this review provides unique perspectives for avian sex studies and helps scientists develop more advanced systems for sex regulation in birds.

The cecal ecosystem is a great contributor to intramuscular fat deposition in broilers.

Intramuscular fat (IMF) content is a meat quality trait of major economic importance in animal production. Emerging evidence has demonstrated that meat quality can be improved by regulating the gut microbiota. However, the organization and ecological properties of the gut microbiota and its relationship with the IMF content remain unclear in chickens. Here, we investigated the microbial communities of 206 cecal samples from broilers with excellent meat quality. We noted that the cecal microbial ecosystem obtained from hosts reared under the same management and dietary conditions showed clear compositional stratification. Two enterotypes, in which the ecological properties, including diversity and interaction strengths, were significantly different, described the microbial composition pattern. Compared with enterotype 2, enterotype 1, distinguished by the Clostridia_vadinBB60_group, had a higher fat deposition, although no discrepancy was found in growth performance and meat yield. A moderate correlation was observed in the IMF content between 2 muscle tissues, despite the IMF content of thigh muscle was 42.76% greater than that of breast muscle. Additionally, the lower abundance of cecal vadinBE97 was related to higher IMF levels in both muscle tissues. Although vadinBE97 accounted for 0.40% of the total abundance of genera in the cecum, it exhibited significant and positive correlations with other genera (accounting for 25.3% of the tested genera). Our results highlight important insights into the cecal microbial ecosystem and its association with meat quality. Microbial interactions should be carefully considered when developing approaches to improve the IMF content by regulating the gut microbiota in broilers.

ATAC-seq and RNA-seq analysis unravel the mechanism of sex differentiation and infertility in sex reversal chicken.

BACKGROUND: Sex determination and differentiation are complex and delicate processes. In female chickens, the process of sex differentiation is sensitive and prone to be affected by the administration of aromatase inhibitors, which result in chicken sex reversal and infertility. However, the molecular mechanisms underlying sex differentiation and infertility in chicken sex reversal remain unclear. Therefore, we established a sex-reversed chicken flock by injecting an aromatase inhibitor, fadrozole, and constructed relatively high-resolution profiles of the gene expression and chromatin accessibility of embryonic gonads. RESULTS: We revealed that fadrozole affected the transcriptional activities of several genes, such as DMRT1, SOX9, FOXL2, and CYP19A1, related to sex determination and differentiation, and the expression of a set of gonadal development-related genes, such as FGFR3 and TOX3, by regulating nearby open chromatin regions in sex-reversed chicken embryos. After sexual maturity, the sex-reversed chickens were confirmed to be infertile, and the possible causes of this infertility were further investigated. We found that the structure of the gonads and sperm were greatly deformed, and we identified several promising genes related to spermatogenesis and infertility, such as SPEF2, DNAI1, and TACR3, through RNA-seq. CONCLUSIONS: This study provides clear insights into the exploration of potential molecular basis underlying sex differentiation and infertility in sex-reversed chickens and lays a foundation for further research into the sex development of birds.

FMO3 deficiency of duck leads to decreased lipid deposition and increased antibacterial activity.

BACKGROUND: Most duck eggs possess a fishy odor, indicating that ducks generally exhibit impaired trimethylamine (TMA) metabolism. TMA accumulation is responsible for this unpleasant odor, and TMA metabolism plays an essential role in trimethylaminuria (TMAU), also known as fish odor syndrome. In this study, we focused on the unusual TMA metabolism mechanism in ducks, and further explored the unclear reasons leading to the debilitating TMA metabolism. METHODS: To achieve this, transcriptome, proteome, and metagenome analyses were first integrated based on the constructed duck populations with high and low TMA metabolism abilities. Additionally, further experiments were conducted to validate the hypothesis regarding the limited flavin-containing monooxygenase 3 (FMO3) metabolism ability of ducks. RESULTS: The study demonstrated that liver FMO3 and cecal microbes, including Akkermansia and Mucispirillum, participated in TMA metabolism in ducks. The limited oxidation ability of FMO3 explains the weakening of TMA metabolism in ducks. Nevertheless, it decreases lipid deposition and increases antibacterial activity, contributing to its survival and reproduction during the evolutionary adaptation process. CONCLUSIONS: This study demonstrated the function of FMO3 and intestinal microbes in regulating TMA metabolism and illustrated the biological significance of FMO3 impairment in ducks.

