Line Birds Research Articles

Genome-wide association studies of anserine and carnosine contents in the breast meat of Korean native chickens

Histidine-containing dipeptides (HCDs), such as anserine and carnosine, are enormously beneficial to human health and contribute to the meat flavor in chickens. Meat quality traits, including flavor, are polygenic traits with medium to high heritability. Polygenic traits can be improved through a better understanding of their genetic mechanisms. Genome-wide association studies (GWAS) constitute an effective genomic tool to identify the significant single-nucleotide polymorphisms (SNPs) and potential candidate genes related to various traits of interest in chickens. This study identified potential candidate genes influencing the anserine and carnosine contents in chicken meat through GWAS. We performed GWAS of anserine and carnosine using the Illumina chicken 60K SNP chip (Illumina Inc., San Diego, CA) in 637 Korean native chicken-red-brown line (KNC-R) birds consisting of 228 males and 409 females. The contents of anserine and carnosine in breast meat of KNC-R chickens were investigated. The mean value of the anserine and carnosine are 29.12 mM/g and 10.69 mM/g respectively. The genomic heritabilities were moderate (0.24) for anserine and high (0.43) for carnosine contents. Four and nine SNPs were significantly (P < 0.05) associated with anserine and carnosine, respectively. Based on the GWAS result, the 30.6 to 31.9 Mb region on chicken chromosome 7 was commonly associated with both anserine and carnosine. Through the functional annotation analysis, we identified HNMT and HNMT-like genes as potential candidate genes associated with both anserine and carnosine. The results presented here will contribute to the ongoing improvement of meat quality to satisfy current consumer demands, which are based on healthier, better-flavored, and higher-quality chicken meat.

Vision-Based Design and Deployment Criteria for Power Line Bird Diverters

The design of bird diverters should be based upon the perception of birds, not the perception of humans, but until now it is human vision that has guided diverter design. Aspects of bird vision pertinent to diverter design are reviewed. These are applied in an example that uses Canada Geese Branta canadensis as a putative worst-case example of a collision-prone species. The proposed design uses an achromatic checkerboard pattern of high contrast whose elements match the low spatial resolution of these birds when they are active under twilight light levels. The detectability of the device will be increased by movement, and this is best achieved with a device that rotates on its own axis driven by the wind. The recommended spacing of diverters along a power line is based upon the maximum width of the bird’s binocular field and the linear distance that it subtends at a distance sufficient to allow a bird to alter its flight path before possible impact. Given the worst-case nature of this example, other bird species should detect and avoid such a device. The basic design can be modified for use with specific target species if sufficient is known about their vision. Field trials of devices based on these design criteria are now required.

MDV-induced differential microRNA expression in the primary lymphoid organ of thymus.

Marek's disease virus (MDV), a highly contagious cell associated virus, is the etiological agent of Marek's disease (MD), a lymphoproliferative and neuropathic disease of domestic chickens. Clinical signs of MD include transient paralysis, bursal/thymic atrophy, and T cell lymphomas. MicroRNAs (miRNAs) are short single-stranded non-coding RNAs that regulate gene expression by transcriptional suppression or mRNA degradation. Herpesviruses, including MDV, encode for miRNAs that are known to play essential roles in viral pathogenicity, oncogenesis, and evasion of immune responses. In this study, we performed miRNA sequencing in thymuses of control and MDV-infected chickens of MD-resistant (63) and susceptible (72) lines at 21 days post infection (dpi). The thymus is a lymphoid organ that undergoes severe atrophy due to MDV-induced apoptotic mediated destruction of T cells. Sequence analysis identified 658 total chicken miRNAs in the thymuses of control and MDV-infected birds of both lines. Of these, 453 were novel and 205 were known microRNAs. All novel miRNAs mapped to chicken genome with no sequence homology to existing miRNAs in the chicken miRbase. Comparative analysis between the thymuses of control and infected birds of resistant and susceptible lines identified 78 differentially expressed microRNAs that might provide insights into mechanisms of thymus atrophy.

