SEARCH · PubMed Health

Results for “layer chicken”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed2000

Antimicrobial susceptibilities of enterococci isolated from faeces of broiler and layer chickens.

Enterococci were isolated from faecal droppings of chickens in broiler and layer farms and the susceptibilities to nine therapeutic antimicrobial agents and six growth-promoting antibiotics were determined by the agar dilution method. Resistance to therapeutic antimicrobial agents such as ampicillin, clindamycin, erythromycin, streptomycin, tetracycline or tylosin was more frequent in enterococcal isolates from broiler farms than in those from layer farms. Resistance to ofloxacin was rare, occurring in only one (0.7%) of the Enterococcus faecium isolates from broiler farms. Resistance to growth-promoting antibiotics such as avilamycin, salinomycin and virginiamycin was common among isolates from broiler farms. Of the E. faecium isolates from broiler farms, 12.4% were resistant to avilamycin and 27.4% were resistant to virginiamycin. Resistance to salinomycin was detected in all enterococcal species, ranging from 12.4% of E. faecium isolates to 50% of E. hirae isolates.

Animal Husbandry↗

PubMed1984

Lesions in broiler and layer chickens in an outbreak of highly pathogenic avian influenza virus infection.

Fifteen chickens, five broilers and ten layers, from the Pennsylvania 1983 outbreak of highly pathogenic avian influenza virus infection, were examined. Gross lesions in the broilers were limited to serosal petechiae and dehydration. In the layers there was comb edema, vesiculation, and necrosis. Microscopic lesions were mild to severe diffuse nonsuppurative encephalitis, very mild to severe diffuse necrotizing pancreatitis, and very mild to severe subacute necrotizing myositis involving numerous skeletal muscles and most severe in the external ocular muscles and limbs. While many of these lesions have been seen in experimental infections of chickens with influenza viruses, the pattern of organs involved in this group of chickens is distinctive.

Animals↗

PubMed2001

Study on the vertical transmission of arthropathic and amyloidogenic Enterococcus faecalis in a flock of brown layer chickens.

Enterococcus faecalis-related amyloid arthropathy was diagnosed in a sample of birds from a flock of brown layer parent chickens aged 57 weeks. E. faecalis was isolated from amyloidotic knee joints and from blood samples from lame birds. From this flock a smaller one was kept for production purposes to study the vertical transmission of arthropathic and amyloidogenic E. faecalis. Three batches of non-soiled and thoroughly disinfected eggs, to prevent egg-shell contamination, were collected for 6 weeks and submitted for incubation every 2 weeks. No joint pathology was found in the offspring chicks (n = 458) monitored for joint disease until 16 or 21 weeks of age. Fresh and candled eggs (infertiles and dead embryos) obtained at day 18 of the incubation period had negative results at bacteriological examination of the yolk sac, except one non-hatched egg (late embryonal death in shell) from which E. faecalis was isolated. Genotyping by pulsed-field gel electrophoresis (PFGE) of all E. faecalis isolates obtained from blood and joints (except one) of the parent birds and of the non-hatched egg after Sma I digestion showed that all isolates were genetically closely related or identical to a known arthropathic and amyloidogenic E. faecalis strain. In this study, vertical transmission of E. faecalis, although it may occur on a small scale as shown by PFGE, did not seem to play a significant role. Conversely, the chronicity of the condition and the development of an immune response may have affected the efficiency of its transmission.

Amyloidosis↗

PubMed1985

The rate of degradation of myofibrillar proteins of skeletal muscle in broiler and layer chickens estimated by N tau-methylhistidine in excreta.

After N tau-methylhistidine (N tau-MH) distribution among the various organs or the tissues was determined in male broiler chickens of 15 d of age, the rates of degradation of myofibrillar proteins in male layer and broiler chickens at different stages of growth were determined by means of N tau-MH. About 75 and 8% of the total N tau-MH in the tissues occurred respectively in skeletal muscle and stomach, and most of the remainder in the intestine and the skin. The rates of degradation of myofibrillar proteins in the male layer and broiler chickens of 21, 42 and 63 d of age were calculated to be 6.1, 4.5 and 2.4%/d (layer) and 5.0, 2.8 and 0.9%/d (broiler) respectively. These calculations involve the assumption that 80% of the total excreted N tau-MH was derived from skeletal muscle. The results strongly indicate that the rapid growth of the broiler chicken is facilitated by the reduced rate of protein degradation.

