Look at Massena's preparations for the Fuentes de Oñoro campaign for a lot of discussion on the lack of draft horses (and gun carriages) that inhibited his efforts to reengage W. One of the things that was welcomed when Bessières arrived was horseflesh and equipment to allow more guns to be made mobile; there is also some indication (if memory serves) that some of the French guns may have been drawn by oxen in that campaign.