The changes are part of the MLC Horizon portfolios and the MLC Diversified Debt Fund.
The National Australia Bank-owned wealth manager said it had terminated United States managers BlackRock and Bridgewater Associates.
MLC added Deutsche Asset Management, Goldman Sachs JBWere Asset Management, Rogge Global Partners, Wellington Management Company, Amundi Asset Management and Franklin Templeton Investments to its list of debt investment managers.
"These changes are designed to ensure our debt strategies provide diversification when our investors need it most: during periods of weak share markets," MLC Investment Management debt portfolio manager Stuart Piper said.