Feathering in commercial poultry I. Feather growth and composition

Residue depletion of enrofloxacin and flumequine in feathers of broilers based on quantitative UHPLC-MS/MS detection

To explore potential factors contributing to high fluoroquinolone resistance levels, it is essential to develop analytical methods capable of detecting residues and trace amounts of antibiotic use in broilers. The aim of the present study was to develop and in-house validate a sensitive UHPLC-MS/MS method capable of determining enrofloxacin (ENR) and flumequine (FLU) residues at slaughter age (day 45) when the animals were treated with these antimicrobials one day after hatching. Residue depletion of ENR and FLU in feathers was also assessed. Two experimental trials were performed, both consisting of 5 different treatment groups. In the first trial animals were treated with ENR and in the second one with FLU. The developed method was successfully validated and was found to be sensitive enough to detect residues of fluoroquinolones in the feathers up until slaughter age in all treatment groups. Average ENR concentration on day 45 was 10 ng g-1 feather after drinking water treatment, with all concentrations above the limit of quantification (LOQ) of 5 ng g-1 feather. For FLU average concentration on day 45 after drinking water administration was 4 ng g-1 feather, with an LOQ of 1 ng g-1 feather. Therefore, the method is suited for application to monitor fluoroquinolone use in broilers.

Feather's Composition of South Polar Skua (Stercorarius maccormicki) Using WDXRF

This study investigated the feathers' composition of South polar skua (Stercorarius maccormicki) using WDXRF, evaluating the concentration of essential and non-essential elements in the feathers, and dividing it into rachis and barb parts. We collected South polar skuas feathers from Hennequin Point, King George Island, South Shetland, Antarctic Peninsula in January of 2013. Our results show that 18 elements were observed in the composition of the feathers, with a different concentration between the rachis and barbs, qualitatively and quantitatively. Only 3 elements observed were classified as non-essentials but still mostly elements do not have a function described in the literature to the feathers. According to our knowledge, this is the first study that uses this technique to evaluate the concentration of different elements in the feathers. The findings of this study highlight the use of alternative techniques to biomonitoring elements in the ecosystem and bring baseline information for future studies.

The feather epithelium contributes to the dissemination and ecology of clade 2.3.4.4b H5 high pathogenicity avian influenza viruses in ducks

Immature feathers are known replication sites for high pathogenicity avian influenza viruses (HPAIVs) in poultry. However, it is unclear whether feathers play an active role in viral transmission. This study aims to investigate the contribution of the feather epithelium to the dissemination of clade 2.3.4.4b goose/Guangdong/1996 lineage H5 HPAIVs in the environment, based on natural and experimental infections of domestic mule and Muscovy ducks. During the 2016-2022 outbreaks, H5 HPAIVs exhibited persistent and marked feather epitheliotropism in naturally infected commercial ducks. Infection of the feather epithelium resulted in epithelial necrosis and disruption, as well as the production and environmental shedding of infectious virions. Viral and feather antigens colocalized in dust samples obtained from poultry barns housing naturally infected birds. In summary, the feather epithelium contributes to viral replication, and it is a likely source of environmental infectious material. This underestimated excretion route could greatly impact the ecology of HPAIVs, facilitating airborne and preening-related infections within a flock, and promoting prolonged viral infectivity and long-distance viral transmission between poultry farms.

Description of natal down of the ostrich (Struthio camelus) and comparison with common quail (Coturnix coturnix): Developmental and evolutionary implications

Natal down is a feather stage that differs in both form and function from the definitive feathers of adult birds. It has a simpler structure that has been speculated to be similar to the body coverings of non-avian dinosaurs. However, inference of the evolution of natal down has been limited by our understanding of its structural variation in extant birds. Most descriptive work has focused on neognathous birds, limiting our knowledge of the full diversity of feathers in extant taxa. Here, we describe the natal down of a post-hatch ostrich (Struthio camelus) and compare it to that of a post-hatch quail (Coturnix coturnix). We confirm the presence of featherless spaces (apteria) in S. camelus and the lack of barbules on the tips of natal down in both species. We also find differences between dorsal and ventral natal down structures, such as barbule density in S. camelus and the extent of the bare portion of the barb in both species. Surprisingly, we do not find that the neoptiles of either species follow the ideal morphologies for increasing insulation. Finally, we hypothesize that the different barb types present in S. camelus natal down result from a large addition of new barb ridges during development, which is not known except in feathers with a rachis. These results have implications for our understanding of how structure informs function and development in understudied feather types, such as those shared by non-avian dinosaurs.

Non-invasive sampling reveals low mitochondrial genetic diversity for an island endemic species: The critically endangered Grenada Dove Leptotila wellsi

As an island endemic with a decreasing population, the critically endangered Grenada Dove Leptotila wellsi is threatened by accelerated loss of genetic diversity resulting from ongoing habitat fragmentation. Small, threatened populations are difficult to sample directly but advances in molecular methods mean that non-invasive samples can be used. We performed the first assessment of genetic diversity of populations of Grenada Dove by (a) assessing mtDNA genetic diversity in the only two areas of occupancy on Grenada, (b) defining the number of haplotypes present at each site and (c) evaluating evidence of isolation between sites. We used non-invasively collected samples from two locations: Mt Hartman (n = 18) and Perseverance (n = 12). DNA extraction and PCR were used to amplify 1751 bps of mtDNA from two mitochondrial markers: NADH dehydrogenase 2 (ND2) and Cytochrome b (Cyt b). Haplotype diversity (h) of 0.4, a nucleotide diversity (π) of 0.00023 and two unique haplotypes were identified within the ND2 sequences; a single haplotype was identified within the Cyt b sequences. Of the two haplotypes identified, the most common haplotype (haplotype A = 73.9%) was observed at both sites and the other (haplotype B = 26.1%) was unique to Perseverance. Our results show low mitochondrial genetic diversity and clear evidence for genetically isolated populations. The Grenada Dove needs urgent conservation action, including habitat protection and potentially augmentation of gene flow by translocation in order to increase genetic resilience and diversity with the ultimate aim of securing the long-term survival of this critically endangered species.

