Exhibit 10.23

                         AMENDMENT TO SECOND AMENDED AND
                       RESTATED REVOLVING CREDIT AGREEMENT


                  THIS AMENDMENT TO SECOND AMENDED AND RESTATED REVOLVING CREDIT
AGREEMENT, made and entered into as of the _____ day of September,  1997, by and
between PM RESOURCES,  INC., a Missouri corporation ("PM"), ZEMA CORPORATION,  a
Delaware corporation ("Zema"),  and MARDEL ACQUISITION  CORPORATION,  a Delaware
corporation  (which  after  the date  hereof  shall  change  its name to  Mardel
Laboratories, Inc., and referred to herein as "Mardel," and collectively with PM
and Zema  referred to herein as  "Borrowers")  and FIRST BANK, a Missouri  state
banking corporation ("Bank").

                                         WITNESSETH:

                  WHEREAS, PM and Zema heretofore jointly and severally executed
and  delivered  to Bank a  Revolving  Credit  Note dated June 18,  1997,  in the
principal  amount of up to Six Million  Three  Hundred  Fifty  Thousand  Dollars
($6,350,000.00), payable to the order of Bank as therein set forth (the "Note"),
which  Note has a present  outstanding  principal  balance  of Six  Million  Two
Hundred Twenty-Five Thousand Dollars ($6,225,000.00); and

                  WHEREAS, the Note is described in a certain Second Amended and
Restated  Revolving  Credit  Agreement dated June 18, 1997 made by and among PM,
Zema and Bank (as amended, the "Loan Agreement"); and

                  WHEREAS, Borrowers and Bank desire to amend the Loan Agreement
and the Note to add Mardel as a party thereto and a Borrower  thereunder  and to
make certain  other  amendments  thereto on the terms and  conditions  set forth
herein;

                  NOW,  THEREFORE,  in  consideration  of the  premises  and the
mutual  provisions and agreements  hereinafter set forth,  the parties hereto do
hereby mutually promise and agree as follows:

                  1. The Note shall be amended and  restated in the form of that
certain  Revolving  Credit Note attached hereto as Exhibit C, to add Mardel as a
comaker  thereof  and to make  certain  amendments  as set  forth  therein.  All
references in the Loan Agreement to the "Note," the "Revolving  Credit Note" and
other  references  of similar  import  shall  hereafter be amended and deemed to
refer to the Note in the form of the  Revolving  Credit  Note,  as  amended  and
restated in the form attached hereto as Exhibit C.

                  2. The Loan  Agreement  is hereby  amended  to add Mardel as a
party thereto and a Borrower thereunder. All references in the Loan Agreement to
the  "Borrowers"  and other  references  of similar  import  shall  hereafter be
amended  and  deemed  to refer  to PM,  Zema and  Mardel  collectively,  and all
references in the Loan Agreement to a "Borrower," to "either of the  Borrowers,"
to  "each of the  Borrowers"  and  other  references  of  similar  import  shall
hereafter  be amended  and deemed to refer to and  include  Mardel as well as PM
and/or Zema.



<PAGE>




                  3. A new definition of "Eligible  Mardel  Inventory"  shall be
added to  Section  2 of the  Loan  Agreement  in  proper  alphabetical  order as
follows:

                           Eligible Mardel Inventory shall mean all Inventory of
         Mardel,  valued  at the  lower of cost or  current  market  value on an
         average  cost basis,  which  consists  of  unprocessed  raw  materials,
         packaging materials and finished goods with respect to which no further
         processing is necessary  for the sale thereof,  other than (a) any such
         Inventory  which  is  obsolete,  (b)  Inventory  which  is not in  good
         condition  or  does  not  comply  with  all  standards  imposed  by any
         governmental  authority having regulatory  authority over such goods or
         their  manufacture,  use or sale,  or Inventory  which Bank has in good
         faith  determined,   in  accordance  with  Bank's  customary   business
         practices,  is otherwise unacceptable due to age, type, category and/or
         quantity,  (c) Inventory  which is held on  consignment  or consists of
         experimental products or products not yet proven commercially viable by
         reason of a significant  number of purchase  orders,  or Inventory held
         for promotional  purposes and as samples,  or Inventory returned due to
         defects  or  product  warranty  problems,  (d)  Inventory  which is not
         maintained at one of the places of business and/or  locations  provided
         in the Security  Agreement executed by Mardel, (e) Inventory not either
         useable or saleable,  at prices not less than the standard cost, in the
         ordinary  course of Mardel's  business,  or (f) Inventory  which is not
         subject to a first  priority  perfected  security  interest in favor of
         Bank.

