Biomedical subjects

T E Carpenter

Publications and source records attributed to T E Carpenter.

90 records · Page 5Linked to original sources

PubMedDate not supplied

Fowl cholera in California multiplier breeder turkeys: 1985-86.

One hundred twenty-nine multiplier breeder turkey flocks on 45 premises in California were monitored for outbreaks of fowl cholera (FC) (Pasteurella multocida) for 1 year (Aug. 1, 1985, through July 31, 1986). Fourteen (11%) flocks on 10 (22%) premises experienced outbreaks. Nine (64%) outbreaks occurred in the fall or winter. FC-outbreak flocks had significantly shorter lay cycles (24.6 weeks vs. 27.9 weeks) and correspondingly lower total egg production per hen (84 eggs vs. 103 eggs) than non-outbreak flocks. A case-control investigation was performed on 11 FC-outbreak (case) flocks, and nine non-outbreak (control) flocks. Case flocks were located statistically closer to other livestock species than were control flocks (0.28 miles vs. 0.68 miles) and were more likely to utilize on-farm disposal of dead birds.

Age Factors↗

PubMedDate not supplied

Differentiation of field isolates of Pasteurella multocida serotype 3,4 from live vaccine strain by genotypic characterization.

Fifty-five serotype 3,4 isolates of Pasteurella multocida, isolated from turkeys dead from fowl cholera, were characterized (fingerprinted) genotypically for comparison with the serotype 3,4 live fowl cholera vaccine principally used in turkeys in California. Twenty-three isolates were obtained from turkeys vaccinated with the M9 live vaccine, and 32 additional isolates were from turkeys not vaccinated for fowl cholera. Methods of characterization included restriction endonuclease analysis of chromosomal DNA and ribotyping, a technique for highlighting restriction site heterogeneity of highly conserved ribosomal RNA genes and associated sequences using a radiolabeled rRNA probe. Eight different genotypes or ribotypes were detected in these isolates by the above methods. Of 23 isolates from M9-vaccinated turkeys flocks, 19 were the same ribotype as M9. Thirty of 32 isolates recovered from unvaccinated turkeys were different ribotypes from M9. The remaining two isolates resembled M9 and were recovered from two different flocks placed in succession on a turkey farm where a flock placed previously had been vaccinated with M9, suggesting interflock transmission. Ribotyping and restriction endonuclease analysis appear to be useful tools to aid in the determination of the role that the live vaccine plays in fowl cholera epidemiology.

Animals↗

PubMedDate not supplied

Pasteurella multocida recovered from live turkeys: prevalence and virulence in turkeys.

Swabs of the oropharynges of 801 live turkeys (621 meat birds and 180 breeders), collected from 15 flocks that had experienced an outbreak of fowl cholera and from 12 non-outbreak flocks, were screened for the presence of Pasteurella multocida. Turkeys from outbreak flocks were sampled within 2 to 9 weeks of the outbreak. Forty-nine isolates of P. multocida were recovered from turkeys in 11 of the outbreak flocks, and none were recovered from turkeys in non-outbreak flocks. Isolation rates varied from 0 to 72% of turkeys sampled in a flock. Nineteen isolates were tested for virulence by injecting them intravenously into turkeys, and 14 were lethal. Results demonstrated that for purposes of disease control, meat birds in fowl-cholera-outbreak flocks should be considered carriers of potentially virulent P. multocida for the life of the flock.

Animals↗

PubMedDate not supplied

Epidemiology and financial impact of fowl cholera in turkeys: a retrospective analysis.

A retrospective study of the epidemiology and financial impact of fowl cholera (FC) in California meat turkeys during 1984 was performed. Data were collected from 64 flocks--23 FC-outbreak flocks and 41 controls (non-outbreak)--raised in the Central Valley of the state. Mean flock age at the time of the FC outbreak was 11.3 weeks. Flocks that reported a colibacillosis outbreak had increased odds (P = 0.11) of also having an FC outbreak. (This association may or may not indicate a cause-effect relationship.) There was no significant difference between FC-outbreak and control flocks in number of diseases reported, age at onset, or duration of diseases or syndromes except age at onset of roundheart disease. The relative mortality rates were 52% higher in FC-outbreak toms and 26% higher in FC-outbreak hens than in their controls. Medication costs were nearly tripled, and the relative condemnation rate was 60% higher in FC-outbreak flocks than in control flocks. The average costs of FC were nearly $0.40 per bird, or $18,750 per flock, in an outbreak flock of 50,000 birds, and $0.12 per bird, or $6000 per flock, in non-outbreak flocks vaccinated against FC.

Animals↗

PubMedDate not supplied

Pasteurella multocida in wild mammals and birds in California: prevalence and virulence for turkeys.

