Corticotropin-releasing factor regulates caspase-3 and may protect developing zebrafish from stress-induced apoptosis.

The corticotropin-releasing factor (CRF) system is expressed in the earliest stages of zebrafish development, long before its canonical function in the endocrine stress response is realized, and yet its function during embryogenesis is unknown. We tested the hypothesis that CRF protects embryos from stress-induced apoptosis. Here we confirm that a 1 h heat shock applied at either 6 h post-fertilization (hpf) or 30 hpf elicits an increase in caspase-3 activity, a key effector of apoptosis. Temporal changes in the expression of crf and its binding protein (crf-bp) during recovery from heat shock indicate that the CRF system is responsive to stressors experienced as early as gastrulation. Next, we heat shocked embryos that were microinjected with crf mRNA, and showed that caspase-3 induction is significantly reduced in embryos that overexpress CRF relative to control embryos. In addition, incubating embryos in the presence of the CRF receptor type 1 (CRF-R1) antagonist, antalarmin, during recovery from heat shock significantly increased caspase-3 activity, suggesting that CRF regulates caspase-3 via a CRF-R1-dependent pathway. Finally, we show that most heat shock-induced mortality occurred during the first hour of recovery, long before a significant increase in caspase-3 activity was detected. Indeed, the delayed caspase-3 induction coincided with a mortality plateau, and neither CRF overexpression nor antalarmin treatment altered heat shock induced mortality, supporting previous in vitro evidence that CRF-mediated cytoprotection occurs through the slow and tightly controlled apoptotic pathway. This study provides novel in vivo evidence that CRF regulates stress-induced apoptosis in a vertebrate model species, and demonstrates for the first time a function for the CRF system in early development that precedes its role in the endocrine stress response.

Genetic architecture of white striping in turkeys (Meleagris gallopavo).

White striping (WS) is a myopathy of growing concern to the turkey industry. It is rising in prevalence and has negative consequences for consumer acceptance and the functional properties of turkey meat. The objective of this study was to conduct a genome-wide association study (GWAS) and functional analysis on WS severity. Phenotypic data consisted of white striping scored on turkey breast fillets (N = 8422) by trained observers on a 0-3 scale (none to severe). Of the phenotyped birds, 4667 genotypic records were available using a proprietary 65 K single nucleotide polymorphism (SNP) chip. The SNP effects were estimated using a linear mixed model with a 30-SNP sliding window approach used to express the percentage genetic variance explained. Positional candidate genes were those located within 50 kb of the top 1% of SNP windows explaining the most genetic variance. Of the 95 positional candidate genes, seven were further classified as functional candidate genes because of their association with both a significant gene ontology and molecular function term. The results of the GWAS emphasize the polygenic nature of the trait with no specific genomic region contributing a large portion to the overall genetic variance. Significant pathways relating to growth, muscle development, collagen formation, circulatory system development, cell response to stimulus, and cytokine production were identified. These results help to support published biological associations between WS and hypoxia and oxidative stress and provide information that may be useful for future-omics studies in understanding the biological associations with WS development in turkeys.

Factors Associated with Reproductive Success in Captive Vancouver Island Marmots (Marmota vancouverensis).

The Vancouver Island marmot (Marmota vancouverensis) is Canada's most endangered endemic mammal. In 1997, a conservation breeding-for-release program was established to supplement wild marmot populations. Retrospective analyses of captive breeding studbook records since 2000 indicate the age of the sire and the dam significantly impacted the odds of successfully weaning a litter. Dams and sires between 5 and 7 years of age had more than double the odds of reproductive success compared to older animals. Successful reproduction by the dam in the previous year also doubled the odds of successfully weaning a litter in subsequent years. Assessment of adrenal function via fecal glucocorticoid analyses indicated established breeding pairs had decreased stress compared to new pairs (5.74 ± 0.28 ng/g vs. 7.60 ± 0.34 ng/g; p < 0.0001). Pairs that were ultimately successful at weaning pups in a breeding season had decreased stress compared to unsuccessful pairs (6.05 ± 0.34 ng/g vs. 7.22 ± 0.28 ng/g; p = 0.0006). These endocrine results suggest social buffering via familiarity and breeding/pair bond formation may be decreasing stress in established and successful pairs, respectively. The results of this study will be used to assist in the captive breeding management of this species to optimise numbers of animals produced to supplement the wild populations.