Investigating Level of Inbreeding and Its Effects on Productive Traits of Napri X Broiler Chickens

Inbreeding refers to the mating together of individuals that are more closely related than would be the case if mating was at random. In this study, we investigate inbreeding and its effect on productive traits in NAPRI X broiler chickens. Traits measured were bodyweight and morphometric traits (Neck length, back length, keel length, breast length, thigh length and shank length). Pedigree information which consists of the base generation, 1060 (sire line) and 341 (dam line) birds; in generation 1, there were 565 (sire line selection), 859 (dam line selection), 433 (sire line control), and 592 (dam line control); and in generation 2, there were 595 (sire line selection), 764 (dam line selection), 457 (sire line control), and 654 (dam line control) were used to calculate inbreeding using J.M.P genomics software. Inbreeding significantly (p&lt;0.05) influenced bodyweight and morphometrics in a positive direction (0.020 -1.052) though some of the traits are tending to zero. The trend in inbreeding coefficient was quadratic from the base generation to the second generation with a range of 0.38-0.81 in SLS, 0.41-0.96 in DLS, 0.51-0.80 in SCL and 0.30-1.03 in DCL. It is therefore concluded that there is a gradual build-up of inbreeding in NAPRI X population thus, the use of mate allocation programs is hereby recommended to put a limit or constraint on the level of inbreeding for the future progeny of NAPRI X broiler chickens.

Prevalence of Viral Neoplastic Diseases with Special Reference to Avian Leukosis and their Infectious Status in Different Pure Line Indigenous Chickens

Viral neoplastic diseases in poultry causes huge economic loss all over the world. The prevalence of avian leukosis in different indigenous breeds of chicken is not known and needs to be addressed for its effective control. A study was designed to record the prevalence of viral neoplasms in poultry, screening of avian leukosis virus/viruses (ALV) antigen in various pure line chicken, and the infectious status of ALV (viremia or shedding) in indigenous birds. Routine necropsy was carried out to identify the birds that were died of neoplasm and the representative samples were collected. Out of 4195 birds necropsied, 90 birds were recorded with neoplastic lesions in various organs with a prevalence of 2.1%. Grossly, tumor lesions were recorded in various organs in which the high frequency of tumors were recorded in liver, spleen, and kidney. Histopathological examination revealed 13.5% of the samples had myeloid leukosis, 25.2% were lymphoid leukosis, 20.3% were histiocytic sarcomas and 40.7% were Marek’s disease. PCR screening of the tumor samples revealed the prevalence rate of 45.5% Marek’s disease virus (MDV), 53.3% ALV, and 1.1% reticuloendotheliosis virus (REV). Co-infections of MDV and ALV were recorded in 37.7% (34/90) samples and MDV, ALV, and REV were recorded in 1.1% (1/90) samples. Among ALV positive cases, 54.1% (26/48) were positive for ALV E and 25% (12/48) were positive for ALV J. Screening of ALV p27 antigen by antigen ELISA in various pure line chickens revealed the prevalence rate of 76.3% in Kadaknath, 73.5% in Ghagus, 76.5% in Aseel, 20.1% in PB-1, 18.8% in PB-2, 19.6% in PD-1, 14.3% in PD-4 and 8.6% in CB. Further molecular detection of ALV was carried out in buffy coat and albumen samples from the birds of Kadaknath, Ghagus, and Aseel that showed high SPR value to determine the infectious status of the ALV. Infectious status of ALV in the birds revealed 40% in Kadaknath, 68.4% in Ghagus and 85.7% in Aseel were viremic shedders (V+S+); 33.3% in Kadaknath, 10.5% in Ghagus and 0% in Aseel were viremic non shedders (V+S-); 16.6% in Kadaknath, 10.5% in Ghagus and 14.2% in Aseel were non viremic shedders (V-S+). This is the first study that documented the prevalence of ALV in different indigenous pure line birds and their infectious status in India.

