secondary conversion

This disease causes significant economic losses in the swine industry worldwide, as it results in serious atrophy of the turbinate bones, inefficient feed conversion and reducing growth rates of the swine. Besides, it leads to secondary infection of other respiratory pathogens.

PAR能导致猪鼻甲骨发生不可逆的萎缩变形，饲料转化率降低，猪只生长速度下降，同时易引起其他呼吸道病原的继发感染，给世界各地的养猪业造成了巨大的经济损失。

This paper studied outside the upgrading of industrial, namely the primary industry, secondary industry, tertiary industry structure between the conversion.

产业升级有产业内升级和产业外升级的区别，本文所研究的产业升级是产业外升级，即第一产业、第二产业、第三产业之间的结构转换。