<PAGE>

                                                                  EXHIBIT 4.5(a)

                            SMITHFIELD FOODS, INC.

                           AMENDMENT AGREEMENT NO. 1


                                                          As of December 7, 2001


To each of the Current Holders
Named in Annex 1 hereto

Ladies and Gentlemen:

     Smithfield Foods, Inc., a Virginia corporation (together with its
respective successors and assigns, the "Issuer") agrees with you as follows:

1.   PRELIMINARY STATEMENTS.

     1.1.  Note Issuance, etc.

     The Issuer issued and sold:

          (a) Seventy-Five Million Dollars ($75,000,000) in aggregate principal
     amount of 8.25% Series M Senior Secured Notes due March 2, 2006 (as they
     may be amended, restated or otherwise modified from time to time, the
     "Series M Notes"); and

          (b) Twenty-Five Million Dollars ($25,000,000) in aggregate principal
     amount of its LIBOR Rate Series N Senior Secured Notes due March 2, 2002
     (as they may be amended, restated or otherwise modified from time to time,
     the "Series N Notes");

pursuant to those separate Note Purchase Agreements each dated as of June 2,
2000 between the Issuer and the purchasers named in Annex 1 thereto (the
"Existing Purchase Agreements").  The register kept by the Issuer for the
registration and transfer of the Notes indicates that each of the Persons named
in Annex 1 hereto (collectively, the "Current Holders") is currently a holder of
the aggregate principal amount of the Notes indicated in such Annex.

                                   Annex 1-1
<PAGE>

2.   DEFINED TERMS.

     Capitalized terms used herein and not otherwise defined herein have the
meanings ascribed to them in the Existing Purchase Agreements.

3.   AMENDMENTS TO EXISTING PURCHASE AGREEMENTS; PREPAYMENT.

     3.1  Amendments.

     Subject to Section 5, the Current Holders and the Issuer hereby agree to
each of the amendments to the Current Holders' rights with respect to the
Existing Purchase Agreements as provided for by this Amendment Agreement No. 1
(this "Amendment Agreement") in the manner specified in Exhibit A.  Such
amendments are referred to herein, collectively, as the "Amendments".

4.   REPRESENTATIONS AND WARRANTIES OF THE ISSUER.

     To induce you to enter into this Amendment Agreement and to consent to the
Amendments, the Issuer represents and warrants as follows:

     4.1.  Material Adverse Effect.

     Since the date of the last audited consolidated financial statements of the
Issuer delivered to each of the Current Holders, no event has occurred or
condition exists which has had, or could reasonably be expected to have, a
Material Adverse Effect.

     4.2.  Organization, Power and Authority, etc.

     The Issuer is duly organized and validly existing under the laws of its
jurisdiction of organization and has all requisite corporate power and authority
to enter into and perform its obligations under this Amendment Agreement.

     4.3.  Legal Validity.

     The execution and delivery of this Amendment Agreement by the Issuer and
compliance by the Issuer with its obligations hereunder: (a) are within the
corporate powers, of the Issuer; and (b) are legal and do not conflict with,
result in any breach of, constitute a default under, or result in the creation
of any Lien upon any Property of the Issuer under the provisions of: (i) any
charter instrument or bylaw to which the Issuer is a party or by which the
Issuer or any of its Property may be bound; (ii)

                                   Annex 1-2
<PAGE>

any order, judgment, decree or ruling of any court, arbitrator or governmental
authority applicable to the Issuer or its Property; or (iii) any agreement or
instrument to which the Issuer is a party or by which the Issuer or any of its
Property may be bound or any statute or other rule or regulation of any
governmental authority applicable to the Issuer or its Property, except where
such conflict, breach or default could not reasonably be expected to have a
Material Adverse Effect.

     This Amendment Agreement has been duly authorized by all necessary action
on the part of the Issuer, has been executed and delivered by a duly authorized
officer of the Issuer, and constitutes a legal, valid and binding obligation of
the Issuer, enforceable in accordance with its terms, except that enforceability
may be limited by applicable bankruptcy, reorganization, arrangement,
insolvency, moratorium, or other similar laws affecting the enforceability of
creditors' rights generally and subject to the availability of equitable
remedies.

