Data were collected over four consecutive years from four, rotationally grazed, grassland management systems each with 15 spring-calving beef suckler cows and their progeny to 13 months of age. The Systems were high stocking rate (SR), high fertiliser nitrogen (N), 2 silage harvests -- HH2; high SR, low N, 2 silage harvests -- HL2; low SR, low N, 2 silage harvests -- LL2, and low SR, low N, 1 silage harvest -- LL1. High and low SR were 0.49 and 0.59 ha cowp# unit, respectively, and high and low N amounted to an annual input of 239 and 57 kg hap# on the grazing areas, respectively. Where applicable, the four Systems received 114 and 80 kg of N hap# for the first and second silage harvests, respectively. Equal areas of Systems HH2, HL2 and LL2 were conserved as silage (0.29 and 0.21 ha for first (24 May) and second (4 August) harvests, respectively cowp# unit) each year. Silage from System LL1 (0.37 ha cowp# unit) was conserved 14 days after the other first harvests. Following the final harvesting for silage within any System these areas of grassland were then grazed. During the winter all animals were housed and cows were offered grass silage and calves were offered silage plus 1 kg of concentrate per head daily. Good cow and calf performance at pasture were obtained at both high SR and high N or low SR and low N. At the high SR, increasing the level of fertiliser N application increased cow liveweight gain at pasture by 24 kg, improved body condition score (BCS) gain at pasture by 0.36 units and prolonged the grazing season by 7 days. Similarly, at the low level of fertiliser N, reducing the SR, increased cow liveweight gain at pasture by 21 kg, improved BCS gain at pasture by 0.23 units and prolonged the grazing season by 7 days. At the low SR all the winter silage requirements could be provided in one as opposed to two harvests thereby reducing the conservation area. However, delayed harvesting of silage resulted in lower silage digestibility and reduced calf performance in winter. The results indicate the specifications for a planned lower N grassland system, particularly where qualification for EU environmental schemes is dependent on moderate stocking densities.
展开▼
机译：连续四年从四个轮牧，草地管理系统收集数据，每个系统都有15头春季产犊牛和13个月大的后代。这些系统是高放养率（SR），高肥料氮（N），2个青贮饲料-HH2;高SR，低氮，2吨青贮饲料-HL2;低SR，低氮，2青贮收割-LL2和低SR，低N，1青贮收割-LL1。高和低SR分别为0.49和0.59公顷牛cow＃单位，高和低氮分别在放牧区分别为239和57 kg hap＃的年输入量。在适用的情况下，四个系统分别在第一次和第二次青贮饲料中收获了114千克和80千克N hap＃。系统HH2，HL2和LL2的面积相等，分别作为青贮饲料保存（每年第一（5月24日）和第二（8月4日）收成分别为Cowp＃单位0.29和0.21公顷）。在其他第一次收获后的第14天，保留了LL1系统（0.37公顷作物单位）的青贮饲料。在最终收获任何系统内的青贮饲料之后，将这些草地放牧。在冬季，将所有动物圈养起来，给母牛喂草青贮饲料，给小牛喂青贮饲料，每头每天加1公斤精矿。高SR和高氮或低SR和低N时在牧场上都表现出良好的牛和小牛表现。在高SR时，增加施氮水平可使牧场的牛增重24 kg，改善身体状况（ BCS）在牧场上获得了0.36个单位的收获，并将放牧季节延长了7天。同样，在低氮肥水平下，降低SR，使牧场牛的增重增加21 kg，牧场BCS增幅提高0.23个单位，放牧季节延长7天。在低SR的情况下，所有冬季青贮饲料的需求都可以提供一次，而不是两次收获，从而减少了保护区。但是，青贮饲料的延迟收获导致青贮饲料消化率降低，冬季小牛性能下降。结果表明了计划中的低氮草原系统的规范，特别是在欧盟环境计划的资格取决于适度的种群密度的情况下。
展开▼
