Mowing pasture to improve milk production

Abstract

Mowing pasture before grazing, and topping pasture after grazing were studied as methods to increase pasture quality, dairy cow dry matter intake, and milksolids production from September 1997 to February 1998. Three 2.8-ha experimental areas were subjected to mowing, topping, or control treatments, and were grazed by three Friesian cows/ha (18 cows per treatment). Cows were allocated to each treatment according to a crossover design and pastures were grazed every 28 days. Mowing pasture, either before or after grazing, reduced pasture production by 20%, and reduced milksolids production by 11% during October, but increased milksolids production by 12% during summer. Liveweight change responded similarly; mowing or topping resulted in greater liveweight gain (0.76 kg/cow/day) during summer compared with the control. This was associated with an increase in the metabolisable energy content of summer pastures that had been mown before grazing (0.2 MJME/kg DM), or topped after grazing (0.6 MJME/kg DM). Topping pastures after grazing reduced milksolids production in October by 0.11 kg MS/cow/day, and increased milksolids production in summer by 0.13 kg MS/cow/day. Mowing pasture before grazing increased average dry matter content of the wilted material by 7.5% units compared with the control, but dry matter intake was reduced by 2.4 kg DM/cow/day in November, and milksolids production was reduced by 0.12 kg MS/cow/day during spring. Mowing before grazing increased milksolids production in summer by 0.13 kg MS/cow/day. Overall, only the topping treatment increased total milksolids produced during the six 14-day experimental periods (by 80 kg MS, or 4.6%). However, an additional 5184 kg of DM was removed from the control pastures by extra cows, which could have produced an additional 415 kg milksolids. Therefore, although mowing or topping can increase the quality of pasture and the yield of MS per cow in summer, the overall benefits for MS production per ha are small or negative. Keywords: dairy cow, herbage mass, milksolids, milk yield, mowing, nutritive value, pasture intake, topping