Animals↗

PubMed2006

Sarcomas and myelocytomas induced by a retrovirus related to myeloblastosis-associated virus type 1 in White Leghorn egg layer chickens.

An outbreak of subcutaneous sarcomas in commercial White Leghorn egg layers was observed in the northeastern United States during late 2004. Subcutaneous tumors were confined to three flocks distributed in two locations and belonging to the same company. The tumors were first observed grossly by farm personnel at approximately 7 wk of age and persisted throughout the economic life of the flocks. Most of the tumors observed during the growing period were present on the facial region or around the head, wings, and legs. There was no gross evidence of bursal or visceral involvement. Microscopically, most tumors were undifferentiated sarcomas and myxomas. There was no microscopic evidence of Marek's disease or lymphoid leukosis. Reticuloendotheliosis virus proviral DNA was not detected by polymerase chain reaction either in tumors or in cell cultures. Egg production and mortality rates were within normal limits in the affected flocks and many of the chickens exhibiting tumors seemed healthy otherwise, albeit approximately one-half of the daily mortality exhibited tumors. Avian myeloblastosis-associated virus type 1 (MAV-1) was isolated from tumors, plasma, and serum. Upon initial virus neutralization, the viruses isolated seemed at least partially related antigenically to avian leukosis virus (ALV) subgroups A and B but not to subgroup J (ALV-J). Sequencing of the variable and hypervariable regions of gp85 in the envelope gene revealed that the viruses involved are closely related to MAV-1. Attempts to reproduce subcutaneous sarcomas with MAV-1 isolated from White Leghorn chickens in the case herein reported produced exclusively myelocytomas indistinguishable histologically from those induced by ALV-J in meat type chickens.

Animals↗

PubMed1994

Spontaneous aortic arteriosclerosis in layer chickens.

Aortas of 21 grower chickens (both sexes) aged 30-130 days and of 51 layer hens aged 500 days were examined histopathologically. Aortic sclerotic lesions were classified histopathologically into six stages. As early as 30 days, the abdominal aortas of growers had cellular-fibrous plaques that became more severe with advancing age. The majority of the abdominal aortas of all the 500-day-old layers had a conspicuous increase of collagen fibres, with atheromatous lesions in 23 (45.1%). These sclerotic changes were most severe in the distal aortas.

Animals↗

PubMed1993

Comparison of calpain and calpastatin activities in skeletal muscle of broiler and layer chickens.

1. The objective of this study was to estimate the difference between broiler and layer chicks in the activities of calpain and calpastatin (inhibitor of calpain) in breast muscle. Differences between broilers and layers in body weight, daily gain at 3 weeks of age and fractional growth rate (FGR) during 2 and 3 weeks of age were statistically significant (P < 0.01). 2. Calpain and calpastatin activities were measured at three weeks of age with alkali-denatured casein as a substrate. The m-calpain (calpain activated by millimolar calcium concentration) activities in units/g muscle and units/mg extractable muscle protein were 0.779 and 0.353 for broilers, and 1.042 and 0.440 for layers, respectively. The calpastatin activities in units/g muscle and units/mg extractable muscle protein were 0.332 and 0.153 for broilers, and 0.262 and 0.112 for layers, respectively. 3. Broilers with high FGR showed low m-calpain and high calpastatin activities. In contrast, layers with low FGR showed high m-calpain and low calpastatin activities. 4. These results suggest that m-calpain and calpastatin activities in skeletal muscle vary between breeds which have different rates of muscle production.

Animals↗

PubMed1992

Successful treatment of mycoplasmosis in layer chickens with single dose therapy.

