Gastro-intestinal parasites in calves in Colombia.

This study was conducted at Carimagua Research Centre in a high savanna area in the eastern plains of Colombia. The objectives were to identify the pathogenic parasites prevalent in the area and to study their seasonal variations and ecological conditions for use in planning control measures. The calves from two groups of 50 cows each (zebu crossbred) were used. Group I calves were born at the beginning of the rainy season and Group II calves later in the same period. The highest faecal egg counts observed were of trichostrongylid eggs. In necropsied animals Cooperia had high populations followed by Haemonchus. Throughout the rainy season there were favourable conditions for development and transmission of calf nematodes; animals born towards the end of the rainy season developed a lower infestation level which is probably easier to control. The animals were particularly susceptible to infestation with gastro-intestinal parasites at weaning. From these observations and in view of the relatively low stocking rate and the sequential burning of the savanna it is suggested that deworming be done at eight and 18 months of age.