Breeding success in the broiler chicken has been accompanied by gait problems which are detrimental to productivity and welfare. Although these gait issues have not been reported to the same extent in Pekin ducks, there is concern that such problems will manifest if the duck continues on its current selection trajectory. In order to understand how changes in morphology due to selection have affected gait in both species, divergent lines were objectively assessed for gait using a pressure platform (12 birds per line at three, five and seven weeks of age). The broiler chicken was compared to the slower growing layer chicken and the Pekin duck to its slower growing ancestor, the mallard. Two breeding lines of Pekin duck were also assessed. After gait assessment, the leg bones (femur and tibiotarsus) were scanned by computed tomography to measure morphological changes which have occurred due to selection for high growth and meat yield. Results were analysed by ANOVA, accounting for age and sex. During walking, heavy lines walked at a slower velocity, displayed a wider stance and spent more time supporting their mass on both feet than their lighter conspecifics, strategies which are likely to improve balance. The foot angle while walking differed between lines; all duck lines rotated their feet internally whereas the layer chickens’ feet were aligned with the direction of travel. Conversely the broiler chicken rotated its feet externally by seven weeks of age. Morphologically, the main differences were between species. Duck lines reached adult leg size earlier than chickens, which may be a response to differing adaptive environments prior to domestication. This early cessation of bone growth in ducks may provide more opportunity for the bones to remodel to handle the loads imposed on them. Lower levels of porosity and a unique cortical architecture observed in ducks endow relatively greater bone strength. Bone curvature also differed between species; the tibiotarsus curved more laterally in ducks than in chickens and may be a swimming adaptation that hinders locomotion on land in the modern production bird. In order to improve the objectivity of selection for better gait in poultry, the genetic parameters of gait components selected on the basis of results in this thesis were estimated using a linear mixed model in a population of Pekin ducks of known pedigree. As they are a simpler measure, similar or improved heritability estimates were estimated for these gait components when compared with the standard commercial gait score which is based on a subjective view of walking ability. Intense selection for economic traits has altered gait in similar ways in both species. To improve gait in poultry, greater breeding success may be achieved by focussing on those components of gait which have changed through selection, rather than using a subjective overall visual gait score. Furthermore, in both species, adaptations for pre-domesticated life may have affected the ability with which the selected lines have accommodated their gait to other morphological changes associated with increasing body mass.

No description available.

No description available.

<p>  </p> <p>Glucocorticoids (GC) play a critical role in regulating the physiological response to stress. Disruptions to baseline levels due to stress can have negative implications on a variety of factors including growth and development, physical body conditions, metabolism, immune functions, and expression of normal behaviors, although this list is not exhaustive. When birds are unable to adapt to the stressor and return to homeostasis, the energy expenditure associated with the failed attempt at coping can lead to significant declines in the overall health, welfare, production, and performance of the bird. This can go on to impact producers and consumers as well, indicating the extensive repercussions of stress. Recently, scientists have been investigating thorough and efficient methods of quantifying stress in birds, such as measuring heterophil-to-lymphocyte ratio (HLR) or detecting glucocorticoid levels through enzyme-linked immunoassays (ELISA). However, the precise mechanism behind HLR increase during stress is unknown and ELISAs may not provide accurate results depending on when the blood is being measured. </p> <p><br></p> <p>GC are differentially released and exert their effects in a manner that is dependent on sex, age, and time. However, before investigating this, it was critical to validate the GC kits to ensure that they were measuring cortisol and corticosterone separately along with zero cross reactions with other precursors. Chapter 2 had 4 experiments carried out. The objective of experiment 1 was to validate ELISAs to ensure that they were measuring the GC accurately and separately since both cortisol and corticosterone were being measured. To do this, duck serum was pooled and charcoal-stripped to remove the presence of steroids. 