1998 Volume 51 Issue 5 Pages 237-240
Six-to 17-month-old Holstein heifers pastured during the period of May to October in 1995 in Iwate Prefecture, were subjected to evaluation of deworming effects of ivermectin (IVM). The prevalent nematode species were Ostertagia ostertage, Trichostrongylus sp., Cooperia sp., Strongyloides papillosus and Oesophagostomum sp. On days 28 and 60 of pasture, 29 of 44 heifers were treated with IVM (0.2mg/kg s.c.), and the remaining 15 remained untreated. In the treated heifers the egg counts of rectal feces were remarkably decreased after the first treatment. Weight gain during pasturing was significantly higher in the treated heifers than controls. In August, serum pepsinogen concentrations were significantly higher in controls, and from June to August serum albumin concentrations were significantly higher in the treated heifers than controls. Moreover, the treated heifers were able to be artificially inseminated about one month earlier than controls, and the costbenefit ratio of IVM treatment was caluculated to be 1: 1.52.
