Efficacy of abamectin against gastrointestinal tract nematodes and lungworms of cattle was determined in 4 experiments. The first 2 experiments were controlled trials in which efficacy was determined at necropsy in calves with either experimentally induced (n = 14) or naturally acquired (n = 16) infections. Half the calves in each experiment were treated with abamectin (200 micrograms/kg of body weight, sc), and half were left untreated as controls. Efficacy was > 99% against adult stages of Dictyocaulus viviparus, Haemonchus placei, Ostertagia ostertagi, Trichostrongylus axei, Cooperia punctata, Trichuris discolor, and C oncophora, and was 92.4% against Nematodirus helvetianus. The second 2 experiments were clinical trials in which efficacy was determined by fecal egg count reduction in naturally infected yearling heifers (n = 75) or 2-year-old heifers (n = 75). Within replicates of 5, 4 heifers were assigned at random to treatment with 200 Kg of abamectin/kg and 1 was left untreated as a control. Abamectin was 100% effective in eliminating strongylate nematode eggs from the feces of these heifers. In all experiments, adverse reactions were limited to small, clinically unimportant injection site swellings in 29% of abamectin-treated calves. Abamectin was judged to be safe and effective in these trials.

gastrointestinal nematodes in calves (exper.) causing severe anemia, effect on preparation of carrier erythrocyte ghosts and erythrocyte survival

gastrointestinal nematodes, calves (exper.), efficacy of ivermectin given subcutaneously or given orally as drench or paste

gastrointestinal helminths in calves, field conditions, febantel, no activity against Moniezia benedeni, no signs of intoxication

Anthelmintic efficacy of doramectin, a macrocyclic lactone of the avermectin family, was evaluated against larval parasitic nematodes in calves. The investigational product was given sc at a dosage of 0.2 mg/kg of body weight to 10 calves infected 6 days previously with third-stage larvae of the genera Haemonchus, Ostertagia, Cooperia, and Nematodirus. Ten additional calves with identical larval exposure were given saline solution SC also at 6 days after inoculation, and served as the nonmedicated controls. At 14 or 15 days after treatment, the calves were slaughtered in complete replicate for nematode recovery and subsequent quantifications. In comparing nematode numbers at necropsy for the saline- and doramectin-treated groups, nematocidal effectiveness as directed against fourth-stage larvae was: 100% for Haemonchus placei and Cooperia spp, > 99% for Ostertagia ostertagi, and 64.5% for Nematodirus helvetianus. All treatments were easily administered, and adverse behavioral or tissue reactions were not seen to result from doramectin administration.

nematodes, calves, albendazole evaluated

nematodes of ruminants, large scale technique for recovery of worms migrating from gastro-intestinal ingesta gelled in agar, significantly more male than female worms failed to migrate, L4 stages generally migrated more efficiently than did adult worms, some genera migrated more efficiently than others, applications for use in quantitative worm recovery such as in anthelmintic testing

Twenty, 2-3-month-old worm free male Holstein calves, were assigned to two groups each containing ten animals. Each group was offered one of two diets: High (HP) and Low (LP) protein with 257 and 91 gkg-1 dry matter respectively, balanced for energy and minerals. After an initial period of 4 weeks on the diets, the calves from each group were subdivided into two groups of four and six calves. A trickle infection of 5,000 Haemonchus placei L3 was given twice a week for nine weeks to the sub group of six calves (I). The remaining four calves from each dietary group were used as non-infected control (C). Four weeks after the last infection, all calves were slaughtered and worm burdens counts. Carried out Biochemical determinations, faecal egg counts and body weights were carried out once a week. The HP group had significantly higher mean adult worm burdens (11,900 ± 7,660) when compared with BP (5,450 ± 7,895). Faecal egg counts were higher in the HP than LP group. Despite higher worm burdens, resilience was increased in the HP calves, with higher packed cell volume values as well as body weight when compared with the LP group. | Vinte bezerros com 2 a 3 meses de idade criados livres de vermes foram divididos em 2 grupos com 10 animais cada alimentados com alta proteína (HP) e baixa proteina (LP) com 257 e 91 g kg-1 de proteína na materia seca respectivamente, devidamente balanceado em energia e minerais. Após 4 semanas submetidos a estas duas dietas cada grupo original foi subdividido em 2 grupos, um contendo 4 animais não infectado (C) e 6 animais infectados (I). O grupo infectado recebeu 5.000 larvas de Haemonchus placei duas vezes por semana por um período de 9 semamas, após 4 semanas da última infecção todos os animais foram sacrificados e realizada a contagem de vermes. Semanalmente foram feitas as pesagens dos animais, número de ovos por grama de fezes e colheita de sangue para determinação do hematócrito, hemoglobina, albumina e proteína total. A contagem de ovos por grama de fezes foi superior no grupo de HP em relação ao grupo de LP, tendo em vista que o número de vermes adultos no grupo HP (11.900 ± 7.660) foi maior que o grupo de LP (5.450 ± 7.895) . Apesar do número superior de vermes encontrado no grupo HP, observou-se valores superiores de hematócrito e peso vivo quando comparado com o grupo de LP (p<0,05), demonstrado que a suplementação protéica possibilita uma melhor resilience em bezerros infectados com Haemonchus placei.