Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Paul H. Kohler


Six-to 8-months-old Hereford heifers categorized as grubby or grub-free calves were used for this research. Forty calves were purchased in 1968 and also in 1969. The grubby calves were obtained from Highmore, South Dakota, an area where calves have a history of heavy grub infestations of both Hypoderma bovis (L.) and Hypoderma lineatum (de Villers). The grub-free calves were purchased in Fargo, North Dakota. Calves raised in this area seldom are infested with cattle grubs. Specified groups of calves were subjected to 30 minutes of continuous exercise or the withholding of feed and water for 24 hours prior to treatment with a pour-on formulation of fenthion. The exercise and ration abstinence simulated stress conditions common to many livestock regions. Pretreatment and posttreatment jugular vein blood samples were evaluated to determine the effects of stress and fenthion on blood cholinesterase (ChE). According to statistical analysis, exercise and feed and water abstinence had little influence on ChE levels. Insecticide treatment produced the most consistent and significant variation in ChE. Fluctuations in ChE levels suggest that fenthion absorption occurs within 24 to 48 hours following treatment. Generally, insecticide influence was apparent throughout each of the 4 research phases in 1968 and 1969. Cattle origin and year also contributed to major ChE depression. Animal toxicosis was minimal throughout this study. One calf did display typical subacute organophosphate side effects. Animal reaction to the insecticide climaxed at 26 hours posttreatment and recovery was uneventful.

Library of Congress Subject Headings

Cattle -- Parasites
Cattle -- Diseases
Warble flies



Number of Pages



South Dakota State University

Included in

Entomology Commons