Preening cups in duck housing are associated with an increase in central dopamine activity that suggests a negative affective state.

Preening cups are a form of environmental enrichment that provides Pekin ducks a semi-open water source to express their natural behaviors. We recently observed that preening cups may increase feather pecking behaviors in ducks. Thus, we set out to determine if this form of enrichment can impact the affective state of Pekin ducks. To accomplish this goal, we evaluated the effect of preening cups on serotonin (5-HT) and dopamine (DA) turnover via mass spectrometry and their respective synthetic enzyme gene expression via qRT-PCR. Our study investigated the link between aggressive pecking with levels and activity of brain 5-HT and DA. Brain 5-HT and DA levels and activity have been established for decades to be associated with affective states. Grow-out Pekin ducks (n = 260) were housed at Purdue and raised per industry standards. On day 18, brains were collected from ducks in pens before preening cups were placed (PRE, n = 6) and, again on day 43, in pens with (PC, n = 6) and without (CON, n = 6) preening cups. Brains were dissected into right and left halves, then further microdissected into 4 brain areas: caudal mesencephalon (CM), rostral mesencephalon (RM), diencephalon (DI), and forebrain (FB). The right hemisphere was used for mass spectrometry to determine the neurotransmitter concentration (ng/mg of tissue) and those concentrations were applied to neurotransmitter turnover equations. There were no differences across treatments for 5-HT turnover in any brain area. There were differences in DA turnover across age (P = 0.0067) in the CM and across treatments (P = 0.003) in the RM. The left hemisphere of the brain was used to perform qRT-PCR on the genes of 5-HT and DA production enzymes. Within the CM, day 43 duck brains had increased (P = 0.022) tryptophan hydroxylase and tyrosine hydroxylase relative mRNA levels. All other brain areas showed no differences. Our data suggest that ducks housed with preening cups and that showed increased feather pecking are associated with increased brain DA activity. The increased DA in the brain may lead to a predisposition for increased aggression in the form of feather pecking.

Effect of immunization against OPN5 on the reproductive performance in Shan Partridge ducks under different photoperiods.

Photoperiod is an important environmental factor that influences seasonal reproduction behavior in birds. Birds translate photoperiodic information into neuroendocrine signals through deep brain photoreceptors (DBPs). OPN5 has been considered candidate DBPs involved in regulating seasonal reproduction in birds. We found that OPN5 could mediate light to regulate the follicle development in ducks. In this study, we further verified the effect of OPN5 on follicular development in Shan Partridge ducks by immunizing against the extracellular domain (ECD) of OPN5. We investigated the specific regulatory mechanism of photoperiod mediated by OPN5 on the reproductive activity of ducks. The trial randomly divided 120 Shan Partridge ducks into 3 groups with different treatments: the immunization of OPN5 group was done at d0, d15, d30, and d40 with 1 mL of vaccine containing OPN5 protein (thus containing 1, 1, 0.5, and 0.5 mg of OPN5-KLH protein), and the control group (CS and CL groups) was injected at the same time with the same dose of OPN5-uncontained blank vaccine. The group of CS (900 lux), OPN5 (600 lux), and CL (600 lux) lasted for 40 d in 12 L:12 D photoperiods, respectively. Then, the groups of CS, OPN5, and CL subsequently received 12 L:12 D, 12 L:12 D, and 17 L:7 D light treatments for 33 d, respectively. The ducks were caged in 3 constant rooms with the same feeding conditions for each group, free water, and limited feeding (150 g per duck each day). Duck serum and tissue samples were collected at d 40, d 62, and d 73 (n = 12). It was found that before prolonged light, the group of immunization (group OPN5) and the group of strong light intensity (group CS) were higher than the group of CL in egg production. Subsequent to prolonged light, the group CL in egg production rose about the same as the group immunization, while the strong light group (group CS) was lower. Group OPN5 increased the ovarian index of ducks, and both the immunization of group OPN5 and group CL (extended light) increased the thickness of the granular layer and promoted the secretion of E2, P4, LH, and PRL hormones. Compared with group CS, group CL and OPN5 increased the mRNA level and protein expression of OPN5 in the hypothalamus on d 62 and d 73 (P < 0.05). The gene or protein expression patterns of GnRH, TRH, TSHß, DIO2, THRß, VIP, and PRL were positively correlated with OPN5, whereas the gene expression patterns of GnIH and DIO3 were negatively correlated with OPN5. The results showed that immunization against OPN5 could activate the corresponding transmembrane receptors to promote the expression of OPN5, up-regulate the expression of TSHß and DIO2, and then regulate the HPG axis-related genes to facilitate the follicular development of Shan Partridge ducks. In addition, in this experiment, prolonging the photoperiod or enhancing the light intensity could also enhance follicle development, but the effect was not as significant as immunizing against OPN5. Our results will offer beneficial data and more supportive shreds of evidence in favor of elucidating the role of OPN5 in relation to photoperiods and reproduction.

