Insulin-like growth factor-I (IGF-I) and myostatin (MSTN) are a pair of critical positive and negative growth regulators. The aim of the current study was to examine the age-dependent and muscle-specific expression of IGF-I and MSTN mRNAs in black Muscovy ducks in order to understand their roles in regulating the postnatal muscle growth of domestic ducks.

The full-length cDNA of the black Muscovy duck MSTN gene was cloned and the age-dependent mRNA expression profile was compared with that of the IGF-I mRNA in skeletal muscles.

The cDNA sequence of the MSTN gene was 1128 bp in length and encodes 375 amino acids, with more than 94.9% homology with poultry MSTN genes, and 83.0–92.0% homology with that of human and mammals (accession: KR006339.1).

The IGF-I and MSTN mRNA expression exhibited opposite trends in age-dependency and in different muscles: IGF-I mRNA level was high in the early postnatal stage and low in the late mature stage, corresponding positively to growth; while the MSTN mRNA was low in the early stage, increased gradually and reached the highest level in mature muscles, and was negatively related to muscle growth. In the breast muscles, IGF-I mRNA was much higher than in the leg muscles; the opposite effect was seen in MSTN mRNA.

These data suggest that the relative expression levels of IGF-I and MSTN are essential determinants in the temporal and muscle-specific regulation of postnatal skeletal muscle growth in Muscovy duck and possibly in other poultry species as well.

Activin receptor type 2A (ACVR2A) acts as receptor for myostatin (MSTN) protein involved in inhibiting satellite cell proliferation and differentiation. The importance of the ACVR2A gene during embryonic and post-hatch periods in broiler and layer chicken was studied in an in vitro cell culture system.

The expression pattern of the ACVR2A gene during embryonic stages was similar in broiler and layer lines. Post-hatch expression of the ACVR2A gene varied significantly between broiler and layer lines.

Five shRNA molecules were designed to knockdown expression of the ACVR2A gene in chicken myoblast cells. The silencing of the ACVR2A gene in a cell culture system varied from 60% to 82%.

It is concluded that between broiler and layer lines, there were no significant changes in expression of the ACVR2A gene during embryonic stages but it varied significantly during the post-hatch period. The shRNA showed silencing of the ACVR2A gene under an in vitro cell culture system.

The post-mortem proteolysis and tenderisation between male and female duck breast muscles were compared.

The results showed that μ-calpain activity, desmin content and shear force decreased more quickly in female than in male samples stored at 5°C.

It is suggested that the post-mortem proteolysis and tenderisation are more rapid and extensive in female duck breast muscle.

Gonadotropin-releasing hormone (GnRH), a neuropeptide, plays a vital role in the hypothalamus–pituitary–gonadal (HPG) axis. In vertebrates, GnRH is crucial for the onset of sexual development and the entire reproductive process. The purpose of this study was to identify genetic factors associated with egg-laying traits of Muscovy ducks.

The full-length cDNA (474 bp) of Muscovy duck GnRH was obtained and characterised. It encodes 92 amino acids containing a 1-amino acid signal peptide cleavage site. Phylogenetic analysis revealed that Muscovy duck GnRH has a close relationship with Anas platyrhynchos GnRH.

GnRH showed significantly different expression profiles between 4 developmental periods in the hypothalamus, pituitary, and ovary. The expression of GnRH in the laying period (36 weeks) was higher than at other periods in the three tissues. GnRH was widely expressed in 12 examined tissues of nesting and laying Muscovy ducks. In the hypothalamus, pituitary and gonads, the expression of GnRH was higher than in other tissues.

In laying Muscovy ducks, the expression of GnRH in the hypothalamus, pituitary, ovary, muscular stomach, pancreas, heart, duodenum and spleen was significantly higher than in nesting dusks. Differences were detected in the liver and glandular stomach between laying ducks and nesting ducks. Differences between the kidney and lung were not significant.

In the pituitary, the GnRH and GnRH receptor (GnRHR) genes shared the same expression profiles during 4 time points. Both genes had the highest expression at 36 weeks of age.

A mutation (g.206G > A) in the 5?-flanking region was associated with egg-laying performance. Individuals with genotype GG had better egg-laying performance than the individuals with genotype AA. GnRH may be used as a marker gene for laying performance in the Muscovy duck.

