Duck Breeds Research Articles

West Nile Virus-Induced Drop in Egg Production in Commercial Pekin Duck Breeders.

A sudden drop in egg production in commercial poultry flocks can be economically devastating, and rapid identification of the cause often requires a combined effort between the producer, veterinarian, and pathologist. In September 2019, a 35-wk-old commercial Pekin breeder duck flock in Indiana suffered a drop in egg production from 1700 to 1000 eggs daily (41.2% drop). Again, in September 2021, three Pekin breeder duck flocks aged 32, 58, and 62 wk from the same company suffered a similar drop in egg production, with a mild increase in weekly mortality of 1.0% to 2.5%. In 2019 and in 2021, birds from affected flocks were submitted to the Veterinary Diagnostic Laboratory at Michigan State University for postmortem examination. Common gross examination findings included flaccid, shrunken, or atrophied ova (all hens), pododermatitis, airsacculitis, hepatomegaly, splenomegaly, ascites, and pallor of the left ventricle. Histopathologic examination of cerebrum, cerebellum, and brainstem revealed mild lymphocytic perivascular cuffing, vasculitis, and gliosis, suggesting viral encephalitis. In the heart, there was mild multifocal cardiomyocyte necrosis, mineralization, and infiltration by lymphocytes and macrophages. PCR for Newcastle disease virus, avian influenza virus, eastern equine encephalitis virus, and West Nile virus (WNV) was performed. Brain and heart samples were positive for WNV by PCR, and WNV antigen was detected in the cerebellum by immunohistochemistry. This is the first report to associate WNV infection with a drop in egg production in waterfowl, which are known to be important reservoir species for WNV and, as such, are generally asymptomatic.

Genetic characteristics and pathogenicity of avian pox virus for a new host, Cherry Valley breeder ducks in China

ABSTRACT Cherry Valley breeder ducks in Shandong province in northern China have experienced swollen eyes, lachrymation, pox scabs on glabrous or glabrous skin, depression and dysentery since 2021. The spread of this infectious disease has seriously affected the breeder ducks in major Cherry Valley duck farms in China. The virus causing clinical signs in Cherry Valley breeder ducks was isolated by chicken embryo inoculation. We successfully isolated a strain of duck pox virus from diseased breeder ducks by virus replication. We have also successfully conducted experiments for duck pox disease using the isolated strains to infect ducklings. By comparison with 22 pox viruses already published in GenBank, the virus strain obtained in this study was most homologous (about 99.7%) to the strain isolated from infected domestic ducks in Guangxi, China in 2014 (KJ192189), and belonged to the same A5 subtype. Since there were no previous cases of avian pox virus infecting white or Cherry Valley duck breeds, this study identified a new host for avian pox virus infection and provided theoretical support and data for the development of avian pox virus research. RESEARCH HIGHLIGHTS Avian pox virus can infect a new host type – Cherry Valley breeder ducks. The avian pox virus isolated from Cherry Valley breeder ducks showed highest identity with Guangxi hemp duck-derived avian pox virus. Cherry Valley breeder ducks were infected with avian pox virus of subtype A5.

Pathogenicity and pathogenesis of a recent highly pathogenic avian influenza subtype H5N8 in mule ducklings in Egypt.