3 standard curves were run to confirm that there was no cross reactivity. The objective of experiment 2 was to further validate the ELISA kits with mass spectrometry by checking for both glucocorticoids in the pooled samples. Once the validation process was complete, experiment 3 was carried out to look at the effect of ACTH stimulation on GC release. 16-week-old drakes and hens were given either intramuscular (IM) injections of cosyntropin (0.06 mg/kg) or saline as control. The cosyntropin dose was chosen according to previous studies reporting relatively high physiological responses, therefore, we wanted to replicate this. N was 10/sex/treatment. Blood was then collected at 0, 1, and 2 hours after injections and serum was analyzed by ELISAs. Lastly for experiment 4, 14-week-old developer drakes and hens at Maple Leaf Farms were assessed for a transportation stress experiment. Blood from 10 ducks/sex/time/barn were collected at 24 hours before transport to the breeder barn, immediately after a 1-hour transport, 24 hours after, and 1 week after transport. The results from experiment 1 yielded that both cortisol and corticosterone can be measured without the presence of unwanted contaminants or other products. Experiment 2 identified the greater sensitivity of mass spectrometry when reading GC levels, although the differences were linear. Experiment 3 showed that serum corticosterone levels were significantly increased at 1 hour after ACTH injections in both drakes and hens, with levels continuing to increase for the drakes. Serum cortisol levels were significantly increased at 1 hour after ACTH injections in both sexes, however, the hens had greater levels compared to the drakes. Serum cortisol levels returned to levels similar to that of saline-injected ducks at the 2-hour mark. Lastly, the transportation stress portion showed that cortisol was released at about 1/3 of corticosterone levels in both sexes. Hens showed increased levels of serum corticosterone compared to drakes at all time points except for 1 week after transport, and also had significantly increased serum cortisol levels at all time points. In conclusion, the ELISA kits were verified for future use when measuring GC as well as mass spectrometry. GC were detected in the ACTH and transportation stress experiments with hens displaying a greater sensitivity to GC release due to increased circulating levels compared to drakes. Although it was nonsignificant, there was a trend for GC to increase in response to transport. </p> <p><br></p> <p>There are sex differences in GC release and HLR for Pekin ducks and various challenges from the studies support this. With hens showing increased sensitivity to stress and drakes with more transient and gradual levels, we have consistently seen that both GC have differential roles in the stress response and not only is it critical to study both hormones, the timing of when measurements are taken are important as well to get a clear understanding of when the stress response is initiated. </p> <p><br></p> <p>Chapter 3 went further to understand the response of GC and HLR. The objective was to  investigate the release of cortisol and corticosterone in response to an ACTH dose response challenge. In Chapter 2, only one dose of cosyntropin was used and sample collection times only went to 2 hours after injections. In this study, 2 additional doses and an extra hour of sample collection were added to obtain more information. Pekin ducks were either given IM cosyntropin injections or saline for control, with an N of 10/sex/treatment. There were 3 treatment doses: High (0.06 mg/kg), medium (0.03 mg/kg), and low (0.015 mg/kg). All injections were given promptly at 0730 hours. Blood was collected at 0, 1, 2 and 3 hours after injections from the tibia veins to obtain serum for ELISAs. Blood smears were done to analyze HLR and sent to an independent lab to obtain values. The results indicated that both GC had significant sex x dose x time interactions. The low dose injection had no effect on corticosterone in hens with a slight increase for drakes at the first hour. The high dose for hens led to a spike in corticosterone levels at the first hour with a gradual decrease, and drakes had an increase that lasted for 2 hours until they returned to baseline at the last hour. The high dose in drakes stimulated cortisol release during the first 2 hours after injection with a similar effect in hens. However, hens had elevated levels compared to drakes. Finally, there was no dose response effect for HLR, although interestingly, the low dose injection elevated HLR even though there was no effect in GC. There were sex differences in the HLR response where the drakes given the high dose had levels that plateaued by the third hour, while the hens still had elevated levels. In conclusion, the ACTH dose-response test identified that ACTH has a dose-dependent effect in both GC and sex differences in their release. HLR also showed sex differences that did not depend on the dose given.