Effect of pre-grazing herbage mass on production performance of dairy cows in mid-lactation

摘要

The objective of this experiment was to investigate the effect of a high (H - 2100 kg DM ha~(-1)) and low (L - 1500 kg DM ha~(-1)) pre-grazing herbage mass (HM) on mid-lactation milk production from spring-calving dairy cows offered two levels of daily herbage allowance (> 4 cm) (16 kg or 20 kg DM cow~(-1) day~(-1)). Sixty-eight spring calving Holstein Friesian dairy cows were assigned to a 4 treatment (n = 17) grazing study (HI6, H20, L16 or L20) from 4 April until end July. No supplement was offered. Pre- and post-grazing sward height and milk yield were recorded daily. Milk fat, protein, lactose content, liveweight and body condition score were recorded weekly. Herbage mass had no affect on any milk production parameters. Allocating extra herbageincreased milk production performance by 0.25 kg milk per kg grass offered (23.1 kg (16 kg) and 24.1 kg (20 kg), respectively). Yield of milk solids (P > 0.01) was higher with the high herbage allowance treatments. Higher grass utilization was achievedon the low herbage mass treatments. Preliminary results indicate that the balance of attaining high sward utilisation and high cow performance from pasture is achieved by using lower pre-grazing HM and allocating cows a high DHA.