Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-22-00091
Ella Günther, Rob Moore, Silke Rautenschlein
{"title":"Investigation of Spotty Liver Disease and <i>Campylobacter hepaticus</i> in Layer Flocks-A Field Study.","authors":"Ella Günther, Rob Moore, Silke Rautenschlein","doi":"10.1637/aviandiseases-D-22-00091","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-22-00091","url":null,"abstract":"<p><p><i>Campylobacter hepaticus</i> (<i>C. hepaticus</i>) was recently discovered as the causative agent of Spotty Liver Disease (SLD). SLD affects laying hens and causes significant economic losses in egg production in several countries throughout the world. Field observations reveal that cases of SLD appear with a high risk of reoccurrence, specifically in free-range and organic brown-feathered layer lines. Possible factors contributing to the development of SLD still have to be elucidated. In this field study, one free range (Flock 1) and one organic flock (Flock 2) of brown laying hens kept on farms with a history of clinical SLD were monitored for <i>C. hepaticus</i> colonization, clinical signs, and egg production from 16 to 79 wk of age on the first farm and from 17 to 83 wk of age on the other. The flocks showed a significant drop in egg production at 32 to 39 or 56 wk of age, respectively, which was associated with macroscopically visible liver lesions typical for SLD. Interestingly, in both cases observed clinical disease was linked to a stressful event: heat stress for Flock 1 and respiratory symptoms for Flock 2. <i>C. hepaticus</i> was detected by PCR during the acute phase of the disease in Flock 1. At 50 wk after the initial clinical outbreak had waned, <i>C. hepaticus</i> was still able to be isolated by culture in this flock. This clearly demonstrates that <i>C. hepaticus</i> persists either in the birds or their environment. We speculate that this long persistence may favor chronic SLD in affected flocks and the reoccurrence of SLD in subsequent flocks. Clinically less severe SLD outbreaks may be observed after re-exposure of clinically recovered flocks.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"202-208"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9979981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-22-00050
Awol M Assen, Priscilla F Gerber, Stephen W Walkden-Brown
{"title":"Protection Efficacy of the Infectious Laryngotracheitis (ILT) Serva CEO Vaccine Strain in Broiler Chickens Under Different Vaccination Coverage Conditions.","authors":"Awol M Assen, Priscilla F Gerber, Stephen W Walkden-Brown","doi":"10.1637/aviandiseases-D-22-00050","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-22-00050","url":null,"abstract":"<p><p>Mass vaccination against infectious laryngotracheitis virus (ILTV) in drinking water can result in variable initial vaccine take. Partial initial vaccine coverage of 20% with an Australian ILT vaccine (A20) previously resulted in significant protection against virulent ILTV challenge. This follow-up study used the international Serva ILT vaccine strain in a factorial design testing four levels of vaccination coverage (0%, 10%, 20%, or 100% of chicks eye-drop vaccinated with the live vaccine at 7 days of age) and three levels of ILTV challenge (no challenge or challenge at 7 or 21 days postvaccination [DPV]). The increase in ILTV load in choanal cleft swabs detected by qPCR after challenge was significantly reduced by 20% and 100% but not by 10% vaccination coverage. Vaccination reduced weight gain in unchallenged birds. Daily weight gain of birds was not affected by ILTV challenge at 7 DPV in any group, but following challenge at 21 DPV, it was significantly reduced in unvaccinated and 10% vaccinated groups relative to 20% and 100% vaccinated groups. Vaccination of 20% of the chickens provided substantial but incomplete protection (protective index range 44%-70%) against the severity of clinical signs and mortality following challenge while 10% vaccination coverage provided limited or no protection. Clinical signs were more severe and appeared earlier following challenge at 21 DPV than at 7 DPV. Within the vaccination treatments, eye-drop-vaccinated birds were better protected than their in-contact cohorts. In conclusion, partial vaccination of 20%, but not 10% of chickens, induced substantial protection against subsequent challenge. However, the attendant risks of reduced protection against early challenge and the possible reversion to virulence of vaccine virus when transmitted to unvaccinated chickens make it essential that 100% initial vaccine take be the goal of mass vaccination programs.