Exhibit 4.1.5

      FIFTH SUPPLEMENTAL INDENTURE ("Fifth Supplemental Indenture"), dated as of
October 1, 2003, among Phibro Animal Health Corporation, a New York corporation
(f/k/a Philipp Brothers Chemicals, Inc.) (the "Company"), each of the Guarantors
named herein (including each Guarantor whose guarantee is confirmed by, or
becomes effective pursuant to, this Fifth Supplemental Indenture), as
guarantors, and JPMorgan Chase Bank, as successor to The Chase Manhattan Bank,
as Trustee (the "Trustee"). All capitalized terms not otherwise defined herein
shall have the meaning assigned to them in the Indenture (as defined herein).

      WHEREAS, pursuant to a certain Indenture, dated as of June 11, 1998, among
the Company, the Guarantors named therein and the Trustee (as amended and as
otherwise in effect on the date hereof, the "Indenture"), the Company issued its
9 7/8% Senior Subordinated Notes due 2008, Series A and Series B (the "Notes");
and

      WHEREAS, in accordance with the Indenture, the Company has obtained the
written consent of the Holders of at least a majority in aggregate principal
amount of the outstanding Notes to certain amendments (the "Amendments") to the
Indenture as set forth in this Fifth Supplemental Indenture;

      WHEREAS, pursuant to Sections 9.02 and 12.16 of the Indenture, the Company
and the Guarantors, when authorized by resolution of their respective Boards of
Directors, and the Trustee, together, with the written consent of the Holders of
at least a majority in aggregate principal amount of the Notes then outstanding,
are authorized to amend or supplement the Indenture as set forth in this Fifth
Supplemental Indenture;

      WHEREAS, the Company, each of the Guarantors and the Trustee desire and
have agreed to execute and deliver this Fifth Supplemental Indenture as herein
provided and all conditions and requirements necessary to make this Fifth
Supplemental Indenture a valid, binding and legal instrument in accordance with
its terms have been performed and fulfilled and the execution and delivery
hereof have been in all respects duly authorized by all necessary parties.

      NOW, THEREFORE, for and in consideration of the premises contained herein,
it is mutually covenanted and agreed for the benefit of all Holders of the Notes
as follows:

      Section 1. The Indenture is hereby amended as set forth below in this
Section 1:

            a. Section 1.01. Section 1.01 (Definitions) of the Indenture is
      hereby amended by deleting the definition of "Credit Facility" in its
      entirety and replacing it with the following:

                  "Credit Facility" means the Loan and Security Agreement among
            the Company, certain of its Subsidiaries and each lender party
            thereto and Wells Fargo Foothill, Inc., as administrative agent, as
            the same may be amended, modified, renewed, refunded, replaced or
            refinanced from time to time (including extending the maturity of,
            increasing the amount of available borrowings under, extending the
            purpose to include acquisition, working capital and other facilities
            of, changing the conditions and basis
<PAGE>

            of borrowing of, combining the seniority of, changing the covenants
            and other provisions of, and adding Subsidiaries of the Company as
            additional borrowers or guarantors under, or otherwise
            restructuring, all or any portion of the Indebtedness under such
            agreement or any successor or replacement and whether with the same
            or any other agent, lender or group of lenders), including (i) any
            related notes, letters of credit, guarantees, collateral documents,
            instruments and agreements executed in connection therewith, and in
            each case as amended, modified, renewed, refunded, replaced or
            refinanced from time to time, and (ii) any notes, guarantees,
            collateral documents, instruments and agreements executed in
            connection with any such amendment, modification, renewal,
            refunding, replacement or refinancing.

      Section 2. The Company and the Guarantors agree that the Trustee is
permitted, and each of them hereby authorizes the Trustee, to place a notation
about this Fifth Supplemental Indenture on the Notes in accordance with the
provisions of Section 9.05 of the Indenture.

      Section 3. The Trustee accepts this Fifth Supplemental Indenture and
agrees to execute the trust created by the Indenture as hereby supplemented, but
only upon the terms and conditions set forth in the Indenture, including the
terms and provisions defining and limiting the liabilities and responsibilities
of the Trustee, which terms and provisions shall in like manner define and limit
its liabilities and responsibilities in the performance of the trust created by
the Indenture as hereby supplemented.

      Section 4. This Fifth Supplemental Indenture is executed and shall be
construed as an indenture supplemental to the Indenture and, as provided in the
Indenture, this Fifth Supplemental Indenture forms a part thereof. Except as
otherwise expressly provided for in this Fifth Supplemental Indenture, all of
the terms and conditions of the Indenture are hereby ratified and shall remain
unchanged and continue in full force and effect.

      Section 5. The recitals contained in this Fifth Supplemental Indenture
shall be taken as the statements made solely by the Company and the Guarantors,
and the Trustee shall have no liability or responsibility for their correctness,
and, without limiting the generality of the foregoing, the Trustee shall not be
responsible in any manner whatsoever for or with respect to any of (i) the
validity or sufficiency of this Fifth Supplemental Indenture or any of the terms
or provisions hereof, (ii) the proper authorization hereof by the Company and
the Guarantors by corporate action or otherwise, (iii) the due execution hereof
by the Company and the Guarantors or (iv) the consequences (direct or indirect
and whether deliberate or inadvertent) of any amendment herein provided for, and
the Trustee makes no representation with respect to any such matters.

      Section 6. This Fifth Supplemental Indenture shall become effective upon
the execution and delivery hereof by the Company, the Guarantors and the
Trustee.

      Section 7. THIS FIFTH SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, AS APPLIED TO
CONTRACTS MADE AND PERFORMED IN


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<PAGE>

THE STATE OF NEW YORK, WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF
CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAW OF ANOTHER
JURISDICTION WOULD BE REQUIRED THEREBY.

      Section 8. This Fifth Supplemental Indenture may be signed in any number
of counterparts, each of which shall be an original, with the same effect as if
the signatures thereto and hereto were upon the same instrument.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


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<PAGE>

                                   SIGNATURES

      IN WITNESS WHEREOF, the parties hereto have caused this Fifth Supplemental
Indenture to be duly executed, all as of the date first written above.

                                   PHIBRO ANIMAL HEALTH CORPORATION,
                                   a New York corporation

                                   By:      /s/ Jack C. Bendheim
                                      ------------------------------------------
                                   Name:        Jack C. Bendheim
                                   Title:       President

                                   CP CHEMICALS, INC.,
                                   a New Jersey corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   PRINCE AGRIPRODUCTS, INC.,
                                   a Delaware corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   PHIBROCHEM, INC.,
                                   a New Jersey corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer


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<PAGE>

                                   PHIBRO CHEMICALS, INC.,
                                   a New York corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   WESTERN MAGNESIUM CORP.,
                                   a California corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   THE PRINCE MANUFACTURING COMPANY,
                                   an Illinois corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   PHIBRO ANIMAL HEALTH HOLDINGS, INC., a
                                   Delaware corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer

                                   PHIBRO ANIMAL HEALTH U.S., INC.,
                                   a Delaware corporation, as Guarantor

                                   By:      /s/ David C. Storbeck
                                      ------------------------------------------
                                   Name:        David C. Storbeck
                                   Title:       Chief Financial Officer


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<PAGE>

                                   JPMORGAN CHASE BANK, as Trustee

                                   By:      /s/
                                      ------------------------------------------
                                   Name:
                                   Title:       Authorized Officer


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