Effectiveness and safety of electroacupuncture for ankylosing spondylitis: A protocol for a systematic reviews and meta-analysis.

INTRODUCTION: Ankylosing spondylitis (AS) is a type of autoimmune disease commonly characterized by joint pain and stiffness. This disease progression can exhibit common deformities and other activities with limited symptoms and significantly impacts people's work and life. Electroacupuncture (EA) as a traditional Chinese therapy, showing several advantages (e.g., safety, economy, and less side effects), has been extensively used to treat AS. However, its curative effect is supported by limited evidence. Accordingly, the present study aims to comprehensively assess the reliability of EA in AS treatment. METHODS AND ANALYSIS: The study will conduct a systematic review and meta-analysis. Seven databases, including the Embase, Cochrane Library, Pubmed, SinoMed, CNKI, VIP, and Wanfang Data, will be searched using predefined search terms to identify relevant studies. The primary outcomes will be the clinical efficiency, the Bath AS Disease Activity Index, and the Visual Analog Scale. Eligible studies should report at least 1 of these primary outcomes. Eligible studies designed as randomized controlled trials will be included for meta-analysis, while other related clinical studies will be reviewed. The methodological quality of the included studies will be assessed with a previously established checklist. The Cochrane Collaboration's bias risk tool will be used for assessing the bias of included randomized controlled trials. Stata 17.0 software is used for meta-analysis. RESULTS: The protocol will be used to assess the efficacy and safety of EA in AS treatment. CONCLUSION: This review reliably evidences whether EA is a reliable method for the intervention of AS.

Comparative analysis of the characteristics of digestive organs in broiler chickens with different feed efficiencies.

Improving feed efficiency is one of the main goals of chicken breeding and production. The function of the digestive system, where feed is digested and nutrients are absorbed, is closely related to feed efficiency. However, the association between feed efficiency and the development of different digestive organs in chickens remains unclear. Here, we investigated the individual feed efficiency of 207 broilers during the fast-growing period with an electronic feeder and examined the characteristics of 8 organs of their digestive system (the liver, bile, proventriculus, gizzard, duodenum, jejunum, ileum, and cecum) at market age. Both the feed conversion ratio (FCR) and residual feed intake (RFI) were significantly negatively correlated with the gizzard weight (GW) and significantly positively correlated with the relative weight of the liver (RLW). Additionally, we found an obvious negative relationship between the FCR and cecal length (CL). A two-tailed t test further confirmed these correlation analysis results. Specifically, compared to birds with the lowest feed efficiencies, the GW of broilers with the highest feed efficiencies (the lowest FCR or RFI) was 22.74% and 17.97% higher, respectively. The RLW of chickens with the highest feed efficiencies was 10.82 to 13.73% less than that of chickens with the lowest feed efficiencies. In addition, we found that increased CL (5.42-12.09%) was significantly associated with better feed efficiency. Thus, our study showed that the feed efficiency of broilers was related to the development of the gizzard, liver, and cecum. These findings provide new insight into the genetic and physiological regulation of feed efficiency in broilers.

Effects of different duck rearing systems on egg flavor and quality and microbial diversity.