The aim of this study was to identify molecular techniques which enable clear discrimination between Mycoplasma synoviae isolates for improved epidemiology.

Multilocus sequence analysis (MLSA) of 6 M. synoviae loci was conducted for genotyping of isolates with previously determined 5?-vlhA sequences.

Sequencing of three polymorphic genes (5?-vlhA, cysP and nanH) enables good discrimination between isolates with different genotypes. Such a genotyping scheme revealed 10 distinct genotypes, which were confirmed by sequencing of an additional three loci of the M. synoviae genome. Epidemiologically linked strains formed clusters with the same genotypes which clearly differed between clusters.

MLSA used in this study is a promising tool for epidemiology of M. synoviae isolates, but it should be evaluated by further investigations using a much higher number of M. synoviae strains.

Agouti signalling protein (ASIP) is an endogenous antagonist of melanocortin-1 receptor (MC1R) and is involved in the regulation of pigmentation in mammals. The objective of this study was to identify and characterise the ASIP gene in domestic goose.

The goose ASIP cDNA consisted of a 44-nucleotide 5?-terminal untranslated region (UTR), a 390-nucleotide open-reading frame (ORF) and a 45-nucleotide 3?-UTR. The length of goose ASIP genomic DNA was 6176 bp, including three coding exons and two introns.

Bioinformatic analysis indicated that the ORF encodes a protein of 130 amino-acid residues with a molecular weight of 14.88 kDa and an isoelectric point of 9.73.

Multiple sequence alignments and phylogenetic analysis showed that the amino-acid sequence of ASIP was conserved in vertebrates, especially in the avian species.

RT-qPCR showed that the goose ASIP mRNA was differentially expressed in the pigment deposition tissues, including eye, foot, feather follicle, skin of the back, as well as in skin of the abdomen. The expression level of the ASIP gene in skin of the abdomen was higher than that in skin of the back.

Those findings will contribute to further understanding the functions of the ASIP gene in geese plumage colouring.

Sudden death syndrome (SDS) in broilers is a cardiac disease associated with ventricular tachycardia (VT) and ventricular fibrillation (VF); however, its pathogenesis at the molecular level is not precisely determined.

Downregulation and mutations of calsequestrin 2 (CASQ2), a major intracellular Ca²⁺ buffer, have been associated with VT and sudden cardiac death (SCD) in humans but in chickens there is no report describing CASQ2 abnormalities in cardiac diseases.

In order to better understand the molecular mechanisms predisposing the myocardium to fatal arrhythmia in broilers, the mRNA expression level of chicken CASQ2 gene (chCASQ2) in the left ventricle of dead broilers with SDS was determined and compared to healthy broilers using quantitative real-time PCR (qPCR). To determine the probable mutations in chCASQ2, PCR and direct sequencing were also done.

Results showed a reduction in chCASQ2 expression in broilers dead by SDS. Three novel mutations (K289R, P308S, D310H) which are absent in healthy broilers were observed in chCASQ2.

It is concluded that susceptibility to fatal cardiac arrhythmia in SDS may be associated with changes in intracellular Ca²⁺ balance due to mutation and downregulation of chCASQ2.

Quantitative real-time PCR was carried out to evaluate gene expression of heat shock proteins (HSP) (HSP27, HSP56, HSP60, HSP70, HSP90 and ubiquitin) in the brain (hindbrain, midbrain, forebrain) of chickens with cold-induced pulmonary hypertension.

The ratio of the right ventricle to the total ventricle (index of pulmonary hypertension in chickens) was increased in the cold-induced pulmonary hypertensive chickens at 42 d of age compared with control. The HSP genes were expressed in the three parts of the brain in the two experimental groups.

In the hindbrain of cold-induced pulmonary hypertensive chickens, the relative gene expression of HSP27, HSP60, HSP70 and HSP90 was decreased while gene expression of HSP56 and ubiquitin was increased compared with controls.

In the midbrain of cold induced-pulmonary hypertensive chickens, the expression of HSP56, HSP60, HSP70 and ubiquitin genes was increased compared with controls while HSP27 and HSP90 were decreased.