The Defeathering Effect by Scalding in Chickens Follows Their Intrinsic Dermal Histologies

This study aimed to delineate the fundamental skin histology and its association with feathers in broilers and native Red-Feather (RF) chickens and further elucidate their thermal alterations in respect to the defeathering effect by scalding. Comparisons of skin thickness between fresh samples and those after dehydration and fixation, as well as their collagen contents and histological differences, suggested that RF chickens had a thicker dermal layer with more collagen deposition and compact architecture, particularly in the neck and abdominal skin, but a thinner hypodermal layer in the back, chest, and abdomen skin. Despite an adolescent age, RF chickens showed a shorter calamus depth of tail feathers but a larger calamus diameter of wing feathers. Within the feather follicle punch, a very intense follicle sheath layer with compact collagenous matrixes to fulfill the space next to the inner feather root sheath was observed in RF chickens. Under both soft and hard scalding, RF chickens showed a lower degree of denaturation on hip skins and were more resistant to structural disintegration, primarily within the epidermal and dermal layer. Accordingly, a much narrower gap space between the feather sheath and surrounding follicle sheath was observed, and the gap expansion was also resistant to thermal changes. These results suggest that the defeathering effect by scalding follows the intrinsic skin histologies in chickens of various breeds and ages, primarily depending on the interaction of the feather calamus with the surrounding follicle sheath and neighboring cutaneous tissues, reflecting their resistance to thermal denaturation, but is irrelevant to the feathers per se.

Presence and Depletion of Sulfadiazine, Trimethoprim, and Oxytetracycline into Feathers of Treated Broiler Chickens and Impact on Antibiotic-Resistant Bacteria

The valorization of poultry byproducts, like feathers (processed to feather meal), in animal feed could contribute to the presence of veterinary drugs, including antibiotics. An animal study was carried out to study the fate of sulfadiazine, trimethoprim, and oxytetracycline in feathers, plasma, and droppings of broiler chickens. Cage and floor housing, different from current farm practices, were studied. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A longer presence of antibiotics was observed in feathers compared to plasma, with sulfadiazine being present the most. The internal presence (via blood) and the external presence (via droppings) of antibiotics in/on feathers were shown. Analysis of Escherichia coli populations, from droppings and feathers, highlighted that resistant bacteria could be transferred from droppings to feathers in floor-housed animals. The overall results suggest that feathers are a potential reservoir of antimicrobial residues and could contribute to the selection of antibiotic-resistant bacteria in the environment, animals, and humans.

Genome-wide association analysis of the primary feather growth traits of duck: identification of potential Loci for growth regulation

The feather is an important epidermal appendage, plays an important role in the life activities of avian specie, and has important economic value. Revealing the molecular regulation mechanism of feather growth has a significant meaning in studying adaptive evolution, physiology, and mating of avian species and also provides a theoretical reference for poultry breeding. In this study, the genome-wide association analysis (GWAS) of 358 ducks was based on primary feather length phenotypic data (28-60 d), length growth rates (LGRs), and maturity scores (60 d) to explore the genetic basis affecting feather growth and maturation. The results showed that, among the primary feather 1 to 5 in ducks, the mean LGR of primary feather 2 was the fastest, with the longest length. The primary feathers in males grew and matured slightly faster than in females. The mean maturity scores of primary feather 10∼7 were higher than primary feather 1 to 3 in ducks. GWAS further showed 116 SNPs associated with feather length traits. In addition, 2 candidate regions (Chr1: 127,407,230-127,524,879 bp and Chr21: 182,061,707-183,616,298 bp) were associated with LGR, which contain total 13 candidate genes (The extremely significant SNPs were mainly located in 2 genes: Chr1: REPS2 and Chr21: PTPRT). Four candidate regions (Chr1: 29,113,036-28,675,018 bp, Chr2: 18,253,612-149,111,290 bp, Chr15: 6,489,774 to 12,138,221 bp and Chr21: 6,578,021-8,472,904 bp) were associated with feather maturity, which contain total 24 candidate genes (The extremely significant SNPs were mainly located in 4 genes: Chr1: IMMP2L, DOCK4 and DDX10, Chr2: LDLRAD4). In conclusion, sex factors influence feather growth and maturity, and the genetic basis of the growth /maturity trait between different feathers is similar. REPS2, PTPRT genes, and IMMP2L, DOCK4, DDX10, and LDLRAD4 are important candidate genes that influence feather growth and maturity, respectively.

