Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/25/2004
Publication Date: 12/30/2004
Citation: Stuedemann, J.A., Kaplan, R.M., Franzluebbers, A.J., Ciordia, H., Stewart, T.B., Seman, D.H. 2004. Bermudagrass management in the southern piedmont usa: v. maintaining parasite-free pastures while restoring degraded cropland. Veterinary Parasitology. 126:375-385. Interpretive Summary: Scientists at the J. Phil Campbell, Sr., Natural Resource Conservation Center, of the USDA, Agricultural Research Service at Watkinsville, Georgia in cooperation with scientists at the University of Georgia and Louisiana State University have found that gastrointestinal parasite-free cropland that is converted to pasture can be maintained parasite-free for at least five years. Gastrointestinal parasites can drastically influence the health and productivity of grazing cattle. It has been generally assumed that parasite infections are inevitable in grazing animals; therefore treatment and control programs have primarily been aimed simply at reducing rather than eliminating the effect of parasites. However, this assumption may not be true. Cropland with no exposure to cattle for several years should have relatively few nematode parasite larvae. If these croplands are converted to pasture, and cattle are treated with dewormers prior to placing the cattle on the pastures, theoretically, it should be possible to maintain the pastures in a parasite-free state or at very low levels indefinitely. Cattle producers that utilize this practice with weaned calves could potentially realize from 0.2 to 0.5 pound improvement in daily gain as compared to allowing the fields to become contaminated with parasites.
Technical Abstract: The objective of this report was to determine if parasite-free pastures could be maintained by anthelmintic treatment of animals prior to placing them on pastures. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994-1998, steers grazed the paddocks for a 140-day period from mid-May until early October each year. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 hours prior to stocking of pastures, with the cattle remaining in drylot during the 48-hour period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Rectal fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals thereafter except in years one, four and five when egg counts were also performed on day -21. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although there were statistical treatment differences in epg among both the fertilization and forage mass treatments, the very low average epg (0.7 to 3.0) indicated that there were no biological differences. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. Consequently, we can say that under the conditions of this experiment, pastures were maintained in a parasite-free condition for at least five years by simply therapeutically treating animals prior to placing them on the parasite-free pastures. The therapeutic treatment prevented transport of larvae to the pastures, thus preventing pasture contamination and reinfection.