Document:

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                                                                    Exhibit 4.28

                                                               EXECUTION VERSION

                    SIXTH AMENDMENT dated as of June 15, 2005 (this
               "Amendment"), to the AMENDED AND RESTATED FIVE-YEAR CREDIT
               AGREEMENT dated as of October 11, 2001 (as amended, supplemented
               or otherwise modified from time to time, the "Credit Agreement"),
               among LAND O'LAKES, INC., a cooperative corporation organized
               under the laws of the State of Minnesota (the "Borrower"), the
               several banks and other financial institutions and entities from
               time to time party thereto (the "Lenders"), and JPMORGAN CHASE
               BANK, N.A., as administrative agent (in such capacity, the
               "Administrative Agent") and AMENDMENT NO. 2 dated as of June 15,
               2005 to the GUARANTEE AND COLLATERAL AGREEMENT dated as of
               October 11, 2001 (as amended, supplemented or otherwise modified
               from time to time, the "Collateral Agreement") among the
               Borrower, the Subsidiaries named therein and JPMorgan Chase Bank,
               N.A., as collateral agent (in such capacity, the"Collateral
               Agent").

          A. Capitalized terms used but not defined herein shall have the
meanings assigned to such terms in the Credit Agreement, as amended hereby.

          B. The Borrower has notified the Administrative Agent that it intends
to contribute up to $88,000,000 to Cheese & Protein International LLC ("CPI"), a
Delaware limited liability company and a subsidiary of the Borrower of which, on
the date hereof, the Borrower owns approximately 97.5% of the Equity Interests,
in order to permit CPI to prepay all amounts outstanding under the CPI Lease (as
defined herein) (the foregoing transactions being referred to herein as the "CPI
Lease Transactions"). The Borrower has proposed that, in connection with the CPI
Lease Transactions, CPI will become a Restricted Subsidiary and a Subsidiary
Loan Party and will satisfy the Collateral and Guarantee Requirement.

          C. The Borrower has requested that the Lenders amend certain
provisions of the Credit Agreement in connection with the CPI Lease Transactions
as set forth herein.

          D. The Required Lenders are willing to effect such amendments on the
terms and subject to the conditions of this Amendment.

          E. Accordingly, in consideration of the mutual agreements herein
contained and other good and valuable consideration, the sufficiency and receipt
of which are hereby acknowledged, the parties hereto agree as follows:

          SECTION 1. Amendment of the Credit Agreement. Effective as of the
Amendment Effective Date:

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                                                                               2

          (a) Section 1.01 of the Credit Agreement is amended by deleting the
definition of "Restricted Subsidiaries" and replacing it with the following:

          'Restricted Subsidiaries' means (i) Land O'Lakes Purina Feed LLC, (ii)
     each existing and subsequently acquired or organized domestic and foreign
     direct or indirect Wholly Owned Subsidiary of the Borrower, Land O'Lakes
     Purina Feed LLC or PMI, and (iii) CPI.

          (b) Section 1.01 of the Credit Agreement is amended to add definitions
of the following terms in appropriate alphabetical order:

          'CPI' means Cheese & Protein International LLC, a Delaware limited
     liability company and a Subsidiary of the Borrower.

          'CPI Contribution' means the contribution by the Borrower to CPI of up
     to $88,000,000 on or prior to July 1, 2005 in order to permit CPI to prepay
     all amounts outstanding under the CPI Lease.

          'CPI Lease' means the lease dated June 2, 2000, as heretofore amended,
     by and between CPI, as Lessee and U.S. Bank, National Association (as
     successor to State Street Bank and Trust Company of California, National
     Association) not in its individual capacity, but solely as Certificate
     Trustee under the Trust Agreement dated as of June 2, 2000, as Lessor.

          'CPI Lease Transactions' means the consummation of the CPI
     Contribution and the prepayment by CPI on July 1, 2005 of all amounts
     outstanding under the CPI Lease.