</p> <p><br></p> <p>Chapter 4 observed acute exposure of GC in ducks. Pekin ducks were assigned 10/sex/treatment to receive either IM control, cortisol, or corticosterone injections. In addition, a low-dose cortisol treatment was given to represent the endogenous levels of cortisol compared to corticosterone. The control injections contained safflower oil, which was chosen as vehicle due to the low levels of genistein present. This is important as genistein is a plant estrogen and this could interact with the GC and alter the results. Blood was collected at 0, 1, 2, and 3 hours after injections for serum analysis with ELISAs, and blood smears were collected for complete blood count (CBC) differentials. Significant sex x treatment x time interactions were notable in both GC. Hens had significant increases at the first hour after injections in all treatments compared to controls, and drakes had increases at 2 hours after injections in all treatments except the low-dose cortisol. </p> <p><br></p> <p>After observing the effect of acute stress in ducks, the next step was to investigate the effects of chronic stress in chapter 5. Adult breeder Pekin ducks were randomly distributed into 3 groups: corticosterone, cortisol, or control treatments. The GC were in crystalline steroid form distributed through 2 capsules that were subcutaneously implanted on the backs of the neck. The ducks in the control group were given empty capsules. Blood smears, blood draws for serum, egg collection, body weights, and organ samples were collected over a period of 2 weeks. For the results, the corticosterone implants elevated corticosterone levels in both sexes. Interestingly, cortisol levels were elevated in both GC treatments in both sexes. Cortisol elevated HLR in drakes 1 day after implants with no effect from corticosterone. Hens had elevated HLR from both GC at all timepoints throughout the experiment. There were no significant differences in morphometrics in either sex. Corticosterone was not present in eggs, but cortisol was elevated in the albumen on day 7 and 14 of the experiment. Overall, there were sex differences in HLR where hens had greater levels in both GC treatments.</p>

<p>  </p> <p>Heat stress affects breeder ducks raised in North America and other parts of the world, but the effects of such stress on the progenies is not known. Therefore, the objectives of this study were to investigate: 1) The objectives of this thesis were to first investigate the effect of heat stress or exposure to exogenous glucocorticoid (GC) on fertility, production performance, egg biochemistry, egg quality, and welfare of breeder Pekin ducks. 2) the effects of maternal GC on phenotypic plasticity and behavior of the F1 generation. Three studies were carried out to investigate these objectives.</p> <p>The first experiment was conducted to test the hypothesis that chronic treatment with low levels of either corticosterone or cortisol would alter heterophil to lymphocyte ratio (HLR) and immune organ morphometrics. Further, we wanted to determine if chronic treatment with either GC would elicit an increase in cortisol levels in egg albumen. To test our hypotheses, we implanted silastic capsules subcutaneously under the skin of the neck of adult ducks (n = 5/sex/dose) using propofol anesthesia. Capsules contained corticosterone, cortisol, or empty capsules as controls. Over the course of 2 weeks, blood serum, blood smears, body weights, and egg quality data were collected. After 2 weeks, ducks were euthanized using pentobarbital (FatalPlus, 396 mg/ml/kg) and body weight, weights of spleens, livers, and the number of active follicles were recorded. Blood smears were analyzed for HLR by a lab unaware of the treatment groups. Albumen GC levels were assessed using mass spectrometry. Data were analyzed using a 2- or 3-way ANOVA as appropriate and <em>post hoc </em>with Fishers protected least squares difference (PLSD). There were no treatment effects on egg quality measures or body weight. Corticosterone treatment did elicit an increase in serum corticosterone (p < 0.05), but not cortisol levels, compared to controls in both sexes. Both cortisol and corticosterone treatments increased (p < 0.05) serum levels of cortisol compared to controls. Relative spleen weights were higher (p < 0.05) in hens following corticosterone but not cortisol treatment. No other organs showed any differences among the treatment groups. Both GCs elicited an increase (p < 0.001) in HLR in hens at all time-points over the 2-week treatment period compared to controls. Cortisol, not corticosterone, elicited an increase in HLR for drakes (p < 0.05) compared to controls at day 1 after implants. Chronic treatment with cortisol, but not corticosterone, elicited an increase (p < 0.01) in egg albumen cortisol levels compared to other groups. Corticosterone was not detected in any albumen samples.