In the forebrain of cold induced-pulmonary hypertensive chickens, the expression of HSP56, HSP60, HSP70 and ubiquitin genes was increased while the expression of the HSP27 gene was decreased compared with controls.

It is concluded that overexpression of HSPs in the forebrain and midbrain probably delays the pathological process of cold stress whereas diminished expression of HSP genes in the hindbrain may affect the normal function of brain centres in this area to exacerbate pulmonary hypertension.

The epidemiology of chicken lice species such as Menacanthus stramineus, M. cornutus and M. pallidulus were studied during an observational, analytical and sectional survey, to determine predisposing factors for their occurrence in laying hen farms in the State of Minas Gerais, Brazil. A total of 431 houses on 43 farms were visited in 2012.

M. cornutus, M. stramineus and M. pallidulus occurred in 20.9%, 11.6% and 11.6% of farms, respectively. The frequencies of occurrence of M. cornutus, M. stramineus and M.pallidulus in poultry houses were 10.4%, 8.8% and 3.7%, respectively.

The epidemiological determinants for the occurrence of these species were investigated using Poisson or logistic regression models.

The region of the farm, the recent use of acaricides and the presence of birds, such as saffron finch (Sicalis flaveola), feral pigeon (Columba livia) and Guira cuckoo (Guira guira) around the farms were related to the epidemiology of M. cornutus.

Infestation by M. stramineus was associated with age of birds, number of birds per cage and the presence of Guira cuckoo and Chopi blackbird (Gnorimopsar chopi) near the poultry houses.

The occurrence of M. pallidulus was influenced by the type of facilities, presence of cattle egret (Bubulcus ibis) and free-range domestic hens around the farm.

The use of wire mesh nets in the houses and of forced moulting did not influence lice infestation.

The growth of the avian embryo is paralleled by an exponential increase in the rate of whole-embryonic oxygen consumption, which potentially increases oxidative damage.

Age-related patterns of tissue lipid peroxidation were characterised in brain, liver and heart tissue of developing Japanese quail (Coturnix japonica) embryos between 9 and 15 d of age, over which embryo mass increased by a factor of 6. Lipid peroxidation was quantified in each tissue by spectrophotometric measurement of malondialdehyde using the thiobarbituric acid reactive substances assay.

In all tissues, lipid peroxidation increased greatly as development proceeded. Concentrations of malondialdehyde increased in parallel with the cumulative amount of oxygen consumed by the developing embryo consistent with the hypothesis that oxidative stress results from the production of free radicals due to oxidative metabolism.

This study describes in vivo oxidative stress in developing avian embryos and suggests that rates of embryonic growth, oxidative metabolism and oxidative damage likely vary in parallel.

The cDNA sequence of the growth hormone receptor (GHR) from the black Muscovy duck was obtained and compared to the mRNA expression of growth hormone (GH) in the breast and leg muscles during 2–13 weeks of age using quantitative RT-PCR.

The cDNA sequence of the Muscovy duck GHR gene is 1903 bp in length, with an 1830 bp coding region that encodes 609 amino acids. It exhibits > 92.9% homology with the poultry GHR cDNA and amino acid sequences.

Overall, GHR mRNA expression was the highest at 2 weeks and the lowest at 13 weeks of age, exhibiting different profiles in different muscles. In the breast muscles, the GHR mRNA level declined sharply at 2–4 weeks, maintained at a plateau at 4–10 weeks and decreased slightly at 10–13 weeks. In the leg muscles, a gradual and slow decrease was observed during the whole period of 2–13 weeks.

Robust extra-pituitary GH mRNA expression was detected in the muscles and the expression profile was highly correlated with that of GHR mRNA, in contrast to the inverse correlation between the pituitary GH and tissue GHR levels shown previously.

These data suggest that the locally synthesised GH in the muscles, rather than the pituitary GH, is more closely associated with GHR and may be more critical for the regulation of muscle growth and contribute to the tissue-specific effects of GH.

The objective of the study was to investigate the distribution of LPIN2 variants and haplotypes among breeds and perform an association analysis of the variants and haplotypes with the broiler traits in chickens.

Six breeds were used to study the variation and distribution of chicken LPIN2, and an F₂ resource population was used to measure growth traits, carcass traits, meat quality traits and serum biochemistry parameters.

