A measurement of Formula omitted meson production by the LHCb experiment in its fixed-target configuration is presented. The production of Formula omitted mesons is studied with a beam of 2.5 Formula omitted protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of Formula omitted. The sum of the Formula omitted and Formula omitted production cross-section in Formula omitted collisions in the centre-of-mass rapidity range Formula omitted is found to be Formula omitted where the first uncertainty is statistical and the second is systematic. The Formula omitted production asymmetry is also evaluated and suggests a trend towards negative values at large negative Formula omitted. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 Formula omitted intrinsic charm and 10 Formula omitted recombination contributions better describe the data than the other models considered.