Experimental Trichostrongylus Colubriformis Infection Profile in Sheep and Goats and in Vitro Nematocidal Effect of Arthrobotrys Oligospora against L3 of the Parasite
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2020-06
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Abstract
Trichostrongylus colubriformis is one of the major gastro intestinal nematodes (GINs), which cause severe morbidity and mortality in small ruminants worldwide. This comparative study on the infection profile of sheep and goats with an intestinal worm Trichostrongylus colubriformis was aimed to assess the performance of the parasite and the responses of the hosts. It also evaluated the effect of a local isolate of nematophagus fungus species, Arthrobotrys oligospora on the L3 of the parasite in vitro. A total of 14 sheep and 14 goats were employed in such a way that half of them were drenched with 10000 L3/animal and the remaining halves were uninfected controls. The infection profile and impacts of infection on the animals were assessed by measuring faecal egg count, packed cell volume and body weight gain for up to 8 weeks. After 8 weeks of infection, experimental animals were killed in humane manner, worms were recovered from the intestines, counted, and worm burdens were determined. In addition, nematophagous fungus (Arthrobotrys oligospora) was used for in vitro trial against L3 after incubating the fungus and the worms in potato dextrose agar supplemented with 0.05% chloramphenicol. Accordingly, faecal egg count at 18, 45, 52 and 56 days post infection was significantly higher in goats than in sheep, and so is worm burden at the end of the study (P<0.05). Packed cell volume was significantly reduced in both sheep and goats (P<0.05). However, it came back to normal earlier in sheep while it remained significantly lower than the value of control in infected goats. Goats experienced significantly lower weight gain compared with sheep. In vitro trial revealed, Arthrobotrys oligospora reduced survival of 84% of infective larvae after 10 days incubation. In conclusion, sheep performed better than goats to the impacts of experimental infection by T. colubriformis based on assessed parameters. Efficacy of the local strain of A. oligospora is a promising step for future biological control options against nematodes. Therefore, husbandry management of small ruminants particularly goats, in which infection results in severe production loss, in the areas where T. colubriformis prevails should use local epidemiological knowledge and focus on minimizing the exposure to infective stage in the field. A wide scale in vitro trail and further in vivo studies about efficacy of Arthrobotrys oligospora against T. colubriformis and other GINs is also recommended.
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Arthrobotrys oligospora, Experimental infection, Goat, Sheep, T. colubriformis