The fishy odor of duck eggs has restricted their consumption and industrial development, a problem that producers need to address. We estimated the effects of cage, floor, and pond rearing systems on duck egg flavor, egg quality, and microbial diversity by evaluating yolk trimethylamine (TMA) content, egg quality, and the differences between duck cecum (cage cecum, CC; floor cecum, FC; pond cecum, PC) and the environment (cage environment, CE; floor environment, FE; pond environment, PE). The results show that the yolk TMA content of the floor-rearing and pond-rearing systems was significantly higher than that of the cage-rearing system (P < 0.001), with no difference between the floor and pond-rearing systems. No significant differences were detected in egg quality among the rearing systems. Firmicutes, Actinobacteria, and Bacteroidetes were the dominant phyla in the cecum, and in the rearing environment, Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria were the dominant phyla. The results of α and ß diversity analyses show that changes in the rearing system affected the composition and diversity of duck cecal microbes. In addition, we screened several genera that may be related to the production of TMA in duck cecum under different rearing systems using LEfSe analysis; for example, Subdoligranulum in the CC group; Romboutsia in the FC group; and Lactobacillus, Clostridium, and Streptococcus in the PC group. In conclusion, the rearing system affects the cecal microbes of ducks, which in turn affect the deposition of TMA in duck eggs but have no adverse effect on egg quality. This study provides a basis for the development of rearing strategies to reduce the fishy odor of egg yolk in the duck industry.

Temporal Expression of Myogenic Regulatory Genes in Different Chicken Breeds during Embryonic Development.

The basic units of skeletal muscle in all vertebrates are multinucleate myofibers, which are formed from the fusion of mononuclear myoblasts during the embryonic period. In order to understand the regulation of embryonic muscle development, we selected four chicken breeds, namely, Cornish (CN), White Plymouth Rock (WPR), White Leghorn (WL), and Beijing-You Chicken (BYC), for evaluation of their temporal expression patterns of known key regulatory genes (Myomaker, MYOD, and MSTN) during pectoral muscle (PM) and thigh muscle (TM) development. The highest expression level of Myomaker occurred from embryonic days E13 to E15 for all breeds, indicating that it was the crucial stage of myoblast fusion. Interestingly, the fast-growing CN showed the highest gene expression level of Myomaker during the crucial stage. The MYOD gene expression at D1 was much higher, implying that MYOD might have an important role after hatching. Histomorphology of PM and TM suggested that the myofibers was largely complete at E17, which was speculated to have occurred because of the expression increase in MSTN and the expression decrease in Myomaker. Our research contributes to lay a foundation for the study of myofiber development during the embryonic period in different chicken breeds.

Effect of Xanthan Gum, Kappa-Carrageenan, and Guar Gum on the Functional Characteristics of Egg White Liquid and Intermolecular Interaction Mechanism.

This study evaluated the effects of three polysaccharides, xanthan gum (XG), kappa-carrageenan (CA), and guar gum (GG), on the foaming and emulsifying properties of egg white liquid (EWL) and explored the intermolecular interactions and aggregation states in the initial polysaccharide−EWL complex. The results showed that the addition of XG and GG significantly improved the foaming stability of EWL on the one hand, from 66% to 78% and 69%, respectively (p < 0.05). On the other hand, the addition of XG and GG significantly improved the foam uniformity and density, and the average foam area decreased from 0.127 to 0.052 and 0.022 mm2, respectively (p < 0.05). The addition of XG and CA significantly improved the emulsification activity index (from 13.32 to 14.58 and 14.36 m2/mg, respectively, p < 0.05) and the emulsion stability index (from 50.89 to 53.62 and 52.18 min, respectively, p < 0.05), as well as the interfacial protein adsorption at the oil−water interface; it also reduced the creaming index. However, GG negatively affected these indicators. Furthermore, the electrostatic and hydrophobic interactions among molecules in EWL due to XG and the electrostatic, hydrogen bonding, and hydrophobic interactions among molecules in EWL due to CA ultimately led to the irregular aggregation of egg white proteins. Hydrophobic interactions and disulfide bonds between molecules in EWL−containing GG formed filamentous aggregations of egg white proteins. This work reveals that molecules in the polysaccharide−egg white complexes aggregate by interaction forces, which in turn have different effects on the foaming and emulsifying properties of egg white proteins.