What are the challenges in this part of the digestive tract?

A combination of low pH and host enzyme activity (pepsin) in this region can negatively impact the viability of a probiotic organism and efficacy of feed enzymes respectively.

What solution could be provided by an enzyme/probiotic combination?

Look for a product that employs an optimised combination of pepsin-resistant enzymes which are functional at a broad pH range in conjunction with probiotic strains administered in spore form to survive low pH conditions. This ensures that the enzyme and probiotic reach the small intestine at an effective dose.