Traditional sexing methods and external egg characteristics combination allow highly accurate early sex determination in an endangered native turkey breed

Early sex determination methods are not only crucial in the worldwide massive poultry industry, but also for small-holder producers. The profitability of sexing techniques must be accounted for when aiming to boost management, nutrition, and conservation practices in endangered poultry breeds. This becomes pivotal when the local breed dealt with belongs to an understudied species, such as the turkey. So, the main objective of this study is to identify which method combination may report a higher likelihood of successful sex determination in poults across the three-pattern varieties of the Andalusian turkey breed. A total of 84 one to two days old Andalusian turkey poults (42 black, 28 black-roan, and 14 bronze-roan) were evaluated in this study. Sex determination was performed using 15 methods, which included testing external egg metrics and eggshell color, poult morphological appraisal and phaneroptics, and behavioral traits. Possible differences across plumage varieties and the interaction between sex and plumage were observed when external egg quality was measured. Sex determination through behavioral methods in black base feathered (black and black-roan) male sex individuals showed seven times higher sensitivity when compared to the rest of the studied individuals (χ2 = 7.14, df = 1, P < 0.01). In contrast, for the black-roan plumage females, the method based on the color of down feathers was approximately four times more sensitive (χ2 = 3.95, df = 1, P ≤ 0.05). For the bronze-roan pattern, none of the sexing techniques was reported to efficiently predict sex itself. However, the most proper method combination to determine sex, independent of plumage color, was physical external egg characteristics, the color of down feathers, and behavioral approaches (“English method” and “slap technique”). The specificity values were found to be 49.12, 93.33, and 100%, while the sensitivity values were observed to be 74.64, 91.03, and 100%, which translated into accuracy of 63.10, 92.26, and 100% in black, black-roan, and bronze-roan poults, respectively. Our results suggest that the method combination tested in this study could be considered a highly accurate, simple, and affordable alternative for sex determination in turkeys. This could mean a pivotal advance for small producers of turkeys, as early sex detection can help to plan timely conservational management strategies, which is of prominent importance in the context of endangered poultry breeds.

Composition of feathers and pulp of two broiler genotypes

1. Cobb and Ross broilers (200 of each sex and breed) were fed four phases of diets ad libitum formulated with balanced protein to match their amino acid requirements throughout growth. Ten birds per genotype were sampled and euthanised at two-weekly intervals from 14 to 112 d of age. All feathers were dry-plucked from each of the seven tracts (specific skin areas) and pulp (the centre of the feather filament) was removed from primary and secondary remiges.2. Daily losses of feathers were collected from an additional 20 individually-caged broilers of each breed. These feathers were separated into natal down, contour feathers, remiges and rectrices and then pooled by type, sex and genotype to quantify water and protein contents. Only those feathers collected from male Cobb 500 MX broilers were analysed for amino acid content.3. Amino acid contents of feathers from the seven tracts were measured only in Cobb males on days 1, 28 and 70; for pulp on days 28 and 70; and for the four types of moulted feathers.4. Protein content on a dry matter basis remained relatively constant over all ages and tracts during growth. Water content decreased with age in both sexes and genotype. Lysine and methionine content in feathers decreased with age while cystine, valine, leucine and serine increased. Lysine, methionine and histidine levels were higher in pulp than in mature feathers whereas cystine and valine were higher in mature feathers than in pulp.5. These results, together with information about moulting patterns in broilers, enabled the effects of age of the bird and of the type of feather, to be taken into account when determining the rate of deposition of amino acids in feathers.

Plumage Response of Young Turkeys to Diets with Increased Methionine to Lysine Ratios at Three Dietary Arginine Levels

Simple Summary

An adequate supply of essential amino acids through the diet is critical for maintaining a fast growth rate, good health, and proper immune function as well as feather-cover development in poultry species. Feathers contain about 90% of protein, therefore the optimal ratios of limiting amino acids, in particular the sulfur-containing amino acids are indicated as necessary for the synthesis of feather keratin. This study evaluated the effects of different dietary methionine (Met) and arginine (Arg) levels on plumage development in young turkeys. An increased supply of sulfur-containing amino acids via supplemental Met promoted feather growth in turkeys at 16 weeks of age. Different concentrations of Arg (90%, 100%, and 110% of lysine content) had no influence on plumage development. The data on feather growth can contribute to a better understanding of the amino acid requirements in modern commercial turkey-farming systems.

Abstract

A 2 × 3 factorial experiment was conducted to evaluate the effects of two dietary methionine levels (Met; 30% and 45% of Lys content) and three arginine levels (Arg; 90%, 100%, and 110% of Lys content) on plumage development in 4- and 16-week-old female turkeys. One-day-old turkey poults were assigned to six groups (eight replicate pens per group and 18 birds per pen) and fed experimental diets containing 1.6%, 1.5%, 1.3%, and 1.0% of Lys in four successive four-week periods. After weeks 4 and 16 of feeding, eight turkeys per group were selected for plumage evaluation. Feathers were collected from the outer side of one thigh and from an area of 4 cm² in the interscapular region. Plumage was evaluated based on an established pattern of five feather development stages in turkeys, from stage I (pinfeathers covered in sheaths) to stage V (mature feathers). An increase in the Met inclusion rate to 45% of Lys content had no significant effect on feather growth in 4-week-old turkeys, but it accelerated the development of feathers in 16-week-old birds. A lower percentage of stage II (p = 0.035), stage III (p = 0.019), and stage IV (p = 0.003) immature feathers, and a higher percentage of stage V (mature) feathers (p = 0.001) were observed. Methionine exerted a greater effect on the development of thigh feathers (p = 0.001) than interscapular feathers (p = 0.074). Unlike Met, different Arg concentrations had no influence on plumage development in turkeys. Overall, the present results indicate that supplemental Met has a potential for accelerating feather development in 16-week-old turkeys via an increased supply of total sulfur amino acids.