Samples collected from the oropharynx of wild mammals and birds trapped on 36 turkey farms in California were evaluated for the presence of Pasteurella multocida. A total of 966 animals were collected from 18 premises that had experienced an outbreak of fowl cholera within the past 2-8 months; samples were collected from 16 of these 18 premises within 2-8 weeks of outbreak notification and while the infected flock was still present. A total of 939 animals were trapped from an additional 18 premises that had not reported any outbreaks of fowl cholera within at least 4 months, if ever. Forty-eight isolates of P. multocida, of a variety of somatic serotypes, were recovered from 6 species of mammals and 3 species of birds. On only 2 of 7 premises was the somatic serotype of the isolates obtained from wildlife the same as the isolate obtained from tissues of turkeys that had died of fowl cholera on the same premises. Tests for virulence to turkeys were conducted with 31 of the isolates. Seventeen of these isolates caused mortality in turkeys. Wide ranges in mortality rates and median times to death were observed.

Animals↗

PubMedDate not supplied

A descriptive study of fowl cholera in California meat turkeys: August 1985-July 1986.

One hundred sixty meat-turkey premises in California were monitored for outbreaks of fowl cholera from August 1985 through July 1986. Nearly 27 million turkeys in 720 flocks were at risk during the year. Fifty-three flocks of approximately 3 million turkeys on 34 different premises experienced confirmed fowl cholera outbreaks. The epidemic curve for the year indicated that the majority of outbreaks occurred in the late summer and fall, particularly in October. The incidence of outbreaks during this time was not significantly associated with seasonal variation in the size of the turkey population. The mean flock age at outbreak was 10.8 weeks, with a range of 5-18 weeks.

Animals↗

PubMedDate not supplied

Evaluation of factors associated with infection of commercial layers with Mycoplasma gallisepticum and M. synoviae.

Information on factors possibly associated with the risk of infection with Mycoplasma gallisepticum (MG) or M. synoviae (MS) were collected from nearly 400 layer flocks in California. Factors associated with the probability of flock infection with either MG or MS were identified, and their magnitude was quantified by statistical analysis. More frequent administration of several vaccines was associated with decreased probability of both MG and MS infection of flocks. Also identified were housing or hygiene factors and system of management (i.e., multiple-age status) that could reduce the probability of infection of flocks with mycoplasma. The change in probability of MG infection resulting from modifying certain management factors was examined.

Animals↗

PubMedDate not supplied

Economic impact of Mycoplasma gallisepticum and M. synoviae in commercial layer flocks.

An egg-production function was constructed, using data collected from 366 commercial layer flocks in California, to predict the impact of Mycoplasma gallisepticum (MG) and M. synoviae (MS) on egg production while controlling for confounding factors. In the first and second cycles, respectively, an MG-infected flock produced 12 and 5 fewer eggs per hen than an uninfected flock. Flocks that became infected with MG after F-strain vaccination produced 6 eggs/hen more than unvaccinated infected flocks in the first cycle, but no significant difference was observed between such groups in the second cycle. No association was found between MS-infection and egg production. Commercial layer producers in Southern California lost an estimated 127 million eggs because of MG in 1984. This lost egg production and associated MG-control-program costs amounted to an estimated financial loss of approximately $7 million. This represented a loss of approximately $6 million in consumer surplus.

Animals↗

PubMedDate not supplied

A statistical model to optimize enzyme-linked immunosorbent assay parameters for detection of Mycoplasma gallisepticum and M. synoviae antibodies in egg yolk.

An enzyme-linked immunosorbent assay (ELISA) was developed to quantify Mycoplasma gallisepticum (MG) and M. synoviae (MS) antibodies in egg-yolk extract. Various parameters of ELISA were evaluated and optimized. A statistical model was developed to study the relationship between ELISA absorbance (A) and antigen concentration, antibody concentration, and time of reading of the test. These factors explained 62% of the variability in A for the MG antigen and 74% of the variability in A for the MS antigen. The optimum concentration of MG antigen was 4 micrograms protein/ml, and that for MS antigen was 3 micrograms protein/ml. A similar model was developed to study the relation between A and conjugate concentration, antibody concentration, and time of reading of the test. The optimum concentration of the conjugate was found to be 1:4000. The within-run and between-run coefficients of variation for MG were 8% and 9%, respectively, and those for MS were 9% and 7%, respectively, indicating a high degree of reproducibility of these tests. There was a high correlation between ELISA and hemagglutination-inhibition test results.

Animals↗

PubMedDate not supplied

Comparison of egg yolk and serum for the detection of Mycoplasma gallisepticum and M. synoviae antibodies by enzyme-linked immunosorbent assay.