Possibility to use erythrocyte antigens and feather coloration genes to determine resistance to non-plastic diseases

Non-plastic diseases are a problem in both medical and veterinary practice. These include lymphoid leukemia (LL) and Marek's disease (CM). It should be noted that HM causes losses to poultry three times higher than LL. CM is a highly contagious viral neoplastic disease of chickens. It is known that the degree of resistance of different breeds and lines of chickens to Marek's disease (CM) and lymphoid leukemia (LL) is not the same. To date, little attention has been paid to the role of erythrocyte antigenic factors in the bird's response to morbidity. There is a relationship between the incidence among vaccinated birds and the natural susceptibility to HM birds of certain breeds and lines. The effect of protective reactions in chickens associated with erythrocyte antigenic factors in poultry selected for resistance to non-plastic diseases is still unclear. The objects of the study were chickens and 11-day-old embryos of poultry from one of the farms of Ukraine. The studies were performed on Rhode Island, Leghorn D4 and P-37 chickens. Standard strains of Rouse's sarcoma virus (HRV) were used in the study. Embryos of 11 days of incubation were infected with Rouse virus on the chorio-allantoic membrane (САМ). The results of the studies proved that the resistance to HRV had a significantly opposite correlation only with the presence of B16 antigen and the absence of X31. In chickens of the P-37 line we noted a probable difference in the number of birds of different genetic groups at loci B18 and E 8. Among birds of this line of genotypes rs and ss no individuals with locus E8 were found, while among chickens with genotype rr rarely found a bird with a locus B18. In hens of line D-4 with genotype rr, the frequency of the A12 locus was set more often than in genotypes rs and ss. As for the frequency of the B33 locus, the opposite pattern was observed. Tumor regression was probably more common in birds with antigenic factor B1 and in the absence of B33. Hypersensitivity to non-plastic diseases of chickens carrying B2, B21, B29, X50 antigens has been established. The bird, more resistant to neoplasms, had an increased number of antigens B3, B18, C26. and research in this direction continues. It is assumed that the plumage color gene (s), if present in homozygous form, is an inhibitor of sensitivity. The experiments used embryos and chickens with different plumage color: red, black, white with a yellow tinge, pure white. Their ratio is approximately 2:1:1 or 3 parts “colored” and 1 part white. It was found that among the “colored” embryos were more stable than sensitive. In fact, the resulting cleavage was close to expected.

Genetic and phenotypic responses to genomic selection for timing of breeding in a wild songbird

Abstract The physiological mechanisms underlying avian seasonal timing of reproduction, a life‐history trait with major fitness consequences, are not well understood. Comparing individuals that have been selected to differ in their timing of breeding may prove to be a promising in studying these mechanisms, making selection lines a valuable tool. We created selection lines for early and late timing of breeding in great tits (Parus major) using genomic selection, that is selection based on multi‐marker genotypes rather than on the phenotype. We took in nestlings (F1 generation) from wild broods of which the mother was either an extremely early (“early line”) or extremely late (“late line”) breeder. These chicks were then genotyped and, based on their “genomic breeding values” (GEBVs), we selected individuals for early and late line breeding pairs to produce the F2 generation in captivity. The F2 offspring was hand‐reared, genotyped and selected to produce an F3 generation, which were then again genotyped and selected. This way we obtained laying dates in aviaries for F1, F2 and F3 birds. We studied the genetic response to the artificial selection and found increased genetic differentiation between the early and late reproducing selection lines over generations (F1–F3), indicated by both diverging GEBVs and increased fixation indices (FST). We studied the phenotypic response to selection for birds breeding in outdoor breeding aviaries. We found that early line birds laid earlier than late line birds, and this difference increased over the generations (F1–F3), with non‐significant line effects for the F1 and F2, but highly significant line differences for the F3. We also assessed whether there was correlated selection on two traits that are potentially part of the mechanisms underlying seasonal timing: the endogenous free‐running period of the day/night clock (tau) and basal metabolic rate, but found no correlated selection. We have successfully created selection lines on seasonal timing in a wild bird species and obtained an instrument for future studies to investigate the physiological mechanisms underlying timing of breeding, and the genetic variation in these mechanisms, an essential component for evolutionary change in timing of reproduction. A free Plain Language Summary can be found within the Supporting Information of this article.

Effects of genomic selection for intramuscular fat content in breast muscle in Chinese local chickens.

