Centennial Review: History and husbandry recommendations for raising Pekin ducks in research or commercial production

CVAE-DF: A hybrid deep learning framework for fertilization status detection of pre-incubation duck eggs based on VIS/NIR spectroscopy

Unfertilized duck eggs not removed prior to incubation will deteriorate quickly, posing a risk of contaminating the normally fertilized duck eggs. Thus, detecting the fertilization status of breeding duck eggs as early as possible is a meaningful and challenging task. Most existing work usually focus on the characteristics of chicken eggs during mid-term hatching. However, little attention has been paid to the detection for duck eggs prior to incubation. In this paper, we present a novel hybrid deep learning detection framework for the fertilization status of pre-incubation duck eggs, termed CVAE-DF, based on visible/near-infrared (VIS/NIR) transmittance spectroscopy. The framework comprises the encoder of a convolutional variational autoencoder (CVAE) and an improved deep forest (DF) model. More specifically, we first collected transmittance spectral data (400-1000 nm) of 255 duck eggs before hatching. The multiplicative scatter correction (MSC) method was then used to eliminate noise and extraneous information of the raw spectral data. Two efficient data augmentation methods were adopted to provide sufficient data. After that, CVAE was applied to extract representative features and reduce the feature dimension for the detection task. Finally, an improved DF model was employed to build the classification model on the enhanced feature set. The CVAE-DF model achieved an overall accuracy of 95.94 % on the test dataset. These experimental results in terms of four metrics demonstrate that our CVAE-DF method outperforms the traditional methods by a significant margin. Furthermore, the results also indicate that CVAE holds great promise as a novel feature extraction method for the VIS/NIR spectral analysis of other agricultural products. It is extremely beneficial to practical engineering.

New evidence for gut-muscle axis: Lactic acid bacteria-induced gut microbiota regulates duck meat flavor

The interaction between gut microbiota and muscles through the gut-muscle axis has received increasing attention. This study attempted to address existing research gaps by investigating the effects of gut microbiota on meat flavor. Specifically, lactic acid bacteria were administered to ducks, and the results of e-nose and e-tongue showed significantly enhanced meat flavor in the treatment group. Further analyses using GC-MS revealed an increase in 6 characteristic volatile flavor compounds, including pentanal, hexanal, heptanal, 1-octen-3-ol, 2,3-octanedione, and 2-pentylfuran. Linoleic acid was identified as the key fatty acid that influences meat flavor. Metagenomic and transcriptomic results further confirmed that cecal microbiota affects the duck meat flavor by regulating the metabolic pathways of fatty acids and amino acids, especially ACACB was related to fatty acid biosynthesis and ACAT2, ALDH1A1 with fatty acid degradation. This study sheds light on a novel approach to improving the flavor of animal-derived food.

Ferroptosis: First evidence in premature duck ovary induced by polyvinyl chloride microplastics

Ferroptosis is frequently observed in fibrosis and diseases related to iron metabolism disorders in various mammalian organs. However, research regarding the damage mechanism of ferroptosis in the female reproductive system of avian species remains unclear. In this study, Muscovy female ducks were divided into three groups which were given purified water, 1 mg/L polyvinyl chloride microplastics (PVC-MPs) and 10 mg/L PVC-MPs for two months respectively, to investigate the ferroptosis induced by PVC-MPs caused ovarian tissue fibrosis that lead to premature ovarian failure. The results showed that the high accumulation of PVC-MPs in ovarian tissue affected the morphology and functional activity of ovarian granulosa cells (GCs) and subsequently caused the follicular development disorders and down-regulated the immunosignaling of ovarian steroidogenesis proteins 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), CYP11A1 cytochrome (P450-11A1) and CYP17A1 cytochrome (P450-17A1) suggested impaired ovarian function. In addition, PVC-MPs significantly up-regulated positive expression of collagen fibers, significantly increased lipid peroxidation and malondialdehyde (MDA) level, along with encouraged overload of iron contents in the ovarian tissue were the characteristics of ferroptosis. Further, immunohistochemistry results confirmed that immunosignaling of ferroptosis related proteins Acyl-CoA synthetase (ACSL4), Cyclooxygenase 2 (COX2) and ferritin heavy chain 1 (FTH1) were significantly increased, but solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase (GPX4) were decreased by PVC-MPs in the ovarian tissue. In conclusion, our study demonstrates that PVC-MPs induced ferroptosis in the ovarian GCs, leading to follicle development disorders and ovarian tissue fibrosis, and ultimately contributing to various female reproductive disorders through regulating the proteins expression of ferroptosis.

