Effect of nitrogen fertiliser and supplements on pasture production and milksolids yield from dairy farm systems

摘要

Seven farmlets of 6.48 ha grazed by Friesian cows at stocking rates of either 3.24 or 4.48 cows/ha were used to evaluate the effect of high rates of nitrogen fertiliser (N) and rolled maize grain on milksolids (MS) production, Annual applications of 213 and 379 kg N/ha increased annual net herbage accumulation by 3350 and 4650 kg DM/ha respectively. At 3.24 cows/ha extra DM resulted in a three fold increase in pasture conservation, providing silage for use in late lactation, and increasing productionby 72 kg MS/cow. The extra pasture reduced the amount of supplement required at 4.48 cows/ha. Offering supplementary feed when cows were over grazing or being under fed resulted in an extra 43g milkfat and 47g milk protein/kg DM at the low stocking rateand 45g milkfat and 36g milk protein/kg DM at the high stocking rate. Responses to extra feed were greatest when used to extend lactation. Increased stocking rates will be necessary to maintain pasture utilisation when large amounts of extra feed are introduced.