追施氮对多花黑麦草再生产量和品质的影响

Effects of Additional Nitrogen on Regrowth Yields and Feeding Qualities of Italian Ryegrass

以多花黑麦草早、晚熟品系为材料,研究了追施不同氮量对再生产量和饲用品质的影响。结果表明,2个品系的再生草干物质产量(DM)、可消化干物质产量(DDM)、粗蛋白含量(CP)和干物质体外消化率(IVDMD)均随追施氮量的增加而增加,而中性洗涤纤维含量(DNF)、酸性洗涤纤维含量(ADF)和非结构性碳水化合物含量(NSC)则呈下降趋势。同一施氮量下,晚熟品系再生草的DM、DDM、NSC和IVDMD高于早熟品系,NDF和ADF低于早熟品系。2个品系的第2茬草DM、DDM、NSC和CP均高于第3茬草,NDF、ADF相反。随着追施氮量的增加,氮素利用效率呈下降趋势。综合牧草适口性、饲草品质和氮素利用率等因素,南京地区多花黑麦草早、晚熟品系再生草最适宜的追施氮量为300 kg/hm2。

Early and late maturity lines of Italian ryegrass were used to study the effects of different additional nitrogen application levels on yields and feeding qualities of regrowth plant. The results indicated that dry matter yield（ DM）, digestible dry matter yield （DDM）, crude protein content （CP）and in vitro dry matter digestibility （ⅣDMD）of regrowth of ryegrass increased according to increase of additonal nitrgen,and the content of neutral detergent fiber（ NDF）, acid detergent fiber（ADF）, non-structural carbohydrate （NSC） decreased. DM, DDM, NSC and IVDMD of regrowth in late maturity line were more than those in early maturity line;NDF and ADF reversed. DM and DDM,NSC and CP of the second cut of early and late maturity lines of regrowth were more than those of the third cut, NDF and ADF reversed. Utilzation rate of nitrogen showed downtrend with increase of additonal nitrgen. In view of palatability, feeding qualities and utilization rate of nitrogen ,the favorable application rate of additional nitrogen for early and late maturity lines was 300 kg/hm^2 in Nanjing reglon.