In-house ammonia induced lung impairment and oxidative stress of ducks.

Ammonia (NH3) is a toxic gas that in intensive poultry houses, damages the poultry health and induces various diseases. This study investigated the effects of NH3 exposure (0, 15, 30, and 45 ppm) on growth performance, serum biochemical indexes, antioxidative indicators, tracheal and lung impairments in Pekin ducks. A total of 288 one-day-old Pekin male ducks were randomly allocated to 4 groups with 6 replicates and slaughtered after the 21-d test period. Our results showed that 45 ppm NH3 significantly reduced the average daily feed intake (ADFI) of Pekin ducks. Ammonia exposure significantly reduced liver, lung, kidney, and heart indexes, and lowered the relative weight of the ileum. With the increasing of in-house NH3, serum NH3 and uric acid (UA) concentrations of ducks were significantly increased, as well as liver malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPX-Px) contents. High NH3 also induced trachea and lung injury, thereby increasing levels of tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) in the lung, and decreasing the mRNA expressions of zonula occludens 1 (ZO-1) and claudin 3 (CLDN3) in the lung. In conclusion, in-house NH3 decrease the growth performance in ducks, induce trachea and lung injuries and meanwhile increase the compensatory antioxidant activity for host protection.

Genome-wide association study for bone quality of ducks during the laying period.

The cage-rearing model of the modern poultry industry makes the bones of birds, especially egg-laying birds, more vulnerable to fracture, which poses serious damage to the health of birds. Research confirms that genetic material plays an important role in regulating bone growth, development, and remodeling. However, the genetic architecture underlying bone traits is not well understood. The objectives of this study are to identify valuable genes and genetic markers through a genome-wide association study (GWAS) for breeding to improve the duck bone quality. First, we quantified the tibia and femur quality traits of 260 laying ducks. Based on GWAS, a total of 75 SNP loci significantly associated with bone quality traits were identified, and 67 potential candidate genes were annotated. According to gene function analysis, genes P4HA2, WNT3A, and BST1 et al may influence bone quality by regulating bone cell activity, calcium and phosphate metabolism, or bone collagen maturation and cross-linking. Meanwhile, combined with the transcriptome results, we found that HOXB cluster genes are also important in bone growth and development. Therefore, our findings were helpful in further understanding the genetic architecture of the duck bone quality and provided a worthy theoretical basis and technological support to improve duck bone quality by breeding.

Human access constrains optimal foraging and habitat availability in an avian generalist.

Animals balance costs of antipredator behaviors with resource acquisition to minimize hunting and other mortality risks and maximize their physiological condition. This inherent trade-off between forage abundance, its quality, and mortality risk is intensified in human-dominated landscapes because fragmentation, habitat loss, and degradation of natural vegetation communities is often coupled with artificially enhanced vegetation (i.e., food plots), creating high-risk, high-reward resource selection decisions. Our goal was to evaluate autumn-winter resource selection trade-offs for an intensively hunted avian generalist. We hypothesized human access was a reliable cue for hunting predation risk. Therefore, we predicted resource selection patterns would be spatiotemporally dependent upon levels of access and associated perceived risk. Specifically, we evaluated resource selection of local-scale flights between diel periods for 426 mallards (Anas platyrhynchos) relative to wetland type, forage quality, and differing levels of human access across hunting and nonhunting seasons. Mallards selected areas that prohibited human access and generally avoided areas that allowed access diurnally, especially during the hunting season. Mallards compensated by selecting for high-energy and greater quality foraging patches on allowable human access areas nocturnally when they were devoid of hunters. Postseason selection across human access gradients did not return to prehunting levels immediately, perhaps suggesting a delayed response to reacclimate to nonhunted activities and thus agreeing with the assessment mismatch hypothesis. Last, wetland availability and human access constrained selection for optimal natural forage quality (i.e., seed biomass and forage productivity) diurnally during preseason and hunting season, respectively; however, mallards were freed from these constraints nocturnally during hunting season and postseason periods. Our results suggest risk-avoidance of human accessible (i.e., hunted) areas is a primary driver of resource selection behaviors by mallards and could be a local to landscape-level process influencing distributions, instead of forage abundance and quality, which has long-been assumed by waterfowl conservation planners in North America. Broadly, even an avian generalist, well adapted to anthropogenic landscapes, avoids areas where hunting and human access are allowed. Future conservation planning and implementation must consider management for recreational access (i.e., people) equally important as foraging habitat management for wintering waterfowl.