          'Pollution Control Bonds' means the $10,000,000 California Pollution
     Control Financing Authority Tax-Exempt Variable Rate Demand Solid Waste
     Disposal Revenue Bonds (Cheese & Protein International LLC Project), Series
     2001A issued on April 11, 2001 pursuant to the Trust Indenture between the
     California Pollution Control Financing Authority, as Issuer, and Wells
     Fargo Bank Minnesota, N.A., as Trustee, and the related promissory note
     issued by CPI and held by the California Pollution Control Financing
     Authority.

          'Sixth Amendment' means the Sixth Amendment, dated as of June 15,
     2005, to this Agreement.

          'Sixth Amendment Effective Date' means the date on which the Sixth
     Amendment became effective in accordance with Section 4 thereof.

          (c) Amendment of Subsection 6.01(a)(iv). Subsection 6.0l(a)(iv) of
the Credit Agreement is amended to read in its entirety as follows:

          "(iv) the Capital Securities in an aggregate amount not in excess of
     $200,000,000 at any time outstanding and the Pollution Control Bonds in an
     aggregate amount not in excess of $10,000,000 at any time outstanding;"
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                                                                               3

          (d) Amendment of Section 6.04. Section 6.04 is amended by (i) deleting
the reference in paragraph (e) to "clause (m)" and replacing it with "clause
(n)", (ii) deleting the reference in paragraph (f) to "clause (m)" and replacing
it with "clause (n)", (iii) deleting the word "and" at the end of paragraph (l),
(iv) inserting a new paragraph (m) that reads in its entirety as follows:

          "(m) the CPI Contribution; and"

and (v) lettering existing paragraph (m) as paragraph (n).

          (e) Amendment of Subsection 6.08(b). Subsection 6.08(b) is amended by
(i) deleting the word "and" at the end of clause (v), (ii) deleting the period
at the end of clause (vi) and replacing it with "; and" and (iii) inserting a
new clause (vii) that reads in its entirety as follows:

          "(vii) prepayments by CPI on July 1, 2005 of all amounts outstanding
     under the CPI Lease.".

          SECTION 2. Amendment of the Collateral Agreement. Effective as of the
Amendment Effective Date,

          (a) Section 1.01 of the Collateral Agreement is amended by deleting
the definition of "Equipment" and replacing it with the following:

          'Equipment' means all Equipment (as defined in the New York UCC).

          (b) The heading of Section 3.02 of the Collateral Agreement is amended
to read as "Delivery of the Pledged Collateral; Certification of Limited
Liability Company and Limited Partnership Interests."

          (c) Section 3.02 of the Collateral Agreement is amended by adding a
new paragraph (d) that reads in its entirety as follows:

          "(d) Each interest in any unlimited liability company, limited
liability company or limited partnership required to be pledged hereunder shall
be represented by a certificate, shall be a "security" within the meaning of
Article 8 of the New York UCC and shall be governed by Article 8 of the New York
UCC and shall bear a legend to such effect that shall be satisfactory to the
Collateral Agent. The organizational document of each unlimited liability
company, limited liability company or limited partnership controlled by any
Pledgor and pledged hereunder shall contain a provision whereby it elects that
all interests in such entity are securities governed by Article 8 and references
such legend and that no change to such provision shall be effective until
outstanding certificates are surrendered and new certificates bearing such
legend are issued. The foregoing provisions shall not apply to any unlimited
liability company, limited liability company or limited partnership that is not
a Wholly Owned Subsidiary to the extent that the terms of the organizational

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                                                                               4

documents of such entities would require the consents of Persons other than Loan
Parties for such pledge (other than CPI, if and to the extent that, the consent
of any such Person is necessary)."

          SECTION 3. Representations and Warranties. To induce the other parties
hereto to enter into this Amendment, the Borrower represents and warrants to
each of the Lenders, the Administrative Agent and the Collateral Agent that, as
of the Amendment Effective Date:

          (a) This Amendment has been duly authorized, executed and delivered by
it and this Amendment and the Credit Agreement, as amended hereby, constitutes
its legal, valid and binding obligation, enforceable against it in accordance
with its terms except as such enforceability may be limited by bankruptcy,
insolvency, reorganization, moratorium or other similar laws affecting
creditors' rights generally and by general principles of equity (regardless of
whether such enforceability is considered in a proceeding at law or in equity).