A wing-assisted incline running exercise regime during rearing increases initial flight velocity during descent in adult white- and brown-feathered laying hens.

Domestic laying hens rely primarily on their hindlimbs for terrestrial locomotion. Although they perform flapping flight, they appear to use maximal power during descent and thus may lack control for maneuvering and avoiding injuries on landing. This in turn may result in injury in open rearing systems. Wing-assisted incline running (WAIR) requires a bird to use its wings to assist the hindlimbs during climbing of an incline, and training in WAIR may therefore provide a useful method to increase a hen's power reserve and control for flight. We subjected hens to an exercise regimen involving inclines to induce WAIR for 16 wk during rearing. We then measured wing and body kinematics during aerial descent from a 155 cm platform. We hypothesized that birds reared with exercise would be better able to modulate their wing and body kinematics for making slower, more-controlled descent and landing. Brown-feathered birds exhibited greater wing beat frequencies than white-feathered birds, which is consistent with the higher wing loading of brown-feathered birds and WAIR-trained birds exhibited greater initial flight velocities compared to control birds. This may indicate that WAIR training provided an improved capacity to modulate flight velocity and strengthen the leg muscles. Providing incline exercises during rearing may therefore improve welfare for adult laying hens as greater initial flight velocity should reduce the power required for supporting body weight in the air and allow a hen to direct her excess power toward maneuvering.

Reduction of wing area affects estimated stress in the primary flight muscles of chickens.

In flying birds, the pectoralis (PECT) and supracoracoideus (SUPRA) generate most of the power required for flight, while the wing feathers create the aerodynamic forces. However, in domestic laying hens, little is known about the architectural properties of these muscles and the forces the wings produce. As housing space increases for commercial laying hens, understanding these properties is important for assuring safe locomotion. We tested the effects of wing area loss on mass, physiological cross-sectional area (PCSA), and estimated muscle stress (EMS) of the PECT and SUPRA in white-feathered laying hens. Treatments included Unclipped (N = 18), Half-Clipped with primaries removed (N = 18) and Fully-Clipped with the primaries and secondaries removed (N = 18). The mass and PCSA of the PECT and SUPRA did not vary significantly with treatment. Thus, laying hen muscle anatomy may be relatively resistant to changes in external wing morphology. We observed significant differences in EMS among treatments, as Unclipped birds exhibited the greatest EMS. This suggests that intact wings provide the greatest stimulus of external force for the primary flight muscles.

Genetic parameters of feather corticosterone and fault bars and correlations with production traits in turkeys (Meleagris gallopavo).

Robustness can refer to an animal's ability to overcome perturbations. Intense selection for production traits in livestock has resulted in reduced robustness which has negative implications for livability as well as production. There is increasing emphasis on improving robustness through poultry breeding, which may involve identifying novel phenotypes that could be used in selection strategies. The hypothalamic-pituitary-adrenal (HPA) axis and associated hormones (e.g., corticosterone) participate in many metabolic processes that are related to robustness. Corticosterone can be measured non-invasively in feathers (FCORT) and reflects the average HPA axis activity over the feather growing period, however measurement is expensive and time consuming. Fault bars are visible feather deformities that may be related to HPA axis activity and may be a more feasible indicator trait. In this study, we estimated variance components for FCORT and fault bars in a population of purebred turkeys as well as their genetic and partial phenotypic correlations with other economically relevant traits including growth and efficiency, carcass yield, and meat quality. The estimated heritability for FCORT was 0.21 ± 0.07 and for the fault bar traits (presence, incidence, severity, and index) estimates ranged from 0.09 to 0.24. The genetic correlation of FCORT with breast weight, breast meat yield, fillet weight, and ultimate pH were estimated at -0.34 ± 0.21, -0.45 ± 0.23, -0.33 ± 0.24, and 0.32 ± 0.24, respectively. The phenotypic correlations of FCORT with breast weight, breast meat yield, fillet weight, drum weight, and walking ability were -0.16, -0.23, -0.18, 0.17, and 0.21, respectively. Some fault bar traits showed similar genetic correlations with breast weight, breast meat yield, and walking ability but the magnitude was lower than those with FCORT. While the dataset is limited and results should be interpreted with caution, this study indicates that selection for traits related to HPA axis activity is possible in domestic turkeys. Further research should focus on investigating the association of these traits with other robustness-related traits and how to potentially implement these traits in turkey breeding.