Improvements in living standards have resulted in consumers having higher expectations for chicken meat quality. This is particularly true in Asia, where there is high consumer preference for local breeds. Nothing is presently known about the effectiveness of using genomic selection (GS) strategies in chickens to genetically improve meat quality traits that cannot be measured in living potential parents. In this study, 724 Beijing-You chickens were used as a training population; all were genotyped using Illumina 60K SNP chips, and intramuscular fat content in breast muscle (IMFbr ) was measured. Birds in the GS line were selected based on genomic estimated breeding values, IMFbr being the sole trait. Genetic progress in one generation was compared to that from conventional family-based selection, and both were evaluated against random-bred controls. Results showed that relative to the random-bred controls, IMF percentage was improved 9.62% using GS, comparable to the 10.38% improvement using family-based selection. We quantified the effectiveness of GS when applied to a meat quality trait with low heritability in chickens. We plan to introduce custom SNP chips, appropriate for native chicken breeds in China, to assist in applying GS in local breeding and accelerate genetic gain.

Effect of Two Transport Options on the Welfare of Two Genetic Lines of Organic Free Range Pullets in Switzerland.

Simple SummaryAnimal welfare has been of increasing interest to consumers and producers of animal products in Europe. Issues during transport affect both the wellbeing and the productivity of livestock. This study was conducted to analyze two practice-oriented transport variants of organically mixed-held white and brown pullets. No significant difference could be found between the transport variants. Instead, we discovered clear differences between the two genetic pullet lines.The welfare of two genetic lines of organic layer hen pullets—H&N Super Nick (HNS) and H&N Brown Nick (HNB)—was compared during two commercial transport variants of 15 flocks of mixed-reared birds. Birds were either transported overnight (with a break in travel), or were transported direct to the layer farm (without a break in travel). Samples of feces were collected non-invasively from 25 birds of each genetic line per flock for each transport variant before transportation to evaluate baseline values of glucocorticoid metabolites, and at 0 h, 3 h, 6 h, 10 h, 24 h, 34 h, 48 h, 58 h, and 72 h after the end of transportation, to measure transportation and translocation stress. We assessed the fear toward humans with the touch test before transportation, and we checked the birds’ body condition by scoring the plumage condition and the occurrence of injuries. Body weight before and weight loss after transportation were determined, and ambient temperature was measured before, during, and after transportation. Stress investigations showed no significant differences between the transport variants (effect: −0.208; 95% confidence interval (CI): (−0.567; 0.163)). Instead, we discovered differences between the pullet lines (effect: −0.286; 95% CI: (−0.334; 0.238)). Weight loss was different between the transport variants (2.1 percentage points; 95% CI: (−2.6; −1.5)) and between the genetic lines, as HNB lost significantly less weight than HNS (0.5 percentage points; 95% CI: (0.3; 0.7)).

Expression and effect of Calpain9 gene genetic polymorphism on slaughter indicators and intramuscular fat content in chickens.

Calpain 9 (CAPN9) is expressed in the stomach and small intestine. CAPN9 has regulatory roles in hypertension, heart disease, gastric mucosal defense, and kidney disease. The involvement of CAPN9 has not been reported in the development of chickens. CAPN9 mRNA was found in adipose and muscle tissue in this study. Two linkage single nucleotide polymorphisms (SNP; G7518A and C7542G) in intron 4 were screened from 160 birds of the D2 chicken line. The 2 mutation sites were associated with carcass weight, evisceration weight, abdominal fat weight (AFW), abdominal fat percentage (AFP), and breast muscle percentage (all P < 0.05). Intramuscular fat (IMF) content was not significantly different in the 3 genotypes. But, the AA(7518)/GG(7542) genotype had the highest IMF content, highest breast muscle weight, and lower AFW and AFP. Moreover, the mRNA level of CAPN9 in abdominal fat tissue was significantly different (P < 0.05 or P < 0.01) between any 2 genotypes, consistent with AFW and AFP. In summary, the expression of CAPN9 in adipose and breast muscle tissue is reported for the first time. CAPN9 affected production performance of chickens. As a marker, the linkage G7518A and C7542G polymorphisms in intron 4 of CAPN9 could affect the production traits by regulating mRNA expression. The findings concerning the marker enrich the theoretical foundation for molecular breeding of high-quality broilers.