In late 2017, an H5N8 highly pathogenic avian influenza (HPAI) virus, clade 2.3.4.4, was isolated from domestic ducks in Egypt, which was associated with high morbidity and low mortality. The pathogenicity increased due to the continuous circulation of virus in ducks. Thus, this study aimed to monitor the pathogenesis and pathogenicity of new H5N8 Avian influenza (AI) virus in mule ducklings. The lethal dose 50 (LD50) for this new local HPAI H5N8 isolate was calculated. Twenty ducklings were inoculated with 0.1 mL of dilution containing 10 LD50 HPAI per duck. The clinical signs and mortalities were recorded until 30 days post-infection (DPI) to confirm viral pathogenesis. Reverse transcription polymerase chain reaction was used to detect viral shedding from collected cloacal swabs after 3rd, 5th, 7th, 10th, 14th, 21st, and 30th DPI. The main histopathological lesions associated with the presence of HPAI virus were also recorded on the 3rd and 14th DPI. The result showed that the LD50 of the new HPAI H5N8 was 104 log10. Clinical signs were observed after 2nd DPI, but it was clinically severe on 3rd, 4th, and 5th DPI in the form of respiratory and gastric disorders, forming 90% of all diseased ducklings, whereas 30% of the infected ducks only showed nervous signs. The mortality rate peaked on 4th and 5th DPI with a cumulative mortality rate of 60% for the inoculated ducks, whereas no mortality was recorded after 6th DPI. Dead ducks showed typical postmortem lesions of AI disease. Necrosis and ecchymotic or petechial hemorrhages on the heart, pancreas, liver, and spleen were observed, whereas the lung showed pneumonia. With regard to viral shedding, infected ducklings shed the virus from its gut until 7th DPI, but the number of duck shedders gradually decreased until 14th DPI after viral shedding. The histopathological findings indicated that the spleen and thymus showed necrosis and hemorrhages, whereas the brain showed multifocal malacic foci and spread meningitis. Moreover, the lung had intrabronchial hyaline degeneration and fibrinous pneumonia on 3rd DPI. Furthermore, the liver showed multifocal necrotic foci and subcapsular hemorrhage, whereas the kidney showed remarkable tubular degeneration, mostly within the collecting tubules. Furthermore, the heart showed marked myocardiolysis of the cardiac muscle fibers. On 14th DPI, all histopathological lesions of the examined organs were restored to normal. The currently circulating HPAI H5N8 virus strain has high virulence, particularly for imported mule ducks that originated from non-vaccinated breeder ducks. Therefore, vaccination and quarantine measures must be applied on imported 1-day-old mule ducklings. Moreover, the pathogenesis must be reviewed and monitored for updating circulating AI strains caused by the continuous and rapid evolution of AI viruses.

Performance of various types of West Sumatera female ducks at starter period

West Sumatra has several breeds of germplasm ducks that have good potential for breeding, including Bayang Ducks, Kamang ducks, Pitalah ducks, and Sikumbang Janti ducks. This type of duck develops in the origin area to produce eggs and meat. The diversity of the performance of these ducks is still high. This study aims to determine the performance of various West Sumatra female ducks during the starter period. One hundred twenty heads of local female ducks were used in this study. This study used an experimental method of Completely Randomized Design (CRD) with four treatments and five replicates; each cage unit consisted of 6 ducks. The treatments in this study consisted of four breeds of local female ducks from West Sumatra, namely A (Bayang duck), B (Kamang duck), C (Pitalah duck), and D (Sikumbang Janti ducks). This study showed that four breeds of local female ducks in West Sumatra had no significant effect (P>0.05) on feed consumption and body weight gain. In comparison, four breeds of local female ducks in West Sumatra significantly affected feed conversion (P<0.05). The feed conversion for Bayang, Sikumbang janti, Kamang, and Pitalah ducks was 4.60, 4.89, 4.60, 4.38, and 4.29. Based on the feed conversion, female Pitalah ducks were more efficient than others.

Characterisation and approaches to the conservation of the Nigerian local duck population: A Review

Abstract Research, development, and breeding of ducks in Nigeria are on the rise and continuous breeding of ducks needs basic information on their production environment, genetic background, and diversity. Nigerian local ducks (NLD) have been phenotypically characterised based on morphological characteristics which have provided a reasonable representation of their genetic difference. Morphological and morphometric variations exist among indigenous ducks of Nigeria and mottled plumage colour is preponderant. Low genetic diversity exists among Nigerian duck populations implying that ducks are in close genetic relationships irrespective of distinctive and varying phenotypic, biochemical, and physiological characteristics, whereas the phylogenetic tree revealed clustered relationships. Large-scale duck farming is uncommon; rather, ducks are kept as a pastime business. The scavenging feeding system is majorly practiced among small flock sizes which are highly predominant. NLDs lay between 100 and 125 eggs yearly when reared under an intensive system of management and also have a high hatching rate of above 70% even though high environmental temperature affects their reproductive performance. There are no organised duck markets in Nigeria. Duck eggs are rarely consumed or sold; rather they are majorly used for breeding purposes. Myths, poor funding, lack of standard laboratories, and lack of skilled workforce are among the factors affecting the development and conservation of indigenous ducks in Nigeria. Introducing improved breeds of duck and establishing conservation programmes will help promote greater duck production and conservation. Duck business is a profitable but seasonal business and can efficiently bridge the noticed protein gap in rural communities.

