Young Ducks Research Articles

Short beak and dwarfism syndrome among Pekin ducks: First detection, full genome sequencing, and immunohistochemical signals of novel goose parvovirus in tongue tissue.

Novel goose parvovirus (NGPV) is continuously threatening the global duck industry, as it causes short beak and dwarfism syndrome among different duck breeds. In this study, we investigated the viral pathogenesis in the tongue of affected ducks, as a new approach for deeper understanding of the syndrome. Seventy-three, 14- to 60-day-old commercial Pekin ducks were clinically examined. Thirty tissue pools of intestine and tongue (15 per tissue) were submitted for molecular identification. Clinical signs in the examined ducks were suggestive of parvovirus infection. All examined ducks had short beaks. Necrotic, swollen, and congested protruding tongues were recorded in adult ducks (37/73, 51%). Tongue protrusion without any marked congestion or swelling was observed in 20-day-old ducklings (13/73, 18%), and no tongue protrusion was observed in 15-day-old ducklings (23/73, 32%). Microscopically, the protruding tongues of adult ducks showed necrosis of the superficial epithelial layer with vacuolar degeneration. Glossitis was present in the nonprotruding tongues of young ducks, which was characterized by multifocal lymphoplasmacytic aggregates and edema in the propria submucosa. Immunohistochemical examination displayed parvovirus immunolabeling, mainly in the tongue propria submucosa. Based on polymerase chain reaction, goose parvovirus was detected in 9 out of 15 tongue sample pools (60%). Next-generation sequencing confirmed the presence of a variant goose parvovirus that is globally named NGPV and closely related to Chinese NGPV isolates. Novel insights are being gained from the study of NGPV pathogenesis in the tongue based on molecular and immunohistochemical identification.

Proteomic-metabolomic combination analysis reveals novel biomarkers of meat quality that differ between young and older ducks

In order to explore the difference and its underlying mechanism between young and older ducks, 60-day-old (D60) and 300-day-old (D300) of young ducks and 900-day-old ducks (D900) of older ducks were selected and studied. HE staining indicated that breast muscle fibers in the D900 group were more inseparable than D60 and D300 groups and the greater redness were showed in D300 and D900 groups. Quantitative proteomic analyses were conducted to further identify differences between young and older ducks that 61 proteins overlapped in the comparative analysis of the D900 vs. D60 and D900 vs. D300 groups. Furthermore, metabolomics analysis from the D900 group showed marked differences from the results of the D60 and D300 groups in 31 unique metabolites. In particular, lower guanosine, hypoxanthine, guanine, and doxefazepam levels indicated the increased nutritional value of older ducks. Integrated proteomics and metabolomics analysis showed that purine metabolism was specifically enriched, indicating that NME3, RRM2B, AMPD1, and AMPD3 might mainly affect meat from older ducks. In conclusion, our results indicated that meat from 900-day-old ducks possessed a unique biochemical signature that could provide candidate biomarkers to distinguish young ducks from older ducks.

The effectiveness of the biologically active additive «Activio» using when feeding young ducks

Agricultural poultry has a number of biological features: intensive metabolism and rapid growth, rapid maturity and significant reproductive potential, high body temperature, resistance to many infectious diseases, etc. The scientific article presents the results of an experimental study of the effect of the biologically active additive Activio, which contains essential oils of cinnamon, rosemary, oregano and chili pepper extract, on the productive qualities of young ducks. To realize the set goal, two experimental groups of ducks were formed: 1st group - Peking ducks, 2nd group - Cherry Valley ducks, which were fed the drug Activio as part of a complete and balanced diet in terms of nutrients and energy, at the rate of 100 g ha 1 t of compound feed . It has been established that the introduction of the drug Activio into the diet of young ducks contributes to the increase in feed consumption, live weight gains and the survival of ducklings, which is primarily due to the fact that the essential oils of cinnamon, rosemary, oregano, chili pepper extract have positive, stimulating biological effects. improve the functioning of the digestive, immune, nervous systems and musculoskeletal system. During the breeding of poultry, an important indicator is the average daily feed consumption, which according to the data of the article in the period from 1 to 7 days was 27.15 g/head/day in the ducks of the first group, and 28.41 g/head/day in the ducks of the second group, and in the period from the 22nd to the 28th day, the value of the average daily feed consumption is 259.36 g/go/day in the first group, and 270.36 g/go/day in the ducks of the second group. The use of the drug Activio did not have a negative effect on the body of young ducklings and made it possible to realize the genetic potential of the productivity of ducks, which was more clearly expressed in the young ducklings of the Cherry Valley breed, which was obtained on the basis of Peking ducks through in depth selection using the paternal line 151 and maternal line 102 and has higher growth energy compared to Peking ducks. Key words: ducks, Peking breed, Cherry Valley, feed supplement, «Activio», gains, live weight, preservation.

