Why did the Roman army base on infantry?

[Michael Kerr]

Mark Hygate wrote:

I am happy to believe that one of the main reasons the vast majority of the Greek & Roman armies, in the 400BC to 200AD period at least, were light on cavalry was also down to the relative scarcity of the availability of suitably sound and trained horses, let alone the additional logistics needed to sustain them.

I also think that racing at the Circus Maximus which was very popular would have competed with the military in acquiring horses. It was in the politicians' and later on the emperors' interests to keep racing going. They raced up to 135 days a year and there would have been a high turnover of horses.

Regards
Michael Kerr