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Study Casts Doubt on Efficacy of Helminth Control in US Broiler Breeders

31 December 2013

US - Nearly all the 281 breeders sampled in the south-east of the country had intestinal parasites of at least one of four helminth types and the numbers present showed some correlation with the ranking of the breeder farm for which the birds originated.

A survey conducted to determine the incidence and magnitudes of parasitic helminth populations in broiler breeders is reported in the current issue of the Journal of Applied Poultry Research.

T. Yazwinski of the University of Arkansas and co-authors there and with Elanco Animal Health explain that intact intestinal tracts were submitted by personnel from 10 poultry companies located in the southeastern United States. A total of 281 intestines were submitted, with five to six intestines being submitted from each of 47 breeder barns representing the 10 poultry companies.

The birds selected for sacrifice were obtained at random from each barn, and ranged in age from approximately 30 to 49 weeks at posting. Intestines were extracted on site, placed individually in plastic bags, chilled and mailed overnight to the University of Arkansas for parasite collection, identification and quantification. All intestines were identified with company, farm, bird age and grower ranking.

The majority of intestines were submitted with information relative to anthelmintic treatments given previously to the birds in the pullet house as well as specifics concerning bedding (number of flocks on current bedding).

Of the 281 intestines submitted in the survey, only three were found to be void of helminth parasites, resulting in an overall infection incidence of 98.9 per cent.

Helminths isolated and identified from the intestinal tracts (and overall incidences) were Heterakis gallinarum (96 per cent), Capillaria obsignata (75 per cent), Ascaridia galli (63 per cent) and Raillietina cesticillus (14 per cent).

Helminth counts for individual birds ranged from zero to a maximum of 3,240, 1,280, 940 and 445 for H. gallinarum, C. obsignata, A. galli and R. cesticillus, respectively.

Helminth levels varied significantly by company but not significantly by grower ranking although a direct correlation was evident between each parasite population and grower ranking; lower producer rankings were associated with higher helminth burdens.

No correlation was detected between the helminth levels as seen in the surveyed birds and prior anthelmintic usage when the birds were in pullet production.

The researchers suggest this was an illustration of the refractory or compensatory nature of helminths and the inability of current treatments to control helminthiasis in breeders.


Yazwinski T., C. Tucker, E. Wray, L. Jones, Z. Johnson, S. Steinlage and J. Bridges. 2013. A survey on the incidence and magnitude of intestinal helminthiasis in broiler breeders originating from the southeastern United States. J. Appl. Poult. Res. 22(4):942-947. doi: 10.3382/japr.2013-00776

Further Reading

You can view the full report (fee payable) by clicking here.
Find out more about the parasites mentioned by clicking here.

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