Abstract

Varying the regrowth interval, pre-graze herbage mass and mowing pasture prior to grazing are strategies used to try to improve pasture quality and nutrient availability to grazing livestock. This study compared the nutritive value of pastures which had been mown before grazing, or grazed as standing pastures following a long (Long, 28 days) or moderate (Mod, 21 days) regrowth interval. Nutritive value and dry matter percent were determined at 0, 1, 2, 3, 4, 6, 12 and 24 hours in replicated paddocks during a 24-hour grazing period following allocation to dairy cows at 0700 h. Due to previous grazing management, which maintained a high proportion of leafy material in the grazed stratum, the nutritive value of the available herbage before grazing was similar for all treatments. Mowing before grazing resulted in a relatively constant nutrient supply over a 24 h grazing period; however, this did not alter cow performance (e.g., milksolids production or BCS) compared with grazing standing pasture. By contrast preferential selection of higher quality pasture by cows grazing standing pasture resulted in lower concentration of herbage crude protein (P<0.05) and greater concentration of fibre (P<0.05) at the end of the grazing period. When pastures were mown, herbage wilted, increasing DM from 17.5 to 39.4% DM within 24 hours (P<0.05). Despite large differences in pasture management, extending the regrowth interval and using repeated pre-graze mowing did little to alter herbage nutritive content.

RH, Bryant, P Edwards, C Thomas, J Kay, and A Clement

New Zealand Journal of Animal Science and Production, Volume 79, Palmerston North, 103-107, 2019