Under The Livestock Manure and Mortalities Management Regulation under The Environment Act in Manitoba it is illegal to burn manure.
http://web2.gov.mb.ca/laws/regs/current/_pdf-regs.php?reg=42/98
Burning of livestock manure prohibited
10.2(1)
No person shall burn livestock manure at any time unless
(a) the director has given prior authorization for the burning: and
(b) the person complies with the terms of the authorization.
The Department only authorizes the burning of manure in an emergency, which doesn't happen very often. I would strongly encourage you to cease burning manure.