A c.-599G>A variant was located in the promoter region of LPIN2 and c.444G>A and c.1730A>T (E577D) coding variant mutations were detected. Linkage disequilibrium tests showed that these three variants were under moderate linkage disequilibrium in the 6 breeds and 7 haplotypes were constructed. The distribution of variation/haplotypes presented clear differences among breeds.

Association analysis showed that c.-599G>A was associated with leg muscle weight, jejunum length, ileum length, leg muscle fibre density and leg muscle fibre diameter; c.444G>A was associated with spleen weight, ileum length, body weight at hatch and metatarsus length at 8 weeks; c.1730T>A had significant effects on chicken liver weight, heart weight, body weight at 10 weeks, serum albumin and glucose.

Diplotypes were significantly associated with body weight at hatch, heart weight, pancreas weight, duodenum length, leg muscle fibre density and lactate dehydrogenase.

The aim of this study was to assess mRNA abundance of calpain 1 (CAPN1) and calpain 3 (CAPN3) in breast muscle of 80 fast-growing (FG) and slow-growing broilers (SG) and relate gene expression in relation to growth and Warner Bratzler (WB) shear force of breast muscle.

The expression of CAPN1 and CAPN3 genes was higher in the FG compared to the SG line, but significant results were obtained only for CAPN1. The CAPN1 mRNA level was strongly dependent on line and gender interaction.

Lower values of shear force were observed in the FG line, where a higher level of calpain expression was shown.

A new panel of housekeeping genes (RPL4 and SDHA) for normalisation of gene expression in muscle tissues could be used in other studies of gene expression in chicken.

A DiagNose II electronic nose (e-nose) system was tested to evaluate the performance of such systems in the detection of the Salmonella enterica pathogen in poultry manure.

To build a database, poultry manure samples were collected from 7 broiler houses, samples were homogenised, and subdivided into 4 portions. One portion was left as is; the other three portions were artificially infected with S. enterica.

An artificial neural network (ANN) model was developed and validated using the developed database.

In order to test the performance of DiagNose II and the ANN model, 16 manure samples were collected from 6 different broiler houses and tested using these two systems.

The results showed that DiagNose II was able to classify manure samples correctly as infected or non-infected based on the ANN model developed with a 94% level of accuracy.

The types and methods of use of antibiotics in poultry farms in Cameroon, residual levels and potential microbial resistance were determined.

A questionnaire-based survey identified the different antibiotics used and high-performance liquid chromatography (HPLC) was used to determine residual levels of antibiotics.

Pathogens were isolated, identified by use of commercial API kits and minimum inhibition concentration (MIC) was determined.

Oxytetracyclin, tylocip and TCN (oxytetracycline, chloramphenicol and neomycin) were the most frequently used antibiotics. Antibiotics screened by HPLC were chloramphenicol, tetracycline and vancomycin. All of them except vancomycin were detected, and the concentration of these antibiotics was higher than the maximum residual limits (MRL) set by regulatory authorities.

No residues of various antibiotics were found in egg albumen or yolk. The concentration of tetracycline was significantly higher in liver (150 ± 30 µg/g) than in other tissues.

Foodborne pathogens, including Salmonella spp., Staphylococcus spp., Listeria spp., Clostridium spp. and Escherichia spp., were identified. Most of the pathogens were resistant to these various antibiotics tested.

These findings imply the need for better management of antibiotic use to control sources of food contamination and reduce health risks associated with the presence of residues and the development of resistant pathogens by further legislation and enforcement of regulations on food hygiene and use of antibiotics.

The objective of this study was to identify any issues arising during the laboratory testing of samples collected under the National Control Programme for Salmonella.

A questionnaire-based survey was conducted among Defra (Department for Environment, Food and Rural Affairs)-approved testing laboratories in order to identify any complicating factors that the laboratories may encounter during the processing of samples.

Samples were reported to arrive in good condition and within the specified time frame after collection. The only concern was that new clients may be unaware of the procedure or correct sampling consumables to use.

There was evidence of variability between laboratories regarding the sample testing procedure used, with deviation from the guidelines in some cases.

This finding suggests that further guidance for laboratories on methodology is likely to be beneficial as this could help improve the detection of low levels of Salmonella.