Some uncertainties still lie ahead for cattlemen even though the country's enhanced feed ban is now in effect.The new regulations require the removal of specified risk materials from all pet food, animal feed, and fertilizers.  Manitoba Cattle Producers Association President Martin Unrau says many of the organization's members feel the rules will be challenging to comply with at the outset.  He hopes a regional system is put into place to deal with SRM removal, hopefully meaning a reduction in the potential costs incurred by producers.  Agriculture Minister Rosann Wowchuk says a regional approach will be taken for SRM disposal in Manitoba.  The development of that network will be supported by $17.2 million in funding announced this week by the Feds and Province.