Growth performance and carcass characteristics of the black and pearl guinea fowl (&lt;i&gt;Numida meleagris&lt;/i&gt;) and their crosses

This study was carried out to estimate and evaluate the growth performance and carcass yield of the black and pearl guinea fowl and their crosses. The following three mating groups were established: Pearl male X Pearl female (PXP), Black male X Black female (BXB) and Black male X Pearl female (BXP), from which a total of 317 guinea fowl keets were obtained in six hatches and used for the study. There were 100 PXP, 118 BXB and 99 BXP keets. Growth parameters estimated were body weight, body weight gain, feed intake and feed conversion ratio. Carcass traits studied include live weight at point of slaughter, slaughter weight, dressed weight and dressing percentage. Carcass traits were taken at 14 weeks of age. All the growth performance traits studied did not differ significantly (P > 0.05) across the genotype groups, except body weight at 10, 12 and 14 weeks of age. Birds of the PXP pure line were significantly higher (P < 0.05) at 10-14 weeks old than the other two genotype in this respect. The average bi-weekly body weight gains (g/bird) were 149.34, 126.78 and 124.24g and average daily body weight gains were 9.33, 9.06 and 8.87g for birds in the PXP, BXP and BXB genotypes respectively. The average daily feed intake were 47.92, 47.15 and 47.18g for the PXP, BXB and BXP genotypes respectively while average feed conversion ratios were 5.14, 5.22 and 5.32 for the PXP, BXP and BXB genotypes respectively. Significant differences were not observed among the genotype groups in all the carcass traits. The dressing percentages were 75.83, 75.17 and 74.50 for the BXB, PXP and BXP genotypes respectively. It was concluded that the genotype groups did not differ significantly in their growth performance and carcass traits due to a probable genetic relatedness among the ancestors. Keywords : Weight gain, Feed Conversion Ratio, Slaughter weight, Dressing Percentage

Genetic selection on abdominal fat content alters the reproductive performance of broilers

The effects of obesity on reproduction have been widely reported in humans and mice. The present study was designed to compare the reproductive performance of lean and fat chicken lines, divergently selected for abdominal fat content. The following parameters were determined and analyzed in the two lines: (1) reproductive traits, including age at first egg and total egg numbers from generations 14 to 18, absolute and relative testicular weights at 7, 14, 25, 30, 45 and 56 weeks of age, semen quality at 30, 45 and 56 weeks of age in generation 18, and fertility and hatchability from generations 14 to 18; (2) reproductive hormones at 7, 14, 25, 30, 45 and 56 weeks of age in generation 18; (3) and the relative mRNA abundance of genes involved in reproduction at 7, 14, 25, 30, 45 and 56 weeks of age in generation 18. In females, birds in the lean line laid more eggs from the first egg to 40 weeks of age than the birds in the fat line. In male broilers, the birds in the lean line had higher absolute and relative testicular weights at 7, 14 and 25 weeks of age, but lower absolute and relative testicular weights at 56 weeks of age than the birds in the fat line. Male birds in the lean line had greater sperm concentrations and larger numbers of motile and morphologically normal sperms at 30, 45 and 56 weeks of age than the birds in the fat line. Fertility and hatchability were also higher in the lean line than in the fat line. Significant differences in the plasma levels of reproductive hormones and the expression of reproduction-associated genes were also found at different ages in the lean and fat birds, in both males and females. These results suggest that reproductive performance is better in lean birds than in fat birds. In view of the unique divergent lines used in this study, these results imply that selecting for abdominal fat deposition negatively affects the reproductive performance of birds.

Uticaj ishrane sa dodatkom ekstrudiranog semena lana na sadržaj holesterola i sastav masnih kiselina mesa brojlera

The cholesterol content and fatty acids profile of white (breast) and dark meat (leg-thigh) were examined by feeding two groups (both with males and females) of 1000 birds of the Ross hybrid line by standard feed (control group – CONM and CONF) and with the addition of 6% of extruded flaxseed mixture (experimental group – EXPM and EXPF). The addition of extruded flaxseed to the diet of chickens did not affect (P>0.05) the content of cholesterol in meat, which was between 46.13 and 52.94 mg/100g in white meat and 51.31–55.47 mg/100g in dark meat. The content of α-Linolenic acid increased significantly (P<0.01) in both white [0.72(CONF)–1.62(CONM) to 2.20(EXPF)–3.03(EXPM)] and dark meat [1.75(CONF)–1.98(CONM) to 4.47(EXPM)–4.66(EXMF)], as did the content of ω-3 FA and PUFA, while the ω-6/ω-3 ratio decreased, reaching values below 6. The effect was more pronounced in the meat of females and in dark meat. By adding extruded flaxseed to chicken feed the nutritional characteristics of meat can be improved.

