REVOLVING PROMISSORY NOTE

EXHIBIT 10.23

Loan No. 18

REVOLVING PROMISSORY NOTE

     FOR VALUE RECEIVED, Professional Veterinary Products, Ltd. , a Nebraska corporation (“PVPL”), ProConn, LLC , a Nebraska limited liability company (“ProConn”), Exact Logistics, LLC , a Nebraska limited liability company (“Exact”, together with PVPL and ProConn, collectively and individually herein referred to as “Borrower”), promises to pay, on or before January 1, 2005, to the order of U.S. Bank National Association , a national banking association (the “Bank”) at the Bank’s office at 1700 Farnam Street, Omaha, NE 68102, or at such other address as the holder hereof may from time to time designate in writing, the principal sum of FORTY MILLION AND NO/100 DOLLARS ($40,000,000.00) or, if less, the aggregate unpaid principal amount of all Revolving Loans evidenced by this Revolving Promissory Note (this “Note”) under the Amended and Restated Loan Agreement by and between Borrower and Bank dated as of May 12, 2003, as amended by the First Amendment to Amended and Restated Loan Agreement dated as of December 29, 2003, and as further amended by the Second Amendment to Amended and Restated Loan Agreement of even date herewith (collectively herein, the “Loan Agreement”), together with interest from the date the proceeds of the Revolving Loan are initially disbursed until maturity on the principal balance from time to time remaining unpaid hereon and remaining unpaid on January 1, 2008 at the rates, in the manner and on the dates specified in the Loan Agreement.

     The obligations of PVPL, ProConn and Exact under this Note shall be joint and several. Each of PVPL, ProConn and Exact hereby represent, warrant and covenant for the benefit of Bank that it is the intention of each of PVPL, ProConn and Exact that this Note be fully enforceable against each of them in accordance with its terms to the same extent as if such party had been the only party identified as “Borrower” hereunder.

     The Bank shall record on its books or records or on the schedule to this Note which is a part hereof the principal amount of each Revolving Loan made under Section 2.1 of the Loan Agreement, all payments of principal and interest and the principal balances from time to time outstanding. The record thereof, whether shown on such books or records or on the schedule to this Note, shall be prima facie evidence as to all such amounts; provided, however, that the failure of the Bank to record any of the foregoing shall not limit or otherwise affect the obligation of the undersigned to repay all Revolving Loans made under Section 2.1 of the Loan Agreement together with accrued interest thereon.

     This Note is the Revolving Note referred to in and issued under and subject to the Loan Agreement. Prepayments may be made hereon and this Note may be declared due prior to the expressed maturity hereof, all in the events, on the terms, and in the manner and amounts

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provided in said Loan Agreement. All capitalized terms used in this Note, except terms otherwise defined herein, shall have the same meaning as such terms have in the Loan Agreement.

     This Note is secured by certain Collateral as set forth in a Security Agreements dated as of May 12, 2003 executed by Borrower in favor of Bank, as amended, and certain other Collateral Documents (as defined in the Loan Agreement), to which reference is hereby made for a description of the Collateral and a statement of the terms and conditions upon which the Bank may exercise rights with respect to such Collateral.

     All payments on this Note shall be made in lawful money of the United States and in immediately available and freely transferable funds at the place of payment.

     If this Note is placed in the hands of an attorney for collection, Borrower agrees to pay reasonable attorneys’ fees and costs incurred by the Bank in connection th