English to Spanish Science Livestock / Animal Husbandry field study - vaccines

Mi duda es si aplica "viabilidad de los huevos" como única traducción para ambos términos. Gracias!!

Reversion to Virulence
A study was carried out to determine the lack of reversion to virulence, when passed 5 times in SPF chickens.

The Master Seed Virus (MSV) was inoculated at the dose 39811 pfu by in ovo route to SPF chickens (Group G1) corresponding to the first passage.
White Blood Cells (WBC) suspension were prepared from blood collected from G1 and were re-inoculated by intraperitoneal route to a second group of day-old SPF chickens (Group G2) corresponding to the second passage.
This passage operation was carried out until the fifth passage in SPF chickens (G5).
At each passage, presence of the virus in the White Blood Cells (WBC) suspension was checked by virus isolation.
At the first passage, safety of the in ovo inoculation of the MSV was assessed through monitoring of hatchability and viability until 7 days of age and comparison to control group G0 inoculated with Marek’s diluent.