Ludacris' Baby Mama -- You Treat Our Kid Worse Than a Dog

Ludacris would rather spend his money on Kibbles 'n Bits than his newborn daughter ... so claims the rapper's baby mama.

Tamika Fuller just filed docs in her paternity battle with Luda -- responding to the rapper's bid to put a $1700 cap on his child support obligations.

Tamika grouses ... Luda has millions of bucks -- an impressive $80 mil between 2006 and 2012 -- and spends roughly $7,000 a month on lawn care and $5,000 a month on his pets.

So Tamika's calling BS and wants Ludacris to pay ALL of her lawyer's fees so she can afford to hire an attorney who will take him to the cleaners in court.