Quality and Processability of Modern Poultry Meat.

The poultry meat industry has gone through many changes. It moved from growing dual-purpose birds (meat and egg production) taking ~110 days to reach 1.2 kg 100 years ago, to developing specialized meat breeds that grow to 2.5 kg within ~40 days. It also moved from selling ~80% whole birds to mostly selling cut up and further processed products in the Western world. This necessitated building large, centralized processing plants, capable of processing 15,000 birds per hr on a single line (60 years ago only 2500), that require higher bird uniformity (size, color, texture). Furthermore, consumer demand for convenient products resulted in introducing many cut-up fresh poultry (some companies have 500 SKU) and further processed products (chicken nuggets did not exist 50 years ago). Those developments were possible due to advancements in genetics, nutrition, medicine, and engineering at the farm and processing plant levels. Challenges keep on coming and today a rise in myopathies (e.g., so called woody breast, white striping, spaghetti meat), requires solutions from breeders, farmers, and processing plants, as more automation also requires more uniformity. This review focuses on the changes and challenges to the processing industry segment required to keep supplying high quality poultry to the individual consumer.

The usual suspects: Co-occurrence of integument injuries in turkey flocks.

The present study investigated the prevalence and co-occurrence of integument injuries in Canadian turkeys. Participating farmers scored 30 birds in their flock for integument injuries to the head/neck (HN), back/tail (BT), and footpad (FP) using a simplified scoring system (0: no sign of injury, 1: mild injury, 2: severe injury). Information from 62 flocks was used to calculate the prevalence of any (score ≥1) and severe (score 2) injuries on a flock- and individual-level. Chi-square analyses were performed to determine the likelihood of integument injury co-occurrence. The prevalence of each type of injury varied between flocks. While the majority of flocks reported injuries, the within-flock prevalence was relatively low and largely comprised of mild cases (score 1). Given their higher prevalence, the data indicate that FP injuries are overall more widespread and more severe among Canadian turkey flocks than HN and BT injuries. Co-occurrence of different integument injuries was observed in 7% of birds and 58.1% of flocks reported at least one bird with co-occurring injury types. Despite the low prevalence of multiple injury types, birds with one type of injury were more likely to present with other injury types. Indeed, birds with HN injuries were 4 times more likely to have BT injuries, and birds with FP injuries were 1.5 times more likely to have BT injuries compared to birds that do not have these respective injuries. The data increase our understanding of the co-occurrence of these common integument injuries which can help inform a holistic management approach to rear turkeys with healthy skin and feather cover.

Describing the relationships among meat quality traits in domestic turkey (Meleagris gallopavo) populations.

The presence of meat quality defects is increasing in the turkey industry. While the main strategy for mitigating these issues is through improved housing, management, and slaughter conditions, it may be possible to incorporate meat quality into a turkey breeding strategy with the intent to improve meat quality. Before this can occur, it is important to describe the current state of turkey meat quality as well as the correlations among the different meat quality traits and important production traits. The main objective of the present study was to provide a descriptive analysis of 8 different meat quality traits for turkey breast meat from 3 different purebred lines (A, B, and C), and their correlation with a selection of production traits. Using a total of 7,781 images, the breast meat (N = 590-3,892 birds depending on trait) was evaluated at 24 h postmortem for color (L*, a*, b*), pH, and physiochemical characteristics (drip loss, cooking loss, shear force). Descriptive statistics (mean and standard deviation) and Pearson correlations were computed to describe the relationships among traits within each genetic line. A one-factor ANOVA and post hoc t-test were conducted for each trait and between each of the genetic lines. We found significant differences between genetic lines for some color traits (L* and a*), pHinitial, drip loss, and cooking loss. The lightest line in weight (line B) had meat that was the lightest (L*) in color. The heaviest line (line C) had meat that was less red (a*) with a higher pHinitial and greater cooking loss. Unfavorable correlations between production traits and meat quality were also found for each of the genetic lines where increases in production (e.g., body weight, growth rate) resulted in meat that was lighter and redder in color and in some cases (line B and C), with an increased moisture loss. The results of this study provide an important benchmark for turkey meat quality in purebred lines and provide an updated account of the relationships between key production traits and meat quality. Although the magnitude of these correlations is low, their cumulative effect on meat quality can be more significant especially with continued selection pressure on growth and yield.