Egg yolk was evaluated in the enzyme-linked immunosorbent assay (ELISA) as an alternative source of antibodies for detection of Mycoplasma gallisepticum (MG) and M. synoviae (MS) infections in chickens. There was no statistically significant difference (P greater than 0.05) between the ELISA geometric mean titers (GMTs) of saline-diluted egg yolk and chloroform-extracted egg yolk, and both preparations had a high correlation coefficient (0.87 for MG; 0.97 for MS). The saline-diluted and chloroform-extracted yolk had a relative sensitivity of 90% and specificity of 98% in the MG ELISA; in MS ELISA they were 100% and 96%, respectively. Hemagglutination-inhibition (HI) results with chloroform-extracted samples were satisfactory, but those with saline-diluted samples were not. Neither preparation was satisfactory for use in the rapid plate agglutination (RPA) test. A 1-ml sample of yolk was compared with the whole-yolk method. The chloroform-extracted whole yolk yielded a significantly higher (P less than 0.05) GMT in the MG ELISA; however, there was no statistically significant difference (P greater than 0.05) between GMTs yielded by the two procedures in the MS ELISA. The correlation coefficients for the two sampling methods were 0.73 for MG ELISA and 0.63 for MS ELISA. ELISA detected no statistically significant difference (P greater than 0.05) between GMTs of serum and chloroform-extracted yolk from individual birds. Results with the HI test were comparable to those with ELISA on the same samples. The RPA test yielded comparable results on the serum samples. No statistically significant differences (P greater than 0.05) were observed in HI or ELISA antibody levels between egg-yolk samples and sera on random samples collected from nine flocks that were MG- and MS-free or were infected with MG, MS, or both; however, egg-yolk samples tended to have slightly higher titers than sera in both tests. The optimum screening dilution of chloroform-extracted yolk for detecting MG and MS antibodies by ELISA was 1:800.

Agglutination Tests↗

PubMedDate not supplied

Prevalence of Mycoplasma gallisepticum and M. synoviae in commercial layers in southern and central California.

The prevalence of Mycoplasma gallisepticum (MG) and M. synoviae (MS) in commercial pullet and layer flocks in Southern and Central California was estimated by testing serum and egg-yolk samples from 360 sample flocks in Southern California and 41 sample flocks in Central California. Data relating to potential risk factors associated with MG and MS infections were collected. The estimated true prevalence rate of MG was 73% in Southern California and 3% in Central California. The estimated true prevalence rate of MS was 91% in Southern California and 32% in Central California. Compared with uninfected flocks, MG-infected flocks in Southern California were significantly older and were medicated less (P less than 0.05). More managements were under a multiple-age system, more flocks had molted, more were vaccinated with F-strain, and more had concurrent infection with MS (P less than 0.05). Only one sample flock in Central California was MG-infected; none were vaccinated with F-strain. In Southern California, MS-infected flocks were older than uninfected flocks, more had molted, more were medicated, and more had concurrent infection with MG (P less than 0.05). In Central California, MS-infected flocks did not differ significantly from uninfected flocks in any factor examined; the lack of statistical significance may be due to small sample size.

Age Factors↗

PubMedDate not supplied

The effect of Mycoplasma meleagridis infection and egg dipping on the weight-gain performance of turkey poults.

Turkey poults were observed throughout their first 7 weeks of life to evaluate the effects of embryonic infection with Mycoplasma meleagridis (MM) and the effects of a control measure, egg dipping with tylosin and gentamycin. Fifty-thousand poults from four sister flocks were divided among eight groups according to MM-infection status [MM (+) or MM (-)] , sex, and egg-dipping status (dipped or nondipped). These birds were raised under natural field conditions in the Central Valley of California. The MM (+) poults had significantly (P less than 0.05) greater weights during the first part of the trial and, although usually not significantly (P greater than 0.05), consistently during the later part.

Ammonia↗

PubMedDate not supplied

The effect of experimental turkey embryo infection with Mycoplasma meleagridis on weight, weight gain, feed consumption, and conversion.

Turkey poults were obtained from an earlier trial where hatchability performance of a group of embryos experimentally infected with Mycoplasma meleagridis [MM(+)] was compared with that of a group of uninfected cohorts [MM(-)]. In the present trial, post-hatch production parameters compared were weight, weight gain, feed consumption, feed conversion, culling, and mortality. Both toms and hens were monitored for 16 weeks, and a group of randomly selected toms was monitored for 22 weeks. Final liveweights and dressweights of hens were compared at 17 weeks, and those of the toms were compared at 23 weeks. Hens showed no significant (P less than 0.05) differences in the measured parameters during the 16-week period, nor did the initial population of toms, except in weight gain during the final period (weeks 12-16) and in final weight at week 16, which were significantly (P less than 0.05) greater in the MM(+) toms than in their MM(-) cohorts. Dressweights at slaughter of MM(+) hens were significantly greater than those of MM(-) hens, but liveweights of hens at slaughter and both liveweights and dressweights of toms at slaughter did not differ significantly. This inability of MM(-) turkeys to demonstrate a comparative advantage over MM(+) birds agrees with an earlier trial (4), in which MM(+) poults had weights superior to those of MM(-) cohorts during the first 3 to 4 weeks of life (4). These data indicate that the theory of superior performance in association with MM(-) birds must be reevaluated before the benefits derived from an M. meleagridis eradication program can be measured.

