Avoir besoin des?

Danielle, 

yes, avoir besoin can be followed by the contractions of the preposition de and the definite articles le or les - ' du (de le) " or ' des ( de les ) ' when referring to ' need something/s specific. ' 

( Of course, it can also be followed by the specific, non-contracting ' de l'/de la '. )

It is 'de qqc' however when referring to something non-specific, partitive or indefinite.

eg 

J'ai besoin du beurre du frigo - I need the butter from the fridge

 or 

J'ai besoin des asperges que j'ai achétées hier - I need the asparagus (that) I bought yesterday 

J'ai besoin de la farine qui est sur la table dans la cuisine - I need the flour that is on the table in the kitchen

See link from Laura Lawless for more details on use of ' de/de la/de l'/du/des ' in verb expressions requiring the preposition de .

https://www.lawlessfrench.com/grammar/de-vs-du-de-la-des-verbs/