Fluctuations of Herbage Infestation on Calf Pastures and Weather from 1973 to 1979

Abstract

Duplicate herbage samples were taken from pastures at the Mecklenhorst state farm from July 1973 to December 1979 at two week intervals during the grazing season and at longer intervals during the rest of the year. Larvae of gastro-intestinal nematodes were counted. Each pasture was grazed three or four times per year for approximately one to two weeks by cattle, mainly calves during their first grazing season, but occasionally by older stock. Weather records of the nearby official weather station at Hannover-Langenhagen were compared with the fluctuations of larval counts.

The number of larvae per kilogram of dry herbage was generally high in February or March, this decreased considerably during March and April and was negligible from the beginning of May to at least the beginning of July. Larval counts rose again to substantial levels between late July and early October. An additional increase to produce high levels occurred on many pastures during October or November.

The first increase during (late) summer coincided with or was preceded by a period of cool and rainy weather with at least 20 mm of precipitation evenly spread over a period of approximately one week.