Effect of daily herbage allowance restriction on pasture characteristics and milk production by grazing dairy cows in spring

Abstract

The cumulative effects of daily herbage allowance (DHA) restriction on pasture

characteristics and the sustainability of pasture-based dairy systems were evaluated. Sixty-four

dairy cows were randomly assigned to one of two grazing treatments (20 and 30 kg DM cow-1

day-1). Milk yield and pre- and post-grazing herbage mass were recorded for every grazing

event. Botanical and chemical compositions of the pasture were evaluated. Low DHA increased

the stocking rate by 0.7 cows ha-1 and consequently increased grazing efficiency from 41 to 47%.

Daily herbage allowance restriction did not affect pasture characteristics or milk production per

cow, but DHA restriction increased milk production per hectare (+27%). The results suggest

that restriction on daily herbage allowance ensures a higher level of herbage utilization and

milk output per ha than high DHA, without affecting pasture characteristics. Therefore, DHA

might be a useful grazing management tool for improving the profitability and sustainability of

grazing-based dairy systems.