Detection of humoral and cell mediated immune responses among breeder ducks vaccinated against riemerellosis

Riemerellosis is an infectious disease that primarily affects young ducklings, although it can infrequently be manifested in a chronic localised form in older ducks. Though an inactivated vaccine has been found to be most effective in preventing the disease in ducklings, its potency in adult breeder ducks has not been assessed yet. To investigate the same, 200 Kuttanad breeder ducks maintained in the University Poultry and Duck Farm (UPDF), Mannuthy were grouped into two, of 100 birds each, T1 being the control group and T2, the treatment (vaccinated) group. The oil-adjuvanted inactivated vaccine, prepared as per the previously standardised protocol, was administered to the T2 group in two doses, one week apart. Blood samples in serum vials, 20 each from T1 and T2, were collected on days 0, 14, 28, 56 and 90 post-immunisation (PI) whereas blood samples in heparin vials, eight each from both the groups, were collected on days 0, 14, and 28 PI. Humoral immunity (HI) and cell mediated immunity (CMI) in the adult ducks were assessed by enzyme-linked immunosorbent assay (ELISA) and lymphocyte proliferation assay (LPA), respectively. The two assays revealed that the inactivated vaccine elicited a good immune response in the adult ducks, with HI noticed until 90th day PI and an increasing CMI that peaked on 28th day PI.

Efficiency of Candidate Gene Approach, Gene Expression and Economic Evaluation for Rigorous Selection of Growth Performance in Ducks

This study examined the growth characteristics, nucleotide sequence variations, and economic evaluation of two duck breeds. For this investigation, 150 each of 300 male Muscovy and Pekin ducklings aged one week were used. Body weight gain (BWG) as well as the initial and final live body weights were noted. Feed conversion ratios (FCR) and average feed intake (AFI) were also calculated. The percentages of the giblets and eviscerated carcass to live body weight were recorded after the giblets and carcass were weighed. For the purpose of extracting DNA, blood samples from ducks of each breed were taken and placed in tubes with disodium EDTA as an anticoagulant. For real-time analysis, RNA was taken from the liver and breast muscle of each breed. In terms of economic criteria, each breed's total variable costs (TVC), total costs (TC), total return (TR), net return (NR), values for the difference in net profit, and economic efficiency percent were assessed. In comparison to Pekin breed, the Muscovy breed exhibited higher ultimate BW, BWG, dressing percentages, and liver percentages. However, the Muscovy breed experienced a considerable fall in AFI and FCR. PCR-DNA sequencing of IGFBP3, FGF5, MSTN, PGAM2, ApoVLDL-II, ACACA, SCD, FASN and LPL genes revealed nucleotide sequence variations in the form of single nucleotide polymorphisms (SNPs) between Muscovy and Pekin breeds. Muscovy had a much higher gene expression profile for growth markers than Pekin breed. Muscovy breed displayed greater TR, NR, net profit difference%, and economic efficiency% compared to Pekin ducks. According to this study, Muscovy ducks showed greater growth features than Pekin ducks. Identified SNPs and the gene expression profile of growth promoters, together with economic factors, may serve as proxy indicators for selection the best breed of ducks.