                  4. The definition of "Security Agreements" in Section 2 of the
Loan  Agreement  shall be  deleted  in its  entirety  and in its place  shall be
substituted the following:

                           Security Agreements shall mean the Security Agreement
         executed by PM Resources,  the Security  Agreement executed by Zema and
         the  Security  Agreement  executed by Mardel,  each  delivered  to Bank
         pursuant to Section  5.1, as the same may from time to time be amended,
         and Security Agreement shall mean any of them.

All  references in the Loan  Agreement to a "Security  Agreement," to "either of
the  Security  Agreements,"  to  "each of the  Security  Agreements"  and  other
references of similar  import shall  hereafter be amended and deemed to refer to
and include the Security Agreement executed by Mardel on the date hereof as well
as those Security Agreements previously executed by PM and Zema.

                  5. Section  3.1(c) of the Loan  Agreement  shall be deleted in
its entirety and in its place shall be substituted the following:

                    (c)   Borrowing Base.  For purposes of computing the amount
         of the Bank's Facility A Commitment, the "Borrowing Base" shall mean 
         the sum of:



                                                  - 2 -

<PAGE>



                           (i)   Seventy-Five Percent (75%) of the face amount 
         of Eligible Accounts of each of the Borrowers, plus

                           (ii) Fifty  Percent  (50%) of the  Eligible  Non-Chow
         Inventory of PM Resources, plus

                           (iii)  Sixty  Percent  (60%)  of  the  Eligible  Chow
         Inventory of PM Resources, plus

                           (iv)  Thirty-Five Percent (35%) of the Eligible Zema 
         Inventory, plus

                           (v)   Thirty-Five Percent (35%) of the Eligible 
         Mardel Inventory.


The Borrowing Base Certificate shall be amended and restated in the form of that
certain  Borrowing Base Certificate  attached hereto as Exhibit A to incorporate
the above changes and to add Mardel as a party  thereto.  All  references in the
Loan  Agreement to the  "Borrowing  Base  Certificate"  and other  references of
similar  import shall  hereafter be amended and deemed to refer to the Borrowing
Base certificate in the form attached hereto as Exhibit A.

                  6.  The  last  four  sentences  of  Section  3.2 of  the  Loan
Agreement  shall be  deleted  in their  entirety  and in  their  place  shall be
substituted the following:

         Borrowers  further  request  and  authorize  Bank,  in Bank's  sole and
         absolute discretion, to make a Prime Loan to Borrowers hereunder at the
         end of each day in which  Borrowers  shall have an overdraft  (negative
         ledger  balance)  in  either  or  both of (1) PM  Resources'  operating
         account  (Account  No.  9800802535)  with  Bank or  Mardel's  operating
         account  (Account No.  ____________)  with Bank,  after  crediting  all
         deposits  received in  immediately  available  funds and  debiting  all
         withdrawals made and checks presented against such accounts and honored
         by Bank as of such  date,  which  Prime  Loan shall be in the amount of
         such  overdraft (or if overdrafts  exist in both such accounts then the
         sum of such  overdrafts)  without  any other  request or  authorization
         therefor  from  Borrowers and without  notice to Borrowers.  Similarly,
         Borrowers request that Bank apply any collected balances in excess of a
         mutually predetermined amount remaining at the end of any day in either
         of PM Resources' operating account and/or in Mardel's operating account
         to the  repayment of the principal  balance of  Borrowers'  Obligations
         outstanding as Prime Loans under the Note.  Borrowers also hereby agree
         jointly and severally to indemnify Bank and hold Bank harmless from and
         against  any and all claims,  demands,  damages,  liabilities,  losses,
         costs and expenses  (including,  without  limitation,  Attorneys' Fees)
         relating to or arising out of or in connection  with the  acceptance of
         instructions    for    making    Loans   or    repayments    hereunder.
         Contemporaneously with the execution of this Agreement, Borrowers shall
         execute and deliver to Bank a Note of  Borrowers  dated the date of its
         execution and payable jointly and severally to the order of Bank in the


                                                  - 3 -

<PAGE>



         original  principal  amount  of Six  Million  Two  Hundred  Twenty-Five
         Thousand Dollars ($6,225,000.00) in the form attached hereto as Exhibit
         C and  incorporated  herein by reference  (as the same may from time to
         time be amended, modified, extended or renewed, the "Note").

