Numeric values that are 0 (not null) are not serialized and don't appear in the Xml file. The reason for this is, that the numeric types in Dynamics Ax are not nullable (must have a value) and do interpret the value 0 as a "null value" (0 as a ‘magic number’) during the serialization.

The only possibility is to declare these columns as mandatory, so that they are serialized even with 0 as value. Another way is to inform the consumer application (which might be BizTalk) that non mentioned values should be deserialized with a default value (in this case with 0).