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"160-169"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9977857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cellular Immune Responses in Lymphoid Tissues of Broiler Chickens Experimentally Infected with Necrotic Enteritis-Producing <i>Clostridium perfringens</i> Strains.","authors":"Raveendra R Kulkarni, Carissa Gaghan, Javid Mohammed, Shayan Sharif, Khaled Taha-Abdelaziz","doi":"10.1637/aviandiseases-D-23-00012","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-23-00012","url":null,"abstract":"<p><p>Host cellular responses against <i>Clostridium perfringens</i> (CP), the causative agent of necrotic enteritis (NE) in chickens, are poorly understood. In the present study, we first tested the NE-producing ability of seven <i>netB</i><sup>+</sup> CP strains (CP5, CP18, CP26, CP64, CP67, CP68, and NCNE-1), using an experimental infection model of broiler chickens. Evaluation of intestinal gross lesions showed that all the strains, except CP5, were able to produce NE, while CP26 and CP64 strains produced relatively more severe lesions when compared with other groups. Next, cellular responses in the cecal tonsil (CT), bursa of Fabricius, and spleen were evaluated in chickens infected with strains representing variation in the level of virulence, namely, avirulent CP5, virulent CP18, and a relatively more virulent CP26 strain. Immunophenotyping analysis showed that CT or splenic macrophage frequencies were significantly higher in CP18- and CP26-infected chickens compared with uninfected controls, while the frequencies of γδ T-cells and B-cells in the CT of CP26-infected chickens were significantly higher than those in the uninfected, CP5- or CP18-infected groups. The T-cell analysis showed that chickens infected with CP18 and CP26 had a significantly higher number of splenic CD4<sup>+</sup> and CD8<sup>+</sup> T-cells expressing CD44 and CD28 activation molecules, while CP26-infected chickens also had significantly increased CT frequency of these activated CD4<sup>+</sup> and CD8<sup>+</sup> T-cells when compared with uninfected or CP5-infected groups. Collectively, our findings suggested that cellular responses, including activation of T-cells, are selectively induced against virulent CP strains and that the NE-producing characteristics of this pathogen may influence the outcome of immunity to NE.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"186-196"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9979985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-23-00010
Roel Becerra, Daniel Maekawa, Maricarmen García
{"title":"Protection Efficacy of Recombinant HVT-ND-LT and the Live Attenuated Tissue Culture Origin Vaccines Against Infectious Laryngotracheitis Virus When Administered Individually or in Combination.","authors":"Roel Becerra, Daniel Maekawa, Maricarmen García","doi":"10.1637/aviandiseases-D-23-00010","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-23-00010","url":null,"abstract":"<p><p>Infectious laryngotracheitis (ILT) is a respiratory disease that causes significant economic losses to the poultry industry. Control of the disease is achieved by vaccination and implementation of biosecurity measures. The use of bivalent and trivalent recombinant herpesvirus of turkey (rHVT) vaccines expressing infectious laryngotracheitis virus (ILTV) genes has increased worldwide. In the United States, vaccination programs of long-lived birds (broiler breeders and commercial layers) against ILT include immunizations with either HVT recombinant vector vaccines, <i>in ovo</i> or at hatch, or live attenuated vaccines administered via drinking water (chicken embryo origin [CEO]) or eye drop (tissue culture origin [TCO]). The efficacy of bivalent rHVT-LT at hatch followed by drinking water or eye-drop CEO vaccination has been shown to provide more robust protection than rHVT-LT alone. The objective of this study was to evaluate the protection efficacy of a commercial trivalent rHVT-ND-LT when administered at 1 day of age followed by TCO vaccination via eye drop at 10 wk of age. Groups vaccinated with only rHVT-ND-LT or TCO, the combination of rHVT-ND-LT + TCO, and one nonvaccinated