Investigation into the characteristic volatile flavor of old duck

In order to explore the characteristic aroma flavor and its formation mechanism of old ducks, two ages (30 days and 60 days) of young ducks and three ages of old ducks (300 days, 900 days, and 1500 days) were selected and studied. An electronic nose was applied to evaluate the overall aroma flavor, and the result showed significant differences between the five duck samples. By gas chromatography-mass spectrometry (GC–MS), forty-eight volatile flavor compounds were detected, including seven aldehydes, six esters, five alcohols, five nitrogen compounds, twenty-one hydrocarbons, and four others. Among these compounds, twelve components, such as hexanal and dimethyl anthranilate, were considered as the characteristic flavor compounds along with duck aging. Furthermore, correlation analysis indicated that meat's unsaturated free fatty acids, especially linoleic acid (C18:2), were responsible for the duck's characteristic flavor formation. These data contribute to the flavor research and identification of old ducks.

Age is a determinant factor in the susceptibility of domestic ducks to H5 clade 2.3.2.1c and 2.3.4.4e high pathogenicity avian influenza viruses.

High pathogenicity avian influenza (HPAI) is a viral disease with devastating consequences for the poultry industry worldwide. Domestic ducks are a major source of HPAI viruses in many Eurasian countries. The infectivity and pathogenicity of HPAI viruses in ducks vary depending on host and viral factors. To assess the factors influencing the infectivity and pathogenicity of HPAI viruses in ducks, we compared the pathobiology of two HPAI viruses (H5N1 clade 2.3.2.1c and H5N6 clade 2.3.4.4e) in 5- and 25-week-old ducks. Both HPAI viruses caused mortality in a dose-dependent manner (104, 106, and 108 EID50) in young ducks. By contrast, adult ducks were infected but exhibited no mortality due to either virus. Viral excretion was higher in young ducks than in adults, regardless of the HPAI strain. These findings demonstrate the age-dependent mortality of clade 2.3.2.1c and clade 2.3.4.4e H5 HPAI viruses in ducks.

Placenta-specific 8 facilitates the infection of duck hepatitis A virus type 1 by inhibiting the TLR7 MyD88-dependent signaling pathway

The placenta-specific 8 (PLAC8) gene, also known as ONZIN or C15, codes for a cysteine-rich peptide originally identified in mouse placental tissue and subsequently identified in a variety of epithelial tissues and immune cells. PLAC8 is also expressed in birds, such as ducks, where its functional roles remain unknown. Here, we aimed to determine the mRNA and protein expression profiles and the functional role of duck PLAC8 during the infection of duck hepatitis A virus type 1 (DHAV-1). We found that the duck PLAC8 is also a cysteine-rich polypeptide composed of 114 amino acid residues, with no signal peptide. Duck PLAC8 is highly expressed in the immune organs of young cherry valley ducks, including the thymus, bursa fabricius, and spleen. However, it has negligible expression level in liver, brain, kidney, and heart. Additionally, PLAC8 expression was considerably induced after DHAV-1 infection both in vitro and in vivo, especially in the immune organs of ducklings. This tissue expression distribution and induction upon infection suggest that PLAC8 might play a critical role in innate immunity. Our data showed that PLAC8 significantly suppressed the expression of Toll-like receptor 7 (TLR7), leading to decreased expression of downstream signaling molecules including myeloid differentiation primary response gene 88 (MyD88) and nuclear factor kappa-B (NF-κB). This ultimately resulted in low levels of type I interferon and interleukin 6 (IL-6). Additionally, PLAC8 positively regulated DHAV-1 replication levels. RNAi against PLAC8 in duck embryo fibroblasts considerably inhibited DHAV-1 propagation, while PLAC8 overexpression significantly facilitated DHAV-1 replication.