Behavioral and physiological responses of different genetic lines of free-range broiler raised on a semi-intensive system

The aim of the study was evaluate the ability of adaptation of seven different genetic lines of free range broilers to a semi-intensive raising system. Four hundred and twenty chicks of the Pescoco Pelado (PP), Carijo (CG), Colorpak (CPK), Tricolor (TRC), Caboclo (CBC), Gigante Negro (GNG) and Pesadao Vermelho (PS) genetic groups were used. At 28 days of age the birds were allowed access the paddocks and after three days of adaptation the monitoring of the animals has started, being performed behavioral visual observations from 07:00 to 17:00. Cloacal temperature (CT) and respiratory rate (RR) were collected once a week. The environment was monitored considering the temperature, relative humidity and black globe temperature at various points of the paddocks and the shed. The physiological variables were evaluated using a randomized complete block design with a split plot arrangement. Behavioral variables were analyzed using nonparametric Friedman test. Birds of Carijo and Colorpak genetic line presented greater RR, 34.6 mov/min and 36.0 mov/min respectively, compared to the birds of the Caboclo and Gigante Negro genetic line, 29.0 mov/min and 28.4 mov/min respectively. The average values of RR and CT for all genetic lines were higher in the afternoon. At 7:00 and 17:00 the foraging behavior was more intense. The Caboclo and Gigante Negro genetic line were those that stood out in the behavior of foraging, consequently, they are more able to adapt to the semi-intensive raising system.

Divergent selection on home pen locomotor activity in a chicken model: Selection program, genetic parameters and direct response on activity and body weight.

General locomotor activity (GLA) in poultry has attracted attention, as it negatively influences production costs (energy expenditure and feed consumption) and welfare parameters (bone strength, litter quality, feather pecking and cannibalism). Laying hen lines diverging in the average level of spontaneous locomotor activity in the home pen were developed by genetic selection using the founder New Hampshire line. Activity was recorded using RFID technology at around five weeks of age during four to five days in the home pen. After initial phenotyping, the least active birds were selected for the low activity line and the most active for the high activity line, with no gene transfer between lines. In each of six generations, approximately ten sires were mated to twenty dams producing 158 to 334 offspring per line per generation. The response to selection was rapid and of a considerable magnitude. In sixth generation, the level of GLA was approximately halved in the low and doubled in the high line compared to the control (7.2, 14.9 and 28.7 recordings/h). Estimated heritability of locomotor activity in the low and high line was 0.38 and 0.33, respectively. Males, in general, were more active than females. High line birds were significantly heavier than low line birds. In fourth, fifth, and sixth generation, low as well as high line birds were lighter than control line birds. This selection experiment demonstrates variation in heritability for GLA and, as a result, genetically diverged lines have been developed. These lines can be used as models for further studies of underlying physiological, neural and molecular genetic mechanisms of spontaneous locomotor activity.

Selection for pro-inflammatory mediators produces chickens more resistant to Campylobacter jejuni