Dynamic vegetation cover and decline in common eider breeding numbers in Nova Scotia, Canada

The American common eider ( Somateria mollissima dresseri) is a colonially nesting sea duck breeding on islands in the coastal regions of Atlantic Canada. Declines in colony size have been pronounced in some parts of its range, notably in Nova Scotia, and may be attributable to a variety of interconnected factors including changes in habitat conditions. Using surveys collected two decades apart, we compared nesting habitat types, availability, and use by breeding eiders on 16 islands that supported >1600 eider nests in 1992–1993, but 830 nests in 2013. While general patterns of eider nesting habitat use remained consistent (e.g., nesting preferences exhibited for Low Shrubland and Grassland habitats, and avoidance of forest or beach habitats), overall vegetation cover declined, but relative habitat changes were inconsistent across islands. Three of the islands with the greatest change in vegetation had cormorant ( Phalacrocorax spp.) colonies in 2013 that were not there in the earlier years. We suggest that changes in vegetation, in some cases facilitated by cormorant colony formation, influenced susceptibility of nesting females to predators, and these interconnected factors may be contributing to local population declines.

Genome-wide association study reveals the genetic determinism of serum biochemical indicators in ducks

BackgroundThe serum is rich in nutrients and plays an essential role in electrolyte and acid–base balance, maintaining cellular homeostasis. In addition, serum parameters have been commonly used as essential biomarkers for clinical diagnosis. However, little is known about the genetic mechanism of the serum parameters in ducks.ResultsThis study measured 18 serum parameters in 320 samples of the F2 segregating population generated by Mallard × Pekin duck. The phenotypic correlations showed a high correlation between LDH, HBDH, AST, and ALT (0.59–0.99), and higher coefficients were also observed among TP, ALB, HDL-C, and CHO (0.46–0.87). And then, we performed the GWAS to reveal the genetic basis of the 18 serum biochemical parameters in ducks. Fourteen candidate protein-coding genes were identified with enzyme traits (AST, ALP, LDH, HBDH), and 3 protein-coding genes were associated with metabolism and protein-related serum parameters (UA, TG). Moreover, the expression levels of the above candidate protein-coding genes in different stages of breast muscle and different tissues were analyzed. Furthermore, the genes located within the high-LD region (r2 > 0.4 and − log10(P) < 4) neighboring the significant locus also remained. Finally, 86 putative protein-coding genes were used for GO and KEGG enrichment analysis, the enzyme-linked receptor protein signaling pathway and ErbB signaling pathway deserve further focus.ConclusionsThe obtained results can contribute to new insights into blood metabolism and provide new genetic biomarkers for application in duck breeding programs.

PELATIHAN PRODUKSI TELUR ASIN ASAP SEBAGAI UPAYA MENINGKATKAN NILAI JUAL TELUR BEBEK

Pulo Kaum is one of the remote hamlets within the administrative scope of Kutagandok Village, Kutawaluya District, Karawang Regency, West Java. Unexpectedly, it turns out that this remote village in the middle of a hug rice field, there is potential of all fields. there are several duck breeders who produce boiled salted eggs and are produced in a traditional way with the amount of production not being too large. Since marketing is limited due to many similar industries in a single village as well as in a sub-region, almost every sub-region also has salted egg production communities. because duck eggs have a relatively cheap selling value here, it is necessary to do smoking to increase the selling value of the duck eggs and of course this process can also help the duck eggs to be durable. The purpose of this activity is to increase the selling value of duck eggs, and of course this process can also contribute to the durability of ducks eggs. The aim of this activity is to increase the sales value of duck eggs and to produce sustainable duck eggs using the smoking method. The operation will take place from August to September 2022 in Pulo Kaum Hamlet, Kutagandok Village, Kutawaluya District, Karawang Regency, West Java. The method of carrying out the activity consists of counseling, training and mentoring the residents of Pulo Kaum Hamlet, especially the housewives. The result of this program is an increase in sales value and income from the sale of smoked salted eggs, as well as the creation of smoked salted eggs with a longer shelf life. The conclusion of this program is that producing more and more duck eggs can further increase profits.

