Efficacy of Morantel Tartrate in a Sustained Release Bolus on the Control of Subclinical Gastrointestinal Parasitism in First-Year Grazing Dairy Replacements

摘要: Thirty-four heifers (24 Holstein, 8 Ayrshire, 2 Jersey) and 12 Holstein steer calves were grouped into 23 blocks of animals each according to breed, sex, body weight. Animals in block randomly assigned control or treated groups. The group received an anthelmintic bolus containing morantel tartrate before they permitted access pasture. A 2.6 ha pasture was divided half with a double fence; the resulting two pastures had separate feed water troughs. Steer slaughtered upon termination trial ascertain gastrointestinal parasite burdens. Two worm-free tracer placed on every mo after 4 wk grazing determine infectivity pastures. Herbage samples obtained monthly analyzed for infective larvae. conducted 141 d during season. Treatment resulted 90% reduction larvae pasture, 74% fecal worm-eggs, 91% adult worm burdens, trend toward reduced burdens by 52%. An overall average daily gain .68 .88 kg animals. Reproductive data remaining herd from showed that treatment 44 less days first breeding.