</p> <p>The goal of our second experiment was to test the hypothesis that heat stress (HS) would alter welfare, egg quality, and morphometrics of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen due to recent exciting findings that cortisol, not corticosterone, is isolated in egg albumen. To test our hypothesis, 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) (such as footpad quality, eyes, nostrils, feather cleanliness, and feather quality scores), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 350C for 10h/day and to 29.50C for the remaining 14h/day for 3 weeks while the control room was maintained at 220C. Eggs were collected daily, and body weights were taken on days 0 and 21 relative to the onset of heat treatment. BCS were collected weekly. Eggs were collected weekly for quality assessment and albumen glucocorticoid (GCs) levels assessment 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 of HS or control exposures using pentobarbital and birds necropsied. Body weight, weights of the liver, spleen, and the number of maturing follicles were recorded. Data analyses were done by 2- or 3-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p value ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens while there was no significant difference in the circulating levels of corticosterone in drakes compared to the controls. The circulating levels of cortisol increased significantly at week 1 (p < 0.05), week 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at week 2 and 3 only (p < 0.05) in the drakes compared to the controls. 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 compared to controls, higher BCS indicate a decline in welfare. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3 and a descriptive decrease in the number of fertile eggs upon candling at 10 days of incubation, numeric decrease hatchability and increase in the number of dead embryos in the HS group after the incubation period. Hens in the HS group showed a significantly decreased BW (p < 0.001), and number of ovarian follicles (p < 0.05) compared to controls. Shell weight decreased significantly at week 1 (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).</p> <p>The third experiment was conducted to determine if parental exposure to heat stress would impair performance, hypothalamic pituitary adrenal (HPA) axis response, welfare, or behavior of their offspring. To achieve these goals, we treated adult drakes and hens at peak lay to heat stress or control temperature for 3 weeks and incubated eggs collected from the last 3 days of the experiment. A total of 76 ducklings were placed into pens from each parental treatment group: control (CON-F1) and heat stress (HS-F1) and raised as grow-out ducks. Weekly data for body weights, body condition scores (BCS), and novel object test (NOT) were collected weekly. At 3 weeks of age, ducks (n = 6 per treatment group) were subjected to adrenocorticotropic hormone (ACTH) (ACTH/cosyntropin, 0.0625 mg/kg) challenge or vehicle as control. Blood samples were collected from the metatarsal vein into serum-separator tubes at 0, 1, 2, 3, and 4 hours relative to treatment for the determination of serum glucocorticoids. Blood smears were also produced from these same samples to determine heterophil to lymphocyte ratios (HLR). All injected birds were euthanized with pentobarbital on the second day relative to ACTH administration, spleen and bursa were removed and weighed immediately. Duck level analyses were completed using 1-, or 2 -way ANOVA as appropriate. BCS were analyzed using a chi-squared test. We observed that HS-F1 had a lower hatch weight (p < 0.05) compared to CON-F1. However, growth rates during the 5-week grow-out period were not significantly different between the two flocks. NOT (N = 4) analyses showed that the HS-F1 had a greater fear response (P< 0.001) compared to CON-F1. Similarly, an ACTH stimulation test showed that the HS-F1 ducks had significantly heightened corticosterone and HLR responses compared to CON-F1 ducks (p < 0.05). The HS-F1 showed altered baseline and ACTH-stimulated levels of cortisol compared to controls.</p> <p>In conclusion, GC elicit differential effects and although corticosterone has been stated to be the predominant GC in avian species, cortisol may provide critical information to further understand and improve welfare. HS decreased performance, fertility, and productivity of breeder ducks. In addition, HS and exogenous GC elicited a selective deposition of cortisol, not corticosterone, in the egg albumen. The maternal cortisol deposited in eggs alter the hypothalamic-pituitary adrenal (HPA) axis and behavioral responses of the F1 generation. This suggests that maternal hormones can alter the phenotypic plasticity of the offspring and can be used to produce offspring that have better adaptation to the rising temperatures as a result of climate change. Finally, the measure of cortisol in egg albumen can be used as a non-invasive marker of stress.</p>