Genetic Parameters of White Striping and Meat Quality Traits Indicative of Pale, Soft, Exudative Meat in Turkeys (Meleagris gallopavo).

Due to the increasing prevalence of growth-related myopathies and abnormalities in turkey meat, the ability to include meat quality traits in poultry breeding strategies is an issue of key importance. In the present study, genetic parameters for meat quality traits and their correlations with body weight and meat yield were estimated using a population of purebred male turkeys. Information on live body, breast, thigh, and drum weights, breast meat yield, feed conversion ratio, breast lightness (L*), redness (a*), and yellowness (b*), ultimate pH, and white striping (WS) severity score were collected on 11,986 toms from three purebred genetic lines. Heritability and genetic and partial phenotypic correlations were estimated for each trait using an animal model with genetic line, hatch week-year, and age at slaughter included as fixed effects. Heritability of ultimate pH was estimated to be 0.34 ± 0.05 and a range of 0.20 ± 0.02 to 0.23 ± 0.02 for breast meat colour (L*, a*, and b*). White striping was also estimated to be moderately heritable at 0.15 ± 0.02. Unfavorable genetic correlations were observed between body weight and meat quality traits as well as white striping, indicating that selection for increased body weight and meat yield may decrease pH and increase the incidence of pale meat with more severe white striping. The results of this analysis provide insight into the effect of current selection strategies on meat quality and emphasize the need to include meat quality traits into future selection indexes for turkeys.

Influence of Post Mortem Muscle Activity on Turkey Meat Quality.

Wing flapping and body movement can occur during the slaughter of poultry. Wing movement and flapping are driven primarily by the breast muscles (Pectoralis major and minor), and this muscle activity may have implications for meat quality. The objective of this study was to evaluate turkey post mortem activity during slaughter at a commercial poultry processing plant. Post mortem activity (during bleeding) was scored on 5,441 male turkeys, from six different genetic lines, using a 1-4 scale from none to severe wing flapping. Meat quality was measured on these birds in terms of pH (initial, ultimate, delta or change), color (L*, a*, b*), and physiochemical traits (drip loss, cooking loss, shear force). Linear mixed models were used to analyze the effect of activity (score 1-4), genetic line (A-F), and season (summer vs. autumn) on the nine meat quality traits. Post mortem activity influenced a*, drip loss, and shear force although the magnitude of the effects was small. There was an effect (P < 0.05) of genetic line on all the meat quality traits except for L*, cooking loss, and shear force. In general, larger, faster-growing lines had higher pH, but the relationship between the lines for the other traits is not as clear. Season affected all the meat quality traits, except for pHdelta, with meat having a higher pH, L*, b*, drip loss, cooking loss, and shear force in the summer. This study provides an exploratory assessment of post mortem activity in turkeys and identifies meat quality traits which are most affected while also accounting for the effects of genetic line and season. Although identified effect sizes are small, the cumulative effect on turkey meat quality may be more substantial.

The Adrenal Cortisol Response to Increasing Ambient Temperature in Polar Bears (Ursus maritimus).

Our objective was to identify the upper ambient temperature threshold that triggers an increase in cortisol in response to increased thermoregulatory demands in polar bears. The results reported here include endocrine data collected over two years from 25 polar bears housed in 11 accredited zoological institutions across North America. The effects of ambient temperature, sex, age group (juvenile, adult, elderly), breeding season and humidity on fecal cortisol metabolite (FCM) concentrations (N = 8439 samples) were evaluated using linear mixed models. Ambient temperatures were placed into five different categories: <5 °C, 6−10 °C, 11−15 °C, 16−20 °C, and >20 °C. Ambient temperature and humidity had a significant (p < 0.05) effect on FCM concentrations with significant (p < 0.05) interactions of sex, age and breeding season. Once biotic factors were accounted for, there was a significant (p < 0.05) increase in FCM concentrations associated with ambient temperatures above 20 °C in adult polar bears. The implications of these findings for the management of both zoo and wild polar bears are discussed.