CHARAKTERYSTYKA BIOMETRYCZNA CZERNICY AYTHYA FULIGULA (LINNAEUS, 1758) Z POMORZA ZACHODNIEGO (POLSKA)

The purpose of this work was to perform morphometric characteristics of the Tufted Duck Aythya fuligula obtained in Western Pomerania, according to their sex and age. The research material consisted of 197 Tufted Ducks obtained in December 2013. The biometric characteristics was performed on the basis of 20 measurements of linear and mass quantities. All internal organs measured and most of the individual body parts of the Tufted Duck were slightly larger in the case of males. Despite the differences in the body size of males and females, the studied birds showed similar variability in both length and mass. The differences between adult and young Tufted Ducks were not so well defined. Adult Tufted Ducks had significantly larger body mass, pectoral muscle mass and lung mass than juveniles. No significant differences were found in the linear values of the examined features.

EFFECTS OF STOCKING DENSITY ON GROWTH AND DEVELOPMENT OF REPLACEMENT YOUNG DUCKS IN SEPARATE GROWING BY GENDER

An excessively high stocking density can affect the growth and development of ducks. The optimal stocking density should change with the age of ducks. The article presented the results of the experiment on the effect of stocking density on the growth, development and viability of replacement young ducks of the local population during separate growing at the Bishkul Poultry Farm LLP in Northern Kazakhstan in 2022. The study was carried out in ages the day of birth to 49 days in 3 stages with a transfer on day 22 and day 35, respectively. The stocking density of ducks before transfer in the first growing period, in the control group was 20 birds/m2, in the first experimental group - 18 birds/m2; in the second experimental group - 16 birds/m2; and in the third experimental group - 14 birds/m2, respectively. After transfer in the second growing period, the stocking density of the ducks in the control group was 10 birds/m2, in the first experimental group - 9 birds/m2; in the second experimental group - 8 birds/m2; and in the third experimental group - 7 birds/m2. In the third period, the stocking density in the control group was 7 birds/m2, in the first experimental group - 6 birds/m2; in the second experimental group - 5 birds/m2; and in the third experimental group - 4 birds/m2. In the study, increasing stocking density had a negative effect on the growth and development of ducks. It is noted that with an increase in stocking density in experimental groups bodyweight, absolute gain and average daily gain decreased, thus negatively affected these indicators.

Эффективность комбинированного коли‑сальмонеллезного бактериофага в условиях утководческой фермы

Salmonella-escherichia infections are widespread and of particular relevance in poultry farming, are the most common causes of intestinal outbreaks in young ducks. Salmonellosis of waterfowl causes great damage to farms and is caused mainly by Salmonella enterica var. typhimurium – S. typhimurium. This paper presents the results of commission studies of preventive, therapeutic efficacy, as well as the harmlessness of a drug based on bacteriophages in an industrial duck-breeding enterprise. The rationale for initiating trials of the combined coli-salmonella bacteriophage was the periodically recorded cases of infectious pathology caused by enterogenic bacteria Salmonella variants S. typhimurium, S. infantis and Escherichia coli. The scientific justification is also the experience of phage application in other branches of poultry and livestock breeding. Preventive use of the drug based on bacteriophages "Eshrifag" will allow to achieve protective and microbiological efficiency without the use of antibiotics, which contributes to the development of organic poultry farming in Russia. During the tests, three groups were formed: the 1st experimental, the 2nd experimental and the control. Evaluation of the preventive effectiveness of the use and harmlessness of the drug was carried out from the first days of life. In the course of the study, five exposures and five spray treatments were carried out for 70 days. lives. The positive effect of this scheme was recorded in the absence of cases of salmonella and coli-bacterial infections in the experimental group of poultry during the entire observation period. The absence of isolation of pathogens of salmonellosis and colibacteriosis is confirmed by the results of a bacteriological study of a slaughtered bird. For therapeutic purposes, the drug was prescribed when cases of salmonellosis, colibacteriosis were detected in the experimental group, of which three outbreaks were observed during the test period. During the use of the drug, the ability of the drug to localize the disease was established. The evaluation of the effectiveness of the use by production indicators reflected the preventive and economic feasibility of the phage agent "Eshrifag", its harmlessness and high medicinal efficacy for the prevention and treatment of gastrointestinal infections of ducks caused by Salmonella spp. and Escherichia coli.