                  7. The  agreements  of Bank  contained  herein  are  expressly
conditioned upon deliver by Borrowers of the following:

                           (a)      the executed original of this Amendment to 
Second Amended and Restated Revolving Credit Agreement;

                           (b)      the executed original of the amended and 
restated Note;

                           (c)      the executed original Security Agreement of
Mardel, together with such UCC-1 financing statements and other documents 
required by Bank pursuant thereto;

                           (d)      a copy of resolutions of the Board of 
Directors of each of the Borrowers, duly adopted, which authorize the execution,
delivery and performance of this Amendment to Second Amended and Restated  
Revolving Credit Agreement and the amended and restated  Note,  the Security  
Agreement of Mardel and the other Transaction Documents, certified by the 
Secretary of each such Borrower;

     (e)  certificates  of  corporate  good  standing  of  Mardel  issued by the
Secretary of State of the State of Delaware and by the Secretary of State of the
State of Illinois;

     (f) the  original  of the new  Guaranty  of  Agri-Nutrition  Group  Limited
guarantying  all of the  indebtedness  of each of the  Borrowers  to Bank,  duly
executed by Agri- Nutrition Group Limited;

     (g) a copy of resolutions of  Agri-Nutrition  Group Limited,  duly adopted,
which  authorize  the  execution,  delivery  and  performance  of the  Guaranty,
certified by the Secretary of Agri-Nutrition Group Limited;

     (h) the  Consent  of  Agri-Nutrition  Group  Limited  in the form  attached
hereto,  acknowledging  the  amendments  contained  herein  and  the  continuing
effectiveness  of the Pledge  Agreement and the  Subordination  Agreement,  duly
executed by Agri-Nutrition Group Limited;

     (i) a  Subordination  and  Standby  Agreement  duly  executed  by  Ramon A.
Mulholland in favor of Bank subordinating all indebtedness of Borrowers to Ramon
A.  Mulholland  to  Borrowers'  Obligations  to Bank under the Agreement and the
Note;

     (j) an opinion of counsel of Dyer, Ellis & Joseph,  independent  counsel to
Borrowers and Guarantor, in form and substance acceptable to Bank concerning the
due authorization, execution and validity of the above-referenced agreements and
transactions and such other matters as Bank may reasonably require; and


                                                       - 4 -

<PAGE>




                           (k)  such  other  documents  as Bank  may  reasonably
request.

                  8. Borrowers hereby represent and warrant to Bank that:

          (a)      The execution, delivery and performance by Borrowers of this
Amendment to Second  Amended and Restated  Revolving  Credit  Agreement  and the
amended and restated  Revolving  Credit Note are within the corporate  powers of
Borrowers,  have been duly  authorized  by all  necessary  corporate  action and
require no action by or in  respect  of, or filing  with,  any  governmental  or
regulatory body, agency or official. The execution,  delivery and performance by
Borrowers of this  Amendment to Second  Amended and  Restated  Revolving  Credit
Agreement  and the amended and  restated  Revolving  Credit Note do not conflict
with,  or result in a breach  of the  terms,  conditions  or  provisions  of, or
constitute  a  default  under or  result in any  violation  of,  and none of the
Borrowers is now in default  under or in violation of, the terms of the Articles
of  Incorporation  or Bylaws of such  Borrower,  any  applicable  law, any rule,
regulation,  order,  writ,  judgment or decree of any court or  governmental  or
regulatory  agency or  instrumentality,  or any agreement or instrument to which
any of the Borrowers is a party or by which any of them is bound or to which any
of them is subject;

                (b)      This Amendment to Second Amended and Restated Revolving
Credit  Agreement and the amended and restated  Revolving  Credit Note have been
duly  executed  and  delivered  and  constitute  the  legal,  valid and  binding
obligations of Borrowers enforceable in accordance with their terms; and

       (c)      As of the date hereof, all of the covenants, representations and
warranties of Borrowers set forth in the Loan Agreement are true and correct and
no "Event of Default"  (as defined  therein)  under or within the meaning of the
Loan Agreement has occurred and is continuing.

