Wilbur-Ellis says its April 4 shipment contained one bag (out of 146) that was marked “melamine”. The AP article does not make it clear whether the company distributed any bags marked melamine to Diamond Pet Foods, which made the Natural Balance products. It does say that the 146 bags were quarantined and tested. The bag marked melamine tested, you guessed it, positive for melamine.
Also, 2 out of 5 says their shipment was not contaminated:
Thacher [CEO of Wilbur-Ellis] declined to identify his company’s other four customers, except to say two tested the ingredient and found no melamine. Wilbur-Ellis has not heard from the other two, both of whom received limited amounts of the ingredient, Thacher said.
(Bumped. Original timestamp 00:04)