Influence of enzyme drugs in the composition of compound feed on the meat productivity of ducklings

Duck breeding is one of the most precocious branches of meat poultry farming. Industrial production methods made it possible to turn it into one of the most eff ective branches of animal husbandry. Currently, ducklings for meat are reared in specialized farms using intensive technology of year-round rearing of ducklings without reservoirs and feeding them with dry complete compound feed. The use of enzyme drugs in poultry feeding has long been a characteristic feature of modern industrial poultry farming. Due to numerous scientifi c studies and increasing demands for improving the functioning of the gastrointestinal tract and stimulating poultry productivity, most poultry farmers are well aware of the need and results of the use of enzymes. The purpose of the work was to study the eff ect of a mixture of enzyme grugs of domestic production (Amylosubtilin G3x, ProtosubtilinG3x and Cellolux-F) when included in compound feed for ducklings on the quality indicators of meat productivity. A scientific and economic experiment was carried out on purebred young ducks of the cross Agidel. The material was normally developed, healthy ducklings. For the experiments three groups of ducklings per 50 heads in each were formed according to the principle of groups of analogues with respect to sex and age. The age of the ducklings when tested was 1 day. It was found that the use of enzyme drugs according to the developed scheme contributed to an increase in meat productivity. Based on the conducted studies, it can be recommended to include mixtures of enzyme drugs Amylosubtilin G3x + Cellolux-F in the amount of 100 and 75 g/t, respectively, into the compound feed for ducklings.

Age-related changes in eggshell physical properties, ultrastructure, calcium metabolism-related serum indices, and gene expression in eggshell gland during eggshell formation in commercial laying ducks

This study evaluated the changes in eggshell mechanical properties, ultrastructure, calcium metabolism-related serum indices, and gene expression in eggshell gland during eggshell formation between laying ducks in the peak (young duck) and late phase (aged duck) of production. A total of 84 healthy young (31 wk of age) and 84 healthy aged (65 wk of age) Longyan laying ducks were each divided into 6 replicates of 14 birds, and caged individually. All the ducks were fed in one house with the same corn-soybean meal-based diet for 5 wk. The eggshell mechanical properties (shell proportion, thickness, breaking strength, and fracture toughness) and chemical components (matrix proteins, calcium, phosphorus, and magnesium) decreased in aged laying ducks (P < 0.05). Shell structural indices: total thickness, effective thickness and its proportion decreased, whereas mammillary knob width and its proportion increased (P < 0.05). The regulation values of early fusion, cuffing, caps, and total score of mammillary knobs were higher in aged laying ducks relative to the young ducks (P < 0.05). During the initial, growth and terminal stages of eggshell formation, shell thickness and breaking strength (terminal), shell weight, and its proportion (terminal) decreased in aged laying ducks (P < 0.05). Ultrastructural changes during shell formation indicated that the mammillary-knob density and effective thickness decreased (P < 0.05). Decreases occurred in serum content of phosphorus (growth), and estradiol and calcium contents (terminal) (P < 0.05). Relative expression of Ca2+ transporter and HCO3− exchanger, and matrix proteins genes decreased in aged laying ducks (P < 0.05) at all stages of eggshell formation. Collectively, the decreased incidence of early fusion and caps, increased thickness and width of mammillary knobs, and decreased effective thickness are the crucial differences leading to the compromised mechanical properties of eggshell in the late laying period. A disturbed regulation of calcium metabolism and uterine expression of ion transporters, especially for HCO3− exchange of aged laying ducks likely contribute to age-induced ultrastructural deterioration of the eggshell.