Understanding Transcriptomic and Serological Differences between Forced Molting and Natural Molting in Laying Hens

Molting is natural adaptation to climate change in all birds, including chickens. Forced molting (FM) can rejuvenate and reactivate the reproductive potential of aged hens, but the effect of natural molting (NM) on older chickens is not clear. To explore why FM has a dramatically different effect on chickens compared with NM, the transcriptome analyses of the hypothalamus and ovary in forced molted and natural molted hens at two periods with feathers fallen and regrown were performed. Additionally, each experimental chicken was tested for serological indices. The results of serological indices showed that growth hormone, thyroid stimulating hormone, and thyroxine levels were significantly higher (p < 0.05) in forced molted hens than in natural molted hens, and calcitonin concentrations were lower in the forced molted than in the natural molted hens. Furthermore, the transcriptomic analysis revealed a large number of genes related to disease resistance and anti-aging in the two different FM and NM periods. These regulatory genes and serological indices promote reproductive function during FM. This study systematically revealed the transcriptomic and serological differences between FM and NM, which could broaden our understanding of aging, rejuvenation, egg production, and welfare issues related to FM in chickens.

A retroviral insertion in the tyrosinase (TYR) gene is associated with the recessive white plumage color in the Yeonsan Ogye chicken

The recessive white (locus c) phenotype observed in chickens is associated with three alleles (recessive white c, albino c^a , and red-eyed white c^re ) and causative mutations in the tyrosinase (TYR) gene. The recessive white mutation (c) inhibits the transcription of TYR exon 5 due to a retroviral sequence insertion in intron 4. In this study, we genotyped and sequenced the insertion in TYR intron 4 to identify the mutation causing the unusual white plumage of Yeonsan Ogye chickens, which normally have black plumage. The white chickens had a homozygous recessive white genotype that matched the sequence of the recessive white type, and the inserted sequence exhibited 98% identity with the avian leukosis virus ev-1 sequence. In comparison, brindle and normal chickens had the homozygous color genotype, and their sequences were the same as the wild-type sequence, indicating that this phenotype is derived from other mutation(s). In conclusion, white chickens have a recessive white mutation allele. Since the size of the sample used in this study was limited, further research through securing additional samples to perform validation studies is necessary. Therefore, after validation studies, a selection system for conserving the phenotypic characteristics and genetic diversity of the population could be established if additional studies to elucidate specific phenotype-related genes in Yeonsan Ogye are performed.

Associations between welfare and ranging profile in free-range commercial and heritage meat-purpose chickens (Gallus gallus domesticus)

Despite consumers' belief that access to an outdoor range improves chicken welfare, still little is known about whether this is true and whether individual ranging profiles relate to the birds' welfare. The aim of the present study was to identify and compare welfare issues of the traditional broiler hybrid Sasso and the Polish heritage chicken Green-legged Partridge, having outdoor access, and examine if the birds' welfare status was associated with the ranging profile: outdoor-preferring, moderate-outdoor, and indoor-preferring. In August 2018, 60 non-beak trimmed birds per genetic strain were housed in groups of 10 from weeks 5 to 10, under conditions exceeding EU requirements of organic meat chicken production. Each pen had access to an individual outdoor range that was video-recorded continuously to obtain frequencies of individual birds' use of the ranges. Plumage condition, comb pecking wounds, skin injuries, dirtiness, toe damage, eye pathologies, footpad dermatitis, hock burns, respiratory infections, diarrhea, and walking difficulties were assessed at the end of the experiment. Statistical analysis was conducted applying generalized linear mixed models, with binomial distribution and logit link using SAS software, applying breed and ranging profile as fixed factors and their interaction, with pen as random factor. A tendency for more respiratory infections was observed in Sasso birds from each ranging profile, as compared to matching ranging profiles presented by Green-legged Partridges (outdoor-preferring: P = 0.0012; moderate-outdoor: P < 0.0001; and indoor-preferring: P = 0.0247). Indoor-preferring Green-legged Partridges tended to present more respiratory infections, as compared to the 2 other ranging profiles within the breed (outdoor-preferring: P = 0.0291; moderate-outdoor: P = 0.0448). Regardless of the breed, toe damages were more frequent in indoor-preferring birds, as compared to other ranging profiles (P = 0.017). It remains unknown whether the use of outdoor areas prevents development of welfare issues or if birds with a suboptimal welfare condition become indoor-preferring individuals.

A description of the growth and moulting of feathers in commercial broilers

1. Changes in feather length and weight and daily losses of down, contour feathers, remiges and retrices were studied in two commercial broiler strains to determine feather growth and moult in broilers up to 112 d of age. 2. Ten pens of 20 chicks for each sex x strain were fed adequate amounts of dietary protein in a four-phase feeding programme. Ten birds were sampled per genotype at 14, 28, 42, 56, 70, 84, 98 and 112 d. Feather loss was determined for individual birds caged within a nylon net. 3. All feathers were dry-plucked from each of seven tracts, with representative feathers from the capital-cervical, dorsopelvic and interscapular, pectoral and femoral tracts being randomly selected. Three rectrices of the dorsocaudal tract and three primaries and secondaries of the humeral-alar tract of the right wing were evaluated. 4. The length of the selected feathers was measured, and the feathers from each tract and from the whole bird were weighed. 5. A wide range of rates of maturing (0.0250-0.0907/d) and mature weights (9.62-52.9 g) were evident between sampled tracts. 6. Feather weight failed to predict some moults which were detected by the measurement of feather losses. From the weight data, moulting was evident only in the humeral-alar and dorsocaudal tracts, whereas, when daily losses were measured, contour feathers accounted for over 0.7 proportion of feather losses. Logistic equations adequately described the cumulative losses of down, contour feathers and remiges. 7. Feather loss needs to be considered when feather growth is determined from feather weight at different ages. 8. The rate of maturing (B) of feathers was numerically higher in Ross males and females than in the Cobb strain. In females, B was higher than in males (0.0483 vs. 0335/d) but the mature weight was lower (162 vs. 230 g).