Evaluation of coffee husks in pellet bedding, performance characteristics, footpad dermatitis scoring, and meat quality of broiler ducks.

The study aimed to analyze the chemical composition of pellet bedding made of straw or coffee husks (10, 25, 50%) and the performance characteristics of broiler ducks and footpad dermatitis. During rearing, the properties of the bedding and utility features of ducks were analyzed, and the frequency of footpad dermatitis (FPD) in ducks was verified. There was a decrease in dry matter from the 28th day of rearing. The crude fiber, NDF, ADF, and nitrogen content decreased compared to fresh bedding, while phosphorus and potassium increased. The highest pH was found in the CH25 and CH50 groups in fresh bedding on day 42 and in CH50 on day 14. High adj. R2 was found due to rearing time and bedding material (0.817-0.985). The ducks' growth rate in the CH25 group was higher at week 6 than in the other groups. In CH10 and CH25 groups, higher carcass weight was found than in group C. In group CH10, a higher weight of pectoral muscles and lower wing proportion was found than in C. In CH25, a higher remains weight was shown than in C and CH50. In CH50, lower water-holding capacity in the pectoral muscles was found than in the other groups. Considering the bedding (the content of nitrogen, phosphorus, and potassium), carcass features, and meat quality (water-holding capacity, intramuscular fat, and water content), it is possible to use 10, 25 or 50% of coffee husks in straw pellets in the rearing of broiler ducks. Due to the FPD, the moisture should be lowered.

The network regulation mechanism of the effects of heat stress on the production performance and egg quality of Jinding duck was analyzed by miRNA‒mRNA.

To explore the differential regulation mechanism of heat stress on the egg production performance and egg quality of Jinding ducks, 200 Jinding ducks (360-day-old) in good health and with similar body weights and a normal appetite were selected and randomly divided into a control (normal temperature [NT]) group (20°C-25°C) and a heat stress (HS) group (32°C-36°C), with 4 replicates in each group and 25 ducks in each replicate. The pretrial period was 1 wk, and the formal trial period was 4 wk. At the end of the 4th wk, 12 duck eggs were collected from each replicate to determine egg quality. Pituitary and ovarian tissues of Jinding ducks were collected, transcriptome sequencing was performed to screen differentially expressed miRNAs and mRNAs related to high temperature and heat stress, and a competitive endogenous RNA regulatory network was constructed. The sequencing data were verified by qRT‒PCR method. The following results were obtained: (1) Compared with the NT group, the HS group had a significantly lower laying rate, total egg weight, average egg weight, total feed intake, and feed intake per duck (P < 0.01), an extremely significantly higher feed-to-egg ratio (P < 0.01), and a higher mortality rate. (2) Compared with the NT group, the HS group had an extremely significantly lower egg weight, egg yolk weight, eggshell weight, and eggshell strength (P < 0.01) and an extremely significantly lower yolk ratio and eggshell thickness (P < 0.01, P < 0.05); however, there was no significant difference in the egg shape index, Haugh unit or protein height (P > 0.05). (3) A total of 1,974 and 1,202 genes were identified in the pituitary and ovary, respectively, and there were 5 significantly differentially expressed miRNAs. The differentially expressed genes were involved in the arginine and proline metabolism pathways, ether lipid metabolism pathway, and drug metabolism-cytochrome P450 pathway, which are speculated to be related to the egg production performance of Jingding ducks under high-temperature heat stress. (4) Novel_221 may target the PRPS1 gene to participate in egg production performance; novel_168 and novel_289 may target PIGW; novel_289 may target Q3MUY2; and novel_289 and novel_208 may target PIGN or genes that may be related to high-temperature heat stress. (5) In pituitary tissue, upregulated novel_141 (center of the network) formed a regulatory network with HSPB1 and HSP30A, and downregulated novel_366 (center of the network) formed a regulatory network with the JIP1 gene. In ovarian tissue, downregulated novel_289 (center of the network) formed a regulatory network with the ZSWM7, ABI3, and K1C23 genes, novel_221 formed a regulatory network with the IGF1, BCL7B, SMC6, APOA4, and FARP2 genes, and upregulated novel_40 formed a regulatory network with the HA1FF10 gene. In summary, heat stress affects the production performance and egg quality of Jinding ducks by regulating the secretion of endocrine-related hormones and the release of neurotransmitters as well as the expression of miRNAs and mRNAs in pituitary and ovarian tissues. The miRNA‒mRNA regulatory network provides a theoretical basis for the molecular mechanism that regulates the stress response in pituitary and ovarian tissues, egg quality, and production performance under heat stress.