<p dir="ltr">Animal welfare is an important part of the poultry industry and is increasingly important to consumers. There are many ways to improve welfare, one way being implementing environmental enrichment. Environmental enrichment varies among poultry species, and it is especially distinct for Pekin ducks. Pekin ducks are waterfowl, so many believe that they should be allowed access to open water to increase positive natural behaviors and reduce unwanted behaviors. Beyond physical enrichment, another emerging approach is auditory enrichment, which has been extensively studied in zoos and is now gaining attention in livestock management. Vocalizations are a way to assess welfare and can be used as auditory enrichment. Birds use vocalizations as an effective way to communicate as vocalizations can travel over long distances and can be used in various environmental conditions. Ultimately, the Pekin duck industry could benefit from a variety of environmental enrichment devices and welfare indicators to enhance the welfare of their flocks. Preening cups may be a form of open water that would allow ducks to express preening behaviors. In Chapter 3 we describe an experiment that tested the prediction 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). We took body weights of 30 ducks per pen, and body condition scores on 50 ducks per pen weekly. On days 18 and 43, 5 ducks per pen were euthanized and their spleen, Bursa of Fabricius, liver, and uropygial gland 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 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 lie down compared to controls (25 d: F1,33 = 4.95, P = 0.0330). 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. The results of this initial study led us to investigate a second form of semi-open water source, the Pekino, and also a non-water-based environmental enrichment device, a whiffle style ball with zip-ties attached. This study, described in Chapter 4, assessed the effects of four enrichment treatments: Nipple line (CON), whiffle ball (EED), preening cup (PC), and Pekino (PEK) on duck welfare, behavior and bacterial exposure. 525 grow-out Pekin ducks were housed in 4 pens in 4 rooms with one of the four enrichment types (N=4 pens/treatment). Body weights and body condition scores of 10 ducks per pen and feed conversion ratio (FCR), ammonia level, and litter moisture percentage were recorded weekly. On days 16 and 44, 3 ducks per pen were euthanized and their organs were weighed and whole brains collected. Behavior data were collected using scan sampling with video being recorded for 72 continuous hours for 3 weeks after enrichment placement. Weekly samples were also collected for viable bacterial counts, and 16S rRNA gene sequencing at baseline and 6 hours after baseliner. Body morphometrics, FCR, ammonia levels, litter moisture % and viable bacteria were analyzed by 2-way ANOVA with repeated measures. Body condition scores were analyzed with PROC LOGISTIC (SAS 9.4). The GLIMMIX procedure (SAS 9.4) was used to analyze behavior. Bacterial communities were characterized using 16S rRNA gene sequencing, and functional potential was predicted using PICRUSt2. PEK and PC ducks were largest in weight (p<0.0001) with better nostril scores (p=0.0005) but had dirtier feathers (p<0.0001), worse litter conditions (p<0.0001) and more viable bacteria in their water sources (p<0.0001), the PC and EED ducks had worse feather quality (p=0.0021). Alpha and beta diversity metrics revealed that microbiota composition was significantly (p<0.05) dependent on environmental enrichment type. Likewise, functional pathway analyses revealed distinct (p<0.05) metabolic capacities, including aerobic respiration and amino acid biosynthesis, between microbiotas of each respective environmental enrichment niche. Our study suggests that semi-open water sources and EEDs may lead to an increase in feather pecking and a decrease in feather quality with a low number of ducks per enrichment as well as an increase in bacteria load and litter moisture. A different type of enrichment is auditory enrichment which potentially requires less maintenance and could be more cost-effective than physical enrichment. This study, described in Chapter 5, compared ducks housed in pens with Mozart music (MOZ; N=4, 30 ducks/pen), Pond sounds (POND; N=4, 30 ducks/pen), or a no sound control (CON; N=4, 30 ducks/pen). The POND and MOZ audio started on week 1 (day 7) and was played starting at 0300h (lights on) until 2100h (lights off) one hour on, one hour off, in a cyclic manner and ranged from 65-75dB. A novel object test (NOT) was conducted on each pen every week. Body condition scores were taken on 10 ducks per pen weekly (final N = 80 ducks/treatment/week). Production data were collected weekly. On weeks 2, 4, and 6, 2 ducks per pen were euthanized, and their organs were weighed (final N=16 ducks/treatment/week). Body condition scores were analyzed using the PROC LOGISTIC procedure (SAS v9.4) and Firth’s penalized likelihood method was used to address quasi-complete separation and odds ratios calculated. All other data were analyzed by 2-way ANOVA with repeated measures using PROC MIXED (SAS v9.4) and Tukey’s test for post-hoc analyses. A p≤0.05 was considered significant. The study was repeated, resulting in experiment 1 and experiment 2. For experiment 1, no significant differences