Reliability of a White Striping Scoring System and Description of White Striping Prevalence in Purebred Turkey Lines.

To efficiently meet consumer demands for high-quality lean meat, turkeys are selected for increased meat yield, mainly by increasing breast muscle size and growth efficiency. Over time, this has altered muscle morphology and development rates, which are believed to contribute to the prevalence of myopathies. White striping is a myopathy of economic importance which presents as varying degrees of white striations on the surface of skinless breast muscle and can negatively affect consumer acceptance at the point of sale. Breeding for improved meat quality may be a novel strategy for mitigating the development of white striping in turkey meat; however, it is crucial to have a reliable assessment tool before it can be considered as a phenotype. Six observers used a four-category scoring system (0-3) to score severity in several controlled rounds and evaluate intra- and inter-observer reliability of the scoring system. After sufficient inter-observer reliability (Kendall's W > 0.6) was achieved, 12,321 turkey breasts, from four different purebred lines, were scored to assess prevalence of the condition and analyze its relationship with important growth traits. Overall, the prevalence of white striping (Score > 0) was approximately 88% across all genetic lines studied, with most scores being of moderate-severe severity (Score 1 or 2). As was expected, increased white striping severity was associated with higher slaughter weight, breast weight, and breast meat yield (BMY) within each genetic line. This study highlights the importance of training to improve the reliability of a scoring system for white striping in turkeys and was required to provide an updated account on white striping prevalence in modern turkeys. Furthermore, we showed that white striping is an important breast muscle myopathy in turkeys linked to heavily selected traits such as body weight and BMY. White striping should be investigated further as a novel phenotype in future domestic turkey selection through use of a balanced selection index.

The Prevalence of Integument Injuries and Associated Risk Factors Among Canadian Turkeys.

Injurious pecking can cause a wide range of damage and is an important welfare and economic issue in turkey production. Aggressive pecking typically targets the head/neck (HN) area, and feather pecking typically targets the back/tail (BT) area; injuries in these separate areas could be used as a proxy for the level of aggressive and feather pecking in a flock. The objective of this study was to identify risk factors for integument injuries in Canadian turkey flocks. A survey containing a questionnaire about housing and management practices and a scoring guide was distributed to 500 turkey farmers across Canada. The farmer scored pecking injuries in two different body areas (HN and BT) on a 0-2 scale on a subset of birds within each flock. Multivariable logistic regression modeling was used to identify factors associated with the presence of HN and BT injuries. The prevalence of birds with integument injuries ranged widely between the flock subsets (HN = 0-40%, BT = 0-97%), however the mean prevalence was low (HN = 6%, BT = 10%). The presence of injuries for logistic regression was defined as flocks with an injury prevalence greater than the median level of injury prevalence in the dataset (3.3% HN and 6.6% BT). The final logistic regression model for HN injuries contained five variables: flock sex, flock age, number of daily inspections, number of different people during inspections, and picking up birds during inspections (N = 62, pR2 = 0.23, α = 0.05). The final logistic regression model for BT injuries contained six variables: flock sex, flock age, litter depth, litter condition, inspection duration, and use of hospital pens for sick/injured birds (N = 59, pR2 = 0.29, α = 0.05). Flock age, and to a lesser extent, sex was associated with both types of injuries. From a management perspective, aggressive pecking injuries appear to be influenced by variables related to human interaction, namely during inspections. On the other hand, the presence of feather pecking injuries, was associated with litter condition and other management factors like separating sick birds. Future research on injurious pecking in turkeys should focus on these aspects of housing and management to better describe the relationship between the identified variables and the prevalence and severity of these conditions.

Meta-analysis to predict the effects of temperature stress on meat quality of poultry.