Dietary non-phytate phosphorus requirements for optimal productive and reproductive performance, and egg and tibial quality in egg-type duck breeders.

Optimal dietary non-phytate phosphorus (NPP) is essential in poultry to maximise productive and reproductive performance, along with indices of egg and bone quality. This study aimed to establish the NPP requirements of egg-type duck breeders aged from 54 to 80 weeks on the following traits: egg production, egg incubation, egg quality, tibial characteristics, reproductive organ, plasma indices, and the expression of genes related to phosphorus absorption. Longyan duck breeders aged 54 weeks (n = 300) were randomly allotted to five treatments, each containing six replicates of 10 individually caged birds. Birds were fed corn-soybean meal-based diets containing 0.18, 0.25, 0.32, 0.38, and 0.45% NPP/kg for 27 weeks. The tested dietary NPP levels did not affect egg production or egg quality indices. The hatchling weight of ducklings increased (quadratic, P < 0.01) as dietary NPP level increased, and the highest value occurred with 0.25% NPP. The number of large yellow follicles (LYF), and the relative weights of LYF and ovary showed linear and quadratic responses to dietary NPP levels; the lowest number and relative weight of LYF occurred with 0.38% NPP, and the lowest ovarian weight was obtained with 0.25% NPP. There were no differences in tibial length, breaking strength, and mineral density in response to dietary NPP levels. In contrast, tibial content of Ca increased (linear, P < 0.01) with dietary NPP levels increasing from 0.18 to 0.45%, and the tibial content of P increased at 0.32% NPP and the higher dietary NPP levels. Plasma concentration of P showed a quadratic (P < 0.05) response to the dietary NPP levels, where the highest value was seen at 0.38% NPP. In conclusion, dietary NPP levels from 0.18 to 0.45% had no effects on egg production, and egg and tibial quality of duck breeders. The duck breeders fed a diet with 0.25% NPP showed the highest hatchling weight of their offspring, while those fed 0.38% NPP had the lowest number and relative weight of LYF. These results indicated that the diet with 0.25% NPP can be used in egg-type duck breeders to improve the hatchling weight of their offspring, without adverse effects on their productivity. The regression model indicated that the maximal hatchling weight of ducklings was obtained from duck breeders fed the diet with 0.30% NPP.

Research Note: Transcriptome analysis reveals differentially expressed genes regulated muscle development in Pekin ducks during dietary threonine deficiency.

To investigate the underlying molecular mechanism of threonine (Thr) regulation on the development of breast muscle in Pekin ducks, 240 male Pekin ducks at 1 d of age were fed a Thr deficiency diet (Thr-D), Thr sufficiency diet (Thr-S), or Thr excess diet (Thr-E) for 21 d. The results showed that Thr-D reduced body weight (BW), average weight gain (ADG), and average feed intake (ADFI), and increased the feed/gain (F/G) in Pekin ducks (P < 0.05), and Thr-E did not affect BW, ADG, ADFI, or F/G (P > 0.05), compared with Thr-S. The diameter and cross-sectional area of the breast muscle fibers in the Thr-S group were larger than those in the Thr-D group (P < 0.05). RNA sequencing revealed 1,300 differential expressed genes (DEGs) between the Thr-D and Thr-S groups, of which 625 were upregulated and 675 were downregulated by Thr-D. KEGG analysis showed that the upregulated genes were enriched in mTOR, FoxO, Wnt, fat digestion and absorption, and other signaling pathways. The downregulated genes were enriched in the MAPK signaling, glycolysis/gluconeogenesis, adipocytokine signaling, and biosynthesis of unsaturated fatty acids signaling pathways. The genes of Wnt family member 3a (Wnt3a), myogenin, myozenin 2, and insulin like growth factor 2 mRNA binding protein were upregulated, and platelet derived growth factor subunit B, PDGF receptor beta and Wnt4 were downregulated by Thr deficiency, which involving in muscle development. Our findings indicated that Thr increased breast fiber size, perhaps because Thr affected the proliferation and differentiation of satellite cells in breast muscle of ducks after hatch. Our results provide novel insights into new understanding of the molecular mechanisms underlying breast muscle development in ducks subjected to dietary Thr.

