Implications of excess nitrogen for intake,diet choice and production of sheep fed temperate pastures
Temperate forages often contain more nitrogen (N) in the dry matter (DM) than required by ruminants, and the excretion of excess N in urine has negative implications for environmental sustainability (leachate to ground water), greenhouse gas emissions, transfer of fertility and animal health.White clover ( Tri f olium repens) is highly palatable for sheep, yet the crude protein ( CP ; N x 6.25 ) content of the DM is frequently higher than 25 ％ and similar values have been measured in ryegrass ( Lolium perenne) pastures fertilized with urea.Disposal of excess N incurs a metabolic cost for ruminants, represents a loss of energy ( Greaney et al., 1996 ) and may affect palatability and intake.A series of trials have been undertaken with sheep to measure the effect of added ammonia on intakes, dietary choice and behaviour.The objective was to determine whether sheep were able to recognise high N intakes administered as an intra‐ruminal ammonia infusion and form an association with a feed choice, so that their choice could be altered to lessen the gross N intake.
forage choice crude protein diet selection aversion
G.C.Waghorn G.P Cosgrove
Dairy NZ,Private Bag 3221,Hamilton,New Zealand Garry AgResearch Grasslands,Private Bag 11008,Palmerston North,New Zealand
国际会议
呼和浩特
英文
2008-06-29（万方平台首次上网日期，不代表论文的发表时间）