The efficacy of treatment with single dose administration of 5 drugs at different dosages to layer hens naturally infected with Mycoplasma gallisepticum was studied. The drugs were tiamulin, which was administered orally, tylosin (parenterally and orally), spiramycin (orally), long-acting oxytetracycline (parenterally) and tylosindihydrostreptomycin (parenterally). Cure was assessed by the absence of nasal discharge. The cure rate was significantly higher (P less than 0.05) in treated hens than in untreated hens, as early as 1 day after treatment. Remission for 33 days was achieved in 60% of hens treated with 100 mg oxytetracycline, in 100% of hens treated with 100 mg or 200 mg spiramycin, in 92% and 85% of hens treated with 100 mg tylosin, parenterally and orally, and in 89% and 88% of birds given 100 mg tiamulin and tylosin-dihydrostreptomycin, respectively.

Administration, Oral↗

PubMed2005

Antimicrobial susceptibilities of Salmonella isolates obtained from layer chicken houses on a commercial egg-producing farm in Japan, 1997 to 2002.

Susceptibility to antimicrobial agents was examined for 325 isolates of Salmonella enterica serotypes Cerro, Infantis, Livingstone, and Montevideo isolated from layer houses on a commercial egg-production farm in the western region of Japan between 1997 and 2002. No antimicrobials were used for therapeutic purposes on the farm during this period. From 1.8 to 3.1% of the isolates were resistant to ampicillin, chloramphenicol, and tetracycline. Resistance to streptomycin and sulfisoxazole was found in 52.9 and 65.5%, respectively, of Salmonella Montevideo isolates and in 0 to 13.2% of the isolates of the other serotypes. All the streptomycin-resistant isolates of Salmonella Montevideo also exhibited resistance to sulfisoxazole. Salmonella Montevideo isolates were first isolated in 1998, and 80.0% of the isolates obtained in this year were resistant to streptomycin and sulfisoxazole. The results suggest that Salmonella Montevideo isolates that had already acquired resistance may have been introduced into the layer houses, although the route and vehicle of transmission were uncertain. The proportion of Salmonella Montevideo isolates resistant to streptomycin and sulfisoxazole significantly decreased (P < 0.01) from 79.5% for 1998 through 1999 to 37.3% for 2000 through 2002. This decrease probably was due to the fact that no antimicrobials were used on the farm. Among 10 isolates from different serotypes obtained from 1997 to 2002 that were resistant to ampicillin, two and five isolates harbored 42- and 63-kb R plasmids and identical DraI restriction enzyme digest patterns, respectively, and carried the blaTEM gene. The results suggest that the ampicillin resistance determinants were transferred among different serotypes of Salmonella in the layer houses.

Animals↗

PubMed2000

Leukocyte responses in two breeds of layer chicken that differ in susceptibility to induced amyloid arthropathy.

Amyloid arthropathy in chicken can be induced by intravenous inoculation of an arthropathic and amyloidogenic Enterococcus faecalis in susceptible breeds. The commercial brown layer hybrids (BL) are more susceptible to the disease compared to their white counterparts (WL). The precursor of amyloid-A protein, which is serum amyloid-A (SAA), is identical in WL and BL. To investigate the factors involved in the breed-restricted susceptibility to amyloid arthropathy, we studied the type of leukocyte response and inflammatory reactions in E. faecalis-induced disease. In the BL, a significant dose dependent peripheral leukocytosis mainly by heterophils, and plasma cell infiltration in arthritic joints was found. In contrast, secondary lymphoid nodular aggregates in the synovial membrane were prominent in the WL. The aggregates consisted mainly of CD8+ T cells. The high number of circulating leukocyte and prolific plasma cell responses in the BL predict extensive humoral and acute phase reactions. This is in agreement with literature data on suppressed T-cell function in casein-induced amyloid-susceptible mice strains. The difference in leukocyte response and type of inflammation between WL and BL, when arthropathic and amyloidogenic bacteria induce infection, in conjunction with susceptibility to amyloid arthropathy, is discussed in view of the murine T-helper responses.

Amyloidosis↗

PubMedDate not supplied

Vaccination with F-strain Mycoplasma gallisepticum to reduce production losses in layer chickens.