Long-term data reveal contrasting impacts of native versus invasive nest predators in Iceland.

Bird species on islands are strongly impacted by biological invasions, with the Icelandic common eider (Somateria mollissima borealis) being particularly threatened. Down collection by local families in Breiðafjörður, West Iceland, provided long-term datasets of nests from two archipelagos, covering 95 islands over 123 years and 39 islands over 27 years, respectively. Using these exceptional datasets, we found that the arrival of the invasive semi-aquatic American mink (Neogale vison) was a more impactful driver of population dynamics than climate. This invasive predator heavily reduced eider nest numbers by ca. 60% in the Brokey archipelago. In contrast, we detected an apparently adaptive response to the return of the native fox in the Purkey archipelago, with dense nests on islands inaccessible to the fox and no apparent impact on eider populations. This difference might be due to the eiders lacking a joint evolutionary history with the mink and therefore lacking appropriate antipredator responses.

Comprehensive transcriptomic and metabolomic analysis of the effect of feed restriction on duck sternal development.

Skeletal characteristics are important to the growth and development of poultry. In feeding management, constant free feeding (FF) of poultry may lead to imbalance between bone development and weight gain. Feed restriction (FR), to a certain extent, is one way to solve this problem. However, the effect of feed restriction on poultry bone development needs further elucidation at the molecular level. Therefore, in the present study, we investigated the effects of different levels of feed restriction (60% FR, 70% FR, 80% FR, and FF) on the sternum development of ducks at 7 and 8 wk old. In the seventh wk, with increasing feed restriction, the values of traits including body weight, breast muscle weight, sternal weight, keel length, and calcified keel length decreased. However, in the eighth wk, the sternum weight and keel length of ducks treated with 60% FR were unexpectedly higher than those of FF individuals, indicative of catch-up growth. Then, we conducted RNA-seq and metabolomic analysis on sterna from 7- and 8-wk-old FF and 60% FR ducks. The results identified multiple differentially expressed genes (DEGs) associated with sternum development that were influenced by feed restriction. Among them, we found that the mRNA expression levels of the chondroitin sulfate synthase 3 (CHSY3) and annexin A2 (ANXA2) which are involved in glycosaminoglycan biosynthesis and bone mineralization, had smaller changes over time under FR treatment than under FF treatment, implying that the FR treatment to a certain extent prevented the premature calcification and prolonged the development time of duck sternum. In addition, the metabolomic and integrative analyses revealed that several antiaging-related metabolites and genes were associated with sternal catch-up growth. Pyrimidine metabolism was identified as the most significant pathway in which most differential metabolites (DMs) between FF and 60% FR were enriched. The results from integrative analysis revealed that the content and expression of 4-aminobutyric acid (GABA) and its related genes showed relatively higher activity in the 60% FR group than in the FF group. The present study identifies multiple biomarkers associated with duck sternum development that are influenced by feed restriction and suggests the potential mechanism of feed restriction-associated duck sternal catch-up growth.

Growth performance, carcass traits, meat quality, and blood variables of small-sized meat ducks with different feed efficiency phenotypes.

The study investigated the effects of feed efficiency (residual feed intake, RFI and residual intake and gain, RIG) on the production performance of small-sized meat ducks. Ninety ducks with intermediate and extreme (high and low) RFI values were selected from 1,083 male ducks of similar body weight, and the 3 groups were then redivided according to RIG. For both efficiency measures, the feed conversion ratio (FCR) and average daily feed intake (ADFI) of efficient ducks were significantly lower than those of inefficient ducks (P < 0.05), while the residual body weight gain (RG) was significantly higher in efficient ducks (P < 0.05). Inefficient-RFI animals showed greater skin fat yield (P < 0.05), but no other differences in carcass traits were observed (P > 0.05). RIG had positive effects on the pH1 value of the breast muscle (P < 0.05), but feed efficiency did not affect the other meat quality traits (P > 0.05). With regard to blood biochemical parameters, efficient ducks had significantly lower triglycerides (TG) (P < 0.05). Correlation analysis demonstrated that RFI was positively correlated with average daily feed intake and feed conversion ratio (P < 0.05), while RIG exhibited a strong negative correlation with both (P < 0.05). The average daily body weight gain was positively correlated with RIG (P < 0.05). RIG had a positive effect on the pH1 value of the breast muscle (P < 0.05). Furthermore, triglyceride and high-density lipoprotein cholesterol levels correlated with both efficiency classifications (P < 0.05). Overall, the efficiency measures did not affect the carcass and meat quality of small-sized meat ducks but could identify ducks with lower feed consumption and fast growth.

