R. Jones
Jul 1, 1981
Citations
1
Influential Citations
56
Citations
Journal
Veterinary Parasitology
Abstract
Abstract The field application of an intraruminal bolus designed to release morantel tartrate continuously for a period of about 60 days after oral administration to grazing calves just prior to turnout onto spring pasture has been tested. The study involved five separate field trials with a common trial design conducted in 1978 on farms in Eastern and South Eastern England. The Morantel Sustained Release Bolus (MSRB) treated calves showed statistically significant weight gain advantages over their contemporary controls at the end of the grazing season on all sites. Advantages varied from 13.4 to 36.5 kg. Overall 109 treated calves gained an average of 24.5 kg more than controls. Outbreaks of clinical parasitic gastroenteritis occurred in the latter part of the grazing season on three sites. Altogether, there were twenty eight cases requiring therapeutic treatment in controls but none in the MSRB treated calves. Parasitology data show that the disease prevention and improved performance were due to the MSRB preventing the mid-summer rise in pasture larval contamination, which was evident in all five sites, and thus eliminating the detrimental effect of high parasite challenge in the latter part of the grazing season.