On resource Zend_Validate.php is as follows:

...
// Zend_Validate_Db_Abstract
"No record matching %value% was found" => "Não foram encontrados registros para %value%",
"A record matching %value% was found" => "Um registro foi encontrado para %value%",
...

And on Zend_Validate_Db_Abstract.php is as follows:

...
   protected $_messageTemplates = array(
        self::ERROR_NO_RECORD_FOUND => "No record matching '%value%' was found",
        self::ERROR_RECORD_FOUND    => "A record matching '%value%' was found",
   );
...

There are only two methods to resolve this problem.

1 - Change the message on the array in all appeals to:

...
// Zend_Validate_Db_Abstract
"No record matching '%value%' was found" => "Não foram encontrados registros para '%value%'",
"A record matching '%value%' was found" => "Um registro foi encontrado para '%value%'",
...

2 - Change the message on the array in Zend_Validate_Db_Abstract.php (I would do this):

...
   protected $_messageTemplates = array(
        self::ERROR_NO_RECORD_FOUND => "No record matching '%value%' was found",
        self::ERROR_RECORD_FOUND    => "A record matching '%value%' was found",
   );
...