yield of grasses meaning in English

产草量

The annual yield of grass carp covers 20 % in total output of the fresh water fish , which is fast growing and tastes delicious , besides , the forages of grass carp are various , with a lower cost of raising , however , at present , the serious diseaes of grass carp results in a lower survival rate 10 - 15 % , which cause more then billions yuan economic losses per year to the fresh water cultiuation , especially , hemorrhagic virus of carp lasts for a long period of time and features a high death rate , therefore , it " s a woed - wide problem for the aquacultural scientific researchers to discover an effective settlement , which is still under the discussion
其生长快、饲料来源广、饲养成本低和肉味鲜美。但草鱼病害多，危害严重，目前草鱼由苗种养至成鱼的成活率仅为10 - 15 ，每年给我国淡水养殖业造成数亿元经济损失。特别是病毒性的草鱼出血病，流行季节长，发病死亡率高，因此，对草鱼出血病的有效防治一直是世界各国水产科学工作者艰苦探索而又未能找到理想解决办法的世界性难题。