were observed among groups for weekly body weights, dissection measures, or FCR. Ducks in the POND group were more passive towards the novel object than ducks in the CON group (p=0.0085). For experiment 2, ducks in the MOZ group weighed less than ducks in the POND (p=0.0010) and CON groups (p=0.0109). POND ducks approached the novel object more than MOZ ducks (p=0.0277) and CON ducks (p=0.0238). CON ducks were more fearful of the novel object than POND (p<0.0001) and MOZ ducks (p<0.0001). MOZ ducks had worse feather cleanliness scores, worse foot pad scores, and worse feather quality scores than POND and CON ducks. These two experiments resulted in different levels of effects, so future research is needed to fully understand how different auditory enrichment affects the behavior, production, and welfare of Pekin ducks under more specific flock conditions. The next step of this dissertation was to develop a complete vocalization repertoire of Pekin ducks. We know from wild bird literature that birds communicate through vocalizations. In this study, described in Chapter 6, 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 1-4 ducks of varying sex ratios into a sound chamber with various stimuli used to encourage new vocalizations. Birds were recorded for 20 minutes with several variations of number and sexes of ducks. Once the ducks were recorded each vocalization was clipped and was named based on a pre-determined naming system. We characterized the vocal system of the ducks under each stimulus and social treatment in four 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. The next step of the Pekin duck vocal repertoire study was to determine how different vocalizations affected conspecific physiology. We exposed Pekin ducks to playbacks of 5 different vocalizations plus a no noise and white noise stimulus as our controls (N=15 ducks/sex/treatment). The “AM long” call is a common vocalization made by both sexes. “Honk” is also produced by both sexes and is thought to be an alarm or distress call. “Pips” and “harmonics” are common vocalizations made only by hens. The “egg laying squiggle” is also only made by hens. Trials consisted of an initial recording in a quiet condition with 5 consecutive measurements of heart rate, blood pressure and respiratory rate. A specific vocalization was then played on repeat while 8 more measurements of blood pressure, heart rate and respiratory rate were taken. Finally, 5 measurements of heart rate and blood pressure were taken post playback along with a final recording of respiratory rate. Data from all blood pressure measurements (systolic, diastolic and mean arterial pressure [MAP]), heart rate (HR) and respiratory rate (RR) were subject to a principal component analysis (Proc Princomp in SAS 9.4). The significant principal components (Prin 1 loaded strongly on blood pressure and Prin 2 loaded strongly on HR and RR) were then analyzed by ANOVA with repeated measures (Proc Mixed, SAS 9.4, subject=duck ID). Our results showed there was a significant main effect of playback type on the blood pressure of ducks during the playbacks (p=0.0276). Ducks experienced an increase in blood pressure when played back the honk vocalization, as well as the white noise control. Additionally, there was a significant interaction between sex and treatment on the after-stimulus blood pressure (p= 0.0008): after the harmonic vocalization was played, the drakes still experienced an increase in blood pressure, but the hens experienced a decrease. The drakes, but not the hens, experienced a decrease in blood pressure after the AM long vocalization was played. Our data show that there are sex differences when it comes to vocalization playbacks in Pekin ducks, but overall, the honk vocalization and white noise control significantly increased ducks’ blood pressure. This study represents a critical steppingstone toward understanding how Pekin duck vocalizations affect conspecific physiology. In conclusion, environmental enrichment is an important part of Pekin duck welfare and production. Though more research is needed to determine the appropriate number of ducks to semi-open water sources. More research is also needed to assess the effects of auditory enrichment during different seasons. The vocalizations of Pekin ducks should also be investigated to see how other calls of their repertoire affect conspecific physiology. We observed that the honk call increased the blood pressure of the ducks, suggesting it is a stress call, so an automated detection system could be used to detect the honk call and alert the producer when their flock produces the call. This system would alert the producer and in turn, the producer is proactive in reducing the flocks’ stress before they drop in production and welfare. Other Pekin duck calls could be used as auditory enrichment or as calming sounds. We found that the egg laying call reduced the hens’ blood pressure so this call could be used during routine management practices or entice the hens to lay their eggs in their nest boxes.</p>