          (b) The representations and warranties set forth in Article III of the
Credit Agreement are, after giving effect to this Amendment, true and correct in
all material respects on and as of the Amendment Effective Date with the same
effect as though made on and as of the Amendment Effective Date, except to the
extent such representations and warranties expressly relate to an earlier date
(in which case they were true and correct in all material respects as of such
earlier date).

          (c) No Default or Event of Default has occurred and is continuing.

          (d) After giving effect to this Amendment, the Collateral and
Guarantee Requirement has been satisfied.

          SECTION 4. Effectiveness. This Amendment and the amendment of the
Credit Agreement effected hereby shall become effective as of the first date
(the "Amendment Effective Date") on which the following conditions have been
satisfied:

          (a) The Administrative Agent (or its counsel) shall have received duly
executed counterparts hereof that, when taken together, bear the signatures of
(i) the Administrative Agent, (ii) the Borrower and (iii) the Required Lenders.

          (b) The Administrative Agent shall have received a certificate of a
Financial Officer to the effect that the representations and warranties set
forth in Section 3 hereof are true and correct on and as of the Amendment
Effective Date.

          (c) The Administrative Agent shall have received a favorable opinion
of counsel to the Borrower and the Subsidiary Loan Parties, addressed to the
Administrative Agent and the Lenders and dated the Amendment Effective Date,
covering such matters relating to this Amendment, the Credit Agreement, as
amended hereby, and the other Loan Documents and the security interests
thereunder, and the satisfaction by CPI of the Collateral and Guarantee
Requirement as the Administrative Agent shall reasonably
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                                                                               5

request, and such opinion of counsel shall be reasonably satisfactory to the
Administrative Agent.

          (d) The Administrative Agent shall have received such documents and
certificates as the Administrative Agent or its counsel may reasonably request
relating to the organization, existence and good standing of each Loan Party,
the authorization of this Amendment and the transactions contemplated hereby
(including the satisfaction by CPI of the Collateral and Guarantee Requirement)
and any other legal matters relating to the Loan Parties, this Amendment, the
other Loan Documents and the transactions contemplated hereby, all in form and
substance reasonably satisfactory to the Administrative Agent.

          (e) At or prior to the time that the CPI Contribution is made, the
Collateral and Guarantee Requirement shall have been satisfied by CPI and with
respect to all Equity Interests of CPI owned by Loan Parties.

          (f) The Administrative Agent shall have received all fees and other
amounts due from any Loan Party hereunder or under the Credit Agreement or any
other Loan Document on or prior to the Amendment Effective Date and, to the
extent invoiced on or prior to the Amendment Effective Date, reimbursement or
payment of all out-of-pocket expenses (including fees, charges and disbursements
of counsel) required to be reimbursed or paid by any Loan Party hereunder or
under the Credit Agreement or any other Loan Document.

The Administrative Agent shall notify the Borrower and the Lenders of the
Amendment Effective Date, and such notice shall be conclusive and binding.

          SECTION 5. Effect of Amendment, (a) Except as expressly set forth
herein, this Amendment shall not by implication or otherwise limit, impair,
constitute a waiver of or otherwise affect the rights and remedies of the
Lenders, the Administrative Agent or the Collateral Agent under the Credit
Agreement or any other Loan Document, and shall not alter, modify, amend or in
any way affect any of the terms, conditions, obligations, covenants or
agreements contained in the Credit Agreement or any other provision of the
Credit Agreement or of any other Loan Document, all of which are ratified and
affirmed in all respects and shall continue in full force and effect. Nothing
herein shall be deemed to entitle the Borrower to a consent to, or a waiver,
amendment, modification or other change of, any of the terms, conditions,
obligations, covenants or agreements contained in the Credit Agreement or any
other Loan Document in similar or different circumstances.

