【摘要】 监测了具有高水平（≥７ｌｏｇ２）新城疫母源ＨＩ抗体的雏鸡在１～２８日龄期间，血清母源抗体水平变化动态．结果表明，随着日龄的增长，血清母源抗体水平逐渐降低，至２８日龄时已不再能检出．免疫接种的临界日龄为１４日龄．更多还原

【Abstract】 The serous ND maternal antibody (MAb) level in the chicks having MAb of high titer (≥7 log2) was determined at the 1～28th day after hatching. The results showed that the serous MAb level gradually decreased with aging and that MAb could not be detected at the 28th day. The fourteenth day was suggested to be the critical age for vaccination.更多还原