                  9.  All  references  in  the  Loan  Agreement  to  "this  Loan
Agreement" and any other  references of similar import shall henceforth mean the
Loan  Agreement  as amended by this  Amendment  to Second  Amended and  Restated
Revolving Credit Agreement.

                  10. This  Amendment to Second  Amended and Restated  Revolving
Credit  Agreement  and the amended and restated  Revolving  Credit Note shall be
binding upon and inure to the benefit of the parties hereto and their respective
successors  and  assigns,  except that  Borrowers  may not  assign,  transfer or
delegate any of their rights or obligations hereunder.

                  11. This  Amendment to Second  Amended and Restated  Revolving
Credit  Agreement  shall be governed by and  construed  in  accordance  with the
internal laws of the State of Missouri.

                  12. In the event of any inconsistency or conflict between this
Amendment to Second Amended and Restated Revolving Credit Agreement and the Loan
Agreement,  the terms,  provisions  and  conditions of this  Amendment to Second
Amended and Restated Revolving Credit Agreement shall govern and control.



                                                       - 5 -

<PAGE>



                  13. The Loan  Agreement,  as hereby amended and modified,  and
the amended and restated  Revolving Credit Note, as hereby amended and restated,
are and  shall  remain  the  binding  obligations  of  Borrowers  and all of the
provisions,  terms,  stipulations,  conditions,  covenants and powers  contained
therein shall stand and remain in full force and effect, except only as the same
are herein and hereby  specifically  varied or amended,  and the same are hereby
ratified  and  confirmed.  If any  installment  of  principal or interest on the
amended  and  restated  Revolving  Credit  Note  shall  not be paid  when due as
provided in the amended and restated  Revolving  Credit Note,  the holder of the
amended and restated Revolving Credit Note shall be entitled to and may exercise
all rights and remedies under the amended and restated Revolving Credit Note and
the Loan Agreement, as amended.

                  14. ORAL  AGREEMENTS  OR  COMMITMENTS  TO LOAN  MONEY,  EXTEND
CREDIT OR TO FOREBEAR FROM ENFORCING REPAYMENT OF A DEBT,  INCLUDING PROMISES TO
EXTEND OR RENEW SUCH DEBT, ARE NOT  ENFORCEABLE.  TO PROTECT  BORROWERS AND BANK
FROM ANY MISUNDERSTANDING OR DISAPPOINTMENT, ANY AGREEMENTS REACHED BY BORROWERS
AND BANK COVERING SUCH MATTERS ARE CONTAINED IN THE LOAN  AGREEMENT,  AS AMENDED
BY THIS AGREEMENT,  WHICH CONSTITUTES A COMPLETE AND EXCLUSIVE  STATEMENT OF THE
AGREEMENTS  BETWEEN  BORROWERS  AND BANK EXCEPT AS BORROWERS  AND BANK MAY LATER
AGREE IN WRITING TO MODIFY.  THE LOAN  AGREEMENT,  AS AMENDED BY THIS AGREEMENT,
EMBODIES THE ENTIRE AGREEMENT AND  UNDERSTANDING  BETWEEN THE PARTIES HERETO AND
SUPERSEDES ALL PRIOR AGREEMENTS AND UNDERSTANDINGS (ORAL OR WRITTEN) RELATING TO
THE SUBJECT MATTER HEREOF.



                                                       - 6 -

<PAGE>



                  IN WITNESS  WHEREOF,  the parties  hereto have  executed  this
instrument  as of the date first  written  above on this _____ day of September,
1997.


                                                 PM RESOURCES, INC.