Establishment of TaqMan-based real-time PCR assay for rapid detection of duck circovirus.

Duck circovirus (DuCV) is widespread across the world and causes feather disorders in young ducks. It was identified as the causative pathogen of duck beak atrophy and dwarfism syndrome and primary sclerosing cholangitis. In this study, we aimed to establish a TaqMan-based real-time PCR assay to detect DuCV. The primers and probe were designed based on the conserved region of the DuCV Rep gene. After optimizing the reaction conditions, the minimum virus detection limit of the designed PCR technique was 39.4 copies/μL, 100 times that of conventional PCR (cPCR). No cross-reaction with six other common duck viruses was observed. The intra- and inter-assay variations were less than 1%. The detection rate of DuCV-positive clinical samples using TaqMan-based real-time PCR was higher than that using SYBR Green-based real-time PCR and cPCR. Collectively, these results showed that the established TaqMan-based real-time PCR detected DuCV with high sensitivity and specificity, and significant repeatability, making it suitable for clinical use. Hence, it may be used as a novel tool for the diagnosis and epidemiological investigation of DuCV.

The Potential Uses of Curcumin and PMSG Hormones to Increase Egg Production of Muscovy Ducks through Increasing Estradiol Concentrations and Shortening Laying Rest Period

The aim of this research was to study the effects of curcumin administration, injection of PMSG hormone, and the combination of curcumin supplementation and PMSG injection on the physiological parameters and performance of female Muscovy ducks. The objects of this research were 40 young female Muscovy ducks, aged 24 weeks, subjected to treatments: control (P1), curcumin supplementation at a dose of 24 mg/100 g feed (P2), intramuscular injection of PMSG hormone at a dose of 0.015 mL/hen (P3), and the combination of curcumin and PMSG (P4). The results showed that the treatment gave nonsignificant improvements in Muscovy duck performances, including feed consumption, egg production, and the day of laying period and molting period. Treatment gave a significant increase in serum estradiol concentration at molting period after treatment. This study concluded that the treatment provides no significant improvement in the performance of female Muscovy ducks because the genetic diversity of Indonesian ducks remains high.

DETERMINATION OF MEAT PRODUCTIVITY OF «BLAGOVARSKY» CROSS DUCKS

Feeding is the main condition for high productivity of ducks. It provides the need for metabolizable energy and nutrients according to modern standards. Ducks have an increased need for arginine, histidine, tryptophan, glycine, threonine and valine, therefore much attention is paid to the amino acid composition of feed in normalizing feeding. It is also important to consider the level of digestibility of the proposed feed. The feed nutrients digestibility depends on various factors and therefore varies considerably.Optimal ratios of carbohydrates, proteins, fats, etc. in the diet contribute to a high level of digestibility. The level of fiber and protein significantly affects the digestibility of nutrients in the feed. Increasing the amount of fiber (especially rich in lignin) reduces the digestibility of fiber and other nutrients. Essential influence on the nutrients digestibility is caused by the available protein content in the feed and its ratio with carbohydrates and fats. In this regard, the protein ratio of feed is determined. The protein ratio shows how many parts of digested nitrogen-free nutrients account for each part of digested protein.In addition, the feed preparation for feeding has a positive effect on their digestibility (moisturizing, enriching, grinding, steaming and others). The nutrients digestibility is also affected by different levels of macro-, micronutrients and vitamins in the feed. Increasing the feed nutrients digestibility is an important factor in reducing their costs, the cost of livestock products and improving the economic efficiency of the industry. Young ducks are characterized by precocity and high growth rate. At the age of 7 weeks, the live weight of hybrid young ducks is 3.2 – 3.4 kg, and during this period the initial weight increases more than 60 times at a feed consumption per 1 kg gain of 2.8 - 3.0 kg and average daily gain 64 - 68 g.The positive effect of the use of the developed vitamin-mineral premix in the compound feed composition on the meat productivity of “Blagovarsky” cross ducks has been determined. It was determined that from the third week of growing the live weight of young ducks of the experimental group was higher of analogues of the control group for 3,2 %. Analysis the main indicators of young ducks productivity showed that the bird of the experimental group exceeded analogues in the following periods of growth: 0 - 7 days, 15 - 21 days, 29 - 35 days, 36 - 42 days, 43 - 49 days.Survival rate of young ducks was at a high level in the range of 97 – 99.5 % for the entire period of growing in both groups. Starting from the 4th week of growing, the survival rate decreased slightly in the control group and amounted to 99.1, which is 0,2 % less than in the experimental group. The increased concentration of premix in the compound feed for the young ducks of the experimental group help to improve their slaughter qualities in comparison with the control group.

