RESUMEN
Nine farms were each visited regularly for a year in 1979 and 1980 in Salta Province in the subtropics of Argentina. A necropsy was done at each visit and faecal and blood samples were taken from other animals mostly aged between 6 and 18 months. Ninety necropsies were done and nearly 1,500 faecal samples collected. Gastro-intestinal helminthiasis was most general and severe in autumn when calves were about 9 months old and this was followed by a dramatic fall in numbers of worms by the end of winter. Helminths were found in other organs but were not considered important. At peak periods 20% of the animals had worm egg counts of more than 750 epg and contained more than 1,000 Haemonchus worms. This species was considered to be the most important but other frequently encountered species were Oesophagostomum, Cooperia and Trichostrongylus spp. A list is given of all species found. Tracer calves were used to determine the periods of infestation. No hypobiosis was encountered. It was concluded that the sharp fall in numbers of worms after the autumn peak was due to the development of immunity by the majority of the young animals.
Asunto(s)
Enfermedades de los Bovinos/epidemiología , Helmintiasis Animal , Animales , Argentina , Bovinos , Heces/parasitología , Hemoncosis/epidemiología , Hemoncosis/veterinaria , Recuento de Huevos de Parásitos/veterinaria , Estaciones del Año , Clima TropicalRESUMEN
Two thousand and ninety beef cattle livers from north-west Argentina were inspected at a large slaughterhouse in Salta; 13% were found to have lesions of fascioliasis and these were classified according to their severity. Of the livers condemned 182 (67.2%) were lightly affected, 77 (28.4%) moderately affected and only 12 (4.4%) severely affected. In a field survey 85 animals, mainly between 6 and 18 months old, were slaughtered and 12 (14%) had lesions of fascioliasis. The influence of Fasciola hepatica on weight gain in beef cattle was assessed on 2 farms. Infected animals were divided into 2 groups and I group was treated monthly. Only on 1 farm were the animals exposed continuously to infection. No differences in weight gain were found over 7 and 14 months respectively when compared to untreated controls. It was concluded that fascioliasis is widespread but at a low level in beef cattle.