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

Abstract

A behavioural study was conducted during spring 1997 to investigate acceptance by dairy cows of grazing pasture recently sprayed with farm dairy effluent (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 m2) at a rate of 140 000 1 ha"1 at 25, 20, 15, 10, and 5 days prior to grazing, with one plot (control) within each strip receiving no FDE. Pasture measurements were taken pre‐ and post‐grazing and a pasture sample was collected for faecal coliform concentrations. Six mature cows 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. Pasture measurements showed that there was a significant difference between the amount of pasture consumed from a plot and the length of time since effluent application. Significant differences were also observed for bite numbers and residence time between FDE treatments. Faecal coliform concentrations were significantly higher on the most recently treated plots but on the plots sampled after 10 or more days faecal coliform concentrations were not different from the control plots.