Classification of Behaviour in Conventional and Slow-Growing Strains of Broiler Chickens Using Tri-Axial Accelerometers

Behavioural states such as walking, sitting and standing are important in indicating welfare, including lameness in broiler chickens. However, manual behavioural observations of individuals are often limited by time constraints and small sample sizes. Three-dimensional accelerometers have the potential to collect information on animal behaviour. We applied a random forest algorithm to process accelerometer data from broiler chickens. Data from three broiler strains at a range of ages (from 25 to 49 days old) were used to train and test the algorithm, and unlike other studies, the algorithm was further tested on an unseen broiler strain. When tested on unseen birds from the three training broiler strains, the random forest model classified behaviours with very good accuracy (92%) and specificity (94%) and good sensitivity (88%) and precision (88%). With the new, unseen strain, the model classified behaviours with very good accuracy (94%), sensitivity (91%), specificity (96%) and precision (91%). We therefore successfully used a random forest model to automatically detect three broiler behaviours across four different strains and different ages using accelerometers. These findings demonstrated that accelerometers can be used to automatically record behaviours to supplement biomechanical and behavioural research and support in the reduction principle of the 3Rs.

Vocalizations of the Pekin duck (Anas platyrhynchos domesticus): how stimuli, sex, and social groups affect their vocal repertoire

Pekin ducks are exposed to stressors such as heat stress, enteric pathogens, mycotoxins, and other environmental stressors. We know from wild bird literature that birds communicate through vocalizations. We hypothesized that Pekin ducks would have a diverse repertoire that is affected by the sex, social group, and specific stimuli. We utilized adult Pekin ducks to develop a vocal repertoire. We placed 1 to 4 ducks of varying sexes into a sound chamber with various stimuli used to encourage new vocalizations. Birds were recorded for 20 min with several variations of number and sexes of ducks. Once the ducks were recorded each vocalization that was clipped was named based on a predetermined naming system. We characterized the vocal system of the ducks under each stimulus and social treatment in 4 ways: overall call rates, call diversity, call repertoire, and call spectral properties. In all cases, normality of residuals and homogeneity of variances for GLM and ANOVA models were confirmed using Proc Univariate (SAS v9.4) where a p ≤ 0.05 was considered significant. We found that Pekin ducks produce up to 16 different vocalizations. The treatments had a significant effect on the overall rate of calls given by the ducks (ANOVA: F6,31 = 8.55, p < 0.0001). Ducks produced the most calls by far when someone was sitting in the chamber with them (30.04 ± 4.45 calls/min). For call diversity, we found that there was a significant main effect of hen number (F218 = 12.21, p = 0.0004) but no main effect of drake number (F3,18 = 3.04, p = 0.0555). Cluster analyses indicated that certain types of calls were given under specific conditions. There were generally 6 major clusters of vocal repertoires (R-square = 0.899, Cubic Clustering Criterion = 9.30). Our results suggest that Pekin ducks are affected by the types of stimuli and social environment in how much they vocalize and in the properties of the calls they use. In addition, males and females differ somewhat in the repertoire of the calls they use, and in the spectral properties of their calls.

Insect live larvae as a new nutritional model in duck: effects on gut health

BACKGROUND

This study aimed to evaluate the effects of Hermetia illucens (Black soldier fly-BSF) and Tenebrio molitor (Yellow mealworm-YMW) live larvae as a new nutritional model on duck's gut health, considering gut histomorphometry, mucin composition, cytokines transcription levels, and microbiota. A total of 126, 3-days-old, females Muscovy ducks were randomly allotted to three dietary treatments (6 replicates/treatment, 7 birds/pen): (i) C: basal diet; (ii) BSF: C + BSF live larvae; (iii) YMW: C + YMW live larvae. BSF and YMW live larvae were administered on top of the basal diet, based on the 5% of the expected daily feed intake. The live weight, average daily gain, average daily feed intake and feed conversion ratio were evaluated for the whole experimental period. On day 52, 12 ducks/treatment (2 birds/replicate) were slaughtered and samples of duodenum, jejunum, ileum, spleen, liver, thymus and bursa of Fabricius were collected for histomorphometry. Mucin composition was evaluated in the small intestine through histochemical staining while jejunal MUC-2 and cytokines transcription levels were evaluated by rt-qPCR. Cecal microbiota was also analyzed by means of 16 S rRNA gene sequencing.