Study the effect of different levels of aqueous extract of licorice on the carcass traits of Chinese ducks

This study was carried out at a private farm for duck breeding in Al-Muthanna Governorate, from 14/12/2021 to 14/2/2022. The field experiment was included to study the effect of adding aqueous extract of licorice to drinking water on the carcass trait from Chinese ducks. A total 60 unsexed, Chinese duck chicks one-day old were used, prepared from one of AlQadisiyah Governorate hatcheries, the chicks were distributed randomly to 4 treatments, included 3 replicates, (5 chicks each replicate), the treatments were as follows: T1: control treatment (without addition). T2, T3 and T4 treatments were 5, 10 and 15 ml aqueous extract of licorice /liter of drinking water, respectively. The results showed a significant improvement in all characteristics of the studied carcass (dressing percentage with and without geblet, the ratio of main and secondary cuts), when aqueous licorice extract is added to drinking water, in addition to the high level of water licorice extract (15 ml of licorice per liter of drinking water), which gave the best results and significantly.

An Empowerment Model for Traditional Pitalah Duck Farmers in Riau Province-Indonesia

The purpose of this research is to create a model to enable traditional duck farmers to increase their income. The data in this study consisted of primary and secondary data. Primary data were collected through a questionnaire about farmer’s attitude toward livestock business and income of the business of Pitalah ducks. Secondary data were collected from libraries and official sources related to the research. Respondents were 180 Pitalah duck breeders from 7 sub-districts. The research data were analyzed using Multiple Linear Regression after a Classic Assumption Test was performed to meet the criteria of BLUE (Best Linear Unbiased Estimator). The lowest revenue received from the business is Rp.10,647,082 while the highest revenue received is Rp. 24,852,811. This range of revenue is due to differences in the revenue received from the sale of eggs (including those consumed) and the final value they have. Real revenue is received from selling Pitalah Duck’s eggs. The results of the regression analysis showed that X1 (knowledge) and X2 (attitude) did not affect the level of income. The value of X3 affected the level of income because of the efforts to increase the income of the farmers, to select the seeds produced, to provide feed and drink, to be responsive whenever there is sick cattle, and to accept new technology in order to increase the income of farmers.

Development and Evaluation of a Monoclonal Antibody-Based Blocking Enzyme-Linked Immunosorbent Assay for the Detection of Antibodies against Novel Duck Reovirus in Waterfowl Species.

The novel duck reovirus (NDRV) is an emerging pathogen that causes disease in various waterfowl species. Since the outbreak, it has caused huge economic losses to the duck industry in China. A rapid, reliable, and high-throughput method is required for epidemiological investigation and evaluation of vaccine immunogenicity. A good first step would be establishing an enzyme-linked immunosorbent assay (ELISA) that could detect NDRV antibodies in different breeds of ducks and geese from the serum and egg yolk. This study used a recombinant NDRV σB protein and a corresponding horseradish peroxidase (HRP)-labeled monoclonal antibody to develop a blocking ELISA (B-ELISA). The cutoff value of the B-ELISA was 37.01%. A total of 212 serum samples were tested by the B-ELISA, and the virus neutralization test (VNT) was the gold standard test. The sensitivity and specificity of the B-ELISA were 92.17% (106/115) and 97.94% (95/97), respectively. The agreement rates between the B-ELISA and VNT were 94.81% (kappa value, 0.896). The B-ELISA could specifically recognize anti-NDRV sera without cross-reacting with other positive serums for other major diseases in ducks and geese. The inter- and intra-assay coefficients of variation (CVs) of the B-ELISA and VNT assays were acceptable. In conclusion, the novel B-ELISA could be a rapid, simple, safe, and economically attractive alternative to the VNT in assessing duck flocks' immunity status and in epidemiological surveillance in multiple waterfowl species. IMPORTANCE NDRV disease is a new epidemic disease in waterfowl that first appeared in China. Compared with the classical DRV (CDRV), NDRV is associated with more severe symptoms, a higher mortality rate, and a broader host range. NDRV has become the prevalent genotype in China. At present, there are no commercially available diagnostic products for the NDRV disease. VNT, as the gold standard serologic test, is not only time-consuming and laborious, but also has high requirements for facilities and equipment, which is not suitable for clinical application. Conventional ELISA requires specific antispecies conjugates that are not currently available. B-ELISA not only has the advantage of higher analysis specificity, but also can be used to test specific antibodies against different waterfowl species, because no species-specific conjugates are required in such detection. Therefore, it is necessary to establish a B-ELISA for the detection of antibodies against NDRV in waterfowl species.