Effects of coated sodium butyrate on growth performance, intestinal morphology, and caecal short-chain fatty acids of growing Pekin ducks.

1. A dose‒response experiment with six supplemental levels of coated sodium butyrate (CSB) (0, 250, 500, 750, 1,000, and 1,250 mg/kg) was conducted to investigate its effects on growth performance, intestinal morphology, and caecal short-chain fatty acids of growing Pekin ducks aged 14 to 35 d. A total of 288 male 14-d-old Pekin ducks were randomly allocated to six dietary treatments. Each treatment had eight replicate pens of six ducks per pen.2. The daily weight gain, daily feed intake, and feed/gain of ducks from 14 to 35 d of age were not influenced by increasing CSB levels. The relative weight and length of the duodenum, jejunum, and caecum increased linearly or quadratically as supplemental CSB increased (P < 0.05).3. For the ileum and caecum, the villus height and height/crypt depth increased linearly or quadratically, and the villus crypt depth decreased linearly as the supplemental CSB increased (P < 0.05). As supplemental CSB increased, the goblet cell numbers of the ileum increased and decreased and changed quadratically (P < 0.05), but caecal goblet cell number increased quadratically (P < 0.05). Increasing the CSB level linearly or quadratically elevated the concentrations of propionic acid and butyric acid in the caecum (P < 0.05).4. It was concluded that CSB can be used as a safe and effective feed additive to promote the intestinal integrity of growing ducks by improving intestinal morphology and increasing the concentration of caecal short-chain fatty acids.

Immunopromoter improves liver apoptosis and immune response in Shaoxing ducklings.

Antibiotics as feed additives, play a vital role in animal husbandry. However, overused antibiotics could cause endogenous infections in animals, and even endanger human health through the food chain. And immunopotentiators can make the low immune function improve and accelerate the induction of immune response. The aim of this study was to investigate the effects of five different immunopotentiators on the expression of liver apoptosis and immune factor related genes in Shaoxing ducklings (Anas Platyrhynchos). A total of 150 one-day-old Shaoxing ducklings were randomly divided into six groups including saline, chlorogenic acid, ß-D-glucan, astragalus flavone, CpG DNA and chicken IgG, which were injected subcutaneously into the neck, respectively. At 18 days old, the liver tissues were collected to detecte the mRNA and protein expression levels of inflammatory and apoptosis-related genes. The results showed that compared with the control group, the mRNA and protein levels of liver Bcl2 with chlorogenic acid, ß-D-glucan, astragalus flavone, CpG-DNA and chicken IgG were significantly decreased (p < 0.05), while the expression level of Caspase3 was up-regulated in some different degrees. In addition,The expression levels of liver iNOS and COX2 were significantly increased after the injection of five immunopotentiators (p < 0.05), and the mRNA levels of IFN-α, IFN-ß, IL-1ß, RIG-I, TLR3 and TLR7 genes were also significantly up-regulated compared with the control group (p < 0.05). In conclusion, chlorogenic acid, ß-D-glucan, astragalus flavone, CpG-DNA and chicken IgG can be used as immunopotentiators to regulate duck innate immunity. This study provides a new way to prevent important infectious diseases of ducks, and also provides a certain reference for the application of antibiotic substitutes in animal production.

TAT gene polymorphism and its relationship with production traits in Muscovy ducks (Cairina Moschata).

In a previous study, the laying pattern of Muscovy duck was explored by macro-fitting the laying curve of Muscovy duck, and transcriptome sequencing technique of the ovarian tissues was used to screen the egg-related gene "TAT." Moreover, recent results have shown that TAT is expressed in organs such as oviduct, ovary, and testis. The objective of this study is to examine the effect of TAT gene on egg production traits of Muscovy ducks. First, the expression levels of TAT gene in highest producing (HP) and lowest producing (LP) in 3 tissues related to reproduction were examined, and the results indicated that the expression of TAT gene in hypothalamus was significantly different between HP and LP groups. Then, 6 SNP loci (g. 120G>T, g, 122G>A, g, 254G> A, g. 270C >T, g, 312G>A, and g. 341C>A) were detected in TAT gene. Further, association analysis between the six SNP loci of TAT gene and egg production traits of 652 individual Muscovy ducks was done. The results showed that g. 254G>A and g. 270C>T were significantly correlated (P < 0.05 or 0.001) with the egg production traits of Muscovy ducks. This study elucidated the molecular mechanism that TAT gene might be regulating the egg production traits of Muscovy ducks.