     4.4.  No Defaults.

     After giving effect to the Amendments set forth in this Amendment
Agreement, no Default or Event of Default will exist.

     4.5.  Credit Agreement.

     All representations and warranties of the Issuer in the Credit Agreement
are true and correct in all material respects.

5.   EFFECTIVENESS OF AMENDMENTS.

     5.1.  Conditions.

     The Amendments shall become effective as of the first date written above
(the "Effective Date"), if at all, at such time as all of the Current Holders
shall have indicated their written consent to such amendments by executing and
delivering the applicable counterparts of this Amendment Agreement.  It is
understood that any Current Holder may withhold its consent for any reason, and
that, without limitation of the foregoing, any Current Holder hereby makes the
granting of its consent contingent upon delivery to it of the following:

           (a) true and correct copies of the fully executed Multi-Year Credit
     Agreement among the Issuer, certain of its subsidiaries, JP Morgan Chase
     Bank as administrative agent and the lenders party thereto dated as of
     December 7, 2001 (the "Credit Agreement");

                                   Annex 1-3
<PAGE>

          (b) the Current Holders shall have received from the Issuer an
     executed Intercreditor Agreement by and among the Issuer, each of the
     subsidiaries of the Issuer identified therein under the caption "Subsidiary
     Guarantors", each of the banks and other financial institutions identified
     therein under the caption "Initial Lenders", JP Morgan Chase Bank in its
     capacity as administrative agent and in its capacity as collateral agent,
     each of the Current Holders, and First Union National Bank as security
     trustee, in form and substance satisfactory to the Current Holders;

          (c) the payment of the expenses to be paid on behalf of the Current
     Holders pursuant to Section 6 of this Amendment Agreement (to the extent a
     statement therefore has been presented to the Issuers on or prior to the
     Effective Date);

          (d) the Current Holders shall have received from each of the
     guarantors to the Credit Agreement (the "Additional Guarantors"), a fully
     executed Guaranty, in form and substance satisfactory to the Current
     Holders, unconditionally guaranteeing in full the obligations of the Issuer
     under or in respect of the Notes and Existing Purchase Agreements; and

          (e) the Current Holders shall have received from special counsel to
     the Additional Guarantors, a closing opinion, dated as of the Effective
     Date, and in form and substance satisfactory to the Current Holders.  This
     Section 4.3(e) shall constitute direction by each of the Additional
     Guarantors to such counsel to deliver such closing opinion to the Current
     Holders.

     5.2.  Agreement and Reaffirmation of each Guarantor.

     By their execution and delivery of this Amendment Agreement, each Guarantor
agrees and consents to the Amendments and reaffirms its obligation to
unconditionally guaranty in full all of the obligations of the Issuer under or
in respect of the Notes and the Existing Purchase Agreements as amended hereby
under its Joint and Several Guaranty dated as of June 2, 2000.

6.   EXPENSES.

     Whether or not the Amendments become effective, the Issuer will promptly
(and in any event within thirty (30) days of receiving any statement or invoice
therefor) pay all fees, expenses and costs relating to this Amendment Agreement,
including, but not limited to, the reasonable fees of your special counsel,
Bingham Dana LLP, incurred in connection with the preparation, negotiation and
delivery of this Amendment

                                   Annex 1-4
<PAGE>

Agreement and any other documents related thereto. Nothing in this Section shall
limit the Issuer's obligations pursuant to Section 1.5 of the Existing Purchase
Agreements.

7.   MISCELLANEOUS.

     7.1. Part of Existing Purchase Agreements; Future References, etc.

          This Amendment Agreement shall be construed in connection with and as
     a part of the Existing Purchase Agreements and, except as expressly amended
     by this Amendment Agreement, all terms, conditions and covenants contained
     in the Existing Purchase Agreements are hereby ratified and shall be and
     remain in full force and effect.  Any and all notices, requests,
     certificates and other instruments executed and delivered after the
     execution and delivery of this Amendment Agreement may refer to the
     Existing Purchase Agreements without making specific reference to this
     Amendment Agreement, but nevertheless all such references shall include
     this Amendment Agreement unless the context otherwise requires.