Monitoring changes in the genetic structure of Brown Tsaiya duck selected for feeding efficiency by microsatellite markers.

Few studies have genetically monitored chickens over time, and no research has been conducted on ducks. To ensure the sustainable management of key duck breeds, we used microsatellite markers to monitor Brown Tsaiya ducks over time genetically. The second, fourth, sixth to eighth generations of the Brown Tsaiya duck selected for feeding efficiency and control lines were included in this study to investigate the genetic variations, effective population size, population structure and the differentiation between populations over time with 11 microsatellite markers derived from Brown Tsaiya duck. The results showed there were a slight decrease in the genetic variations and an increase in within-population inbreeding coefficient (FIS) in both lines, but no consistent increase in FIS was observed in each line. The effective population size in the second and eighth generations was 27.2 for the selected line and 23.9 for the control line. The change in allele richness showed a downward trend over time, and the selected line was slightly lower than the control line in each generation. The number of private alleles (Np) in the selected line were higher than in the control line. Moderate differentiation was observed between the second and eighth generations in the selected line (FST = 0.0510) and the control line (FST = 0.0606). Overall, differentiation tended to increase with each generation, but genetic variation and structure did not change considerably after six generations in the two lines. This study provides a reference for poultry conservation and helps to implement cross-generation genetic monitoring and breeding plans in other duck breeds or lines to promote sustainable management.

Chronic heat stress part 1: Decrease in egg quality, increase in cortisol levels in egg albumen, and reduction in fertility of breeder pekin ducks.

Global warming poses detrimental effects on poultry production leading to substantial economic losses. The goal of our experiment was to test the hypothesis that heat stress (HS) would alter welfare and egg quality (EQ) of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen. Adult Pekin ducks were randomly assigned to two different rooms at 85% lay with 60 hens and 20 drakes per room. Baseline data including body weight, body condition scores (BCS), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 35°C for 10h/day and 29.5°C for the remaining 14h/day for 3 weeks while the control room was maintained at 22°C. Eggs were collected daily and analyzed weekly for quality assessment, and for albumen glucocorticoid (GCs) levels using mass spectrometry. One week before the exposure to HS, 10 hens and 5 drakes were euthanized and the same number again after 3weeks and birds necropsied. Data analyses were done by 1- or 2-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens. The circulating levels of cortisol increased significantly at week 1 and 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at weeks 2 and 3 only (p < 0.05) in the drakes. Feather quality scores (p < 0.01), feather cleanliness scores (p < 0.001) and footpad quality scores (p < 0.05) increased significantly in the HS group. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3. Hens in the HS group showed significantly decreased BW (p < 0.001) and number of follicles (p < 0.05). Shell weight decreased significantly at week 1 only (p < 0.05) compared to controls. Yolk weight decreased significantly at week 3 (p < 0.01) compared to controls. HS elicited a significant increase in albumen cortisol levels at week 1 (p < 0.05) and week 3 (p < 0.05). Thus, cortisol may provide critical information to further understand and to improve welfare.

Genome-wide association analysis reveals 6 copy number variations associated with the number of cervical vertebrae in Pekin ducks.

As a critical developmental stage in vertebrates, the vertebral column formation process is under strict control; however, we observed variations in the number of cervical vertebrae in duck populations in our previous study. Here, we further explored the variations in the number of vertebrae in two duck populations: 421 Pekin duck × mallard F2 ducks and 850 Pekin ducks. Using resequencing data of 125 Pekin ducks with different numbers of cervical vertebrae and 352 Pekin duck × mallard F2 ducks with different numbers of thoracic vertebrae, we detected whole-genome copy number variations (CNVs) and implemented a genome-wide association study (GWAS) to identify the genetic variants related to the traits. The findings verified the existence of variations in the number of cervical vertebrae in duck populations. The number of cervical vertebrae in most ducks was 15, while that in a small number of the ducks was 14 or 16. The number of cervical vertebrae had a positive influence on the neck production, and one cervical vertebra addition could increase 11g or 2cm of duck neck. Genome-wide CNV association analysis identified six CNVs associated with the number of cervical vertebrae, and the associated CNV regions covered 15 genes which included WNT10A and WNT6. These findings improve our understanding of the variations in the number of vertebrae in ducks and lay a foundation for future duck breeding.

