Influence of an Internal Parasite Control on Cattle Grazing Behavior and Production

Six herds of 45 to 90 cow/calf pairs grazing on upland range were used to examine the efficacy of an injectable extended release eprinomectin parasite control on production traits, activity behavior, and efficacy against internal parasitism. In 2016, treatment cows were given a subcutaneous injection of LongRangetm. In 2017, all cows in the study were treated with a short acting Synanthictm treatment and only treatment cows were given an additional LongRangetm treatment. In both 2016 and 2017, fecal egg counts were significantly lower (P \u3c 0.05) in eprinomectin treated cows compared to control cows. Calf gains were 4.8 kg and 8.7 kg greater (P \u3c 0.1) for the calves of dams treated with eprinomectin compared to calves of control cows in 2016 and 2017, respectively. Activity characteristics of cattle were inconclusive, with treated cows having lower (P \u3c 0.01) grazing and traveling times compared to control cows in 2016, and more (P \u3c 0.01) grazing and traveling in 2017. Differences in grazing behaviors based on time within pasture at different times during the growing season also were evaluated. In 2016 and 2017, grazing behaviors (e.g., activity and distance traveled) of cow/calf pairs were examined on upland Nebraska Sandhill range. Five or six cows from each of three herds (45 to 90 cow/calf pairs) in each were randomly selected to wear global positioning system (GPS) collars. Daily distance traveled by GPS-tracked cows early in the growing season had a significant (P \u3c 0.01) quadratic response, but later pastures did not show a similar response. Activity, time at water, and distance from water showed no significant differences (P \u3e 0.37) between grazing period during the growing season, but all three measures exhibited changes as time within pasture progressed (P \u3c 0.02). Hours spent in activity increased, time at water decreased, and distance from water increased as time within pasture progressed. Area covered showed no significant differences (P \u3e 0.07) between pasture treatments or weeks within pasture. Advisors: Mitchell B. Stephenson and Walter H. Schach