Refinar búsqueda
Resultados 1-5 de 5
Use of the sustained-release morantel bolus in stocker calves in southern United States.
1988
Craig T.M. | Field R.W. | Rupp G.P.
Two groups of 21 mixed-breed heifers were wintered on separate permanent pastures. Each heifer from one group was administered a sustained-release morantel bolus on October 7 (day 0), and the other group remained as untreated controls. Body weights were determined and fecal samples were taken at 28-day intervals. At the onset of the trial and at every 56 days, 6 heifers were removed from each group for slaughter to determine the developmental stages and the number of gastrointestinal nematodes. In addition, 3 tracer calves that were free of gastrointestinal nematodes were released on each pasture for 28 days at the beginning of the trial and after the last experimental-group calves had been removed. The 6 calves slaughtered on day 0 of the trial had a mean of 5,544 gastrointestinal nematodes. Tracer calves acquired 31,143 and 30,530 gastrointestinal nematodes from the pastures containing the treated and control heifers, respectively. Throughout the trial, the number of nematodes in the control calves increased at each sampling date (mean, 126,168 worms), whereas the mean number of worms in the treated heifers was 45,458. Tracer calves placed in the pastures after the 168-day trial acquired significantly more worms (9,632 vs 2,899; P < 0.05) from grazing the pastures with control heifers than from grazing the pastures with treated heifers. Counts of eggs per gram of feces were significantly different (P < 0.01) between the 2 groups from day 28 through day 112. Beginning at day 28, mean weight gain in the treated calves (45.1 kg) was significantly (P < 0.01) greater during the trial than was the mean weight gain for the control calves (2.5 kg). The use of a sustained-release morantel bolus in calves on winter pasture in the southern United States proved to be of value on the basis of fewer nematodes acquired and improved weight gains.
Mostrar más [+] Menos [-]Prophylactic efficacy of an ivermectin sustained-release bolus against challenge exposure with gastrointestinal and pulmonary nematode infective larvae in calves
1988
Alva-Valdes, R. | Wallace, D.H. | Egerton, J.R. | Benz, G.W. | Gross, S.J. | Wooden, J.W. | Reuter, V.E.
Twelve Holstein calves mere used to determine the prophylactic efficacy of ivermectin against challenge exposure with gastrointestinal and pulmonary nematodes. Two groups of 6 calves (mean body weight, 205 kg) each were formed by restricted randomization according to body weight. Group-l calves served as nonmedicated controls. Each calf of group 2 was orally given one prototype sustained-release bolus designed to deliver ivermectin at a continuous daily dose of 8 mg. Third-stage nematode infective larvae were given to the calves on posttreatment days 28 and 42. The calves were euthanatized 77 or 78 days after treatment. Ivermectin was 100% effective (P < 0.05) in preventing the establishment of infection by Haemonchus placei, Ostertagia ostertagi, Cooperia spp (C punctata, C oncophora, C surnabada), Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus and was > 99% effective against Trichostrongylus axei. Incidental infection by Trichuris spp was reduced by 94% (P = 0.08).
Mostrar más [+] Menos [-]Efficacy of febantel against naturally acquired gastrointestinal nematodes in calves, and recognition of Oesophagostomum venulosum in Oregon cattle
1988
Hoberg, E.P. | Zimmerman, G.L. | Rickard, L.G. | Schons, D.J.
The efficacy of febantel (5.0 mg/kg) against naturally acquired infections of gastrointestinal nematodes was evaluated in a controlled test in calves during the winter. Twenty steers were allotted to either control or treatment groups of 10 animals each. Seven days after treatment, calves were euthanatized and necropsied for recovery of parasites. Febantel was highly effective against adults of Ostertagia spp (88.6% efficacy based on median), Cooperia spp (97.7%), Trichostrongylus spp (98.2%), Oesophagostomum spp (100%), and Bunostomum phlebotomum (100%). Effects of treatment against adults of Nematodirus spp (100%) were not significant, whereas, degrees of infection of Strongyloides papillosus, Capillaria sp, and Trichuris sp were insufficient for evaluation. The activity of febantel was variable in controlling inhibited and late fourth-stage larvae of Cooperia spp (100% and 100%, respectively) and Ostertagia spp (-81.5% and 36.7%). Numbers of larval Nematodirus and Capillaria sp were insufficient for evaluation. Overall, febantel administered at 5.0 mg/ kg reduced populations of adult and larval strongyles and other gastrointestinal nematodes in calves by 80.7% (P = 0.002). An unexpected finding during the trial was the recovery of Oesophagostomum venulosum from all control calves.
Mostrar más [+] Menos [-]Activity of febantel on natural infections of gastrointestinal helminths in lambs in a controlled test
1988
Lyons, E.T. | Drudge, J.H. | Tolliver, S.C.
The efficacy of febantel paste formulation (6 and 12 mg/kg) against natural infections of gastrointestinal helminths in lambs (n = 33) in Kentucky was evaluated in a controlled test. For the test, 23 lambs were treated orally (17 at 6 mg/kg and 6 at 12 mg/kg) and 10 lambs were not treated. Removals at both dosages in treated lambs were 95% to 100% for species of immature and mature Haemonchus, Trichostrongylus, and Cooperia; and mature Ostertagia females, Nematodirus, and Strongyloides. For immature Nematodirus, removals were 92% and 77% at the dosages of 6 and 12 mg/kg, respectively. Only a few specimens (av less than 100) of some other species or stages were found in the nontreated group and removal of them (at both dosages) were 94% to 100% for Ostertagia (immature and males), Strongyloides (immature), Oesophagostomum (immature), and Monieiza (mature); and 61% (at 6 mg/kg) and 100% (at 12 mg/kg) for Capillaria (mature), 0% for Trichuris (mature, at both dosages), and 67% (at 6 mg/kg) and 100% (at 12 mg/kg) for Oesophagostomum (mature).
Mostrar más [+] Menos [-]Anthelmintic efficacies of fenbendazole, ivermectin, and levamisole against Nematodirus battus infections in lambs
1988
Zimmerman, G.L. | Hoberg, E.P. | Rickard, L.G. | Bishop, J.K.
Anthelmintic efficacies of fenbendazole, ivermectin, and levamisole were evaluated against naturally acquired infections of Nematodirus battus in lambs. Four groups of 10 lambs each were used. Oral administration of 8 mg of levamisole/kg of body weight or 5 mg of fenbendazole/kg significantly (P < 0.01) reduced the degree of infection by N battus (adults) by > 99%. An oral formulation of 200 microgram of ivermectin/kg was 98% effective (P < 0.01). Numbers of other Nematodirus spp (including N filicolis and N spathiger) were significantly reduced.
Mostrar más [+] Menos [-]