          (b) On and after the Amendment Effective Date, each reference in the
Credit Agreement to "this Agreement", "hereunder", "hereof, "herein", or words
of like import, and each reference to the Credit Agreement in any Loan Document
shall be deemed a reference to the Credit Agreement as amended hereby. This
Amendment shall constitute a "Loan Document" for all purposes of the Credit
Agreement and the other Loan Documents.

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                                                                               6

          SECTION 6. Costs and Expenses. The Borrower agrees to reimburse the
Administrative Agent for its reasonable out of pocket expenses in connection
with this Amendment, including the reasonable fees, charges and disbursements of
counsel for the Administrative Agent.

          SECTION 7. Indemnity. It is agreed that for all purposes of Section
9.03(b) of the Credit Agreement, the execution, delivery and performance of this
Amendment and the other transactions contemplated hereby shall all be deemed to
be transactions contemplated by the Credit Agreement.

          SECTION 8. Uniform Commercial Code Filings. The Borrower authorizes
the Collateral Agent at any time and from time to time to file in any relevant
jurisdiction financing statements and amendments thereto describing the
Collateral pledged by the Borrower or any other Loan Party under the Collateral
Agreement as "all assets", "all personal property" or in any other manner deemed
appropriate by the Collateral Agent, and the Borrower hereby confirms and
ratifies the filing by the Collateral Agent prior to the date hereof of any
financing statements containing such a description.

          SECTION 9. Counterparts. This Amendment may be executed in any number
of counterparts and by different parties hereto in separate counterparts, each
of which when so executed and delivered shall be deemed an original, but all
such counterparts together shall constitute but one and the same instrument.
Delivery of any executed counterpart of a signature page of this Amendment by
facsimile transmission shall be as effective as delivery of a manually executed
counterpart hereof.

          SECTION 10. Applicable Law, THIS AMENDMENT SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE LAW OF THE STATE OF NEW YORK.

          SECTION 11. Headings. The headings of this Amendment are for purposes
of reference only and shall not limit or otherwise affect the meaning hereof.<PAGE>

                                                                    Exhibit 4.29

                                                               EXECUTION VERSION

                    SEVENTH AMENDMENT dated as of August 9, 2005 (this
               "Amendment"), to the AMENDED AND RESTATED FIVE-YEAR CREDIT
               AGREEMENT dated as of October 11, 2001 (as amended, supplemented
               or otherwise modified from time to time, the "Credit
               Agreement'"), among LAND O'LAKES, INC., a cooperative corporation
               organized under the laws of the State of Minnesota (the
               "Borrower"), the several banks and other financial institutions
               and entities from time to time party thereto (the "Lenders"), and
               JPMORGAN CHASE BANK, N.A., as administrative agent (in such
               capacity, the "Administrative Agent").

          A. Capitalized terms used but not defined herein shall have the
meanings assigned to such terms in the Credit Agreement, as amended hereby.

          B. The Borrower has notified the Administrative Agent that it intends
to effect an initial public offering pursuant to which it will offer and sell
shares of the common stock of CF Industries Holdings, Inc. ("CFI") in an
underwritten offering registered with the Securities and Exchange Commission
(the "CF IPO"). The Borrower currently owns approximately 38% of the Equity
Interests in CF Industries, Inc., a wholly owned subsidiary of CFI, and intends
to use up to the full amount of the Net Proceeds (as defined below) from the CFI
IPO to finance the repurchase of its Senior Notes, Senior Second Lien Notes
and/or Capital Securities or any combination thereof.

          C. The Borrower has requested that the Lenders amend certain
provisions of the Credit Agreement in connection with the CFI IPO and its
intended use of the Net Proceeds of the CFI IPO and certain other sales of
Equity Interests of CFI as set forth herein.

          D. The Required Lenders are willing to effect such amendments on the
terms and subject to the conditions of this Amendment.