                                       By:
                                           Robert J. Elfanbaum, Vice President
                                                       and Treasurer

                                                 ZEMA CORPORATION



                                       By:
                                            Robert J. Elfanbaum, Secretary

                                                 MARDEL ACQUISITION CORPORATION



                                       By:
                                           Robert J. Elfanbaum, Vice President,
                                                 Secretary and Treasurer

                                   FIRST BANK



                                       By:
                                              Brenda J. Laux, Vice President


                                                       - 7 -

<PAGE>



                  CONSENT TO AMENDMENT TO SECOND AMENDED AND
                      RESTATED REVOLVING CREDIT AGREEMENT


                  The undersigned  hereby consents to the terms of the foregoing
Amendment to Second  Amended and Restated  Revolving  Credit  Agreement  and the
amended and restated  Revolving  Credit Note and other amendments being executed
in connection therewith as referenced therein (collectively,  the "Amendments"),
and  the  undersigned  acknowledges  that  the  execution  and  delivery  by  PM
Resources,  Inc., Zema  Corporation and Mardel  Acquisition  Corporation of said
Amendments  will not  affect  or impair  the  undersigned's  obligations  to and
agreements  with Bank under (i) the Guaranty  dated of even date herewith  being
executed by the undersigned in favor of Bank (the "Guaranty"), (ii) that certain
Agreement of Pledge (Third Party) dated July 14, 1995 made by the undersigned in
favor of Bank (the "Pledge Agreement"),  or (iii) that certain Subordination and
Standby  Agreement  dated July 14, 1995 made by the undersigned in favor of Bank
(the  "Subordination  Agreement"),  which  obligations and agreements are hereby
ratified and confirmed. The undersigned further acknowledges and agrees that all
references  in the  Guaranty,  the  Pledge  Agreement  and in the  Subordination
Agreement to the "Revolving  Credit  Agreement" and other  references of similar
import shall henceforth mean the foregoing Second Amended and Restated Revolving
Credit  Agreement,  amended on the date  hereof and as the same may from time to
time be further  amended;  all references in the Guaranty,  the Pledge Agreement
and the  Subordination  Agreement to the "Note," the "Revolving Credit Note" and
other  references of similar import shall  henceforth mean the Revolving  Credit
Note, as amended and restated,  and as the same may from time to time be further
amended;  and all  references  in the  Guaranty,  the Pledge  Agreement  and the
Subordination  Agreement  to  any  of  the  other  transaction  documents  shall
henceforth  mean such  documents  as the same may have been amended by the other
Amendments and as the same may from time to time be further amended.

Dated:  as of September ___, 1997.

                             AGRI-NUTRITION GROUP LIMITED



                             By:
                                    Robert J. Elfanbaum, Vice President
                                    and Chief Financial Officer




                                                       - 8 -

<PAGE>



                                     EXHIBIT A

                              BORROWING BASE CERTIFICATE


                  This  Borrowing  Base  Certificate  is  delivered  pursuant to
Section  3.1(d) of that certain  Second  Amended and Restated  Revolving  Credit
Agreement  dated June 18,  1997 made by and  between PM  Resources,  Inc.,  Zema
Corporation,   Mardel   Acquisition   Corporation  and  First  Bank  (the  "Loan
Agreement").  All capitalized  terms used and not otherwise defined herein shall
have the respective meanings ascribed to them in the Loan Agreement.

                  Borrowers  hereby  represent  and  warrant  to Bank  that  the
following information is true and correct as of , 19__:

1.       75% of face amount of Eligible Accounts of PM Resources          $

2.       60% of Eligible Chow Inventory of PM Resources, valued
         at the lower of cost or market                                   $

3.       50% of Eligible Non-Chow Inventory of PM Resources, valued
         at the lower of cost or market                                   $

4.       75% of the face amount of Eligible Accounts of Zema              $

5.       35% of Eligible Zema Inventory, valued at the lower
         of cost or market                                                $

6.       75% of the face amount of Eligible Accounts of Mardel            $

7.       35% of Eligible Mardel Inventory, valued at the lower
         of cost or market                                                $

8.       Total Borrowing Base                                             $
         (sum of 1 through 7 above not to exceed $3,000,000.00)


                  Borrowers  hereby  further  represent and warrant to Bank that
the following information is true and correct as of , 19__:

9.       Aggregate principal amount of outstanding Facility A Loans       $

10.      Borrowing Base Excess (Deficit) (Item 8 minus Item 9)
         (Negative amount represents mandatory repayment)                 $

                  If Item 10 above is negative,  this Borrowing Base Certificate
is accompanied by the mandatory repayment required by Section 3.1(e) of the Loan
Agreement.


                                                       - 9 -

<PAGE>




11.      Maximum Available principal amount of Facility B Loans          $

12.      Aggregate principal amount of outstanding Facility B Loans      $

   This Borrowing Base Certificate is dated the _____ day of             
        , 19__.


