In multiple-input multiple-output (MIMO) transmission systems, the channel state information (CSI) at the transmitter can be used to apply linear precoding scheme to the transmitted signals in order to improve the performance and the reliability of the transmission system. We propose to add non-binary low density parity check (NB-LDPC) codes and perform a study in order to determine a well-matched association to the closed-loop MIMO systems. The q elements in the Galois Field, GF(q), are directly mapped to q transmit symbol vectors. This allows NB-LDPC codes to perfectly fit with a MIMO precoding scheme, unlike binary LDPC codes. The new transmission model is detailed and studied for several linear precoders and differently designed LDPC codes. We show that these NB-LDPC codes are particularly well suited with precoding based on the maximization of the minimum Euclidean distance (max-dmin) criterion. These results will be theoretically studied via EXtrinsic Information Transfer (EXIT) analysis, and confirmed by numerical simulations.