Campylobacter spp. are the second leading cause of bacterial-induced foodborne illnesses with an estimated economic burden of nearly $2B USD per year. Most human illness associated with campylobacteriosis is due to infection by C. jejuni and chickens are recognized as a reservoir that could lead to foodborne illness in humans resulting from handling or consuming raw or undercooked chicken. We recently developed a novel breeding strategy based on identification and selection of chickens with an inherently high and low phenotype of pro-inflammatory mediators including IL-6, CXCLi2, and CCLi2, hereafter referred to as the high and low lines, respectively. We have shown the high line chickens are more resistant to the foodborne and poultry pathogens Salmonella enterica serovar Enteritidis, Eimeria tenella, and Clostridium perfringens-induced necrotic enteritis compared to the low line. The objective of this study was to determine whether the same trend of enhanced resistance in the high line birds was observed for C. jejuni. Birds were challenged at 2 d of age by oral gavage (0.5 mL) with 5 × 106 colony forming units (cfu) of C. jejuni/mL, necropsied 4 d post challenge, and cecal content collected to determine if there was a difference in C. jejuni resistance between the high and low line chickens. There were fewer (P = 0.01) chickens from the high line (28/40 = 71.8%) that were colonized by C. jejuni compared to the low line (37/39 = 94.9%). The amount of C. jejuni recovered from the ceca of infected birds was quantified; however, no differences were observed (P = 0.10). Since the high line birds were also more resistant to C. jejuni, it provides additional validation of selection based on pro-inflammatory mediators producing a line of chickens with increased natural resistance against diverse foodborne and poultry pathogens. The poultry industry is moving towards reduced therapeutics and, as such, our breeding strategy would be a viable method to incorporate into traditional poultry breeding programs.

Genetic aspects of auto-immune profiles of healthy chickens

Auto-antibody profiles binding liver antigens differed between chicken lines divergently selected for specific antibody responses to SRBC, and were affected by ageing suggesting both genetic and environmental effects. Presence and levels of IgM and IgG antibodies binding chicken liver cell lysate (CLL) fragments in plasma at 5 weeks of age from 10 individual full sibs and their parents from 5 Hsrbc and 5 Lsrbc line families was studied to reveal genetic relations. Non-genetic maternal effects were studied by comparing auto-antibody profiles of 36 weeks old hens from 2 other unrelated lines with the profiles from their chicks at hatch.IgM and IgG antibodies from parents and progeny from both Hsrbc and Lsrbc lines bound CLL fragments. Significant line and generation differences and their interactions were found for both isotypes. Higher staining of CLL fragments was usually found for Hsrbc line birds. Lines were clustered by auto-antibody profiles, but staining by birds of both lines in both generations was very individual for IgG and IgM. The current data with full sibs therefore not supported a genetic basis for auto-antibody profiles. IgG but not IgM auto-antibody profiles of chicks correlated with maternal auto-antibody profiles.The results suggest that the auto-antibody repertoire of healthy chickens is largely stochastically initiated and may be affected by environmental challenges during ageing, but genetic mechanisms may underlie staining intensity of individual bound CLL fragments. The present results suggest that identification of fragments or profiles to be used at early age for genetic selection for health traits is not feasible yet. Secondly, the IgM profile of neonatal chickens seems non-organised independent of the maternal profile, but the neonatal IgG profile is much more related with the maternal profile. Consequences of these findings for disease susceptibility or breeding for optimal health are discussed.

Early Immune Responses to Marek's Disease Vaccines.

Marek's disease virus (MDV), a highly cell-associated lymphotropic α-herpesvirus, is the causative agent of Marek's disease (MD) in domestic chickens. MDV replicates in chicken cells and establishes a latent infection within CD4+ T cells. Although MD vaccines have been in use for several decades, the exact mechanism of vaccine-induced protection is unclear. It is believed that the innate immune system plays a role in vaccine-induced immunity against pathogenic strains of MDV. To shed light on the possible function of the innate immunity in vaccine-mediated protection, we investigated the effect of vaccination, Rispens/CVI988, on the activation of cellular components of the innate immune system by analyzing the expression pattern of select immune-related genes in the cecal tonsils (CT) and duodenum of two MD-susceptible and MD-resistant chicken lines at 3, 5, and 10 days postvaccination (dpv). The differential expression patterns of the tested genes within the CT and duodenum of vaccinated birds revealed the activation of the innate immune system in both the susceptible and resistant lines. Stronger innate immune response was induced within the CT of the vaccinated birds of the susceptible line at 5 dpv. Upregulation of some of the tested genes at 10 dpv was likely due to the activation and response of the adaptive immune system to vaccination. Immunohistochemical analysis showed no increase in the number of CD3+ T cells in the CT and duodenum of the vaccinated birds of either line at 5 dpv. There was, however, an increase in the macrophage populations within the duodenum of the vaccinated birds of both the susceptible and resistant lines at 5 dpv. The vaccine strain antigen was detected in the CT and duodenum of the susceptible line, but not the resistant line at 5 dpv.

