Control of Strongyles in First-Season Grazing Ewe Lambs by Integrating Deworming and Thrice-Weekly Administration of Parasiticidal Fungal Spores

Abstract

Parasiticidal fungi have been used in several in vivo experiments in livestock farms worldwide, constituting an effective tool for the biocontrol of gastrointestinal parasites in grazing animals. In the first year of study, two groups of eight first-season pasturing ewe lambs infected by strongyles were dewormed with albendazole, and then, the test group received an oral dose of 10⁶ chlamydospores of Mucor circinelloides and 10⁶&nbsp;Duddingtonia flagrans individually and thrice a week from mid-September to May (FS1), while the control group remained without fungi (CT1). In the second year, two new groups of first-season grazing ewe lambs were treated with ivermectin and subjected to the same experimental design (FS2 and CT2, respectively). The anthelmintic efficacy was 96.6% (CT1), 95.6% (FS1), 96.1% (CT2), and 95.1% (FS2). The counts of strongyle egg output increased in the control groups (CT1 and CT2) throughout the study and reached numbers higher than 600 eggs per gram of feces (EPG), while in FS1 and FS2, they were <250 EPG. The values of red blood cell parameters registered for CT1 and CT2 were lower than those of the reference standards, while a significant increment was recorded in FS1 and FS2, and values within the physiological range were attained. It is concluded that integrating efficient anthelminthic deworming with rotational pasturing and the regular intake of chlamydospores of M. circinelloides and D. flagrans provides a helpful strategy for maintaining low levels of strongyle egg output in first-season grazing ewe lambs and improves their health status.

Keywords: Duddingtonia flagrans; EPG counts; Mucor circinelloides; biological control; hematic parameters; ovine; soil-transmitted helminths.

Figure 1

Dynamics of strongyle eggs per gram (EPG) of feces during the first-season grazing Latxa ewe lambs dewormed in September. CT: controls, not exposed to fungi; FS: provided a dosage of 10⁶ chlamydospores of M. circinelloides and 10⁶ chlamydospores of D. flagrans, thrice a week, from mid-September to May. * Month with a significant difference between EPG of FS and CT groups in both years of the field trials.

Figure 2

Design of the study involving first-season grazing Latxa ewe lambs maintained under a rotational pasturing regime from September to May, characterized by 15 days grazing and 45 days resting. For this purpose, a total of 10 fenced prairies of ca. 1 ha were divided into two lots. Every year, two groups were dewormed in September; CT: eight control lambs, not exposed to fungi; FS: eight lambs provided a dosage of 10⁶ chlamydospores of M. circinelloides and 10⁶ chlamydospores of D. flagrans, thrice a week, from mid-September to May. Each group grazed on five different grasslands without the possibility of sharing them. Different grasslands were utilized in the first and second years.