| seasonal occurence of infective nematode larvae on irrigated pasture grazed by cattle in california. | during the period extending from dec 1, 1975, to dec 22, 1976, 3 distinct peaks in the concentration of infective nematode larvae on pasture forage were detected by use of helminth-free tracer calves. two of these peaks, 1 occurring in the spring and 1 in the fall, consisted mainly of ostertagia ostertagi and cooperia sp. it is concluded that these 2 peaks can be anticipated annually and constitute unsafe periods of grazing. the 3rd peak was comprised largely of haemonchus placei and cooperia sp ... | 1981 | 7271041 |