2.4 Samples collection
The eggs from the ducks of the experimental group and the control group
were collected for hatching, and the fertilization rate and hatching
rate of each group were counted. Collect eggs as early as possible every
day to reduce the time that eggs are stored outdoors. Use a disinfectant
to scrub the eggshells to prevent bacterial infections on the eggshells
from affecting the hatching, and then place them in the incubator for
hatching. On the 6th day of hatching, the yolk membrane was collected
from the unfertilized eggs (Wei et al., 2020). The spleen of the dead
embryos during the hatching process was collected, and the hatched
ducklings also received spleen tissue for virus detection. Finally,
samples that test positive are freeze-thawed for virus isolation.