Economic viability of anthelmintic treatment in naturally infected beef cattle under different nutritional strategies after weaning.

The aim of the present study was to evaluate the effects of treatment with different anthelmintic compounds on the productivity of naturally infected calves and the economic viability of these treatments within extensive breeding systems employing different nutritional strategies after weaning. For this purpose, 4 farms with 42-60 calves naturally infected with gastrointestinal nematodes were selected. The calves were distributed into 6 groups (7-10 animals each) per farm and treated with ivermectin 1%, ivermectin 3.15%, eprinomectin 5%, levamisole 7.5%, albendazole 15%, and control group (no treatment). These animals were evaluated over an experimental period of 150 days. Levamisole 7.5% presented the best capacity for the reduction of eggs per gram (EPG) of feces in all herds evaluated, followed by albendazole 15% and eprinomectin 5%. Parasite resistance to multiple drugs was found in all herds, especially those of Cooperia, Haemonchus, Oesophagostomum, and Trichostrongylus. For farm 1, differences in weight gain and EPG reduction percentages led to a difference of US$285.06 between the levamisole and ivermectin 3.15% groups. Similar findings were noted for the levamisole and ivermectin 1% groups of farm 3, with a difference of US$399.37 because of the final weight gain in these groups. For farms 2 and 4, the ivermectin 3.15% and control groups, respectively, were the most profitable; these unexpected results were possibly influenced by variables not measured during the experimental period. This study suggested that anthelmintic treatments should always precede an efficacy test, once they are demonstrated to be most profitable under adequate breeding conditions, to ensure adequate control of gastrointestinal nematode infection.

Relationship of the prevalence of swine helminths to management practices and anthelmintic treatment in Danish sow herds.

During 1982-1984, the occurrence of helminths in 66 sow herds in Denmark was examined by means of faecal samples. The correlations between the prevalences of Ascaris suum and Oesophagostomum spp. and management practices were analysed for fatteners and sows, respectively, resulting in four multivariate models. The helminth prevalences were in general low in large herds, specific pathogen-free (SPF) herds and herds with low weaning age. The multivariate analyses showed that only the two latter correlations were significant. The helminth prevalences of the fatteners were not correlated with anthelmintic treatment. In the sows, anthelmintic treatment was significantly correlated with low prevalences of both helminths, despite samples from recently dewormed sows indicating a rather transitory effect. The prevalences of Oesophagostomum in both fatteners and sows were significantly higher on solid floors with straw bedding than on slatted floors without straw, while this was not the case for Ascaris. Tethering of sows was not significantly correlated with helminth prevalences. Daily cleaning was significantly correlated with low helminth prevalences in fatteners, but not in the sows, while disinfection of the pens was only significantly correlated with low prevalences of Oesophagostomum in fatteners. No correlations to washing of the pens were found. The epidemiology of Ascaris and Oesophagostomum is discussed, especially why the latter is the most sensitive to intensive management.