          E. Accordingly, in consideration of the mutual agreements herein
contained and other good and valuable consideration, the sufficiency and receipt
of which are hereby acknowledged, the parties hereto agree as follows:

          SECTION 1. Amendment of the Credit Agreement. Effective as of the
Amendment Effective Date:

          (a) Section 1.01 of the Credit Agreement is amended to add definitions
of the following terms in appropriate alphabetical order:

          'CFI' means CF Holdings Industries, Inc., a Delaware corporation, and
     its wholly owned subsidiary, CF Industries, an Illinois corporation, in
     which the Borrower owns approximately 38% of the Equity Interests.

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                                                                               2

          'CFI IPO' means an initial public offering pursuant to which the
     Borrower will offer and sell shares of the common stock of CFI in an
     underwritten offering registered with the Securities and Exchange
     Commission.

          'CFI Residual Shares' means the Equity Interests in CFI which are
     required to be retained by the Borrower in connection with the CFI IPO
     pursuant to a lock-up agreement between the Borrower and the underwriters
     managing the CFI IPO, which Equity Interests the Borrower may elect to sell
     on a date at least 12 months after the closing date of the CFI IPO.

          'Net Proceeds' means the cash proceeds received by the Borrower from
     the (a) CFI IPO and (b) the sale of any CFI Residual Shares, in each case
     net of all reasonable fees and out-of-pocket expenses, including without
     limitation legal fees, accountants' fees, underwriters' fees or placement
     agents' fees, discounts or commissions, and other fees paid by the Borrower
     to third parties (other than Affiliates) in connection with the CFI IPO.

          'Seventh Amendment' means the Seventh Amendment, dated as of August
     9,2005, to this Agreement.

          'Seventh Amendment Effective Date' means the date on which the Seventh
     Amendment became effective in accordance with Section 3 thereof.

          (b) Amendment of Subsection 6.05. Subsection 6.05 of the Credit
Agreement is amended by (i) deleting the word "and" at the end of paragraph (g),
(ii) inserting the word "and" at the end of paragraph (h) and (iii) inserting a
new paragraph (i) that reads in its entirety as follows:

          "(i) the sale by the Borrower of (x) the Equity Interests in CFI in
     connection with the CFI IPO and (y) the CFI Residual Shares;"

          (c) Amendment of Subsection 6.08(b). Subsection 6.08(b) is amended by
(i) inserting the words ", and will not" immediately following the words "The
Borrower will not" in the first line of such Subsection, and (ii) (x) deleting
the word "and" at the end of clause (vi), (y) deleting the period at the end of
clause (vii) and replacing it with"; and" and (z) inserting a new clause (viii)
that reads in its entirety as follows:

          "(viii) the Borrower may repurchase any combination of the Senior
     Notes, the Senior Second Lien Notes and/or the Capital Securities in an
     aggregate amount, including accrued and unpaid interest and any redemption
     premiums, not to exceed the greater of (a) $100,000,000 and (b) the Net
     Proceeds; provided that (x) after giving effect to any such repurchase, the
     aggregate principal amount of undrawn Letters of Credit and Loans
     outstanding under the Credit Agreement does not exceed $100,000,000 and (y)
     no Default exists at the time of any such repurchase."

          SECTION 2. Representations and Warranties. To induce the other parties
hereto to enter into this Amendment, the Borrower represents and warrants to
each
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                                                                               3

of the Lenders, the Administrative Agent and the Collateral Agent that, as of
the Amendment Effective Date:

          (a) This Amendment has been duly authorized, executed and delivered by
it and this Amendment and the Credit Agreement, as amended hereby, constitutes
its legal, valid and binding obligation, enforceable against it in accordance
with its terms except as such enforceability may be limited by bankruptcy,
insolvency, reorganization, moratorium or other similar laws affecting
creditors' rights generally and by general principles of equity (regardless of
whether such enforceability is considered in a proceeding at law or in equity).

          (b) The representations and warranties set forth in Article III of the
Credit Agreement are, after giving effect to this Amendment, true and correct in
all material respects on and as of the Amendment Effective Date with the same
effect as though made on and as of the Amendment Effective Date, except to the
extent such representations and warranties expressly relate to an earlier date
(in which case they were true and correct in all material respects as of such
earlier date).

          (c) No Default or Event of Default has occurred and is continuing.

