SOME EFFECTS OF HERBAGE COMPOSITION, AS INFLUENCED BY PREVIOUS GRAZING MANAGEMENT, ON MILK-PRODUCTION BY COWS GRAZING ON RYEGRASS WHITE CLOVER PASTURES .1. MILK-PRODUCTION IN EARLY SPRING - EFFECTS OF DIFFERENT REGROWTH INTERVALS DURING THE PRECEDING WINTER PERIOD

Two experiments (1a and 1b) were carried out to examine the effects of differences in pre-grazing herbage mass and composition on milk production by cows grazing in early spring. Swards with high (5 . 1 t DM ha - 1) or low (2 . 9 t DM ha - 1) pre-grazing masses in early spring were created by either,long or short periods of regrowth during the preceding winter. The low-mass swards contained lower concentrations of grass stem and senescent material, but higher concentrations of clover, than the high-mass swa-rds. Herbage from the low-mass swards was also more digestible. Cows were offered common daily herbage allowances from both swards (26 and 22 kg DM cow-1 in Experiments 1a and 1b respectively). The cows grazing on the low-mass swards produced significantly greater yields of milk, milk fat and milk protein. The results show that herbage from the low-mass swards was of higher feeding value for lactating cows in early lactation. The practical implications for milk production per cow and per hectare are discussed.