Apparent metabolizable energy requirement of feed-restricted White Pekin duck breeder pullets

A dose–response experiment with 5 dietary apparent metabolizable energy (AME) levels (10.00, 10.62, 11.24, 11.87, and 12.49 MJ AME/kg) was conducted to estimate the AME requirement of White Pekin duck breeder pullets from 8 to 24 weeks of age. A total of 240 8-week-old female White Pekin duck breeder pullets were assigned to 5 experimental treatments, and each treatment was replicated 6 times with 8 birds per replicate. The ducks were reared in raised wire-floor pens from 8 to 24 weeks of age. All duck pullets were restricted-fed by limiting feed intake, and the feed intake increased gradually as age increased. At 24 weeks of age, the body weight, weight gain and feed/gain of each treatment were measured, and the relative weight of abdominal fat, skin and fat, and ovary of pullets and the contents of luteinizing hormone, follicle-stimulating hormone, and estradiol in plasma were also determined. As the dietary energy level increased from 10.00 to 12.49MJ AME/kg, the 24-week-old body weight and weight gain increased linearly or quadratically (P < 0.05) and the feed/gain decreased linearly or quadratically (P < 0.05). The absolute or relative weight of abdominal fat and skin and fat of the duck pullets also showed a linear increasing response to increasing dietary energy (P < 0.05). The duck pullets fed with high dietary energy levels had a higher absolute or relative weight of ovary than the birds fed with low dietary energy (P < 0.05) and this was accompanied by linearly or quadratically increasing plasma follicle-stimulating hormone and estradiol as dietary energy increased (P < 0.05). According to broken-line regression, the AME requirements for feed/gain and relative weight of skin and fat were 12.40, and 11.92 MJ/kg, respectively, and low AME requirements should be considered to control body weight and fat before laying age.

Identification of potential candidate genes and regulatory pathways related to reproductive capacity in hypothalamus and pituitarium of male ducks (Anas platyrhynchos) by differential transcriptome analysis.

The improvement of reproductive capacity of poultry is important for the poultry industry. The existing studies on reproductive capacity mainly focus on the testis tissue, but few reports on regulationary effect of brain neuroendocrime on reproductive capacity have been available. The hypothalamus-pituitarium-gonad (HPG) axis is an important pathway regulating spermatogenesis and sexual behavior. This study analyzed the gene expression in the hypothalamus and pituitary tissues of male ducks in high-semen-quality group (DH), low-semen-quality group (DL), and non-response group (DN) by RNA-sequencing. A total of 1980 differentially expressed genes (DEGs) were identified, and significantly less DEGs were found in pituitary gland than in hypothalamus. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that these DEGs were mainly enriched in nerve-related and synapse-related biological processes, mitochondrial inner membrane formation pathway, and ribosome structure pathway. Notably, the neuroactive ligand-receptor interaction pathway significantly enriched in all three comparisons (DH vs. DL, DH vs. DN, and DL vs. DN) was related to different reproductive performance such as semen quality and sexual response. Furthermore, six genes, including POMC, CPLX2, HAPLN2, EGR4, TOX3, and MSH4, were identified as candidate genes regulating reproductive capacity. Our findings provide new insights into the regulation mechanisms underlying the reproductive performance of male poultry, and offer a valuable reference for duck breeding programs aimed at promoting reproductive capacity.