     7.2. Counterparts.

          This Amendment Agreement may be executed in any number of
     counterparts, each of which shall be an original but all of which together
     shall constitute one instrument.  Each counterpart may consist of a number
     of copies hereof, each signed by less than all, but together signed by all,
     of the parties hereto.

     7.3. Governing Law.

          THIS AMENDMENT AGREEMENT SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE
     WITH, AND THE RIGHTS OF THE PARTIES SHALL BE GOVERNED BY, THE LAW OF THE
     COMMONWEALTH OF VIRGINIA EXCLUDING CHOICE-OF-LAW PRINCIPLES OF THE LAW OF
     SUCH STATE THAT WOULD REQUIRE THE APPLICATION OF THE LAWS OF A JURISDICTION
     OTHER THAN VIRGINIA.

                                   Annex 1-5
<PAGE>

     If you are in agreement with the foregoing, please so indicate by signing
the acceptance below on the accompanying counterpart of this agreement and
returning it to the Issuer, whereupon it will become a binding agreement among
you and the Issuer.

                                      SMITHFIELD FOODS, INC.


                                      By: /s/ Daniel G. Stevens
                                          ---------------------
                                      Name: Daniel G. Stevens
                                      Title: Vice President

                                   Annex 1-6
<PAGE>

     The foregoing Amendment Agreement is hereby accepted as of the date first
above written.


JOHN HANCOCK LIFE INSURANCE COMPANY


By: /s/ Scott A. McFetridge
    -----------------------
Name: Scott A. McFetridge
Title: Managing Director


MELLON BANK, N. A., solely in its capacity as
Trustee for the LONG-TERM INVESTMENT TRUST,
(as directed by John Hancock Financial Services, Inc.),
and not in its individual capacity


By: /s/ Bernadette Rist
    -------------------
Name: Bernadette Rist
Title: Authorized Signatory


LUCENT TECHNOLOGIES, INC. MASTER
PENSION TRUST
By:  John Hancock Life Insurance Company,
     as Investment Advisor


By: /s/ Scott A. McFetridge
    -----------------------
Name: Scott A. McFetridge
Title: Authorized Signatory


INVESTORS PARTNER LIFE INSURANCE
COMPANY


By: /s/ Scott A. McFetridge
    -----------------------
Name: Scott A. McFetridge
Title: Authorized Signatory

                                   Annex 1-7
<PAGE>

JOHN HANCOCK VARIABLE LIFE INSURANCE
COMPANY


By: /s/ Scott A. McFetridge
    -----------------------
Name: Scott A. McFetridge
Title: Managing Director

SIGNATURE 1A (CAYMAN), LTD.
By:  John Hancock Life Insurance Company,
     as Portfolio Advisor


By: /s/ Scott A. McFetridge
    -----------------------
Name: Scott A. McFetridge
Title: Authorized Signatory

                                   Annex 1-8
<PAGE>

     The undersigned consent to the Amendments effected by the foregoing
Amendment Agreement.

MURPHY FARMS LLC
CIRCLE FOUR LLC
BROWN'S OF CAROLINA, LLC
CARROLL'S FOODS LLC
SMITHFIELD PACKING REAL ESTATE, LLC
BROWN'S FARMS, LLC
MURPHY-BROWN LLC
QUARTER M LLC,
each a Delaware limited liability company

By   MURPHY-BROWN LLC,
     a Delaware corporation,
     as its sole member of each

     By   JOHN MORRELL & CO.,
          a Delaware corporation,
          as its sole member


          /s/ Daniel G. Stevens
          ---------------------
          Daniel G. Stevens
          Vice President

GWALTNEY OF SMITHFIELD, LTD.
JOHN MORRELL & CO.
THE SMITHFIELD PACKING COMPANY, INCORPORATED
SFFC, INC.
PATRICK CUDAHY INCORPORATED
CARROLL'S REALTY, INC.
CARROLL'S REALTY PARTNERSHIP
NORTH SIDE FOODS CORP.
LYKES MEAT GROUP, INC.
SMITHFIELD-CARROLL'S FARMS
CENTRAL PLAINS FARMS, INC.