RESULTS

Birds' growth performance and histomorphometry were not influenced by diet, with a proximo-distal decreasing gradient from duodenum to ileum (p < 0.001), respecting the physiological gut development. Mucin staining intensity and MUC-2 gene expression did not vary among dietary treatments, even though mucin intensity increased from duodenum to ileum, according to normal gut mucus physiology (p < 0.001). Regarding local immune response, IL-6 was higher in YMW group when compared to the other groups (p = 0.009). Insect live larvae did not affect cecal microbiota diversity, but BSF and YMW groups showed a higher presence of Helicobacter, Elusimicrobium, and Succinatimonas and a lower abundance of Coriobacteriaceae and Phascolarctobacterium compared to C birds (p < 0.05).

CONCLUSIONS

The use of BSF and YMW live larvae as new nutritional model did not impair gut development and mucin composition of Muscovy ducks, but slightly improved the intestinal immune status and the microbiota composition by enhancing regulatory cytokine IL-6 and by increasing minor Operational Taxonomic Units (OTUs) involved in short-chain fatty acids production.

Nutritional Considerations for Juvenile Exotic Companion Animals

Pediatric exotic companion animal nutrition is a broad topic, spanning small mammals, reptiles, and birds. Little research has been performed focusing on the juvenile life stages of these species because they are largely acquired by clients at the young adult stage. The information that does exist has been compiled by wildlife rehabilitators, commercial breeders, and/or exotic captive breeding programs, such as those that exist in zoologic facilities. In this article, we discuss natural history, feeding strategies, energy requirements, digestive physiology and diet digestibility, and key nutrients of concern as factors for determining an appropriate diet for pediatric exotic species.

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.

Preening cups increase apparent wet preening behaviors, but have no impact on other behaviors, body condition, growth, or body morphometrics of grow-out Pekin ducks

Preening cups may be a form of open water that would allow ducks to express preening behaviors. We set out to test the hypothesis that preening cups would not have detrimental effects on ducks or their environment. Control pens (N = 6, 65 ducks/pen) had nipple lines while experimental pens (N = 6, 65 ducks/pen) had the same nipple line plus one preening cup (PC). Body weights of 30 ducks per pen, and body condition scores on 50 ducks per pen were recorded weekly. On d 18 and 43, 5 ducks per pen were euthanized and their spleens, Bursas, liver, and uropygial glands were weighed. Behavior data were collected using scan sampling with video being recorded for 72 continuous hours at 4 different ages: 25 d, 30 d, 36 d, and 40 d. Body morphometrics were analyzed by 2-way ANOVA with repeated measures. Body condition scoring was analyzed by Pearson's chi-square. The GLIMMIX procedure (SAS 9.4) was used for behavioral analyses to examine treatment differences in the proportion of ducks performing dry preening, wet preening, eating, drinking, standing, and laying down. Feather pecking, feather picking, preening conspecifics (also known as allopreening), dunking head, and drinking from preening cup were analyzed using PROC LOGISTIC with the Firth bias correction for quasi-complete separation and odds ratios were calculated. More PC ducks housed with PC performed wet preening compared to control ducks (25 d: F1,26 = 6.90, P = 0.0143; 30, 36, and 40 d; F1,78 = 24.53, P < 0.0001). Ducks in the PC group were also more likely to lay down compared to controls (25 d: F1,33 = 4.95, P = 0.0330). No differences were observed for any other behavior, body condition score, body weight or morphometrics at any age. Although ducks in the preening cup group showed an increase in wet preening, our data suggest that open water is not necessary to maintain feather condition or uropygial gland size.