Pathogenicity of a Jinding duck-origin cluster 2.1 isolate of Tembusu virus in 3-week-old Pekin ducklings

Tembusu virus (TMUV) infection most commonly affects breeder and layer ducks during laying period, and can also affect young ducks below 7 weeks of age. Here, we report our investigation of a TMUV-caused fatal disease of Jingding ducklings (Anas platyrhynchos domesticus) in Northeast China. The disease resulted in mortalities of up to 40 % in 2 to 4-week-old ducks, up to 25 % in 5 to 6-week-old ducks, and less than 10 % in 7 to 8-week-old ducks. Using a TMUV-specific reverse transcription-PCR assay, all 44 ducks collected from 10 different farms were found positive for TMUV. Phylogenetic analysis of the E nucleotide sequence revealed that five of the six TMUV strains detected from three young ducks and three laying ducks were grouped within cluster 2.1. Inoculation of the liver sample of a 40-day-old sick duck in BHK-21 cells resulted in isolation of cluster 2.1 TMUV strain H. In experimental infections performed using 3-week-old Pekin ducklings (Anas platyrhynchos domesticus) (n = 30; 10 birds/group), high mortality (60 %) was caused by strain H, in sharp contrast with a very low mortality (10 %) caused by strain Y which was isolated during outbreaks of the TMUV-related disease of young Jinding ducks in 2014 in the same region. These findings clearly demonstrated that the cluster 2.1 TMUV strain H is more pathogenic for 3-week-old ducklings as compared to the cluster 2.2 TMUV strain Y. The present study may enhance our understanding of pathogenicity of TMUV in young ducks, and will stimulate further studies on the pathogenesis of TMUV infection.

Molecular survey of duck circovirus infection in poultry in southern and southwestern China during 2018 and 2019

BackgroundDuck circovirus (DuCV) is a potential immunosuppressive virus that causes feather disorders in young ducks. In this study, DuCV obtained from various species of ducks was investigated by polymerase chain reaction (PCR) in southern and southwestern China (Guangdong, Guangxi and Yunnan provinces) from 2018 to 2019.ResultsA total of 848 bursa samples were collected from dead Mulard, Cherry Valley Pekin, Muscovy and Mallard ducks from duck farms. The positivity rate of DuCV in the total sample was approximately 36.91%. We found that the prevalence of DuCV in Yunnan (43.09%) was higher than those in Guangxi (34.38%) and Guangdong (34.4%). However, the positivity rates of DuCV in the four duck species were not significantly different (P > 0.05). Nineteen randomly selected complete viral genomes were sequenced. The complete genomes of the DuCV were 1987 to 1995 nt in length, and were 81.7–99.3% homologous to the other 57 sequences in GenBank. Phylogenetic analyses based on the complete genomes of 76 DuCVs showed that the 19 novel DuCV sequences from Guangdong and Guangxi provinces mainly belonged to the DuCV-1 and DuCV-2 genetic groups, respectively. However, the two genotype groups coexisted in Yunnan Province. In addition, recombination analysis showed putative recombination sites in 3 strains in Yunnan that originated from strains Guangdong and Guangxi. Interestingly, the epidemiological investigation showed that Mulard ducks, Cherry Valley Pekin ducks and Muscovy ducks more than 4 weeks old were more susceptible to infection with the novel DuCV than ducks less than 4 weeks old.ConclusionsThese data provide insight into the molecular epidemiology and genetic diversity of DuCVs circulating in southern and southwestern China for the first time.