The effect of Mycoplasma gallisepticum (MG) infection or vaccination of Conn. F-strain MG on 45 weeks of egg production was analyzed using production records from 132 flocks of commercial layer hens. The flocks were located in Pennsylvania, and the data were collected for two years. On the average, layers maintained free from infection with MG laid 15.7 more eggs/hen housed than the MG-infected layers; figures were adjusted for layer-strain effect. This adjusted advantage decreased to 8.7 eggs/hen housed when uninfected flocks were compared with vaccinated flocks. Adjusted average production of vaccinated flocks was 7.0 eggs/hens housed more than production of MG-infected flocks. Egg production of four layer strains was observed with respect to vaccination or natural infection with MG. The four strains responded similarly whether vaccinated or infected. Route of vaccination and age of layer at time of vaccination influenced egg production of vaccinated birds. The adjusted average production/hen housed was 4.9 eggs greater for birds vaccinated via drinking water than for birds vaccinated via spray. The adjusted average was 10.3 eggs/hen housed greater for birds vaccinated between 8 and 18 weeks of age than for birds vaccinated after 18 weeks.

Animals↗

PubMedDate not supplied

Protection and immunity in commercial chicken layers administered Mycoplasma gallisepticum liposomal bacterins.

Six liposomal Mycoplasma gallisepticum (MG) bacterins, differing in charge and size, and two oil-emulsion vaccines (sonicated and non-sonicated) were given to white leghorns in two doses, at 13 weeks and again 1 month later. At 21 weeks of age, all chickens were challenged with a viable 20-hour culture of MG cells (17,800 colony-forming units) intratracheally and with nonviable MG organisms (0.09 mg protein) injected subcutaneously in the wattle center. The three chicken groups that had the lowest tracheal MG-infection rates postchallenge were those given adjuvants of small multilamellar positively charged liposomes (16.67%), large multilamellar negatively charged liposomes (16.67%), and non-sonicated oil-emulsion bacterin (37.5%). These three groups also had significant levels of antibody in sera 4 weeks after the second dose of vaccine. The group given the small multilamellar positively charged liposome also showed significant delayed-type hypersensitivity (wattle swelling) (P less than or equal to 0.05). The group given the large multilamellar negatively charged liposomes had the highest local antibody response (P less than or equal to 0.01) and was the only group that had no microscopic lesions in the trachea.

Animals↗

PubMed2004

Pulsed-field gel electrophoresis-based subtyping of DNA degradation-sensitive Salmonella enterica subsp. enterica serovar Livingstone and serovar Cerro isolates obtained from a chicken layer farm.

Salmonella enterica serovar subsp. enterica Livingstone and serovar Cerro isolates from a commercial egg-producing farm, which had previously been untypeable by pulsed-field gel electrophoresis (PFGE) because of DNA degradation during the PFGE process, successfully gave banding patterns using electrophoresis buffer supplemented with 50 microM thiourea. By PFGE in the presence of thiourea, DNA degradation-sensitive S. enterica serovar Cerro isolates from the commercial egg-producing farm were found to be genetically unrelated to S. enterica serovar Cerro isolates that gave the patterns in the absence of thiourea. Forty-five of 50 (90%) S. enterica serovar Livingstone isolates from the farm showed arbitrarily designated XbaI-digested patterns X1 and X2 that were distinguished by one-band difference and had an identical BlnI-digested pattern. In one of the two layer houses in the farm, the numbers of isolates having the pattern X2 increased from 57% in 1997 to 89% in 1998, whereas virtually all the isolates obtained from the other house in the same period showed the profile X1. This suggests that strains having the pattern X2 might have an advantage to preferentially colonize in the former house.

Animals↗

PubMedDate not supplied

Sewage effluent: likely source of Salmonella enteritidis, phage type 4 infection in a commercial chicken layer flock in southern California.

Following the diagnosis of Salmonella enteritidis, phage type 4, infection in a commercial layer flock in southern California, effluent from a nearby sewer treatment plant was investigated as a potential source of infection. Between July 1994 and March 1995, 68 Salmonella isolations, comprising 27 serotypes, were made from the inflow (raw sewage) and effluent (treated sewage). Thirty-nine of 68 (57%) isolations yielded six serotypes, which consisted of S. enteritidis 12% (8/68), S. cerro 10% (7/68), S. typhimurium 7.4% (5/68), S. tennessee 7.4% (5/68), S. give 7.4% (5/68), S. mbandaka 7.4% (5/68), and S. panama 6% (4/68). The remaining 43% (29/68) isolations were represented by 21 serotypes. Seventeen S. enteritidis isolates originating from the effluent (creek water), resident feral animals (rodents, stray cats, skunks), and chickens (organs, eggs) of the affected flock were subjected to plasmid profile and restriction endonuclease analysis. Twelve of the 17 isolates had identical plasmid profile and restriction digestion patterns. Two of 17 isolates showed similar patterns but both differed from the rest; and 1 of 17 did not yield plasmids. Two other isolates were found to be different from each other and from the rest of the group.