Metabolomic characterization of Liancheng white and Cherry Valley duck breast meat and their relation to meat quality

Liancheng white duck is a typical local duck breed in Fujian Province famous for its meat traits. To better understand how meat quality varies with breed, the chemical composition of breast meats of Liancheng white ducks (LD) and Cherry Valley ducks (CD) were examined using ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS).The correlation between meat quality and the differential metabolites was further analyzed. The results showed that the effects of breed on duck breast meat were significant for pH, color, cooking loss, and shear force. Liancheng white duck breast meat exhibited a higher shear force and pH, and lower cooking loss and lightness (L*24), redness (a*24), and yellowness (b*24) than CD. Metabolomic analysis revealed significant differences between the meat extracts from the 2 duck breeds. A total of 49 and 57 significantly different metabolites were identified in positive and negative ion modes, respectively. These differentially accumulated metabolites (DAMs) could be divided into 28 classes, of which the 4 main categories were carbohydrates, amino acids, fatty acids, and eicosanoids. Liancheng white duck might have better nutritional and medicinal value considering the higher content of (4Z,7Z,10Z,13Z,16Z,19Z)-4,7,10,13,16,19-docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA), and prostaglandinF3α (PGF3α), having anti-inflammatory orantioxidant effects. Carbohydrate concentration negatively correlated with pH24. The 4 metabolites positively correlated with the shear force. These results provide an overall perspective for bridging the gap between variation of duck meat quality and metabolites with respect to breed.

Experimental pathogenesis of aquatic bird bornavirus 1 in Pekin ducks

Aquatic bird bornavirus 1 (ABBV-1) is a neurotropic virus that causes persistent infection in the nervous system of wild waterfowl. This study evaluated whether Pekin ducks, the most common waterfowl raised worldwide, are susceptible to ABBV-1 infection and associated disease. Groups of Pekin ducks were inoculated with ABBV-1 through the intracranial (IC; n, 32), intramuscular (IM; n, 30), and choanal (CH; n, 30) routes. Controls (CO; n, 29) received carrier only. At 1, 12, and 21 weeks postinfection (wpi), 7-14 birds were euthanized to assess virus distribution and lesions. Infection rates in the IC and IM groups were over 70%, while only 4 ducks in the CH group became infected. Neurological signs were observed in 8 ducks only, while over 25% of IC and IM birds had encephalitis and/or myelitis. Seroconversion was highest in the IC and IM groups, and mucosal ABBV-1 RNA shedding was most frequent in the IC group (53%). None of the fertile eggs laid during the experiment tested positive for ABBV-1 RNA. This study shows that Pekin ducks are permissive to ABBV-1 infection and partly susceptible to associated disease. While mucosal shedding may be an important route of transmission, congenital infection appears unlikely.

Chronic Heat Stress Part 2: Increased Stress and Fear Responses in F1 Pekin Ducks Raised from Parents That Experienced Heat Stress

The effects of HS on the welfare of poultry have been reported to have a transgenerational effect on phenotype plasticity. The goal of our experiment was to determine whether parental exposure to HS would impair the performance, HPA axis response, or behavior of their offspring. We treated adult drakes and hens (n = 80 ducks/treatment) at peak lay with HS or the control temperature for 3 weeks and incubated eggs collected from the last 3 days of the experiment. We utilized 76 ducklings/parental treatment group: control (CON-F1) and HS (HS-F1). Weekly data for body weights, body condition scores (BCSs), and novel object test (NOT) were collected. At 3 weeks of age, the ducks (n = 6/treatment) were subjected to adrenocorticotropic hormone (ACTH/cosyntropin, 0.0625 mg/kg) challenge or vehicle as the control. Blood samples were collected at 0, 1, 2, 3, and 4 h relative to treatment for serum glucocorticoid and heterophil-to-lymphocyte ratio (HLR) analyses. All injected birds were euthanized with pentobarbital on the second day relative to ACTH administration, and the spleen and bursa were removed and weighed immediately. Duck level analyses were completed using one- or two-way ANOVA as appropriate. BCSs were analyzed using a chi-squared test. The HS-F1 ducks had a lower hatch weight (p < 0.05) compared with the CON-F1 ducks but no significant difference in growth rates during the 5-week period. NOT (n = 4) analyses showed that the HS-F1 ducks had a greater fear response (p < 0.001) compared with the CON-F1 ducks. Similarly, an ACTH stimulation test showed that the HS-F1 ducks had significantly (p < 0.05) heightened corticosterone and HLR responses compared with the CON-F1 ducks. The HS-F1 ducks showed altered baseline and ACTH-stimulated levels of cortisol compared with the controls. Our data suggest that parental exposure to HS impacts the HPA response and fearfulness of the F1 generation in Pekin ducks.

