Incidence and distribution of helminth parasites and coccidia in Montana cattle.

A survey was conducted to determine the identity, incidence and distribution of internal parasites in Montana beef cattle. Fecal samples were collected from 486 calves less than 18 months of age and 479 adult cattle at five intervals during 1965-66 from six sampling stations representing major climatologic and geographic areas of the state. The results showed that 85.6% of the calves harbored gastrointestinal nematodes, while 59.1% of the adult cattle were similarly infected. The Cooper-ia-Triahostrongytus-Ostevtagia group was the most prevalent type of infection (69.7%), followed by NematodirUs (11.3%), Haemonahus (4.8%), Triahuris (2.0%), Strongyloides (1.3%) and Capillaria(0.3%). Nematodirus and Haemonahus were about ten times as prevalent in calves as in adult cattle. Ten and one-tenth percent of the calves and 4.2% of the adult cattle were positive for Moniezia. Nematode egg counts from 0-49 eggs per gram of feces (EPG) occurred in 88.1% of the calves and 98.3% of the adult cattle. Three and four-tenths percent of all animals sampled had counts over 100 EPG. Seven and one-tenth percent of 422 calves were positive for Dictyocaulus larvae. All of 299 adult cattle similarly examined were negative. Dictyocaulus occurred in calves located in five of the six areas studied, varying from semi-arid sagebrush-grassland range to sub-humid intermountain valley grassland ecosystems. Fasciola ova were present in feces of 1.7% of 59 calves and 20.2% of 88 adult cattle in western Montana. With the exception of one positive sample from the southwestern station, the remaining 644 fecal samples examined for flukes were negative. Of 907 fecal samples, 64.9% contained one or more of nine Eimeria species identified during the survey. INCIDENCE AND DISTRIBUTION QF HELMINTH PARASITES AND COCCIDIA IN MONTANA CATTLE by RICHARD HILDING JACOBSON ■A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in