What might be the effect of crowding on effective exposure rate of individual animals to MTb?

Increase in the chances of individual animals contracting Mtb.

Explanation:

When population density is high, contraction of sickness is more frequent. Crowding may cause the exposure and the mixing that needs to happen in order for transmission of Mtb to occur. Chances of contracting Mtb would be much higher in crowded and poorly ventilated condition.