                                                     PM RESOURCES, INC.



                                                     By:
                                                     Title:


                                                     ZEMA CORPORATION



                                                     By:
                                                     Title:


                                                MARDEL ACQUISITION CORPORATION


                                                     By:
                                                     Title:


                                                      - 10 -

<PAGE>



                                     EXHIBIT C

                              Revolving Credit Note


$6,225,000.00                                           St. Louis, Missouri
                                                        September ___, 1997


                  FOR  VALUE  RECEIVED,  on March 31,  1999 (or such  subsequent
anniversary  thereof as determined pursuant to Section 3.9 of the Loan Agreement
(hereinafter  identified)),  the  undersigned,  PM  RESOURCES,  INC., a Missouri
corporation,  ZEMA CORPORATION,  a Delaware  corporation and MARDEL  ACQUISITION
CORPORATION,  a Delaware  corporation (which subsequent to the date hereof shall
change its name to Mardel Laboratories,  Inc.) (collectively,  the "Borrowers"),
hereby  jointly  and  severally  promise  to pay to the order of FIRST  BANK,  a
Missouri state banking  corporation  ("Bank"),  the principal sum of Six Million
Two Hundred Twenty-Five Thousand Dollars ($6,225,000.00),  or such lesser sum as
may then be outstanding  hereunder.  The aggregate  principal  amount which Bank
shall be committed  to have  outstanding  under  Facility A hereunder at any one
time shall not exceed the lesser of (i) Three Million  Dollars  ($3,000,000.00),
or (ii) the "Borrowing  Base" (as defined in the Loan Agreement (as  hereinafter
defined)),  which amount may be borrowed,  paid, reborrowed and repaid, in whole
or in part, subject to the terms and conditions hereof and of the Loan Agreement
hereinafter  identified.  The  aggregate  principal  amount  which Bank shall be
committed to have  outstanding  under Facility B hereunder at any one time shall
not exceed the lesser of (i) Three  Million  Two  Hundred  Twenty-Five  Thousand
Dollars  ($3,225,000.00) as reduced from time to time pursuant to Section 3.1(b)
of the Loan  Agreement  hereinafter  identified,  which  amount may be borrowed,
paid,  reborrowed  and  repaid,  in whole or in part,  subject  to the terms and
conditions hereof and of the Loan Agreement hereinafter identified.

                  Borrowers  further jointly and severally promise to pay to the
order of Bank  interest on the  principal  amount from time to time  outstanding
hereunder  prior to maturity from the date  disbursed  until paid at the rate or
rates per annum required by the Loan  Agreement or otherwise  selected by either
of the  Borrowers  as set forth in the Loan  Agreement.  All  accrued and unpaid
interest with respect to each principal  disbursement  made  hereunder  shall be
payable (a) monthly on the fifteenth (15th) day of the month following the month
in which such interest accrued,  commencing with the fifteenth (15th) day of the
month  following the month in which any such  disbursement  was made, and on the
fifteenth  (15th) day of each month  thereafter,  (b) if such  disbursement is a
Treasury Rate Loan, such accrued  interest shall also be payable on the last day
of the  Interest  Period with respect  thereto,  and (c) at the maturity of this
Note, whether by reason of acceleration or otherwise. After the maturity of this
Note, whether by reason of acceleration or otherwise,  interest shall accrue and
be payable on demand on the entire outstanding principal balance hereunder until
paid at a rate per annum equal to Three and  One-Half  Percent  (3.50%) over and
above the Prime Rate,  fluctuating as and when said Prime Rate shall change. All
payments  hereunder  (other  than  prepayments)  shall be  applied  first to the
payment of all  accrued and unpaid  interest,  with the  balance,  if any, to be
applied to the


                                                      - 11 -

<PAGE>



payment of principal.  All prepayments hereunder shall be applied solely to the 
payment of principal.

                  All payments of principal and interest hereunder shall be made
in  lawful  currency  of the  United  States  in  Federal  or other  immediately
available funds at the office of Bank situated at 1281 Graham Road,  Florissant,
Missouri  63031,  or at such other place as the holder hereof shall designate in
writing. Interest shall be computed on an actual day, 360-day year basis.