          (d) After giving effect to this Amendment, the Collateral and
Guarantee Requirement has been satisfied.

          SECTION 3. Effectiveness. This Amendment and the amendment of the
Credit Agreement effected hereby shall become effective as of the first date
(the "Amendment Effective Date") on which the following conditions have been
satisfied:

          (a) The Administrative Agent (or its counsel) shall have received duly
executed counterparts hereof that, when taken together, bear the signatures of
(i) the Administrative Agent, (ii) the Borrower, and (iii) the Required Lenders.

          (b) The Administrative Agent shall have received a certificate of a
Financial Officer to the effect that the representations and warranties set
forth in Section 2 hereof are true and correct on and as of the Amendment
Effective Date.

          (c) The Administrative Agent shall have received such documents and
certificates as the Administrative Agent or its counsel may reasonably request
relating to the authorization of this Amendment and the transactions
contemplated hereby and any other legal matters relating to the Loan Parties,
this Amendment, and the transactions contemplated hereby, all in form and
substance reasonably satisfactory to the Administrative Agent.

          (d) The Administrative Agent shall have received all fees and other
amounts due from any Loan Party hereunder or under the Credit Agreement or any
other Loan Document on or prior to the Amendment Effective Date and, to the
extent invoiced on or prior to the Amendment Effective Date, reimbursement or
payment of all out-of-pocket expenses (including fees, charges and
disbursements of counsel) required to be

<PAGE>

                                                                               4

reimbursed or paid by any Loan Party hereunder or under the Credit Agreement or
any other Loan Document.

The Administrative Agent shall notify the Borrower and the Lenders of the
Amendment Effective Date, and such notice shall be conclusive and binding.

          SECTION 4. Effect of Amendment. (a) Except as expressly set forth
herein, this Amendment shall not by implication or otherwise limit, impair,
constitute a waiver of or otherwise affect the rights and remedies of the
Lenders, the Administrative Agent or the Collateral Agent under the Credit
Agreement or any other Loan Document, and shall not alter, modify, amend or in
any way affect any of the terms, conditions, obligations, covenants or
agreements contained in the Credit Agreement or any other provision of the
Credit Agreement or of any other Loan Document, all of which are ratified and
affirmed in all respects and shall continue in full force and effect. Nothing
herein shall be deemed to entitle the Borrower to a consent to, or a waiver,
amendment, modification or other change of, any of the terms, conditions,
obligations, covenants or agreements contained in the Credit Agreement or any
other Loan Document in similar or different circumstances.

          (b) On and after the Amendment Effective Date, each reference in the
Credit Agreement to "this Agreement", "hereunder", "hereof, "herein", or words
of like import, and each reference to the Credit Agreement in any Loan Document
shall be deemed a reference to the Credit Agreement as amended hereby. This
Amendment shall constitute a "Loan Document" for all purposes of the Credit
Agreement and the other Loan Documents.

          SECTION 5. Costs and Expenses. The Borrower agrees to reimburse the
Administrative Agent for its reasonable out of pocket expenses in connection
with this Amendment, including the reasonable fees, charges and disbursements of
counsel for the Administrative Agent.

          SECTION 6. Indemnity. It is agreed that for all purposes of Section
9.03(b) of the Credit Agreement, the execution, delivery and performance of this
Amendment and the other transactions contemplated hereby shall all be deemed to
be transactions contemplated by the Credit Agreement.

          SECTION 7. Counterparts. This Amendment may be executed in any number
of counterparts and by different parties hereto in separate counterparts, each
of which when so executed and delivered shall be deemed an original, but all
such counterparts together shall constitute but one and the same instrument.
Delivery of any executed counterpart of a signature page of this Amendment by
facsimile transmission shall be as effective as delivery of a manually executed
counterpart hereof.

          SECTION 8. Applicable Law. THIS AMENDMENT SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE LAW OF THE STATE OF NEW YORK.

<PAGE>

                                                                               5

          SECTION 9. Headings. The headings of this Amendment are for purposes
of reference only and shall not limit or otherwise affect the meaning hereof.

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