group of chickens were challenged with a virulent ILTV strain at 15 wk of age. After challenge, mortalities were prevented only in the group of chickens vaccinated with the rHVT-ND-LT + TCO. Clinical signs of the disease and challenge virus replication in the trachea were significantly reduced for both the rHVT-ND-LT + TCO- and TCO-vaccinated groups of chickens. To assess challenge virus transmission, contact-naive chickens were introduced to all vaccinated groups immediately after challenge. At 8 days postintroduction, infection of contact-naive chickens was evidenced in those introduced to the rHVT-ND-LT and TCO group but prevented in the rHVT-ND-LT + TCO group. Overall, these results indicated that compared to rHVT-ND-LT or TCO when administered alone, the rHVT-ND-LT + TCO vaccination strategy improved protection against disease and reduced shedding of the challenge virus.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"145-152"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9977854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-23-00014
Shayne Ramsubeik, Simone Stoute, Rodrigo A Gallardo, Beate Crossley, Daniel Rejmanek, Rachel Jude, Carmen Jerry
{"title":"Infectious Bronchitis Virus California Variant CA1737 Isolated from a Commercial Layer Flock with Cystic Oviducts and Poor External Egg Quality.","authors":"Shayne Ramsubeik, Simone Stoute, Rodrigo A Gallardo, Beate Crossley, Daniel Rejmanek, Rachel Jude, Carmen Jerry","doi":"10.1637/aviandiseases-D-23-00014","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-23-00014","url":null,"abstract":"<p><p>False layer syndrome is a condition in which the reproductive tract of chicks is infected with infectious bronchitis virus (IBV) strains that cause permanent damage to the oviduct. These chickens subsequently develop cystic oviducts and do not lay eggs, and affected flocks fail to reach expected egg production peaks. The California Animal Health and Food Safety laboratory, Turlock Branch, received four separate case submissions from a 25-to-28-wk-old commercial ISA Brown layer flock. Birds were submitted for diagnostic evaluation due to suboptimal egg production and vent pecking. Submissions totaled 31 birds and consisted of live layers, recent mortality, and a flat of eggs. No clinical signs were observed in the submitted live birds. The most common gross findings included cystic left oviducts, signs of vent pecking, ovarian regression, and yolk coelomitis. The eggs were abnormally shaped with irregular, white, gritty deposits on the surface of the shell. Microscopically, there was atrophy of the oviducts, glandular hypoplasia, and lymphocytic salpingitis. In addition, lymphoplasmacytic tracheitis was observed, and renal tubules were dilated with multifocal areas of mineralization. IBV was identified by reverse transcription quantitative PCR from cecal tonsil tissue pools and tracheal swab pools. Sequencing of the S1 hypervariable region of IBV and whole-genome IBV sequencing were 97% homologous to the California variant CA1737/04. Definitive proof of the CA1737 strain's causing reproductive abnormalities will require challenge studies with fulfillment of Koch's postulates and evaluation of confounding and risk factors.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"212-218"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9977860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-22-00085
Gunnar Dunnam, Jay Kay Thornton, Martha Pulido-Landinez
{"title":"Characterization of an Emerging <i>Enterococcus cecorum</i> Outbreak Causing Severe Systemic Disease with Concurrent Leg Problems in a Broiler Integrator in the Southern United States.","authors":"Gunnar Dunnam, Jay Kay Thornton, Martha Pulido-Landinez","doi":"10.1637/aviandiseases-D-22-00085","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-22-00085","url":null,"abstract":"<p><p><i>Enterococcus cecorum</i> has been associated mainly with osteomyelitis of the free thoracic vertebra in chickens. However, there are reports of <i>E. cecorum</i> producing septicemic lesions and having tropism for cartilages, resulting in the presentation of femoral head necrosis and synovitis. This paper discusses the presentation of <i>E. cecorum</i> as it relates to an outbreak in one vertical integrator where the main lesions were related to septicemia. Using a convenience sampling method, 100 broiler chicken cases received at the