Temperature stress (TS) is a significant issue in poultry production, which has implications for animal health and welfare, productivity, and industry profitability. Temperature stress, including both hot (heat stress) and cold conditions (cold stress), is associated with increased incidence of meat quality defects such as pale, soft, and exudative (PSE) and dark, firm, and dry (DFD) meat costing poultry industries millions of dollars annually. A meta-analysis was conducted to determine the effect of ambient TS on meat quality parameters of poultry. Forty-eight publications which met specific criteria for inclusion were identified through a systematic literature review. Temperature stress was defined by extracting 2 descriptors for each treatment mean from the chosen studies: (1) temperature imposed for the experimental treatments (°C) and duration of temperature exposure. Treatment duration was categorized for analysis into acute (≤24 h) or chronic (>24 h) treatments. Meat quality parameters considered were color (L*-a*-b* scheme), pH (initial and ultimate), drip loss, cooking loss, and shear force. Linear mixed model analysis, including study as a random effect, was used to determine the effect of treatment temperature and duration on meat quality. Model evaluation was conducted by performing a k-fold cross-validation to estimate test error, and via assessment of the root mean square prediction error (RMSPE), and concordance correlation coefficient (CCC). Across both acute and chronic durations, treatment temperature was found to have a significant effect on all studied meat quality parameters. As treatment temperature increased, meat demonstrated characteristics of PSE meat and, as temperature decreased, meat demonstrated characteristics of DFD meat. The interaction between treatment temperature and duration was significant for most traits, however, the relative impact of treatment duration on the studied traits was inconsistent. Acute TS had a larger effect than chronic TS on ultimate pH, and chronic stress had a more considerable impact on color traits (L* and a*). This meta-analysis quantifies the effect of ambient TS on poultry meat quality. However, quantitative effects were generally small, and therefore may or may not be of practical significance from a processing perspective.

The Effect of Egg Laying on Feather and Plasma Corticosterone Concentrations in Turkey (Meleagris gallopavo) Hens.

Phenological differences in energy demand (i.e., reproductive status) might influence the measurement of corticosterone. The objective of this study was to compare corticosterone concentrations in feathers (FCORT) and plasma (PCORT) for turkey hens before and during egg laying. Secondary feathers 1 and 3, and a plasma sample were collected from 50 hens at 30 weeks (before egg laying) from two purebred lines. The hens were reexamined during lay (45 weeks) to collect regrown feathers and plasma samples. Corticosterone concentrations were measured using an ELISA. Linear mixed models were used to assess the effect of genetic line (A vs. B) and period (pre-lay vs. lay) on FCORT and PCORT levels. An increase in FCORT during lay was detected for line B (p < 0.0001), but not line A (p = 0.3076). An increase in FCORT during lay was detectable in both feather types, but there was a difference between secondary 1 and 3 in FCORT concentration within each line studied. Conversely, PCORT decreased between the pre-lay and lay periods for both lines, although the decrease was more substantial for line A (p < 0.0001). Differences in metabolic investment in egg production between the two genetic lines may explain the different FCORT response during lay. The results from this study provide insight into how periods of high energy demand may influence corticosterone which should be considered when interpreting results.

Farmers' Perceptions About Health and Welfare Issues in Turkey Production.

Farmers play an essential role in the management of animals and ensuring their health and welfare. However, relatively little is known about the health and welfare-related issues farmers themselves find important in the turkey sector. As part of a larger study, a cross-sectional survey of turkey farmers was conducted in Canada to identify the main perceived reasons for culling, mortality, and carcass condemnations in their flocks. Additionally, farmers were asked to rate the importance of different health and welfare-related issues (i.e., mortality, aggressive pecking, disease, leg injuries, leg deformities, breast injuries, and varying body size) during their summer and winter production, as well as for the sector as a whole. A total of 83 responses were analyzed (response rate 20%). The most frequently mentioned reasons for the culling of turkeys included leg-related issues (90.0%), sickness (60.5%), and small body size (58.0%). The perceived reasons for mortality were most often unknown (59.7%), or related to cannibalism (41.6%) or dehydration (42.9%). The main reasons for carcass condemnations at processing were related to skin (33.8%) or subcutaneous conditions (64.7%). Leg deformities and mortality were considered the biggest issues for the turkey production sector. In general, farmers rated items as more of an issue when the question pertained to the sector as a whole rather than to their farm. These results increase our understanding of the health and welfare-related problems in turkey production that farmers find important. This can ultimately help focus research efforts in addressing these issues through improved management adaptations or breeding approaches, thereby improving both the well-being of farmers and birds.

