Martin Smith,
In this period, the mode of action will be pretty much similar to a monogastric. I mean, the greater impact will be on modulating the gut microbiota, by direct reducing the pathogens that possess fimbria (like Salmonella and E. coli) and strengthen the immune system responses (APC's cells present in the gut recognizing the Beta-glucans and modulating the innate immune system responses). That is why it's possible to observe less enteric problems and respiratory disorders (health problems).
Melina.