Feather analysis as a non-invasive alternative to tissue sampling for surveillance of doxycycline use on poultry farms

Intensive chicken production leads to overuse of antibiotics on poultry farms. For food safety control, there is great need for means to use non-conventional matrices allowing analysis of antibiotics during poultry breeding. The main goal of this study was to demonstrate feathers as suitable material for non-invasive detection of doxycycline treatment in poultry. Transfer to and depletion of doxycycline in chicken feathers were investigated after therapeutic, spray, and subtherapeutic treatment. For the quantitative determination of doxycycline in feathers, a validated ultra-high-performance liquid chromatography - tandem mass spectrometry method was used. High concentrations of doxycycline in feathers were detectable for 22 D post treatment in each experimental group, and they were much higher than those in muscle and liver. A washing experiment with the same solvent as for extraction showed different ratios between extractable and non-extractable residues in feathers of chickens treated therapeutically, by spraying and subtherapeutically, which demonstrates the ability of feather analysis to distinguish different forms of treatment. After a segmentation procedure, high amounts of doxycycline were found to be deposited in the upper part of feathers in each treatment group. The obtained results showed that chicken feathers are a suitable material for the detection and non-invasive surveillance of doxycycline.

In vivo assessment of body composition and growth potential of modern broiler using dual-energy X-ray absorptiometry

Context Genetic improvements in modern strains have led to continuous increments in broiler growth rates, which, as a consequence, have resulted in higher economic returns for broiler producers over the last decades. Aim The present study was conducted to characterise the potential growth of the body and feathers of Cobb 500, Hubbard Flex and Ross 308 male and female broilers, as well as to assess the changes in chemical composition that occur up to 16 weeks of age. Methods Birds were fed isoenergetic diets divided in four phases and formulated to marginally exceed the nutritional requirements of the strains throughout the growing period. They were maintained in a controlled environment so as not to limit growth. A dual energy X-ray absorptiometry (DXA) scanner was used to follow the in vivo body composition of 12 broilers of each strain and sex (total of 72 broilers), and the feather weight and composition was determined in four birds of each strain and sex selected at intervals during the growing period (total of 288 broilers) through comparative slaughter with later chemical analysis. Key results Parameters of Gompertz growth curve to describe the strains were estimated for body and feather weight as well as for the growth of their chemical components. Conclusion Differences in the growth rates between strains were evident, indicating the possible differences in selection methods used by geneticists in the different breeding companies. These genetic parameters would explain part of the variation on broiler´s performance which impacts on the way they should be fed and housed during growth. Implications The accurate description of genetic growth potential is useful information to be associated with factorial models that predict nutritional and feed intake requirements of birds. The main advantage of DXA technology is to decrease the variation of body deposition on the Gompertz model, resulting from the use of the same bird throughout its life. Despite the speed of obtaining chemical values of the body, the method is unsuitable for measuring the growth of feathers, which is also important data to be collected and related to the broiler strains.

Alteration of dietary cysteine affects activities of genes of the transsulfuration and glutathione pathways, and development of skin tissues and feather follicles in chickens

The dietary requirement for cysteine is not determined in poultry since it is not an essential amino acid. The cysteine need is expected to be met through the transsulfuration pathway where homocysteine, a precursor of methionine, is converted to cysteine. Cysteine is a major component of plumage, and the degree to which cysteine is involved in plumage and other keratized proteins are unknown. We randomly assigned chicks to control and treatment (deficient in cysteine) diets for 49 d. The thickness of the skin layers, feather follicle length, and thickness were measured at days 10, 24, 34, and 49. We also measured the hepatic mRNA expressions of cystathionine beta synthase (CBS), cystathionine γ-lyase (CTL), cysteine dioxygenase (CDO), and glutathione synthetase (GSS). Chickens fed the treatment diet had reduced epidermis thickness and shorter feather follicles compared with the controls. The chicken fed the treatment diet also had increased mRNA expression of CBS and CTL indicating a disruption of the transsulfuration pathway. The treatment chickens also had a decreased hepatic CDO and increased GSS mRNA expressions which are in concordance with the homeostatic regulation of cysteine. Compromised cysteine metabolism could affect thermoregulation and subsequently affect feed efficiency and welfare of the birds.