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers.

The use of feathers as noninvasive physiological measurements of biomarkers in poultry research is expanding. Feather molting patterns and growth rates, however, are not well described in domestic poultry. These parameters could influence the measurement of these biomarkers. Therefore, the objective of this study was to describe the juvenile primary feather molting patterns and feather growth rates for domestic turkeys. The 10 primary wing feathers of 48 female turkeys were measured weekly from week 1 (0 d of age) to week 20. Feathers were manually measured, and the presence or absence of each primary feather was recorded weekly. Generalized linear mixed models were used to investigate if feather growth differed between the primary feathers. The molting of the juvenile primary feathers followed a typical descending pattern starting with P1 (5 wk of age), while P9 and P10 had not molted by the end of the study (20 wk of age). The average feather growth rate was 2.4 cm/wk, although there was a significant difference between the 10 primary feathers (P < 0.0001, 2.1 to 2.8 cm/wk). Over time, feather growth followed a pattern where the growth rate reaches a peak and then declines until the feather is molted. The results of this study provide a critical update of patterns of molting and feather growth in primary wing feathers of modern turkeys. This can have implications for the interpretation of physiological biomarkers, such as the longitudinal deposition of corticosterone, in the feathers of domestic turkeys.

Housing and Management of Turkey Flocks in Canada.

An increased understanding of the turkey sector and how farmers manage flocks can help maintain and improve the health and welfare of turkeys. We conducted a cross-sectional survey among turkey farmers in Canada to gain information regarding general farm characteristics, housing aspects (incl. lighting, ventilation), litter management, feed and water management, flock characteristics, and flock health management. The survey was distributed to 500 farmers through the Turkey Farmers of Canada in April-December 2019. A total of 83 final responses (response rate approx. 20%) were used for a descriptive analysis to determine the frequency of housing and management practices (77 commercial flocks, 6 breeder flocks). Hen flocks (n = 53) had a median age of eight weeks (IQR: 7-12 weeks) and tom flocks (n = 30) had a median age of 12 weeks (IQR: 9-14 weeks). Turkey flocks within Canada are typically kept in indoor barn systems on a concrete floor (87.5%), with bedding (e.g., straw, wood shavings) provided (100%). The majority followed a brood and move growing system (68.8%), and a large proportion of farmers indicated that they raised turkeys under the 'Raised Without Antibiotics/Antibiotic Free' or the 'Responsible Use of Antibiotics' certification (70.5%). Possible room for improvement could be found in terms of litter management and biosecurity practices, however, further research is needed to make clear recommendations.

Research Note: Quantifying corticosterone in turkey (Meleagris gallopavo) feathers using ELISA.

The measurement of corticosterone in feathers is an appealing tool for assessing glucocorticoids in wild and domestic bird species. Feather corticosterone measurements can be performed noninvasively and can provide a means for comparing glucocorticoid secretion between individual birds; thus, such measurements can be used to assess the welfare of domestic poultry. The focus of this study was to assess the validity of detecting corticosterone in turkey (Meleagris gallopavo) feathers using an ELISA and investigate differences between genetic lines. Primary feather 9 was obtained at a processing plant from 123 individuals from 3 different purebred turkey lines (line A [N = 46], line B [N = 24], and line C [N = 53]). Assay validation tests were performed using a commercially available ELISA kit (Cayman Chemicals, Cedarlane Labs, Canada). Indicators of accuracy, recovery, precision, and sensitivity were sufficient. Significant differences in feather corticosterone concentration between the 3 lines were observed. Line C had significantly higher feather corticosterone than line A (P < 0.0001) and line B (P = 0.036). These results indicate that the quantification of feather corticosterone using an ELISA is a valid method for assessing glucocorticoid levels in turkeys. This is the first report of differences in feather corticosterone between different purebred turkey lines. Differences observed between purebred lines provide an intriguing basis for further investigation into the genetic parameters of glucocorticoid levels in turkeys.