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Home / Equine Research Bank / Poult Sci / Impact of fenbendazole resistance in Ascaridia dissimilis on...
Poultry science2021; 100(11); 101435; doi: 10.1016/j.psj.2021.101435

Impact of fenbendazole resistance in Ascaridia dissimilis on the economics of production in turkeys.

Abstract: Feed conversion efficiency is among the most important factors affecting profitable production of poultry.Infections with parasitic nematodes can decrease efficiency of production, making parasite control through the use of anthelmintics an important component of health management. In ruminants and horses, anthelmintic resistance is highly prevalent in many of the most important nematode species, which greatly impacts their control. Recently, we identified resistance to fenbendazole in an isolate of Ascaridia dissimilis, the most common intestinal helminth of turkeys. Using this drug-resistant isolate, we investigated the impact that failure to control infections has on weight gain and feed conversion in growing turkeys. Birds were infected on D 0 with either a fenbendazole-susceptible or -resistant isolate, and then half were treated with fenbendazole (SafeGuard Aquasol) at 4- and 8-wk postinfection. Feed intake and bird weight were measured for each pen weekly throughout the study, and feed conversion rate was calculated. Necropsy was performed on birds from each treatment group to assess worm burdens at wk 7 and 9 postinfection. In the birds infected with the susceptible isolate, fenbendazole-treated groups had significantly better feed conversion as compared to untreated groups. In contrast, there were no significant differences in feed conversion between the fenbendazole-treated and untreated groups in the birds infected with the resistant isolate. At both wk 7 and 9, worm burdens were significantly different between the treated and untreated birds infected with the drug-susceptible isolate, but not in the birds infected with the drug-resistant isolate. These significant effects on feed conversion were seen despite having a rather low worm establishment in the birds. Overall, these data indicate that A. dissimilis can produce significant reductions in feed conversion, and that failure of treatment due to the presence of fenbendazole-resistant worms can have a significant economic impact on turkey production. Furthermore, given the low worm burdens and an abbreviated grow out period of this study, the levels of production loss we measured may be an underestimate of the true impact that fenbendazole-resistant worms may have on a commercial operation.
Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.
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Publication Date: 2021-08-27 PubMed ID: 34619579PubMed Central: PMC8498455DOI: 10.1016/j.psj.2021.101435Google Scholar: Lookup
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Summary

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The research article focuses on how resistance to the drug fenbendazole in common turkey intestinal parasite Ascaridia dissimilis influences the productive and economic aspects of turkey farming, with a particular focus on feed conversion efficiency.

Background

  • The efficiency of converting feed into animal growth, or feed conversion efficiency, is a crucial aspect in successful and profitable poultry production.
  • Parasitic nematode infections can affect this efficiency negatively, making parasite control through anthelmintics (drugs that expel helminth parasites from the body) critical for overall health management in poultry.
  • In ruminants and horses, resistance to anthelmintics in key nematode species has become prevalent, affecting their control. The researchers have recently identified similar resistance in Ascaridia dissimilis, a common intestinal worm in turkeys, to the drug fenbendazole.

Purpose and Methods of the study

  • With a fenbendazole-resistant variant of Ascaridia dissimilis, the researchers aimed to determine the economic impact of failed parasite control on weight gain and feed conversion in growing turkeys.
  • Turkeys were infected with either a fenbendazole-resistant or susceptible variant of the parasite, with half the birds in each group treated with fenbendazole. Feed intake and bird weight were measured weekly during the study.
  • To understand the efficiency of the treatment, bird feed conversion rates were calculated. Postmortem examinations were carried out to assess worm load in both treated and untreated birds at 7 and 9 weeks after infection.

Results and Conclusions

  • In birds infected with the drug-susceptible isolate, feed conversion significantly improved in the fenbendazole-treated groups as compared to untreated ones.
  • However, for birds infected with the drug-resistant variant, no significant differences in feed conversion were noted between treated and untreated groups.
  • The worm burden was considerably different between treated and untreated birds infected with the drug-susceptible isolate at both the 7th and 9th week point, which was not the case with birds infected with the resistant isolate.
  • Despite the worm population being relatively low in the infected birds, the study found significant effects on feed conversion. This suggests the presence of fenbendazole-resistant worms can drastically harm feed conversion, leading to substantial economic impacts on turkey production.
  • The researchers suggest that the recorded production loss could be an underestimation of the true impact of fenbendazole-resistant worms in a commercial setting, as their study involved a lower worm burden and shorter growth period.

