Animal constraints to pasture treated with farm dairy effluent: Preferenceunder grazing and issues of faecal contamination

A behavioural study was conducted during spring 1997 to investigate accepta nce by dairy cows of grazing pasture recently sprayed with farm dairy efflu ent (FDE) and to measure the extent of faecal bacterial decline. The field experiment was laid out with six strips of six treatments. FDE was applied to small plots (2 m(2)) at a rate of 140 000 1 ha(-1) at 25, 20, 15, 10, an d 5 days prior to grazing, with one plot (control) within each strip receiv ing no FDE. Pasture measurements were taken pre- and post-grazing and a pas ture sample was collected for faecal coliform concentrations. Six mature co ws were used and one cow was allowed to graze freely along one strip for 20 minutes. Residence time and number of bites on each plot were recorded. Pa sture measurements showed that there was a significant difference between t he amount of pasture consumed from a plot and the length of time since effl uent application. Significant differences were also observed for bite numbe rs and residence time between FDE treatments. Faecal coliform concentration s were significantly higher on the most recently treated plots but on the p lots sampled after 10 or more days faecal coliform concentrations were not different from the control plots.