Strategies to improve genomic predictions for 35 duck carcass traits in an F2 population

BACKGROUND

Carcass traits are crucial for broiler ducks, but carcass traits can only be measured postmortem. Genomic selection (GS) is an effective approach in animal breeding to improve selection and reduce costs. However, the performance of genomic prediction in duck carcass traits remains largely unknown.

RESULTS

In this study, we estimated the genetic parameters, performed GS using different models and marker densities, and compared the estimation performance between GS and conventional BLUP on 35 carcass traits in an F₂ population of ducks. Most of the cut weight traits and intestine length traits were estimated to be high and moderate heritabilities, respectively, while the heritabilities of percentage slaughter traits were dynamic. The reliability of genome prediction using GBLUP increased by an average of 0.06 compared to the conventional BLUP method. The Permutation studies revealed that 50K markers had achieved ideal prediction reliability, while 3K markers still achieved 90.7% predictive capability would further reduce the cost for duck carcass traits. The genomic relationship matrix normalized by our true variance method instead of the widely used [Formula: see text] could achieve an increase in prediction reliability in most traits. We detected most of the bayesian models had a better performance, especially for BayesN. Compared to GBLUP, BayesN can further improve the predictive reliability with an average of 0.06 for duck carcass traits.

CONCLUSION

This study demonstrates genomic selection for duck carcass traits is promising. The genomic prediction can be further improved by modifying the genomic relationship matrix using our proposed true variance method and several Bayesian models. Permutation study provides a theoretical basis for the fact that low-density arrays can be used to reduce genotype costs in duck genome selection.

Welfare of ducks, geese and quail on farm

This Scientific Opinion concerns the welfare of Domestic ducks (Anas platyrhynchos domesticus), Muscovy ducks (Cairina moschata domesticus) and their hybrids (Mule ducks), Domestic geese (Anser anser f. domesticus) and Japanese quail (Coturnix japonica) in relation to the rearing of breeders, birds for meat, Muscovy and Mule ducks and Domestic geese for foie gras and layer Japanese quail for egg production. The most common husbandry systems (HSs) in the European Union are described for each animal species and category. The following welfare consequences are described and assessed for each species: restriction of movement, injuries (bone lesions including fractures and dislocations, soft tissue lesions and integument damage and locomotory disorders including lameness), group stress, inability to perform comfort behaviour, inability to perform exploratory or foraging behaviour and inability to express maternal behaviour (related to prelaying and nesting behaviours). Animal-based measures relevant for the assessment of these welfare consequences were identified and described. The relevant hazards leading to the welfare consequences in the different HSs were identified. Specific factors such as space allowance (including minimum enclosure area and height) per bird, group size, floor quality, characteristics of nesting facilities and enrichment provided (including access to water to fulfil biological needs) were assessed in relation to the welfare consequences and, recommendations on how to prevent the welfare consequences were provided in a quantitative or qualitative way.

Catecholamine concentrations in duck eggs are impacted by hen exposure to heat stress

Rapid "fight-or-flight" responses to stress are largely orchestrated by the catecholamines. Moreover, catecholamines and catecholamine precursors are widely recognized to act as interkingdom signaling molecules among host and microbiota, as well as to serve as chemotactic signals for bacterial foodborne pathogens. While albumen and yolk concentrations of glucocorticoids have received extensive attention as non-invasive indicators of hen response to stress, little is known regarding the impact of the hen's stress response on in ovo catecholamine and catecholamine precursor concentrations. The aim of the present study was to determine norepinephrine and L-dopa concentrations in albumen and yolk of eggs laid by hens maintained under normal or heat stress conditions. Norepinephrine and L-dopa concentrations were also measured in oviductal tissue. Breeder ducks (∼35 weeks/age) were kept under normal (22°C) conditions or subjected to cyclical heat stress (35°C day/29.5°C night) for 3 weeks. Eggs (n = 12 per timepoint/group) were collected on a weekly basis. Hens were sacrificed at baseline or after 3 weeks of heat stress for oviductal tissue collection. Albumen, yolk, and oviduct concentrations of norepinephrine and L-dopa were determined using ultra high-performance liquid chromatography with electrochemical detection. Norepinephrine and L-dopa were detected in oviductal tissue as well as egg albumen and yolk. Norepinephrine concentrations were elevated (p < 0.05) in the yolk of eggs laid by the heat stress group compared to those of the control group. Norepinephrine concentrations in albumen were elevated (p < 0.05) in the heat stress group compared to control group at week 2. L-dopa concentrations were not significantly affected (p > 0.05) by heat stress in albumen, yolk, or oviductal tissue. Together, the present study provides the first evidence of the stress neurohormone, norepinephrine, in duck eggs and identifies that hen exposure to heat stress can affect in ovo norepinephrine concentrations. These data highlight the potential utility of in ovo catecholamine concentrations as non-invasive measures of the hen's response to stress, as well as warrants future research into whether hen deposition of stress-related neurochemicals into the egg could serve as a chemotactic signal in the vertical transmission of foodborne pathogens.