Poultry Research and Diagnostic Laboratory of Mississippi State University from April to December of 2021 were analyzed. The peak in cases was observed from June to August. The average age of broilers was 21 days with a range of 15-31 days. Most of these cases were related to systemic disease and leg problems, with gross lesions including characteristic pericarditis along with perihepatitis, osteomyelitis, and arthritis. In six of the 100 cases, <i>E cecorum</i> was isolated from the free thoracic vertebra, with the remaining being recovered from various other locations including liver, pericardium, hock/joint, femoral head, and bone marrow. <i>Enterococcus cecorum</i> identification was performed by using Vitek matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. These results were then sent to the research-use only SARAMIS database for analysis. Once the spectra of the isolates were imported, the relative and absolute taxonomy were analyzed. Two super spectrums and three clusters by homology were identified. The minimal inhibitory concentrations obtained by antimicrobial sensitivity tests were analyzed using WHONET Microbiology Laboratory Database Software. No isolates were pan-susceptible, 80% of isolates were noted to be resistant to ≥3 classes of antibiotics and, in general, isolates exhibited a high degree of variability when examining antimicrobial resistance patterns.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"137-144"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10031491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Regions Important for Hemagglutination Activity and Serotypes of <i>Avibacterium paragallinarum</i> HMTp210 Protein.","authors":"K-P Li, D-H Tan, S-J Ou, Y-S Gong, J-H Shien, P-C Chang","doi":"10.1637/aviandiseases-D-22-00084","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-22-00084","url":null,"abstract":"<p><p><i>Avibacterium paragallinarum</i> is an important respiratory pathogen of domestic chickens. <i>Avibacterium paragallinarum</i> has been subtyped into three serogroups and nine serovars according to the Page and revised Kume schemes. The major hemagglutinin antigen of <i>A. paragallinarum</i> is HMTp210, which is a large protein of about 2000 amino acids (aa), including a 70-aa signal peptide at its N-terminal end. However, the regions important for the hemagglutination (HA) activity and serotypes of HMTp210 remain unclear. In this study we constructed a series of <i>A. paragallinarum</i> strains expressing HMTp210 in-frame deletion mutants and determined their HA titers to identify the regions important for the HA activity and serotypes of HMTp210. Two distinct types of HA activities were found in HMTp210. The type 1 HA activity resided in the region spanning the full-length HA (aa 71-2084), whereas the type 2 resided in the region spanning aa 1003-2084. The putative ligand binding of the type 1 HA activity was located at aa 176-360, which had a structure similar to YadA of <i>Yersinia enterocolitica</i>. The putative ligand binding site of the type 2 HA activity was located at aa 1003-1125, which had a structure similar to UspA1 from <i>Moraxella catarrhalis</i>. The type 1 HA activity appeared to be Page serogroup specific, whereas type 2 appeared to be Kume serovar specific. Finally, sequence analyses of the regions spanning aa 1-400 and aa 1100-1600 of HMTp210 could be useful for the molecular serotyping (the Page and revised Kume schemes) of <i>A. paragallinarum</i> isolates.</p>","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"153-159"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9979984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-06-01DOI: 10.1637/aviandiseases-D-22-00088
Yu-Yang Tsai, Monique Franca, Alvin Camus, Lisa J Stabler, Nicolle Barbieri, Catherine M Logue