Stressor disorders of morphological indicators of bloods of ducks in critical periods of ontogenesis

The article presents data hematol ohichnyh performance blood of ducks in critical periods of postnatal ontogenesis 2, 14, 21, 45, 90, 150, and 240 days of life, which are accordingly related to the full use of the yolk, intensive development of the digestive system and muscular tissue, change of fluff to the primary feather, juvenile molt, the beginning of the oviposition, the formation of the reproductive system and glands of the internal secretion, the continuation of the oviposition and the molt, which is accompanied by the complete renewal of the fine and medium feathers. Blood plays an important role in maintaining homeostasis , and studies of hematological parameters make it possible to assess the intensity of redox processes in tissues and organs, and studies of hematological parameters make it possible to estimate the intensity of redox processes in tissues and organs, namely the need for oxygen in connection with the physico-chemical and biochemical processes that occur in the body in the process of growth and development. They are dynamic and change with different factors faster than performance. The purpose of the study was to determine the dynamics of morphological parameters of duck blood during the critical periods of postnatal ontogeny . Research subject clinically healthy young Beijing duck meat breed performance direction. Changes in hematological parameters of ducks' blood reflect a picture of the impact of critical periods of ontogeny on ducks, characterized by 2 days of life, the numerical values of erythrocytes (2.45 ± 0.11 T/l) and the concentration of hemoglobin (102.90 ± 3.51 g/l), but the value of hematocrit was in the lower levels of physiological norms. While the leukocyte count of 31.20 ± 1.76 was close to the 240-day age, indicating high bird immunity after hatching , more likely to come from the use of yolk. In the study bird on the 14th day recorded an increase in the number of erythrocytes and leukocytes by 10.6 and 14.7%, hematocrit by 10.3% against a decrease in hemoglobin concentration by 12.8% (P &lt; 0.05). At 21 days, the number of erythrocytes and hemoglobin concentration decreased by 8.2%, while hematocrit and leukocyte values ​​approached the initial state of the experiment, amounting to 26.45 ± 2.40%, 32.06 ± 2.93 G/L. The presence of basophils in this age period indicates the launch of a chain of immune responses, indicating the formation of the immune system according to A. Malyukin. (2010). At day 45, erythrocytes and hemoglobin concentrations were reduced by 10.2% and 11.3% (P &lt; 0.05), compared to the baseline period. During this period, hematocrit increased by 12.7%, which indicated an increase in blood cells in the ducts. Results at 90 days indicated a decrease in erythrocyte count by 14.3% (P &lt; 0.05) and hemoglobin concentration by 11.8% (P &lt; 0.05), while leukocyte count and hematocrit increased by 26.1 and 22.1% (P &lt; 0.05) compared with ducklings of 2 days of age. In ducklings at 150 days of age, the erythrocyte count and hemoglobin concentration were close to the baseline, and the leukocyte count and hematocrit were increased by 19.6 and 39.3%, respectively (P &lt; 0.05). At 240 days of ducklings life, an increase in the oxygen-transport system of blood was established in the form of an increase in the number of erythrocytes by 35.1% (P &lt; 0.01), hemoglobin concentration by 28.7% (P &lt; 0.01), hematocrit value by 50, 8% (P &lt; 0.01) compared to 2-days of ducklings life, and the number of leukocytes was close to baseline, indicating a decrease in the reactivity of the organism.