Comparative Transcriptome Analysis Reveals the Key Genes Involved in Lipid Deposition in Pekin Ducks (Anas platyrhynchos domesticus)

There are differences in lipid deposition in fatty-type (FT) and lean-type (LT) ducks. Fatty ducks have a higher rate of sebum and abdominal fat, lower meat yield and hepatic lipid contents than LT ducks. However, the underlying changes in gene expression profiles regarding the lipid deposition between FT and LT ducks have not yet been clarified. To identify the differentially expressed genes in the liver, sebum, and abdominal fat between both ducks, we identified the gene expression profiles in the liver, sebum, and abdominal fat derived from FT and LT ducks by comparing the multistage transcriptomes. Our results showed that there were 622, 1536, and 224 differentially expressed genes (DEGs) in the liver, sebum, and abdominal fat between the FT and LT ducks, respectively. KEGG enrichment showed that the DEGs related to lipid metabolism were enriched in the biosynthesis of unsaturated fatty acid, glycerolipid and fatty acid metabolism in the liver; and were enriched in the fatty acid metabolism, fatty acid biosynthesis, glycerolipid metabolism, linoleic acid metabolism, and the PPAR signaling pathway in the sebum. There was no pathway related to a lipid metabolism enriched in abdominal fat. A gene functional analysis showed that the DEGs involved in adipogenesis were found to be upregulated. In contrast, those involved in lipolysis were downregulated in the liver and serum of FT ducks. The DEGs showed that ATP-binding cassette sub-family G member 8 (ABCG8), fatty acid synthase (FASN), and phospholipid transfer protein (PLTP) were highly expressed in the liver of FT ducks, and acyl-CoA synthetase long-chain family member3 (ACSL3), ACSL5, ACSL6, 1-acyl-sn-glycerol-3-phosphate acyltransferase alpha (AGPAT1), AGPAT9, ELOVL fatty acid elongase 6 (ELVOL6), fatty acid desaturase 1 (FADS1), FADS2, monoacylglycerol O-acyltransferase 1 (MOGAT1), serine/threonine kinase 17a (STK17A), and serine/threonine kinase 39 (STK39) were highly expressed in the sebum of FT ducks. A weighted correlation network analysis (WGCNA) of the DEGs showed ABCG8, FADS2, ACSL5, and ELOVL6 positively correlated with hepatic fatty acid synthesis, and AGPAT1, STK17A, STK32A, FADS1, and ACSL3 positively correlated with lipid deposition in the sebum. In summary, ABCG8 might be the key gene for the reduced hepatic lipid deposition in FT Pekin ducks, and FADS2, ACSL5, ELOVL6, AGPAT1, STK17A, STK32A, FADS1, and ACSL3 were the key genes for lipid deposition in the sebum of FT Pekin ducks. Our results provide new insights into the transcriptome regulation in lipid deposition of Pekin ducks and will be helpful for duck breeding.

An Attention Mechanism-Improved YOLOv7 Object Detection Algorithm for Hemp Duck Count Estimation

Stocking density presents a key factor affecting livestock and poultry production on a large scale as well as animal welfare. However, the current manual counting method used in the hemp duck breeding industry is inefficient, costly in labor, less accurate, and prone to double counting and omission. In this regard, this paper uses deep learning algorithms to achieve real-time monitoring of the number of dense hemp duck flocks and to promote the development of the intelligent farming industry. We constructed a new large-scale hemp duck object detection image dataset, which contains 1500 hemp duck object detection full-body frame labeling and head-only frame labeling. In addition, this paper proposes an improved attention mechanism YOLOv7 algorithm, CBAM-YOLOv7, adding three CBAM modules to the backbone network of YOLOv7 to improve the network’s ability to extract features and introducing SE-YOLOv7 and ECA-YOLOv7 for comparison experiments. The experimental results show that CBAM-YOLOv7 had higher precision, and the recall, mAP@0.5, and mAP@0.5:0.95 were slightly improved. The evaluation index value of CBAM-YOLOv7 improved more than those of SE-YOLOv7 and ECA-YOLOv7. In addition, we also conducted a comparison test between the two labeling methods and found that the head-only labeling method led to the loss of a high volume of feature information, and the full-body frame labeling method demonstrated a better detection effect. The results of the algorithm performance evaluation show that the intelligent hemp duck counting method proposed in this paper is feasible and can promote the development of smart reliable automated duck counting.