Cite This Article

APA
Collins JB, Jordan B, Vidyashankar AN, Castro PJ, Fowler J, Kaplan RM. (2021). Impact of fenbendazole resistance in Ascaridia dissimilis on the economics of production in turkeys. Poult Sci, 100(11), 101435. https://doi.org/10.1016/j.psj.2021.101435

Publication

Poultry science
ISSN: 1525-3171
NlmUniqueID: 0401150
Country: England
Language: English
Volume: 100
Issue: 11
Pages: 101435
PII: 101435

Researcher Affiliations

Collins, James B
  • University of Georgia, Department of Infectious Diseases, College of Veterinary Medicine, Athens, GA 30602, USA. Electronic address: jbc531@uga.edu.
Jordan, Brian
  • University of Georgia, Poultry Diagnostic and Research Center, Department of Population Health, College of Veterinary Medicine and the Department of Poultry Science, College of Agricultural and Environmental Sciences, Athens, GA 30602, USA.
Vidyashankar, Anand N
  • George Mason University, Department of Statistics, Fairfax, VA 22030, USA.
Castro, Pablo Jimenez
  • University of Georgia, Department of Infectious Diseases, College of Veterinary Medicine, Athens, GA 30602, USA.
Fowler, Justin
  • University of Georgia, Department of Poultry Science, College of Agricultural and Environmental Science, Athens, GA 30602, USA.
Kaplan, Ray M
  • University of Georgia, Department of Infectious Diseases, College of Veterinary Medicine, Athens, GA 30602, USA.

MeSH Terms

  • Animals
  • Ascaridia
  • Chickens
  • Fenbendazole
  • Horse Diseases
  • Horses
  • Poultry Diseases / drug therapy
  • Turkeys

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Citations

This article has been cited 6 times.
  1. Levkut M, Levkutová M, Grešáková Ľ, Bobíková K, Revajová V, Dvorožňáková E, Ševčíková Z, Herich R, Karaffová V, Žitňan R, Levkut M. Production of Intestinal Mucins, sIgA, and Metallothionein after Administration of Zinc and Infection of Ascaridia galli in Chickens: Preliminary Data. Life (Basel) 2022 Dec 26;13(1).
    doi: 10.3390/life13010067pubmed: 36676016google scholar: lookup
  2. Rattanapitoon SK, Charoenphon N, Rattanapitoon NK. Beyond fenbendazole: Molecular and integrated pathways for managing poultry ascarid resistance. Poult Sci 2025 Dec;104(12):105942.
    doi: 10.1016/j.psj.2025.105942pubmed: 41061416google scholar: lookup
  3. Collins JB, Choo R, Shaver AO, Schaye ES, Volpe T, Nunn L, Lighty ME, Niel KR, Frye EM, Zamanian M, Andersen EC. A small-scale survey of fenbendazole resistance in Ascaridia galli and Heterakis gallinarum, two common ascarid parasites of poultry. Poult Sci 2025 Nov;104(11):105808.
    doi: 10.1016/j.psj.2025.105808pubmed: 40961778google scholar: lookup
  4. Collins JB, Choo R, Shaver AO, Schaye ES, Volpe T, Nunn L, Lighty ME, Niel KR, Frye EM, Zamanian M, Andersen EC. Survey of benzimidazole resistance in ascarid parasites of poultry. bioRxiv 2025 Aug 13;.
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  5. Collins JB, Shaver AO, Schaye ES, Volpe T, Nunn LR, Zamanian M, Andersen EC. Lack of correlation between parasite burden and key weight metrics in poultry infected with intestinal ascarids. MicroPubl Biol 2024;2024.
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  6. Collins JB, Andersen EC. The turkey ascarid, Ascaridia dissimilis, as a model genetic system. Int J Parasitol 2023 Jul;53(8):405-409.
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