Effects of Swimming Pool Conditions and Floor Types on White Roman Geese's Physical Condition Scores and Behaviors in an Indoor Rearing System

Biosecurity problems, including the continual risk of avian influenza spread by wild birds, have severely affected traditional free-range waterfowl production systems. Regulations and techniques for indoor goose production require more considerations for animal welfare. This study investigated the effects of swimming pool conditions and different floor types on the physical condition scores and behaviors of indoor-reared White Roman geese. A total of 48 male and 48 female White Roman geese reared from the age of 15 to 84 days were randomly allocated to pens with or without a swimming pool and with either mud or perforated plastic floors. Providing a swimming pool improved geese's eye and feather cleanliness and breast blister scores at the age of 84 days. Compared with geese reared on a mud floor, those reared on a perforated plastic floor had better feather cleanliness and higher breast blister scores at the age of 56 and 84 days. Providing a swimming pool to indoor-reared geese may reduce the proportion of abnormal behaviors, such as injurious feather pecking, by increasing water-related behaviors. This study suggests a more appropriate environment design for better balancing commercial goose production with animal welfare in an indoor rearing system.

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 3 weeks 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.

Poultry nutrition

Nutrition is the most important environmental factor affecting development, health status, growth performance and profitability of poultry production. Feeds for poultry constitute up to 70–75% of total production costs. Poultry nutrition differs considerably from that of other livestock, which is determined by the specific anatomy of the gastrointestinal tract. Protein, energy, fat, fiber, minerals, vitamins, and water are of basic importance for poultry nutrition and their content in feeds must cover the requirement that differ depending on the bird’s age and species. In general, feed protein must be of good value including the content of essential amino acids. Among them lysine, methionine, cysteine, threonine and tryptophan are the limiting ones. The main ingredient of poultry feeds are cereal grains, i.e. wheat and maize, which predominantly constitute an energy source because their protein content is insufficient for birds. Because of that cereals cannot be the only feed for poultry and must be combined with protein sources such as soybean or rapeseed meal, legume seeds or protein concentrates. Despite birds’ requirement for nutrients and chemical composition of feeds are well known, nutrition must face many problems. One of the most important issues is to find alternatives to antibiotic growth promoters.

The Impacts of Female Access during Rearing on the Reproductive Behavior and Physiology of Pekin Drakes, and Flock Fertility

Simple Summary

Male and female ducklings are typically reared in same-sex groups. With the goal of improving the males’ reproductive performance, and overall flock fertility, some flock owners place several female ducklings into the otherwise all-male pens during rearing. However, the relationships between rearing, drake reproductive success, and flock fertility have not been confirmed. To fill these knowledge gaps, we compared the frequencies of correctly oriented mounts and circulating testosterone levels of drakes reared with and without physical access to females, and the impacts of these rearing treatments on flock fertility. Rearing treatment did not impact any of the measured variables; however, all were affected by age. Individual variation in behavior and testosterone measures were noted in both treatment groups. We conclude that rearing male ducklings with auditory and visual, but without physical access to female ducklings is sufficient for promoting reproductive behavior and physiology, and securing high fertility within this Pekin duck breed.