Feather Pecking and Cannibalism in Non-Beak-Trimmed Laying Hen Flocks-Farmers' Perspectives

Pecking-related problems are common in intensive egg production, compromising hen welfare, causing farmers economic losses and negatively affecting sustainability. These problems are often controlled by beak trimming, which in Finland is prohibited. An online questionnaire aimed to collect information from farmers about pecking-related problems in Finnish laying hen flocks, important risk factors and the best experiences to prevent the problems. Additionally, the farmers' attitudes towards beak trimming were examined. We received 35 responses, which represents about 13% of all Finnish laying hen farms with ≥300 laying hens. The majority of respondents stated that a maximum of 5⁻7% incidence of feather pecking or 1⁻2% incidence of cannibalism would be tolerable. The majority of respondents (74%) expressed that they would definitely not use beak-trimmed hens. Only two respondents indicated that they would probably use beak-trimmed hens were the practice permitted. Among risk factors, light intensity earned the highest mean (6.3), on a scale from 1 (not important) to 7 (extremely important). Other important problems included those that occurred during rearing, feeding, flock management and problems with drinking water equipment (mean 5.9, each). The most important intervention measures included optimal lighting and feeding, flock management, and removing the pecker and victim. Concluding, Finnish farmers had strong negative attitudes towards beak trimming. The study underlines the importance of flock management, especially lighting and feeding, in preventing pecking problems and indicates that it is possible to incorporate a non-beak-trimming policy into sustainable egg production.

The effect of supplementary ultraviolet wavelengths on broiler chicken welfare indicators

Qualities of the light environment are important for good welfare in a number of species. In chickens, UVA light is visible and may facilitate flock interactions. UVB wavelengths promote endogenous vitamin D synthesis, which could support the rapid skeletal development of broiler chickens. The aim of the study was to investigate the impacts of Ultraviolet wavelengths (UV) on welfare indicators in broiler chickens. Day-old Ross 308 birds reared under commercially representative conditions were randomly assigned to one of three lighting treatments: A) White Light Emitting Diode (LED) and supplementary UVA LED lighting (18-hour photoperiod); B) White LED with supplementary UVA and UVB fluorescent lighting providing 30 micro watts/cm2 UVB at bird level (on for 8 h of the total photoperiod to avoid over-exposure of UVB); C) White LED control group, representative of farm conditions (18-hour photoperiod). Welfare indicators measured were; feather condition (day 24, n = 546), tonic immobility duration (day 29, n = 302), and gait quality, using the Bristol Gait Score (day 31, n = 293). Feather condition was improved in male broilers in the UVA treatment (A), compared to the control treatment (C). Birds in the UVA treatment had shorter tonic immobility durations compared to the control treatment (C), suggesting lower fearfulness. Broilers reared in UVA (A) and UVA + UVB (B) had better Bristol Gait Scores compared to the control (C). Together these results suggest UV may be beneficial for broiler chicken welfare. While treatment A and B both provided UVA, the improvements in welfare indicators were not consistent, which may be due to exposure time-dependent beneficial effects of UVA. The modification of commercial lighting regimes to incorporate UVA wavelengths for indoor-reared broiler chickens would be an achievable change with significant positive impacts on bird welfare.

Determination of Oxytetracycline and 4-Epi-Oxytetracycline Residues in Feathers and Edible Tissues of Broiler Chickens Using Liquid Chromatography Coupled with Tandem Mass Spectrometry

Antibiotics have been widely used in poultry production for the treatment of bacterial diseases. However, drug residues can remain in products derived from animals after the cessation of the drug therapies. Feathers, in particular, have shown an affinity for antibiotics such as tetracycline, suggesting the persistence of these drugs in nonedible tissue. After the birds are slaughtered, feathers are ground into feather meals, which are used as organic fertilizer or an ingredient in animal diets, thereby entering into the food chain and becoming a potential risk for public health. To evaluate the depletion of oxytetracycline (OTC) and its metabolite 4-epi-oxytetracycline (4-epi-OTC) in the muscles, liver, and feathers, 64 broiler chickens, bred under controlled conditions, were treated orally with a commercial formulation of 10% OTC for 7 days. The analytes were quantified using liquid chromatography-tandem mass spectrometry. OTC and 4-epi-OTC were found in the feathers for 46 days, whereas they were found in the muscle and liver for only 12 and 6 days, respectively. These results prove that the analytes remain in feathers in higher concentrations than they do in edible tissues after treatment with tetracyclines. Thus, feather meals represent a potential source of antimicrobial residue contamination in the food chain.

Broiler chicks with slow-feathering (K) or rapid-feathering (k+) genes: Effects of environmental stressors on physiological adaptive indicators up to 56 h posthatch

Two experiments were conducted to examine the effects on the physiological responses of slow-feathering (K) and rapid-feathering (k(+)) genes in neonate broiler chicks subjected to posthatch fasting (PHF). In the first experiment, 300 Ross 308 chicks were denied access to feed and water for 0, 7, 14, 21, 28, 35, 42, 49, and 56 h posthatch. In the second experiment, 625 Ross 308 chicks were subjected to PHF for 0, 12, 24, 36, and 48 h. In experiment 1, the weight loss rate increased over 56 h PHF and did not differ between fast- and slow-feathering chicks up to 28 h posthatch but was greater (P < 0.05) in fast-feathering birds from 28 to 56 h posthatch. The fast-feathering genotypes demonstrated greater serum K levels following 7, 21, and 56 h (P < 0.05) and serum uric acid (UA) levels after 7, 21, 28, 49, and 56 h PHF (P < 0.01). In experiment 2, weight loss increased linearly with no difference between fast- and slow-feathering chicks through 36 h PHF but increased in fast-feathering birds when PHF continued for 48 h. Neonatal fasting periods of 12 to 48 h decreased breast and thigh percentage (P < 0.01), with no difference between feathering genotypes. The fast-feathering genotypes showed greater serum HDL levels at 24 h (P < 0.05) and greater serum UA concentration following 12, 36, and 48 h PHF (P < 0.05). The mean frequency of jumping (P < 0.01) and active wakefulness (P > 0.01) was increased as PHF continued from 12 to 48 h across genotypes. At 48 h, the fast-feathering chicks showed greater frequency of escape attempts from the test field (P < 0.01). It was concluded that slow-feathering chicks are more capable of withstanding PHF periods lasting more than 28 h. This is important to consider when day-old chicks are transported for extended periods without access to feed.