Animals↗

PubMedDate not supplied

Formulating a control program against Mycoplasma meleagridis using economic decision analysis.

Economic decision analysis was applied to a variety of programs for controlling Mycoplasma meleagridis (MM) using a hypothetical commercial turkey multiplier breeder as an example. The analysis demonstrated the economic significance of a particular program for controlling MM and reevaluated current egg-dipping practices. If forced to continue egg-dipping, the hypothetical breeder can expect to gain $1.58 per hen if he follows a MM-control program that includes monitoring and incentive payments. If he can discontinue dipping, he can expect a gain of $2.06 per hen.

Animals↗

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

Decreased hatchability of turkeys eggs caused by experimental infection with Mycoplasma meleagridis.

Turkey eggs experimentally infected with Mycoplasma meleagridis (MM) showed a significant (p less than 0.05) decrease in production of first-quality poults of approximately 20% when compared with uninoculated controls and a placebo group of eggs. Embryo mortality was highest between the time the eggs were transferred from incubator to hatcher (25 days of incubation) and the time the embryos hatched. Risk of embryo mortality associated with infection in this late incubation period for the MM-infected embryo was more than double the risk for uninfected embryos. The number of dead-in-shell and pipped embryos was almost 10% higher than the number found in either control or placebo groups. There appeared to be a stress due to the inoculation of both the placebo and the organism, increasing embryo mortality between 9 and 24 days of incubation. However, this effect was not evident after transfer. Total economic loss associated with decreased hatchability caused by MM and the cost of a control program were estimated to be $9.4 million per year in the United States.

Animals↗

PubMedDate not supplied

Detection of Pasteurella multocida-specific DNA in turkey flocks by use of the polymerase chain reaction.

A polymerase chain reaction (PCR)-based assay using primers constructed to amplify the gene (psl) encoding the P6-like protein (Psl) of Pasteurella multocida was developed. After Southern blotting and hybridization with psl, the assay (PCR-H) was found to be specific (it did not detect a variety of other avian bacterial pathogens) and sensitive (detected > or = 10 P. multocida organisms or > or = 24 femtograms of extracted P. multocida DNA). Samples were collected from the oropharynx of randomly selected birds housed on premises that had recently experienced an outbreak of avian cholera (outbreak farms) or from birds housed on premises that had not reported an outbreak of this disease during the preceding 12 mo (control farms). The PCR-H assay detected 11 infected turkeys out of a total of 178 sampled on six outbreak farms as compared with isolation of P. multocida from 23 turkeys by using mouse inoculation. Neither method detected P. multocida in samples collected from 174 turkeys sampled on six control farms. Statistical analysis using the Kappa test demonstrated that the results of the two tests showed poor agreement from five outbreak flocks (K = 0, 0, 0, 0.35, 0.47) and strong agreement from one outbreak flock (K = 0.89). Combined results from the outbreak flocks showed poor agreement (K = 0.49) between the two methods.

Animals↗

PubMedDate not supplied

Inclusion body tracheitis associated with avian adenovirus in turkeys.

Nine turkey flocks with basophilic intranuclear inclusion bodies, suggestive of adenovirus, within the epithelial cells of the tracheal mucosa were studied. Respiratory signs and increased mortality occurred in turkeys between 6 and 10 wk of age from nine commercial turkey meat flocks in central California. Necropsy findings included tracheitis and occasional mild sinusitis. Histopathology of the tracheas revealed epithelial deciliation, squamous metaplasia, large basophilic intranuclear inclusion bodies within epithelial cells, and lymphoplasmatic inflammation in the mucosa. Electron microscopy of the mucosa revealed hexagonal viral particles, approximately 73 nm in diameter, consistent with adenovirus within the nuclei of epithelial cells. All tracheal sections were negative for adenovirus group II by specific immunoperoxidase staining. Adenovirus group I was isolated from the trachea. In addition, Bordetella avium, Ornithobacterium rhinotracheale, and Klebsiella pneumoniae were isolated from the tracheas of three, three, and two flocks, respectively. Statistically greater total mortality and a smaller percentage of marketed turkeys were observed in the submitted flocks than in randomly selected flocks. No significant difference was observed between the two turkey groups in market weight, feed conversion, or percentage of grade "A" turkeys.

Adenoviridae Infections↗