Effects of L-methionine on growth performance, carcass quality, feather traits, and small intestinal morphology of Pekin ducks compared with conventional DL-methionine

The research studied the effects ofl-methionine (l-Met) on growth performance, carcass quality, feather traits, and small intestinal morphology of Pekin ducks compared with conventionaldl-methionine (dl-Met). A total of 1080, 1-day-old male Pekin ducks were randomly allotted to 9 groups with 6 replicate pens of 20 birds each. During the starter phase (1 to 14 d), ducks were fed a basal diet (Met, 0.30%) or that supplemented with dl-Met or l-Met at 0.05, 0.10, 0.15, or 0.20% of feed. During the grower phase (15 to 35 d), ducks were fed a basal diet (Met, 0.24%) or that supplemented with dl- Met or l-Met at 0.04, 0.08, 0.12, or 0.16% of feed. Compared with ducks fed the basal diet, supplementation with either dl- Met or l-Met increased the body weight (BW) of ducks at days 14 and 35, increased average daily gain (ADG) and average daily feed intake (ADFI), decreased F:G at the starter phase, and increased ADG over the whole 35-d period (P < 0.05). The efficacy of l-Met compared to dl- Met was 140.1% for 14-d BW, 137.6% for ADG and 121.0% for F:G for days 1 to 14. Ducks fed diets supplemented with l-Met had greater proportion of leg muscle, higher than in ducks provided with dl- Met (P < 0.05). The breast muscle proportion was enhanced with dl- Met rather than l- Met supplementation (P < 0.01). The back feathers score and fourth primary wing feather length were increased with dl- Met or l-Met supplementation (P < 0.01), and there was increased efficacy of l-Met relative to dl- Met for back feathers score (153.1%). Dietary dl- Met or l- Met supplementation increased villus height of ileal mucosa of ducks at days 14 and 35 (P < 0.01). Overall, dietary l-Met or dl- Met supplementation affected the growth performance of ducks during the starter phase, and improved the feather traits and small intestinal morphology. The efficacy of l-Met to dl- Met ranged from 120 to 140% for growth performance of young ducks (1 to 14 d) and was 153% for the feather traits of ducks (35 d).

Phytoecdisteroids from Serratula coronata when growing ducklings

This article presents the results of comprehensive studies to analyze the effect of a mixture of phytoecdysteroids extracted from the juice of Serratula coronata L. on the productivity and vitality of ducklings when grown for meat, and the optimal doses of its inclusion in the diet of the bird are revealed. The methodological basis of this study was the earlier works of domestic and foreign scientists on the topic under study. In the studies, a mixture of ecdysteroids extracted from the juice of the Serratula coronata L. was used according to the method developed by a team of scientists of the Ufa Federal Research Center of the Russian Academy of Sciences (Patent RU 2151598). The object of the study was the young ducks of the cross breed "Agidel 34" of the Beijing breed. It was established that the use of phytoecdysteroids in the diets of ducklings at a dose of 1.0 mg/l of drinking water allowed to increase the safety of the livestock by 4.0%, live weight by 4.5% (p < 0.01), average daily live weight gain by 3.0–3.5%, gutted carcass weight – 7.1%. At the same time, feed costs per unit of production decreased by 2.0%, and the profitability of duck meat production increased by 5.2%.

The truncated E protein of DTMUV provide protection in young ducks

Duck Tembusu virus (DTMUV) is a major pathogen of duck industry in China. In the current study, we generated different constructs containing envelope (E) protein, pre-membrane-envelope (prM-E) protein, and C-terminally truncated E protein of the DTMUV. The constructed proteins could induce specific antibody responses in young ducks. When ducklings were immunized with the constructed proteins, they were 100% protected against DTMUV infection. Furthermore, the fluorescent signal of the truncated E protein was stronger than other constructed proteins, when Bac-to-Bac baculovirus expression system was applied. Our data demonstrated that the truncated E protein used in the current study could be applied as a potential vaccine candidate to control DTMUV infection in young ducks.