Monospecific nematode infections of donor calves with Cooperia punctata

During a 25 year period, 48 calves from three states were raised helminth-free from birth and inoculated with Cooperia punctata. These calves served sequentially as donors of the parasite. The following aspects of the monospecific infection were of value in successful donor management and contributed to understanding the host-parasite relationship. Calves with no previous experience with C. punctata were the best hosts for establishing initial infections. Male Holstein calves were satisfactory donors of the parasite. Inoculation of calves 6-24 weeks of age with 10,000-11,200 infective third-stage larvae (L3) over a 2 day period produced the desired donors. Occasional over-feeding of calves appeared to reduce the patent period. Superimposed infection was more likely when calves were still patent from previous infection, whereas reinfection was less likely after patency of the earlier infection had ended. Strong immunity eventually developed following oral administration of L3.