Mallard landing behavior on water follows a -constant braking strategy.

Many flying animals use optic flow to control their flight. During landing maneuvers, pigeons, hummingbirds, bats, Draco lizards and bees use the -constant braking strategy. This strategy regulates the approach by keeping the ratio of distance to an object and the rate of change of that distance constant. In keeping this ratio, , constant, a variety of deceleration profiles can lead to different collision avoidance behaviors. The landing behaviors listed above all qualify as controlled collisions, where the animal is decelerating into the object. We examined whether the same regulatory strategy is employed by mallards when landing on water. Video of mallard landing behavior was recorded at a local pond and digitized. Kinematic and τ parameters were calculated for each landing (N=177). The Pearson correlation coefficient for τ with respect to time to land was 0.99±0.02, indicating mallards employ a controlled-collision strategy. This result implies regulation by the birds to fix as constant while landing (on average, 0.90±0.13). In comparison with other active flyers, mallards use a higher value of when landing (0.775±0.109, 0.710±0.132 and 0.702±0.052 for pigeons, hummingbirds and bats, respectively). This higher may reflect physical differences in substrate from solid to liquid. The higher compliance of water in comparison to a solid substrate may reduce impact forces that could be injurious on a solid substrate, thereby enabling mallards to approach faster and expend less energy for costly, slow flight.

Effects of rosemary extract supplementation in feed on growth performance, meat quality, serum biochemistry, antioxidant capacity, and immune function of meat ducks.

This study aimed to investigate the effects of diets supplemented with different levels of rosemary extract (RE) on the growth performance, meat quality, serum biochemistry, antioxidative capacity, and immunological capacity of Cherry Valley meat ducks. A total of 525 healthy Cherry Valley female meat ducks at 1 d of age were selected for this study. Ducks were randomly divided into 5 treatments with 7 replicates per treatment, and each replicate had 15 ducks. All replicates were randomly assigned to treatments. The study was designed as a dose response experiment. Treatment 1 (CON) was fed with the basal diet, and Treatment 2 to 5 (RE250, RE500, RE750, RE1000) were fed with the basal diet supplemented with 250, 500, 750, and 1,000 g/t RE, respectively. The whole experiment lasted 42 days with early stage (1-21 d) and late stage (22-42 d). Results showed that during 22 to 42 d, ducks that were fed over 500 g/t RE had significantly lower feed gain ratio than the ones in CON (P = 0.006). In addition, ducks in RE750 had significantly lower L* and a* in leg muscle compared with the ones in CON (P < 0.05). Besides, ducks that were fed between 250 and 750 g/t RE had significantly lower total protein level in serum compared with the ones in CON (P = 0.005). Ducks in RE250 and RE750 had significantly lower albumin, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels in serum compared with the ones in CON and RE1000 (P < 0.05), and significant quadratic relationships were noticed between albumin, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol and dietary RE level (P < 0.05). Moreover, ducks that were fed between 500 and 750 g/t RE had significantly higher levels of interleukin-2 in serum compared to the ones in CON and RE1000 (P = 0.003). Ducks in RE250 and RE750 had significantly higher levels of immunoglobulin G in serum compared to the ones in CON and RE1000 (P < 0.001). Ducks that were fed over 500 g/t RE had significantly higher levels of immunoglobulin A in serum compared to the ones in CON (P = 0.001). Finally, ducks that were fed between 500 and 750 g/t RE had significantly higher serum levels of glutathione peroxidase, superoxide dismutase, catalase, and total antioxidant capacity (P < 0.05) compared to the ones in CON. Ducks that were fed over 250 g/t RE had significantly lower serum level of malondialdehyde compared to the ones in CON (P = 0.020). Collectively, dietary supplementation of RE improved the growth performance and meat qualities of meat ducks during 22 to 42 d, which were possibly associated with the antioxidative and anti-inflammatory effects of RE. Based on the serum antioxidative and immunological parameters, we suggested that 500 to 750 g/t was the optimal supplementation rate for RE in diets for meat ducks aged 22 to 42 d.

A colonial-nesting seabird shows no heart-rate response to drone-based population surveys.