Metal exposure influences the melanin and carotenoid-based colorations in great tits

Metals are naturally found in the environment but are also emitted through anthropogenic activities, raising some concerns about the potential deleterious effects of these elements on wildlife. The potential effects of metals on bird coloration have been the focus of several recent studies since animal colored-signals often reflect the physiology of their bearers and are thus used by animals to assess the quality of another individual as a mate or competitor. These studies have shown that the melanin pigmentation seems to be positively associated and the carotenoid-based coloration negatively associated with metal exposure in wild birds. Although these studies have been very useful to show the associations between metal exposure and coloration, only few of them have actually quantified the levels of metal exposure at the individual level; always focusing on one or two of them. Here, we measured the concentrations of eight metals in great tits' feathers and then assessed how these levels of metals were associated with the carotenoid and melanin-based colorations. We found that the melanin pigmentation was positively associated with the copper concentration and negatively correlated with the chromium concentration in feathers. In addition, we have shown that the carotenoid-based coloration was negatively associated with the feather's mercury concentration. This study is the first one to identify some metals that might affect positively and negatively the deposition of melanin and carotenoid into the plumage of wild birds.

Broiler responses to digestible threonine at different ages: a neural networks approach

Three experiments were conducted with broiler chickens to evaluate the effects of digestible threonine (DThr) and crude protein (CP) on their performance at three different phases of age: 1-14, 15-28 and 29-42 days. The measured traits included the following: average daily gain (ADG), feed intake (FI), feed conversion ratio (FCR), carcass crude protein (CCP), body lipid (BL), feather weight gain (FWG), protein deposited in feather (FCP), carcass plus feather protein (CFCP), carcass Thr deposition (CDThr) and nitrogen excretion (NE). A dilution technique was used to create seven diets (with eight replicates) increasing the DThr content from 1.5 to 10 g/kg of diet for phase 1, 1.3-8.9 g/kg of diet for phase 2, and 1.2-8.2 g/kg of diet for phase 3. Data measured were imported into neural networks (NNs) to: (i) predict the measured traits in response to DThr and CP, (ii) rank the importance of DThr and CP on these traits through sensitivity analysis and (iii) find the optimal levels of DThr and CP that lead to the desired (maximum or minimum) responses. For each trait investigated, 50 different random groups of data were generated using a bootstrapping method. These 50 data groups were then used to develop 50 separate NNs which were subsequently combined to construct the final ensemble NN model. In general, accuracy of the models constructed was acceptable, although models of high (ADG, FCR, CFCP, BL, DThr and NE; 0.64 ≤ R(2)  ≤ 0.99) and low (CCP, FWG and FCP; 0.26 ≤ R(2)  ≤ 0.79) accuracy were obtained. All models developed showed the greatest sensitivity to DThr. This may be explained by the dilution technique diet preparation used in these experiments. Optimization results showed decreases in optimal values of DThr and CP with increasing age for all traits. The highest level of DThr was suggested for minimum BL, followed by minimum FCR, maximum ADG, maximum CFCP, minimum NE and maximum CCP respectively. Results showed that the optimal values of DThr for minimum FCR in phases 1-3 were 8.5, 7.4 and 6.4 g/kg of diet, while these values for maximum ADG were 8.2, 7.2 and 6.4 g/kg of diet respectively.

Changes in the amount of lysine in protective proteins and immune cells after a systemic response to dead Escherichia coli: implications for the nutritional costs of immunity

The nutritional demands of the immune system may result in tradeoffs with competing processes such as growth and reproduction. The magnitude of the nutritional costs of immunity is largely unknown. Thus, we examine the lysine content of the systemic components of the immune system in adult male chickens (Gallus gallus domesticus) in a healthy condition (maintenance) and following a robust Escherichia coli-specific immune response. Lysine was used as a metric, because it is found both in leukocytes and in protective proteins. The dynamics of subsets of leukocytes were monitored in primary and secondary immune tissues (thymus, bone marrow, and spleen) that would be expected to be involved in the response following iv injection of E. coli. The systemic immune system at maintenance has the same lysine content as 332 average-sized feathers, 16% of an egg, or 5.4% of a pectoralis muscle from an adult chicken. During the acute-phase response to E. coli, the additional lysine needed would equal 355 feathers, 17% of an egg, or 5.5% of a pectoralis muscle. The acute-phase proteins accounted for the greatest proportion of lysine in the immune system at maintenance and the proportion increased substantially during an acute-phase response. Hypertrophy of the liver required more lysine than all of the leukocytes and protective proteins that were produced during the acute-phase response. Size of the liver and levels of protein during the acute phase returned to normal during the time when the adaptive response began to utilize significant quantities of lysine. The catabolism would release a surfeit of lysine to provision the anabolic processes of the adaptive response, thus making proliferation of lymphocytes and production of immunoglobulins very cheap.