                  Bank may  record  the date and  amount  of all  loans  and all
payments of principal  and interest  hereunder in the records it maintains  with
respect  thereto.  Bank's books and records showing the account between Bank and
Borrowers  shall be admissible in evidence in any action or proceeding and shall
constitute prima facie proof of the items therein set forth.

                  This Note is the Note referred to in that certain  Amended and
Restated  Revolving  Credit  Agreement  dated as of the date  hereof made by and
between  Borrowers  and Bank (as the same may from time to time be amended,  the
"Loan  Agreement"),  to which  Loan  Agreement  reference  is hereby  made for a
statement of the terms and  conditions  upon which the maturity of this Note may
be accelerated, and for other terms and conditions,  including prepayment, which
may affect  this Note.  All  capitalized  terms  used  herein and not  otherwise
defined shall have the meanings assigned to such terms in the Loan Agreement.

                  This Note is secured by that certain Security  Agreement dated
as of July 14, 1995 and executed by PM Resources, Inc. in favor of Bank, by that
certain  Security  Agreement  dated  as  of  July  14,  1995  executed  by  Zema
Corporation in favor of Bank and by that certain Security  Agreement dated as of
September ___, 1997 executed by Mardel Acquisition  Corporation in favor of Bank
(as the same may from time to time be  amended,  the  "Security  Agreements,  to
which  Security  Agreements  reference is hereby made for a  description  of the
security  and a statement  of the terms and  conditions  upon which this Note is
secured.

                  This Note is also  secured by that  certain  Deed of Trust and
Security Agreement dated September 9, 1993 and executed by PM Resources, Inc. in
favor of Katherine D. Knocke,  as trustee for Bank (as the same may from time to
time be  amended,  the "Deed of  Trust"),  to which Deed of Trust  reference  is
hereby made for a  description  of the security and a statement of the terms and
conditions upon which this Note is secured.

                  This Note is also secured by that certain  Agreement of Pledge
(Third  Party)  dated as of July 14, 1995 and executed by  Agri-Nutrition  Group
Limited  in favor of Bank (as the  same may from  time to time be  amended,  the
"Pledge  Agreement"),  to which Pledge Agreement  reference is hereby made for a
description  of  the  additional  security  and a  statement  of the  terms  and
conditions upon which this Note is further secured.

                  If either of the  Borrowers  shall fail to make any payment of
any  principal of or interest on this Note as and when the same shall become due
and payable,  or if an "Event of Default" (as defined therein) shall occur under
or within the meaning of the Loan Agreement,  either of the Security Agreements,
the Deed of Trust or the Pledge Agreement, Bank may, at


                                                      - 12 -

<PAGE>



its option,  terminate its  obligation to make any  additional  loans under this
Note and Bank may further declare the entire  outstanding  principal  balance of
this Note and all accrued and unpaid interest  thereon to be immediately due and
payable.

                  In the event that any payment of any  principal of or interest
on this Note shall not be paid when due,  whether by reason of  acceleration  or
otherwise,  and this  Note  shall be  placed  in the  hands  of an  attorney  or
attorneys  for  collection  or  for   foreclosure  of  either  of  the  Security
Agreements, the Deed of Trust or the Pledge Agreement securing payment hereof or
for   representation  of  Bank  in  connection  with  bankruptcy  or  insolvency
proceedings relating hereto,  Borrowers jointly and severally promise to pay, in
addition to all other amounts  otherwise due hereon,  the  reasonable  costs and
expenses of such collection, foreclosure and representation,  including, without
limitation,  reasonable  attorneys' fees and expenses (whether or not litigation
shall  be  commenced  in  aid  thereof).  All  parties  hereto  severally  waive
presentment  for  payment,  demand,  protest,  notice of  protest  and notice of
dishonor.

                  This Note shall be governed  by and  construed  in  accordance
with the internal laws of the State of Missouri.


                                     PM RESOURCES, INC.



                                     By:
                                            Robert J. Elfanbaum,
                                            Vice President


                                     ZEMA CORPORATION



                                     By:
                                            Robert J. Elfanbaum, Secretary


                                     MARDEL ACQUISITION CORPORATION



                                     By:
                                            Robert J. Elfanbaum, Vice President.
                                            Secretary and Treasurer


                                                      - 13 -