Effects of genotype on hematological and serum biochemical responses of turkey hens to stress

Abstract. Stress accompanying animal production is both an indicator of welfare and a factor that affects economic parameters. Dynamic development of alternative poultry production systems such as outdoor, free range or ecological, strives to achieve best-quality products and to improve the living conditions of birds. Apart from the type and intensity of the external stimuli, the response to stress is determined genetically. Poultry rearing in the aforementioned systems requires selecting the appropriate genotype of birds, often including crosses of fast-growing and slow-growing lines. The objective of this study was to demonstrate differences in the physiological response to stress of fast-growing (FG) and slow-growing (SG) turkeys and their crosses: SF (SG × FG) and FS (FG × SG), based on hematological and biochemical blood analyses. Blood was sampled from 30 turkey hens from each of four genotypes, aged 14 weeks, subjected to standard pre-slaughter handling procedures. Compared to FG and FS turkeys, the SG and SF birds had a high total protein concentration, a higher heterophil (H) ∕ lymphocyte (L) ratio and a higher concentration of cortisol. In turn, the FG turkeys had the highest activity of enzymes: alanine transaminase, aspartate transaminase, lactate dehydrogenase, creatine kinase. Conversely, the FS turkeys had the highest concentrations of total cholesterol and low-density lipoprotein (LDLC) and the lowest concentration of cortisol. Significant positive effects of crossing were reported for total protein, cholinesterase and cortisol. Effects of crossbreeding on the percentage of H, concentrations of total cholesterol, and LDLC and activity of aspartate transaminase in blood of the crosses were significant but negative and more dependent on the sire line. Except for albumins, whose concentration in blood of crosses was higher compared to birds of pure lines, there were no advantages of heterosis. Negative heterosis was estimated for creatinine, the enzymes alanine transaminase and lactate dehydrogenase, and for cortisol. The most similar regarding creatinine, bilirubin, albumins, total protein, H, L and H ∕ L were the FS and SF groups. The greatest differences were in the following parameters: triglycerides, total cholesterol, high-density lipoprotein (HDLC), LDLC, glucose and lactate, which occurred between the pure lines of turkeys. Study results demonstrate various responses to stress in the analyzed groups of turkeys, with the level of stress measured with hematological and biological blood markers being mostly determined by additive genetic variation, and to a lesser extent by the maternal and sire effects.

Severe necrotic dermatitis in the combs of line 63 chickens infected with Marek’s disease virus

ABSTRACTMarek’s disease virus (MDV), the aetiological agent of Mareks' disease (MD), is a highly cell-associated oncogenic α-herpesvirus that replicates in chicken lymphocytes and establishes a latent infection within CD4+ T cells. We investigated the possible effect of MDV infection on the exacerbation of necrotic dermatitis in the combs of MD-susceptible (72) and MD-resistant (63) chicken lines at 21 days post infection. MDV-infected birds of line 63 are relatively resistant to tumour development but exhibit an unusual necrosis of combs, wattles, and footpads that is intensified when infected with MDV. Chickens from line 72, on the other hand, are highly susceptible to MDV infection and tumour development. Real-Time PCR analysis revealed that IL-6, IL-8, IL-12, IL-18, iNOS, and IFNγ were all up regulated in the comb tissues of MDV-infected susceptible line 72 with no visible necrotic damage. With the exception of IL-8 and iNOS, the expression of all the other tested genes was barely detected in the necrotic combs of the resistant line 63. Real-Time PCR analysis revealed the MDV meq oncogene transcripts in the spleen tissues of both infected lines but in the comb tissues of only the susceptible line 72. A significant infiltration of macrophages and lymphocytes was detected in the comb tissues of both resistant and susceptible lines. Histopathological analysis also showed thinning and erosion of epidermis and inflammation, lympho-plasmocytic infiltration, heterophilic, and histocytic cellulitis within the connective tissues of the necrotic combs. Gram stain of the sectioned frozen comb samples exposed the presence of Gram-positive micrococcus.