Dynamics of the systemic components of the chicken (Gallus gallus domesticus) immune system following activation by Escherichia coli; implications for the costs of immunity

The immune response is thought to be costly and deters from growth and reproduction, but the magnitude and sources of these costs are unknown. Thus, we quantified the changes in mass of leukocytes (CD4(+) and CD8(+) T cells, Bu1(+) IgM(+) and Bu1(+) IgG(+) B cells, monocytes/macrophages, heterophils and thrombocytes) and protective plasma proteins in systemic (non-mucosal) components of adult chickens injected intravenously with dead Escherichia coli. During the first day after E. coli injection most types of blood leukocytes decreased and α-1-acid glycoprotein increased. Specific IgM, specific IgY, total IgM, Bu1(+) lymphocytes in the spleen and bone marrow and thymic CD8(+) lymphocytes increased at 5d post-injection. Quantitatively, the increases in the weight of cells and antibodies due to E. coli were dwarfed by the increase in the weight of the liver and acute phase proteins. Thus the acute phase response was markedly more costly than the subsequent adaptive response. The weight of the cells and proteins of the systemic immune system prior to challenge was 0.14% of body weight. Following E. coli injection, the additional weight of the immune components and the hypertrophy of the liver resulted in a 3.6-fold increase in weight which is equivalent to 18.5% of a large egg.

From feathers to syngas - technologies and devices

The poultry waste produced by industrial slaughterhouses typically contains not only feathers, but also a mixture of animal entrails, nails, blood, beaks and whole carcasses. Economical utilisation of this mixture, varying strongly in composition and moisture content, is, in general, difficult. We demonstrate that this awkward material can be successfully used for gasification in a simple, fixed-bed gasifier. The method of gasification, which we developed, enables control of the gasification process and ensures its stability in the operational regime of a working poultry processing plant. The installation, which has been working in Poland for 2 years, utilises 2 tons of feathers per hour and produces syngas of stable composition and fairly high quality. The syngas is burnt in the combustion chamber adjacent to the gasifier. Heat is recuperated in a boiler producing 3.5 tons per hour of technological steam continuously used for the operation of the slaughterhouse. The whole process complies with the stringent emission standards. In the paper we present the end-use device for feather utilisation and describe the underlying gasification and syngas combustion processes. Key elements of the whole installation are briefly discussed. The environmental impacts of the installation are summarized.

Effects of the genetically reduced feather coverage in naked neck and featherless broilers on their performance under hot conditions

Under hot conditions, contemporary commercial broilers do not reach their full genetic potential for growth rate, body weight (BW), or breast meat yield because dissipation of their excessively produced internal (metabolic) heat is hindered by the feathers. Therefore, it was hypothesized that heat stress can be alleviated by using the naked-neck gene (Na) or the featherless gene (sc). The study consisted of 4 experimental genetic groups (fully feathered, heterozygous naked neck, homozygous naked neck, featherless), progeny of the same double-heterozygous parents (Na/na +/sc), and commercial broilers. Birds from all 5 groups were brooded together until d 21 when one-half of the birds from each group were moved to hot conditions (constant 35 degrees C), and the others remained under comfortable conditions (constant 25 degrees C). Individual BW was recorded from hatch to slaughter at d 45 and 52 at 25 and 35 degrees C, respectively, when breast meat, rear part, heart, and spleen weights were recorded. Body temperature was recorded weekly from d 14 to 42. Feather coverage significantly affected the thermoregulatory capacity of the broilers under hot conditions. With reduced feather coverage (naked-neck), and more so without any feathers (featherless), the birds at 35 degrees C were able to minimize the elevation in body temperature. Consequently, only the featherless birds exhibited similar growth and BW under the 2 temperature treatments. The naked-neck birds at 35 degrees C showed only a marginal advantage over their fully feathered counterparts, indicating that 20 to 40% reduction in feather coverage provided only limited tolerance to the heat stress imposed by hot conditions. Breast meat yield of the featherless birds was much greater (3.5% of BW, approximately 25% advantage) than that of their partly feathered and fully feathered counterparts and the commercial birds under hot conditions. The high breast meat yield (at both 25 and 35 degrees C) of the featherless broilers suggests that the saved feather-building nutrients and greater oxygen-carrying capacity contribute to their greater breast meat yield. Because of these results, further research on genetically heat-tolerant broilers should focus on the featherless phenotype.

Quantification of the spatial distribution of surface temperatures of broilers

Thermal comfort is of great importance in chickens to preserve body temperature homeostasis during the growth period and during environmental thermal challenges. Because surface temperatures contribute much to thermal comfort, this research is aimed at studying spatial distribution of surface temperatures of broiler chickens. For this purpose, temperatures of 26 different parts on the chicken body surface were measured using thermography during the growth period of 6 wk. It was observed that there were significant differences in spatial distribution of broiler surface temperatures. The greatest temperatures were measured at the positions with little or no feathering (i.e., cheek, skull, and inner thigh). The least temperatures were observed on the places with thickest feather cover (i.e., wing and breast). The surface temperatures decreased as a function of age from approximately 36 to 28 degrees C. The spatial temperature range on the surface of the bird varied from 6 degrees C in wk 1 to 15 degrees C on wk 6. Temperature differences between the surface of the chicken and its surroundings were also studied, and it was found that in the range of 1 to 6 wk the age of the bird had significant effects on temperature difference (P < 0.0001). The temperature difference between the surface of the chicken and environment was at a maximum on wk 4 during the growth period of 6 wk.