Was doing some early reading today. Tend to read allot of Poultry Journal stuff... Anyway they have found spraying Probiotics on hatching eggs is increasing the viability of the hatch. So I kept researching it and seems there getting some real positive results. Kind makes since since the embryo gets its calcium from the shell as it develops by a break down of CO2 allowing the absorb. Why not?. University of Connecticut published this https://today.uconn.edu/2023/12/nov...as-egg-cellent-growth-promoter-for-chickens/#