Aerial drones are increasingly being used as tools for ecological research and wildlife monitoring in hard-to-access study systems, such as in studies of colonial-nesting birds. Despite their many advantages over traditional survey methods, there remains concerns about possible disturbance effects that standard drone survey protocols may have on bird colonies. There is a particular gap in the study of their influence on physiological measures of stress. We measured heart rates of incubating female common eider ducks (Somateria mollissima) to determine whether our drone-based population survey affected them. To do so, we used heart-rate recorders placed in nests to quantify their heart rate in response to a quadcopter drone flying transects 30 m above the nesting colony. Eider heart rate did not change from baseline (measured in the absence of drone survey flights) by a drone flying at a fixed altitude and varying horizontal distances from the bird. Our findings suggest that carefully planned drone-based surveys of focal species have the potential to be carried out without causing physiological impacts among colonial-nesting eiders.

Effects of dietary substitution of peanut meal for soybean meal on egg production, egg quality, oxidative status, and yolk fatty acid profile in laying ducks.

There is an urgent need to evaluate and introduce alternatives for the unsustainable and traditional feed stuffs in poultry. This study evaluated the effects of graded replacement of soybean meal (SBM) by peanut meal (PNM) on egg production, egg quality, oxidative status, and yolk fatty acid profile in laying ducks. In total, 360 Longyan ducks aged 21 weeks were allocated to five treatments, each containing six replicates of 12 birds. Birds were fed the diets containing PNM replacing 0 (control), 25, 50, 75 or 100% of SBM for 16 weeks. With the increase of PNM level, egg production was improved (quadratic, P < 0.05), egg weight and feed consumption were decreased, feed conversion ratio and egg mass were impaired at 100% PNM, and yolk colour was enhanced (quadratic, P < 0.05). Plasma malondialdehyde concentration was increased at 100% PNM, while plasma glutathione concentration was decreased (quadratic, P < 0.01) as PNM substitution increased. Total cholesterol content in yolk decreased (P < 0.01) in response to increased PNM substitution. The contents of saturated fatty acids C20:0 and C22:0 in yolk increased (linear or quadratic, P < 0.05) with increased PNM substitution, but the contents of saturated fatty acid C18:0, monounsaturated fatty acid C22:1, and polyunsaturated fatty acids C18:3n-3 and C22:6n-3 in yolk were decreased (linear, P < 0.05) as PNM replacement increased. The contents in yolk of polyunsaturated fatty acid C18:2n-6, C20:2n-6, C20:3n-6, C20:4n-6, and total amount of polyunsaturated fatty acids increased with the highest contents obtained at 75% PNM substitution. The ratio between n-6 and n-3 increased (linear, P < 0.05) as PNM substitution increased. The transcript abundance in liver of peroxisome proliferators-activated receptors γ and fatty acid synthase showed quadratic (P < 0.05) responses with PNM replacement, with the highest expression of both genes being obtained with 75% substitution with PNM. Replacement of dietary SBM with 100% PNM decreased egg production and antioxidant capacity and increased the ratio of omega fatty acid in yolk between n-6 and n-3 in laying ducks. The obtained results indicate that PNM can be used to replace up to 75% of SBM in the diet of laying ducks without negative effects on the egg-laying production or egg quality. The regression model indicated that the maximal egg mass was obtained at no more than 67.6% replacement of SBM with PNM in the diet of laying ducks.

Underwater hearing in sea ducks with applications for reducing gillnet bycatch through acoustic deterrence.

As diving foragers, sea ducks are vulnerable to underwater anthropogenic activity, including ships, underwater construction, seismic surveys and gillnet fisheries. Bycatch in gillnets is a contributing source of mortality for sea ducks, killing hundreds of thousands of individuals annually. We researched underwater hearing in sea duck species to increase knowledge of underwater avian acoustic sensitivity and to assist with possible development of gillnet bycatch mitigation strategies that include auditory deterrent devices. We used both psychoacoustic and electrophysiological techniques to investigate underwater duck hearing in several species including the long-tailed duck (Clangula hyemalis), surf scoter (Melanitta perspicillata) and common eider (Somateria mollissima). Psychoacoustic results demonstrated that all species tested share a common range of maximum auditory sensitivity of 1.0-3.0 kHz, with the long-tailed ducks and common eiders at the high end of that range (2.96 kHz), and surf scoters at the low end (1.0 kHz). In addition, our electrophysiological results from 4 surf scoters and 2 long-tailed ducks, while only tested at 0.5, 1 and 2 kHz, generally agree with the audiogram shape from our psychoacoustic testing. The results from this study are applicable to the development of effective acoustic deterrent devices or pingers in the 2-3 kHz range to deter sea ducks from anthropogenic threats.