By: /s/ Daniel G. Stevens
   ----------------------
Daniel G. Stevens
Vice President

                                   Annex 1-9
<PAGE>

Exhibit A

                  AMENDMENTS TO EXISTING PURCHASE AGREEMENTS

     1.   Section 6.9 of the Existing Purchase Agreements is hereby amended and
restated in its entirety to read as follows:

     "6.9 Restrictions on Dividends, etc.

          The Company shall not, and shall not permit any Subsidiary to, create
     or otherwise cause or suffer to exist or become effective any restriction
     or encumbrance (other than statutory, regulatory or common law
     restrictions) on the right or power of any Subsidiary to

          (a) pay dividends or make any other distributions on such Subsidiary's
     stock to the Company or any Subsidiary,

          (b) pay any indebtedness owed by such Subsidiary to the Company or any
     Subsidiary,

          (c) make loans or pay advances to the Company or any Subsidiary, or

          (d) transfer any of its Property to the Company or any Guarantor;

provided, however, that:

          (x) a Subsidiary may be subject to an encumbrance or restriction
     described in subsection (d) above if such encumbrance or restriction (i)
     restricts in a customary manner the subletting, assignment or transfer of
     any property or asset that is subject to a lease, license, or similar
     contract, (ii) exists by virtue of any transfer of, agreement to transfer,
     option, or right with respect to, any property or assets of the Company or
     any Subsidiary not otherwise prohibited by this Note Purchase Agreement, or
     (iii) is contained in a security agreement, mortgage or other similar
     document securing Debt of the Company or any Subsidiary that is permitted
     hereunder to the extent such restriction or encumbrance restricts the
     transfer of the property subject to such agreement, or (iv) ordinary course
     provisions restricting the assignability of contracts;

          (y) a Subsidiary may be subject to restrictions on the payment of
     dividends or the making of other distributions on its

                                  Exhibit A-1
<PAGE>

     stock to the Company or the other Subsidiaries so long as such restrictions
     permit the payment of such dividends and the making of such other
     distributions that are necessary in order to make any and all payments due
     (including, without limitation, any and all amounts due by way of
     acceleration, required or optional prepayment or otherwise) in connection
     with the Notes, the Note Purchase Agreements and the other Financing
     Documents, and any and all indebtedness used to refinance or repay such
     indebtedness (without increase as to principal amount or interest rate of
     such refinancing indebtedness); and

          (z) a Subsidiary may be subject to any such encumbrance and
     restriction that is not otherwise allowed under subsections (x) and (y)
     above, so long as the aggregate contributions to Consolidated EBITDA for
     the period of four (4) fiscal quarters then most recently ended of all
     Subsidiaries subject to such encumbrances and restrictions that are not
     otherwise allowed under subsections (x) and (y) above, are less than or
     equal to fifteen percent (15%) of such Consolidated EBITDA; such
     contribution shall be based on the earnings before interest, taxes,
     depreciation and amortization of each such Subsidiary for such fiscal
     year."

     2.   The following definitions in Section 9.1 of the Existing Purchase
Agreements are hereby amended and restated read as follows:

          "Credit Facility -- means that certain Multi-Year Credit Agreement
     among the Company, certain of the Subsidiaries, JP Morgan Chase Bank as
     administrative agent and the lenders party thereto, providing for an
     aggregate amount of up to seven hundred fifty million dollars
     ($750,000,000) in loans to the Company, as it may be amended, supplemented,
     or modified from time to time and any renewal, increase, extension,
     refunding, restructuring, replacement or refinancing thereof (whether with
     the original administrative agent and lenders or another administrative
     agent or agents or one or more other lenders and whether provided under the
     original Multi-Year Credit Agreement or one or more other credit or other
     agreements)."

                                  Exhibit A-2