Screening parasitic nematode-trapping fungi Arthrobotrys for passage through the gastrointestinal tract of calves

''In vivo'' experiments were performed to test three isolates of nematode-trapping fungi, one isolate of Arthrobotrys musiformis and two isolates of A. robusta for passage through the gastrointestinal tract of calves without losing the ability to entrap infective Haemonchus placei larvae. Following the administration of 20 x 10(6) conidia, divided into four oral doses of 5x10(6), to calves at 3h intervals, only one isolate of A. robusta met that goal when harvested from fecal samples and was, later, able to entrap the infective H. placei larvae. There was no evidence that the other isolates passed through the gastrointestinal tract of the calves. The isolation from the feces occurred between 24 and 48h following the first administration of conidia and 15 and 39h after the last one.