Exhibit 10.1

[***]   —   Certain information in this exhibit have been omitted and filed
separately with the Securities and Exchange Commission.  Confidential treatment
has been requested with respect to the omitted portions.

FIRST AMENDMENT
TO
AMENDED AND RESTATED
BOVINE VACCINE DISTRIBUTION AGREEMENT

           This First Amendment (“Amendment”) is entered into as of the 20th day
of September, 2004 (“Effective Date”) by and between DIAMOND ANIMAL HEALTH,
INC., an Iowa corporation with offices at 2538 Southeast 43rd Street, Des
Moines, Iowa 50317 (“Diamond”) and AGRI LABORATORIES, LTD., a Delaware
corporation, with offices at 20927 State Route K, St. Joseph, Missouri 64505
(“Distributor”) as an amendment to that certain Amended and Restated Bovine
Vaccine Distribution Agreement dated as of September 30, 2002 between Diamond
and Distributor (the “Distribution Agreement”).

           WHEREAS, Diamond and Distributor are parties to the Distribution
Agreement providing for the distribution of certain bovine antigens; and

           WHEREAS, Distributor desires to make a prepayment to Diamond towards
the purchase of Products and/or Initial Products for the Contract Year 2005,
subject to the terms and conditions of this Amendment; and

           WHEREAS, Distributor has requested and Diamond has agreed to assist
in the development of a veterinary biological product based on [ *** ] by
entering into a separate Research, Development and License Agreement; and

           WHEREAS, Distributor has requested that Diamond extend the date on
which exclusivity will expire under the Distributor Agreement if Distributor
fails to meet the Minimum Qualified Revenue or the Minimum Initial Product
Revenue for Contract Year 2004, subject to the terms and conditions of this
Amendment.

           NOW, THEREFORE, the parties agree as follows:

           1.     Definitions. Capitalized terms used herein shall have the
meanings ascribed to them in the Distribution Agreement, unless otherwise
defined herein.

           2.     Prepayment. On or before September 21, 2004, Distributor shall
prepay to Diamond [ *** ], to be credited towards Distributor’s purchase of
Products in Contract Year 2005, payable by (i) check payable to Diamond in
immediately available funds or (ii) wire transfer per Diamond’s instructions
(the “Prepayment”). In consideration of the Prepayment, Distributor shall be
entitled to purchase Products in Contract Year 2005 with an aggregate list price
of [ *** ].

           3.     Extension of Exclusivity. Subject to Distributor’s compliance
with Section 2 of this Amendment, in the event that Distributor fails to meet
the Minimum Qualified Revenue or the Minimum Initial Product Revenue for
Contract Year 2004 and elects not to make the Additional Payment or the
Additional Initial Product Payment required to maintain exclusivity pursuant to
Section 1.04(ii) of the Distribution Agreement, respectively, by January 15,
2005, then notwithstanding any provision of Section 1.04 of the Distribution
Agreement to the contrary, Distributor’s exclusivity rights under Section 1.02
of the Distribution Agreement shall terminate on June 30, 2005, rather than
January 15, 2005.

           4.     Effect of Amendment. This Amendment is hereby incorporated by
reference into the Distribution Agreement as if fully set forth therein, and the
Distribution Agreement as amended by this Amendment shall continue in full force
and effect following execution and delivery hereof. In the event of any conflict
between the terms and conditions of the Distribution Agreement and this
Amendment, the terms and conditions of this Amendment shall control.

           IN WITNESS WHEREOF, the parties have caused this First Amendment be
executed by their duly authorized representatives as of the date first written
above.

                                 DIAMOND ANIMAL HEALTH, INC.

                              By:    /s/  Jason Napolitano     
Its:     Chief Financial Officer

                      AGRI LABORATORIES, LTD.

                              By:    /s/  Steve Schram            
Its:     CEO/President