{"title":"Laser Capture Microdissection, Culture Analysis, and Bacterial Sequencing to Evaluate the Microbiota of Focal Duodenal Necrosis in Egg Layers.","authors":"Yu-Yang Tsai, Monique Franca, Alvin Camus, Lisa J Stabler, Nicolle Barbieri, Catherine M Logue","doi":"10.1637/aviandiseases-D-22-00088","DOIUrl":"https://doi.org/10.1637/aviandiseases-D-22-00088","url":null,"abstract":"SUMMARY: Focal duodenal necrosis (FDN) is a common intestinal disease of table egg layers. In this research we aimed to identify the bacteria commonly found in FDN lesions as seen with histopathological analysis. Fifty-nine ethanol-fixed duodenum samples were collected from egg layers on eight FDN-affected farms, and 42 samples had typical FDN lesions. Excision of bacteria-containing lesions using laser capture microdissection was performed, followed by 16S rRNA gene sequencing of extracted DNA for bacterial identification. Bacterial sequencing analysis revealed no consistent bacterial species identified from samples with FDN. However, analysis of the relative phylum abundance revealed differences in the duodenal microbiota between layers with FDN and healthy birds. There were differences in the abundance of Proteobacteria, Firmicutes, and Actinobacteria between FDN-positive and FDN-negative control samples compatible with intestinal dysbiosis. In addition, 10 duodenal samples with FDN lesions were collected for bacteriological analysis, yielding 47 colonies on tryptone soy agar, MacConkey agar, and blood agar plates. Using 16S rRNA gene PCR, 39/47 (53.8%) colonies were identified as Escherichia coli. PCR for E. coli virulence genes identified 21/39 (53.8%) E. coli isolates as avian pathogenic E. coli–like. PCR analysis for 19 E. coli virulence genes associated with intestinal disease strains including inflammatory bowel disease found 11/39 (28.2%) isolates containing more than 10 of these virulence genes. In conclusion, FDN appears to be a multifactorial inflammatory intestinal disease associated with intestinal dysbiosis, and Gram-negative bacteria including E. coli may contribute to the pathogenesis of this disease. RESUMEN. Microdisección por captura láser, análisis de cultivos y secuenciación bacteriana para evaluar la microbiota de la necrosis duodenal focal en aves de postura de huevo comercial. La necrosis duodenal focal (FDN) es una enfermedad intestinal común en las gallinas de postura de huevo comercial. En esta investigación, el objetivo fue identificar las bacterias que se encuentran comúnmente en las lesiones provocadas por la necrosis duodenal focal tal como se aprecian con el análisis histopatológico. Se recolectaron 59 muestras de duodeno fijadas con etanol de gallinas de postura de ocho granjas afectadas por necrosis duodenal focal, y 42 muestras tenían lesiones típicas de dicha enfermedad. Se realizó la escisión de las lesiones que contenían bacterias mediante microdisección por captura láser, seguida de la secuenciación del gene 16S rRNA del ADN extraído para la identificación bacteriana. El análisis de secuenciación bacteriana no reveló especies bacterianas consistentes identificadas a partir de muestras con necrosis duodenal focal. Sin embargo, el análisis de la abundancia relativa del phylum reveló diferencias en el microbiota duodenal entre gallinas de postura con necrosis duodenal focal y aves sanas. Hubo diferencias en l","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"67 2","pages":"177-185"},"PeriodicalIF":1.4,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9979987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Avian DiseasesPub Date : 2023-05-01DOI: 10.1637/0005-2086-61.2.fmii
Suzanne Y. Dougherty
{"title":"Full Issue","authors":"Suzanne Y. Dougherty","doi":"10.1637/0005-2086-61.2.fmii","DOIUrl":"https://doi.org/10.1637/0005-2086-61.2.fmii","url":null,"abstract":"The passage of landmark deregulatory reforms in the Motor Carrier of Act of 1980 has constantly pressured the U.S. trucking industry to reduce transportation costs. Thanks to such pressure, total logistics costs have declined from 16.5% in 1980 to 10.1% of gross domestic product (GDP) in 2000. In particular, transportation costs have fallen from 7.6% to 5.9% of GDP in 2000. Transportation cost savings definitely benefit shippers, while jeopardizing the viability of carriers. To help transportation carriers cope with enormous cost pressure, this paper examines the impact that “lumper” costs, empty miles, and shipment size have on the very competitive trucking industry. Through an actual case study of a firm based in the Southeast U.S., we illustrate how lumper costs, empty front-haul and backhaul, and shipping weight and pieces can adversely affect the trucking firm’s profitability.","PeriodicalId":8667,"journal":{"name":"Avian Diseases","volume":"61 1","pages":"fmii"},"PeriodicalIF":1.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1637/0005-2086-61.2.fmii","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43519574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}