Animals↗

PubMed1991

Distribution of endogenous viruses in some commercial chicken layer populations.

The distribution of endogenous virus (ev) genes was studied in five commercial layer lines; four were brown-egg types and one was White Leghorn. The DNA samples were obtained from nine birds of each line and digested with SacI and BamHI endonucleases. The DNA fragments were separated by gel electrophoresis, and Southern blots were prepared and examined for the presence of ev genes following hybridization with the labeled recombinant plasmid pRAV-2 and autoradiography. Almost all fragments were present in more than one line, suggesting that each line has drawn a random assortment of ev genes from the same common pool, possibly as a founder effect. A great degree of polymorphism is shown by the ev genes in the lines investigated. Most fragments were present at low or intermediate frequencies. Very few fragments were present in only one line or in only one bird. This suggests that de novo integration of ev genes at new sites is a relatively rare event. Very few fragments were present at high frequencies, and none of the fragments, except for the BamHI internal fragments, were present in all birds of all lines. Considering that ev genes are present in the wild progenitor of the domestic chicken, the lack of fixation of any ev genes in the chicken genome is remarkable. It is proposed that ev genes have general deleterious effects in the chicken (hence, the lack of fixation), but those ev genes that have been retained in the chicken genome have favorable effects under some circumstances with consequent equilibrium at low to intermediate frequencies. It is speculated that the retained ev genes may represent sites of favorable mutation via insertional mutagenesis and, hence, a potential route to the cloning of genes of economic importance in poultry.

Analysis of Variance↗

PubMed2004

Molecular epidemiology of two fowl cholera outbreaks on a free-range chicken layer farm.

Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.

Animal Husbandry↗

PubMedDate not supplied

The role of mice in the epizootiology of Salmonella enteritidis infection on chicken layer farms.

A microbiological survey of 10 mice-infested poultry farms was conducted to determine the role of mice in the epizootiology of S. enteritidis infection. Five of the farms were rated as clean of S. enteritidis and five as contaminated based on culture results of environmental samples for S. enteritidis. Of 2103 environmental samples and 715 mice and rats tested, 5.1% and 16.2%, respectively, were culture-positive for S. enteritidis. On contaminated farms, S. enteritidis was isolated from 24.0% of the mice and 7.5% of the environmental samples, which represented 75.3% of all Salmonella isolations from mice but only 18.0% of Salmonella isolations from environmental samples on these farms. S. enteritidis was not detected in mice on clean farms. Phage types 13a and 14b were the two most frequently isolated phage types from mice and environmental samples. Although only a single phage type was isolated from single free-standing poultry houses, multiple phage types were isolated from multi-house complexes. A bacterial count from the feces of one mouse yielded 2.3 x 10(5) S. enteritidis bacteria per fecal pellet. S. enteritidis persisted at least for 10 months in an infected mouse population.

Animals↗

PubMed1998

Persistence of Salmonella enteritidis from one day of age until maturity in experimentally infected layer chickens.

In each of two replicate trials, 1-d-old chicks were inoculated orally with a phage type 13 Salmonella enteritidis isolate (resistant to nalidixic acid). Although S. enteritidis was found in the livers, spleens, and ceca of all sampled chicks at 1 wk postinoculation, colonization generally persisted beyond 4 wk postinoculation only in the ceca. Nearly half of the remaining hens were still shedding S. enteritidis in their feces at 24 wk of age, but only 1 of 62 hens laid eggs that were internally contaminated with S. enteritidis during the initial 4 to 6 wk of egg production. Chickens exposed to S. enteritidis shortly after hatching can apparently remain infected until maturity, at which time they might produce contaminated eggs or spread the infection to other susceptible, previously unexposed hens.

Aging↗