Abstract

Commercially housed Pekin ducks (Anas platyrhynchos) are typically reared in same sex groups to facilitate separate diet provisioning. Several female ducklings are sometimes mixed into the otherwise all-male pens. This practice is thought to increase flock reproductive success. To evaluate this hypothesis, we reared ducklings in alternating same-sex groups (150 hens or 30 drakes/pen; 8 groups/sex) and evaluated the impacts of rearing on drake mounting behavior, testosterone levels, and flock fertility. At 12 days, three females were placed into four of the male duckling pens. At 20–22 weeks of age, adjacent male and female pens were moved into pens within a breeder barn, and combined to form mixed-sex pens. The number of correctly aligned mounts performed by 10 focal drakes per pen was evaluated over 3 days (12 h/day) at 26, 32, and 45 weeks of age. Circulating testosterone concentrations were analyzed from blood plasma samples collected from the focal drakes at 15 (baseline), 22, 28, 34 and 45 weeks of age. Pen-level fertility was determined at 33–34 and 45–46 weeks of age. Mount and testosterone data were analyzed using a Generalized Linear Mixed Model and a Linear Mixed Model in R 4.0.5, with duck in pen as a random effect. A Linear Mixed Model was used to analyze fertility data, with pen as a random effect. None of the measured variables were impacted by rearing treatment, but all varied with flock age. Physical access to female ducklings during rearing did not enhance flock reproductive success.

Investigation of volatile flavor compounds and characterization of aroma-active compounds of water-boiled salted duck using GC-MS-O, GC-IMS, and E-nose

To clarify the characteristic aroma substances of water-boiled salted duck (WSD), headspace-gas chromatography-mass spectrometry-olfactometry (HS-GC-MS-O), gas chromatography-ion mobility spectrometry (GC-IMS) combined with an electronic nose (E-nose) were used to analyze the volatile flavor profile of three types of WSD (containing four samples). Thirty-one and fifty volatile flavor components were identified by GC-MS and GC-IMS, including aldehydes, alcohols, esters, ketones, hydrocarbons, and others. The characteristic aroma compounds of WSD, including pentanal, hexanal, heptanal, octanal, nonanal, (E)-2-octenal, benzaldehyde, (E)-2-nonenal, decanal, 1-octen-3-ol, 1-octanol, 1-pentanol, ethyl acetate, d-limonene, and 2-pentylfuran, were confirmed by GC-O, odor activity values (OAVs), and aroma-recombination and omission experiments. The aroma description of these aroma-active compounds can be divided into 6 categories, namely, "fruity", "mushroom", "fat", "sweet", "faint scent" and "potato, scorch" aromas. The difference between samples was mainly caused by the differential volatile compounds, followed by the identification method.

Setting research driven duck-welfare standards: a systematic review of Pekin duck welfare research

Globally, the production of Pekin ducks for meat and eggs is considerable, with an estimated >200 million ducks slaughtered yearly for their meat in the United States and the European Union alone. However, despite the size of the Pekin duck industries, there is a lack of research-based guidance regarding the welfare of the ducks. The purpose of this systematic review is to examine and summarize available scientific literature related to the welfare of Pekin ducks raised on commercial farms for meat and eggs. Specifically, we aimed to identify topics where sufficient literature exists to support best-practice duck welfare recommendations, as well as further research needs. The literature search targeted original research papers and review articles published in English. Six pre-establish inclusion/exclusion criteria were applied, yielding 63 publications. We summarized their content based their main topic of focus. For all original studies, we additionally recorded the country where the study was executed, scale of the project (commercial or experimental barns), general information about the housing system and management (waterers, flooring, ventilation, group size, and space allowance), and the types of outcome variables collected. We begin with an overview of key publication trends. We then synthesize and discuss welfare outcomes related to key housing/management decisions: bathing water, flooring and litter, stocking density and space availability, ventilation/air quality, lighting, outdoor access, and for egg laying birds the availability of nest boxes. Throughout, we outline specific research gaps, as well as overarching research needs.

Water for Domestic Ducks: The Benefits and Challenges in Commercial Production

Although we have been farming ducks for at least 4,000 years, with some accounts suggesting domestication having begun more than 38,000 years ago, there are still many unknowns for optimizing domestic duck welfare in a commercial setting. Ducks being waterfowl, are semi-aquatic and have unique behavioral needs when compared to other commonly farmed poultry species. Providing ducks with open water which allows for full body immersion so that they may perform their full repertoire of water-related behaviors is important for their health and welfare. However, in a commercial setting this remains challenging due to biosecurity, contamination, health, and management concerns. An important question is therefore how best to provide ducks with a commercially feasible and safe water source in which they can derive maximum welfare and health benefits with no adverse consequences to health or global water resources. This review considers the amount of water provision necessary to satisfy duck's water-related needs to enhance yet not compromise their welfare in a commercial setting based on current knowledge, as well as identifies the outstanding questions for future research to address.