Incubation is needed to assess hatchability and fertility of eggs. Feed, along with other components incorporated into it, such as enzymes, is among several factors affecting fertility and hatchability. Therefore, incubation is necessary to assess the effect of the enzyme you want to add to feed on fertility and hatchability of chicken egg.

What incubation are you interested in? Incubation of eggs or incubation of feed before providing it to the broilers.

For the first option see the above answer.

For the second: the commercially available enzymes are just added to the feed in the feedmill and then given to the animals. Incubation would require soaking of the feed and thus the possibility of unwanted micro-organisms to grow also during that period.

I was asking for the second actually & thank you everyone for the support on this one.

Yes perhaps, I'm following the best answer.